C.11 LOOK UP TABLES and Presentation States

C.11.1 Modality LUT Module

Table C.11-1 specifies the Attributes that describe the Modality LUT.

Either a Modality LUT Sequence containing a single Item or Rescale Slope and Intercept values shall be present but not both.

Note: This requirement for only a single transformation makes it possible to unambiguously define the input of succeeding stages of the grayscale pipeline such as the VOI LUT.

Table C.11-1MODALITY LUT MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Include Modality LUT Macro Table C.11-1b

Table C.11-1bMODALITY LUT MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
Modality LUT Sequence (0028,3000) 1C Defines a sequence of Modality LUTs. Only a single Item shall be included in this sequence. Shall not be present if Rescale Intercept (0028,1052) is present.
>LUT Descriptor (0028,3002) 1C Specifies the format of the LUT Data in this Sequence. See C.11.1.1 for further explanation. Required if the Modality LUT Sequence (0028,3000) is sent.
>LUT Explanation (0028,3003) 3 Free form text explanation of the meaning of the LUT.
>Modality LUT Type (0028,3004) 1C Specifies the output values of this Modality LUT. See C.11.1.1.2 for further explanation. Required if the Modality LUT Sequence (0028,3000) is sent.
>LUT Data (0028,3006) 1C LUT Data in this Sequence. Required if the Modality LUT Sequence (0028,3000) is sent.
Rescale Intercept (0028,1052) 1C The value b in relationship between stored values (SV) and the output units specified in Rescale Type (0028,1054). Output units = m*SV + b. Required if Modality LUT Sequence (0028,3000) is not present. Shall not be present otherwise.
Rescale Slope (0028,1053) 1C m in the equation specified by Rescale Intercept (0028,1052). Required if Rescale Intercept is present.
Rescale Type (0028,1054) 1C Specifies the output units of Rescale Slope (0028,1053) and Rescale Intercept (0028,1052). See C.11.1.1.2 for further explanation. Required if Rescale Intercept is present.

C.11.1.1 LUT Attribute Descriptions

C.11.1.1.1 LUT descriptor

The three values of the LUT Descriptor (0028,3002) describe the format of the LUT Data in the corresponding Data Element (0028,3006).

The first value is the number of entries in the lookup table. When the number of table entries is equal to 216 then this value shall be 0.

The second value is the first stored pixel value mapped. The Value Representation of the second value (US or SS) is specified by Pixel Representation (0028,0103). This stored pixel value is mapped to the first entry in the LUT. All stored pixel values less than the first value mapped are also mapped to the first entry in the LUT Data. A stored pixel value one greater than the first value mapped is mapped to the second entry in the LUT Data. Subsequent stored pixel values are mapped to the subsequent entries in the LUT Data up to a stored pixel value equal to number of entries + first value mapped - 1 which is mapped to the last entry in the LUT Data. Stored pixel values greater than or equal to number of entries + first value mapped are also mapped to the last entry in the LUT Data.

The third value specifies the number of bits for each entry in the LUT Data. It shall take the value 8 or 16. The LUT Data shall be stored in a format equivalent to 8 bits allocated when the number of bits for each entry is 8, and 16 bits allocated when the number of bits for each entry is 16, where in both cases the high bit is equal to bits allocated - 1.

Note: Some implementations have encoded 8 bit entries with 16 bits allocated, padding the high bits; this can be detected by comparing the number of entries specified in the LUT Descriptor with the actual value length of the LUT Data entry. The value length in bytes should equal the number of entries if bits allocated is 8, and be twice as long if bits allocated is 16.

The third value also conveys the range of LUT entry values. It shall take the value 8 or 16, corresponding with the LUT entry value range of 256 or 65536.

Note: Since the LUT Descriptor (0028,3002) Attribute is multi-valued, in an Explicit VR Transfer Syntax, only one value representation (US or SS) may be specified, even though the first and third values are always by definition interpreted as unsigned. The explicit VR actually used is dictated by the VR needed to represent the second value, which will be consistent with Pixel Representation (0028,0103).

The LUT Data contains the LUT entry values.

The output range of the Modality LUT Module depends on whether or not Rescale Slope (0028,1053) and Rescale Intercept (0028,1052) or the Modality LUT Sequence (0028,3000) are used.

In the case where Rescale Slope and Rescale Intercept are used, the output ranges from (minimum pixel value*Rescale Slope+Rescale Intercept) to (maximum pixel value*Rescale Slope+Rescale Intercept), where the minimum and maximum pixel values are determined by Bits Stored and Pixel Representation.

Note: This range may be signed even if Pixel Representation is unsigned.

In the case where the Modality LUT Sequence is used, the output range is from 0 to 2 n -1 where n is the third value of LUT Descriptor. This range is always unsigned.

C.11.1.1.2 Modality LUT and Rescale Type

Specifies the units of the output of the Modality LUT or rescale operation.

Defined Terms:

OD = The number in the LUT represents thousands of optical density. That is, a value of 2140 represents an optical density of 2.140.

HU = Hounsfield Units (CT)

US = Unspecified

Other values are permitted, but are not defined by the DICOM Standard.

C.11.2 VOI LUT Module

Table C.11-2 specifies the Attributes that describe the VOI LUT.

Table C.11-2VOI LUT MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Include VOI LUT Macro Table C.11-2b

Table C.11-2bVOI LUT MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
VOI LUT Sequence (0028,3010) 1C Defines a sequence of VOI LUTs. One or more Items shall be included in this sequence. Required if Window Center (0028,1050) is not present. May be present otherwise.
>LUT Descriptor (0028,3002) 1 Specifies the format of the LUT Data in this Sequence. See C.11.2.1.1 for further explanation.
>LUT Explanation (0028,3003) 3 Free form text explanation of the meaning of the LUT.
>LUT Data (0028,3006) 1 LUT Data in this Sequence.
Window Center (0028,1050) 1C Window Center for display. See C.11.2.1.2 for further explanation. Required if VOI LUT Sequence (0028,3010) is not present. May be present otherwise.
Window Width (0028,1051) 1C Window Width for display. See C.11.2.1.2 for further explanation. Required if Window Center (0028,1050) is sent.
Window Center & Width Explanation (0028,1055) 3 Free form explanation of the meaning of the Window Center and Width. Multiple values correspond to multiple Window Center and Width values.
VOI LUT Function (0028,1056) 3 Describes a VOI LUT function to apply to the values of Window Center (0028,1050) and Window Width (0028,1051). See C.11.2.1.3 for further explanation. Defined terms: LINEAR SIGMOID When this attribute is not present, the interpretation of the values of Window Center (0028,1050) and Window Width (0028,1051) is linear as in C.11.2.1.2.

C.11.2.1 LUT Attribute Descriptions

C.11.2.1.1 LUT Descriptor

The three values of the LUT Descriptor (0028,3002) describe the format of the LUT Data in the corresponding Data Element (0028,3006).

The first value is the number of entries in the lookup table. When the number of table entries is equal to 216 then this value shall be 0.

The second value is the first input value mapped. The Value Representation of the second value (US or SS) depends on the source of the input to the VOI LUT, and shall be:

- the same as specified by Pixel Representation (0028,0103), if there is no Modality LUT or Rescale Slope and Intercept specified;

- SS if the possible output range after application of the Rescale Slope and Intercept may be signed;

Note: This is always the case for the CT Image IOD in which the Rescale Type is specified to be Hounsfield Units, which are always signed.

- US otherwise.

This input value is mapped to the first entry in the LUT. All input values less than the first value mapped are also mapped to the first entry in the LUT Data. An input value one greater than the first value mapped is mapped to the second entry in the LUT Data. Subsequent input values are mapped to the subsequent entries in the LUT Data up to an input value equal to number of entries + first value mapped - 1 which is mapped to the last entry in the LUT Data. Input values greater than or equal to number of entries + first value mapped are also mapped to the last entry in the LUT Data.

The third value specifies the number of bits for each entry in the LUT Data. If the VOI LUT is included in an Image IOD, the third value of LUT Descriptor (0028,3002) shall be 8 or 16 bits, unless otherwise specialized. If the VOI LUT is included in a Presentation State IOD, the third value of LUT Descriptor (0028,3002) shall be between 8 and 16 inclusive. The LUT Data shall be stored in a format equivalent to 8 bits allocated when the number of bits for each entry is 8, and 16 bits allocated when the number of bits for each entry is 16, where in both cases the high bit is equal to bits stored - 1, and where bits stored is the third value.

Notes: 1. Since the LUT Descriptor (0028,3002) Attribute is multi-valued, in an Explicit VR Transfer Syntax, only one value representation (US or SS) may be specified, even though the first and third values are always by definition interpreted as unsigned. The explicit VR actually used is dictated by the VR needed to represent the second value.

2. Some implementations have encoded 8 bit entries with 16 bits allocated, padding the high bits; this can be detected by comparing the number of entries specified in the LUT Descriptor with the actual value length of the LUT Data entry. The value length in bytes should equal the number of entries if bits allocated is 8, and be twice as long if bits allocated is 16.

The LUT Data contains the LUT entry values.

The output range is from 0 to 2 n -1 where n is the third value of LUT Descriptor. This range is always unsigned.

C.11.2.1.2 Window center and window width

Window Center (0028,1050) and Window Width (0028,1051) specify a linear conversion from stored pixel values (after any Modality LUT or Rescale Slope and Intercept specified in the IOD have been applied) to values to be displayed. Window Center contains the input value that is the center of the window. Window Width contains the width of the window.

Note: The terms “window center” and “window width” are not consistently used in practice, nor were they defined in previous versions of the standard. The definitions here are presented for the purpose of defining consistent meanings for identity and threshold transformations while preserving the common practice of using integral values for center and width.

Window Width (0028,1051) shall always be greater than or equal to 1.

When Window Width (0028,1051) is greater than 1, these Attributes select the range of input values that are to be mapped to the full range of the displayed output.

When Window Width (0028,1051) is equal to 1, they specify a threshold below which input values will be displayed as the minimum output value.

Note: Whether the minimum output value is rendered as black or white may depend on the value of Photometric Interpretation (0028,0004) or the presence of a Presentation LUT Module.

These Attributes are applied according to the following pseudo-code, where x is the input value, y is an output value with a range from y min to y max , c is Window Center (0028,1050) and w is Window Width (0028,1051):

if (x <= c - 0.5 - (w-1)/2), then y = y min

else if (x > c - 0.5 + (w-1)/2), then y = y max ,

else y = ((x - (c - 0.5)) / (w-1) + 0.5) * (y max - y min )+ y min

Notes: 1. For the purpose of this definition, a floating point calculation without integer truncation is assumed, though the manner of implementation may vary as long as the result is the same.

2. The pseudo-code function computes a continuous value over the output range without any discontinuity at the boundaries. The value of 0 for w is expressly forbidden, and the value of 1 for w does not cause division by zero, since the continuous segment of the function will never be reached for that case.

3. For example, for an output range 0 to 255:

c=2048, w=4096 becomes:

if (x <= 0) then y = 0

else if (x > 4095) then y = 255

else y = ((x - 2047.5) / 4095 + 0.5) * (255-0) + 0

c=2048, w=1 becomes:

if (x <= 2047.5) then y = 0

else if (x > 2047.5) then y = 255

else /* not reached */

c=0, w=100 becomes:

if (x <= -50) then y = 0

else if (x > 49) then y = 255

else y = ((x + 0.5) / 99 + 0.5) * (255-0) + 0

c=0, w=1 becomes:

if (x <= -0.5) then y = 0

else if (x > -0.5) then y = 255

else /* not reached */

4. A Window Center of 2 n-1 and a Window Width of 2 n selects the range of input values from 0 to 2 n -1. This represents an identity VOI LUT transformation in the case where no Modality LUT is specified and the stored pixel data are n bit unsigned integers.

5. A Window Width of 1 is typically used to represent a "threshold" operation in which those integer input values less than the Window Center are represented as the minimum displayed value and those greater than or equal to the Window Center are represented as the maximum displayed value. A Window Width of 2 will have the same result for integral input values.

6. The application of Window Center (0028,1050) and Window Width (0028,1051) may select a signed input range. There is no implication that this signed input range is clipped to zero.

7. The selected input range may exceed the actual range of the input values, thus effectively “compressing” the contrast range of the displayed data into a narrower band of the available contrast range, and “flattening” the appearance. There are no limits to the maximum value of the window width, or to the minimum or maximum value of window level, both of which may exceed the actual or possible range of input values.

8. Input values "below" the window are displayed as the minimum output value and input values "above" the window are displayed as the maximum output value. This is the common usage of the window operation in medical imaging. There is no provision for an alternative approach in which all values "outside" the window are displayed as the minimum output value.

9. The output of the Window Center/Width or VOI LUT transformation is either implicitly scaled to the full range of the display device if there is no succeeding transformation defined, or implicitly scaled to the full input range of the succeeding transformation step (such as the Presentation LUT), if present. See C.11.6.1.

10. Fractional values of Window Center and Window Width are permitted (since the VR of these Attributes is Decimal String), and though they are not often encountered, applications should be prepared to accept them.

These Attributes shall be used only for Images with Photometric Interpretation (0028,0004) values of MONOCHROME1 and MONOCHROME2. They have no meaning for other Images.

If multiple values are present, both Attributes shall have the same number of values and shall be considered as pairs. Multiple values indicate that multiple alternative views may be presented.

If any VOI LUT Table is included by an Image, a Window Width and Window Center or the VOI LUT Table, but not both, may be applied to the Image for display. Inclusion of both indicates that multiple alternative views may be presented.

If multiple items are present in VOI LUT Sequence (0028,3010), only one may be applied to the Image for display. Multiple items indicate that multiple alternative views may be presented.

If the VOI LUT Module is defined in an IOD and if neither a VOI LUT Sequence nor a Window Width and Window Center are present, then the VOI LUT stage of the grayscale pipeline is defined to be an identity transformation.

Notes: 1. This requirement is specified so that IODs that define a particular output space for the grayscale pipeline, such as P-Values, are not in an undefined state when no VOI LUT Sequence or Window Width and Window Center are present.

2. Despite the Type 3 requirement for VOI LUT Sequence and Window Center, implementations that render images are expected to implement and apply these transformations when they are present in the image, unless overridden by the user, a presentation state, or a hanging protocol, and to allow the user to select which transformation to apply when multiple transformations are present.

C.11.2.1.3 VOI LUT Function

The VOI LUT Function (0028,1056) specifies a potentially non-linear conversion for the output of the (conceptual) Modality LUT values to the input of the (conceptual) Presentation LUT.

The behavior for the value LINEAR is defined in C.11.2.1.2. For all other values, the VOI LUT Function (0028,1056) shall include a unique descriptor of the LUT function to be used. Each descriptor is associated with a bivariate function of Window Center (0028,1050) and Window Width (0028,1051).

If the VOI LUT Function (0028,1056) is present with a value other than LINEAR, the values provided in Window Center (0028,1050) and Window Width (0028,1051) shall not be interpreted as a linear conversion of the (conceptual) Modality LUT values to the input to the (conceptual) Presentation LUT - but as parameters for the function defined by the VOI LUT Function descriptor in (0028,1056).

When defined, each descriptor must provide the functional relationship between the output of the (conceptual) Modality LUT values to the input of the (conceptual) Presentation LUT.

C.11.2.1.3.1 SIGMOID descriptor

If the value of VOI LUT Function (0028,1056) is SIGMOID, the function to be used to convert the output of the (conceptual) Modality LUT values to the input of the (conceptual) Presentation LUT is given by

[pic] (1)

where

IN is the input value of the LUT (i.e., the output of the (conceptual) Modality LUT).

WC (resp. WW ) is the Window Center (resp. Window Width) defined interactively by the user or by using the values provided in (0028,1050) (resp. 0028,1051).

Output_range is the maximum output value (see Note below on encoding depth)

Note: The encoding depth of the input values for the VOI LUT function is given by the number of bits specified in Bits Stored (0028,0101). The output values of the VOI LUT function must be encoded with an appropriate depth to be then used as input for the Presentation LUT (typically this value is 8 bits) and the Output_range parameter allows this scaling. Moreover, Eq. 1 is given assuming float values for clarity but the actual implementation must include rounding to output integer values.

C.11.3 LUT Identification Module

This section has been retired. See PS 3.3 2006.

C.11.4 Presentation LUT Module

Table C.11-4 specifies the Attributes that describe the Presentation LUT.

Table C.11-4Presentation LUT Module

Attribute name Tag Description
Presentation LUT Sequence (2050,0010) Defines a sequence of Presentation LUTs. Only a single item shall be included in this sequence.
>LUT Descriptor (0028,3002) Specifies the format of the LUT Data in this Sequence. Required if Presentation LUT Sequence (2050,0010) is sent. See C.11.4.1 for further explanation.
>LUT Explanation (0028,3003) Free form text explanation of the meaning of the LUT.
>LUT Data (0028,3006) LUT Data in this Sequence.
Presentation LUT Shape (2050,0020) Specifies pre-defined Presentation LUT shapes. Enumerated Values : IDENTITY = input to the Presentation LUT is in P-Values, no further translation is necessary. LIN OD = input to Presentation LUT is in linear optical density over the range of Min Density (2010,0120) and Max Density (2010,1030). Note: LIN OD is only defined for hardcopy devices and is not applicable to softcopy devices.

C.11.4.1 LUT Descriptor

The three values of the LUT Descriptor (0028,3002) describe the format of the data in LUT Data (0028,3006).

The first value is the number of entries in the lookup table. When the number of table entries is equal to 216 then this value shall be 0. The number of entries shall be equal to the number of possible values in the input. (For 8 bit input will be 256 entries, for 12 bit input it will be 4096 entries)

The second value is the first input value mapped, and shall always be 0. The Value Representation of the second value is always US. This input value is mapped to the first entry in the LUT. Subsequent input values are mapped to the subsequent entries in the LUT Data up to an input value equal to number of entries + first value mapped - 1 which is mapped to the last entry in the LUT Data. There are no input values greater than number of entries - 1.

The third value specifies the number of bits for each entry in the LUT Data. It shall be between 10 and 16 inclusive. The LUT Data shall be stored in a format equivalent to 16 bits allocated where the high bit is equal to bits stored - 1, where bits stored is the third value.

Note: Since the LUT Descriptor (0028,3002) Attribute is multi-valued, in an Explicit VR Transfer Syntax, only one value representation (US or SS) may be specified. Since all three values are always by definition interpreted as unsigned, the explicit VR actually used will always be US.

LUT Data (0028,3006) contains the LUT entry values, which are P-Values.

The output range is from 0 to 2 n -1 where n is the third value of LUT Descriptor. This range is always unsigned.

This range specifies the output range of the P-Values.

C.11.5 Image Histogram Module

Table C.11.5-1IMAGE HISTOGRAM MODULE ATTRIBUTES

Attribute name Tag Type Description
Histogram Sequence (0060,3000) 1 Defines a sequence of Histograms. One or more Items shall be included in this Sequence.
>Histogram Number of Bins (0060,3002) 1 The number of “bins” (entries) in the histogram.
>Histogram First Bin Value (0060,3004) 1 The stored pixel value corresponding to the lowest pixel value counted in the first bin. All image pixel values less than this value are not included in the histogram. Note: The Value Representation of this Attribute is determined by the value of Pixel Representation (0028,0103).
>Histogram Last Bin Value (0060,3006) 1 The stored pixel value corresponding to the highest pixel value counted in the last bin. All image pixel values greater than this value are not included in the histogram. Note: The Value Representation of this Attribute is determined by the value of Pixel Representation (0028,0103).
>Histogram Bin Width (0060,3008) 1 The number of consecutive stored pixel values included in a bin. All bins shall be of equal width.
>Histogram Explanation (0060,3010) 3 Free form text explanation of the meaning of the LUT.
>Histogram Data (0060,3020) 1 Histogram Data encoded as 32 bit unsigned counts of the number of pixel values in each bin.

C.11.5.1 Image Histogram Attribute Descriptions

The Image Histogram is a multi-valued sequence representing a sequential count of binned stored image pixel values in ascending order.

Note: One reason to include a histogram with an image is as an aid to image processing applications. For applications that use them, computations of histograms for very large images can be a significant burden on computer resources and can seriously degrade the response time to the user.

The Image Histogram is multi-valued to support multiple histograms per image. One or more regions of interest or value ranges may be separately computed. A description of the region(s) of interest and value range may be included in the Histogram Explanation (0060,3010). The Image Histogram may be related to parts or all of a specific image.

The Attributes describing the parameters of the histogram are in image pixel value space, as stored in Pixel Data (7FE0,0010), before the application of any transformation such as Rescale Slope and Intercept or Modality LUT.

The range of stored image pixel value instances is described by the Histogram First Bin Value (0060,3004) and Histogram Last Bin Value (0060,3006). All values outside of this range shall be ignored. The number of histogram bins shall be large enough to contain all of the pixels in the range from the smallest to the largest stored image pixel value in that region of the image from which the histogram has been derived (which may or may not be the whole image).

The Histogram Bin Width (0060,3008) describes how many consecutive stored image pixel values are counted as one. All bins shall be of equal width.

Note: For example, a Histogram Bin Width (0060,3008) of 8 means that counts of pixel values in ascending groups of 8 are added together. If Histogram First Bin Value (0060,3004) were 0, then the first bin would contain the count of pixel values in the range of 0-7, the second bin the count of pixel values in the range of 8-15, etc. If Histogram Number of Bins (0060,3002) were 32, then the last bin would contain the count of pixel values in the range of 248-255 and Histogram Last Bin Value (0060,3006) would be 255 (not 248).

This example is illustrated in the following figure, in which the vertical axis represents the count within each bin and the horizontal axis represents each bin in ascending order.

[pic]

C.11.6 Softcopy Presentation LUT Module

Table C.11.6-1 specifies the Attributes that describe the Softcopy Presentation LUT.

Table C.11.6-1SOFTCOPY PRESENTATION LUT MODULE ATTRIBUTES

Attribute name Tag Type Description
Presentation LUT Sequence (2050,0010) 1C Defines a sequence of Presentation LUTs. Only a single item shall be included in this sequence. Required if Presentation LUT Shape (2050,0020) is absent.
>LUT Descriptor (0028,3002) 1 Specifies the format of the LUT Data in this Sequence. See C.11.6.1.1 for further explanation.
>LUT Explanation (0028,3003) 3 Free form text explanation of the meaning of the LUT.
>LUT Data (0028,3006) 1 LUT Data in this Sequence.
Presentation LUT Shape (2050,0020) 1C Specifies predefined Presentation LUT transformation. Required if Presentation LUT Sequence (2050,0010) is absent. Enumerated Values: IDENTITY - no further translation necessary, input values are P-Values INVERSE - output values after inversion are P-Values See C.11.6.1.2.

Note: This Module differs from the Presentation LUT Module used in the hardcopy (print) related SOP Classes in that Optical Density is not supported for Presentation LUT Shape (since Optical Density has no meaning for softcopy display devices).

C.11.6.1 Softcopy Presentation LUT Attributes

When the Presentation LUT is specified as a Presentation LUT Sequence, then the input range of values is specified by the LUT Descriptor as the first value mapped and the number of entries (values mapped). However, there is an implicit linear scaling of the output range of the preceding transformation (such as the VOI LUT transformation) so that it is always mapped to the specified input range of the Presentation LUT.

When the Presentation LUT is specified as Presentation LUT Shape, then the input range is implicitly specified to be the output range of the preceding transformation (VOI LUT, or if the VOI LUT is identity or absent, the Modality LUT, or if the Modality LUT and VOI LUT are identity or absent, the stored pixel values). In this case, the full range of the output of the preceding transformation will be mapped to the full input range of the display device that receives the output of the Presentation LUT.

Note: The output of the preceding transformation may be signed. This does not mean that signed P-Values actually need to be generated, only that the output of the preceding transformation is to be interpreted by the display device as perceptually linear over the range from the minimum to the maximum values output by the preceding step, and that the minimum value be mapped to the lowest JND Index (and hence luminance) that the display can generate, and the maximum value be mapped to the highest JND Index (and hence luminance) that the display can generate.

In other words, in both cases, the Presentation LUT Module is always implicitly specified to apply over the full range of output of the preceding transformation, and it never selects a subset or superset of the that range (unlike the VOI LUT).

The output bit precision of the VOI LUT Sequence is not required to match the input range of the Presentation LUT Sequence.

Notes: 1. For example, if the VOI LUT is specified as a Window Center of 0 and a Window Width of 100, then the range from -50 to +49 is selected to be mapped to the full range of the display or print device (the full range of P-Values) if the Presentation LUT Shape is specified as IDENTITY or INVERSE. This example demonstrates the conventional understanding of the meaning of Window Center and Width to select “values of interest” that are to be displayed across the full range of the output device, without explicitly having to map each choice to P-Values.

2. For example, if the VOI LUT is specified as a Window Center of 0 and a Window Width of 100, and the Presentation LUT Sequence is sent with a LUT Descriptor first value of 256 and second value of 0, then the range from -50 to +49 is implicitly linearly scaled from 0 to 255 before selecting values from the LUT Data in the Presentation LUT Sequence. This example demonstrates that it is not necessary to send a different Presentation LUT for different Window Center and Width values.

3. For example, if the VOI LUT is specified as VOI LUT Sequence with a LUT Descriptor with a 3rd Value of 16, then the range from 0 to 2 16 -1 is selected to be mapped to the full range of the display or print device (the full range of P-Values) if the Presentation LUT Shape is specified as IDENTITY or INVERSE. This example demonstrates that a VOI LUT may be specified with the desired precision, without having to explicitly send a Presentation LUT to rescale that precision to whatever range of P-Values is preferred by the display application.

4. For example, if the VOI LUT is specified as VOI LUT Sequence with a LUT Descriptor with a 3rd Value of 16, and the Presentation LUT Sequence is sent with a LUT Descriptor first value of 4096 and second value of 0, then the range from 0 to 2 16 -1 is implicitly linearly scaled to the range 0 to 4095 before selecting values from the LUT Data in the Presentation LUT Sequence. This example demonstrates the case where, to save space, the Presentation LUT is sent in a compact form that a display application may choose to interpolate more precisely, yet the VOI LUT output may be sent with 16 bit precision.

C.11.6.1.1 LUT Descriptor

The three values of the LUT Descriptor (0028,3002) describe the format of the LUT Data in the corresponding Data Element (0028,3006).

The first value is the number of entries in the lookup table. When the number of table entries is equal to 216 then this value shall be 0.

The second value is the first implicitly scaled input value mapped, and shall always be 0. The Value Representation of the second value is always US. This implicitly scaled input value is mapped to the first entry in the LUT. There are no implicitly scaled input values less than the first value mapped. An implicitly scaled input value one greater than the first value mapped is mapped to the second entry in the LUT Data. Subsequent implicitly scaled input values are mapped to the subsequent entries in the LUT Data up to an implicitly scaled input value equal to number of entries + first value mapped - 1 which is mapped to the last entry in the LUT Data. There are no implicitly scaled input values greater than number of entries + first value mapped.

The third value specifies the number of bits for each entry in the LUT Data. The third value of the LUT Descriptor (0028,3002) shall be between 8 and 16 inclusive. The LUT Data shall be stored in a format equivalent to 8 bits allocated when the number of bits for each entry is 8, and 16 bits allocated when the number of bits for each entry is 16, where the high bit is equal to bits stored - 1, and where bits stored is the third value.

Notes: 1. Since the LUT Descriptor (0028,3002) Attribute is multi-valued, in an Explicit VR Transfer Syntax, only one value representation (US or SS) may be specified. Since all three values are always by definition interpreted as unsigned, the explicit VR actually used will always be US.

2. Some implementations have encoded 8 bit entries with 16 bits allocated, padding the high bits; this can be detected by comparing the number of entries specified in the LUT Descriptor with the actual value length of the LUT Data entry. The value length in bytes should equal the number of entries if bits allocated is 8, and be twice as long if bits allocated is 16.

The LUT Data contains the LUT entry values, which are P-Values.

The output range is from 0 to 2 n -1 where n is the third value of LUT Descriptor. This range is always unsigned.

This range specifies the output range of the P-Values.

C.11.6.1.2 Presentation LUT Shape

A value of INVERSE shall mean the same as a value of IDENTITY, except that the minimum output value shall convey the meaning of the maximum available luminance, and the maximum value shall convey the minimum available luminance. In other words:

P-Value = maximum value - output value

C.11.7 Overlay Activation Module

This Module defines a manner of controlling whether or not bit-mapped overlay and curve information are displayed.

If the corresponding Overlay Group activated is present within the Presentation State, then that Overlay shall be activated and any corresponding Overlay in the referenced image(s) ignored, otherwise the Overlay within the referenced image(s) shall be activated.

An Overlay Group referenced in the Bitmap Display Shutter Module described in C.7.6.15 shall not be activated using the Overlay Activation Module.

Table C.11.7-1 specifies the Attributes that describe the Overlay Activation Module.

Table C.11.7-1OVERLAY ACTIVATION MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Overlay Activation Layer (60xx,1001) 2C The layer (defined in Graphic Layer (0070,0002) of the Graphic Layer Module C.10.7) in which the Overlay described in group 60xx shall be displayed. If no layer is specified (zero length) then the overlay shall not be displayed. Required if Group 60xx is present in the referenced image(s) or the Presentation State instance containing this Module.

Notes: 1. Previously, those bits that are stored in Pixel data (7FE0,0010) above High Bit(0028,0102) could be used as overlay bit planes if they were referenced by an Overlay Bit Position (60xx,0102). This usage has been retired. See PS 3.3 2004. Their contents are unspecified in DICOM and should not be displayed. Usually they will be zero, though if the pixel data is signed, i.e. Pixel Representation (0028,0103) is 0001H, then it is possible that the sign bit may be “extended” through these values. Alternatively, they may have been “masked off” even if the value is signed and negative.

2. Previously, Curve Activation Layer (50xx,1001) was defined in this Module. Its usage has been retired. See PS 3.3 2004.

C.11.8 Softcopy VOI LUT module

Table C.11.8-1 specifies the Attributes that describe the Softcopy VOI LUT. These Attributes have the same meaning and behavior as defined in the VOI LUT Module Section C.11.2.

Table C.11.8-1SOFTCOPY VOI LUT MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Softcopy VOI LUT Sequence (0028,3110) 1 Defines a sequence of VOI LUTs or Window Centers and Widths and to which images and frames they apply. No more than one VOI LUT Sequence containing a single Item or one pair of Window Center/Width values shall be specified for each image or frame. One or more Items shall be included in this sequence.
>Referenced Image Sequence (0008,1140) 1C The subset of images and frames listed in the Presentation State Relationship Module, to which this VOI LUT or Window Center and Width applies. One or more Items shall be included in this sequence. Required if the VOI LUT transformation in this Item does not apply to all the images and frames listed in the Presentation State Relationship Module.
>>Include Image SOP Instance Reference Macro Table 10-3
>Include VOI LUT Macro Table C.11-2b

C.11.9 Presentation Series Module

Table C.11.9-1 contains Attributes that identify and describe a Presentation Series.

Table C.11.9-1PRESENTATION SERIES MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Modality (0008,0060) 1 Type of equipment that originally acquired the data. Enumerated Value: PR = Presentation State See C.7.3.1.1.1.

Note: This implies that presentation states will be in different series from the images to which they apply, which will have different values for Modality.

C.11.10 Presentation State Identification Module

Table C.11.10-1 contains Attributes that identify a Presentation State.

Table C.11.10-1PRESENTATION STATE IDENTIFICATION MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Presentation Creation Date (0070,0082) 1 Date on which this presentation was created. Note: This date may be different from the date that the DICOM SOP Instance was created, since the presentation state information contained may have been recorded earlier.
Presentation Creation Time (0070,0083) 1 Time at which this presentation was created. Note: This time may be different from the time that the DICOM SOP Instance was created, since the presentation state information contained may have been recorded earlier.
Include Content Identification Macro Table 10-12 Note: The Content Label value may be used by an application as a Defined Term in order to imply some grouping of different presentation states, i.e. it may have the same value for different presentation state instances that share some common concept.

C.11.11 Presentation State Relationship Module

Table C.11.11-1 contains Attributes that describe the images to which a Presentation State applies.

Table C.11.11-1PRESENTATION STATE RELATIONSHIP MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Include Presentation State Relationship Macro Table C.11.11-1b

Table C.11.11-1bPRESENTATION STATE RELATIONSHIP MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
Referenced Series Sequence (0008,1115) 1 Sequence of Items where each Item includes the Attributes of one Series to which the Presentation applies. One or more Items shall be included in this sequence.
>Series Instance UID (0020,000E) 1 Unique identifier of a Series that is part of the Study defined by the Study Instance UID (0020,000D) in the enclosing dataset. Note: The Study Instance UID (0020,000D) will be that of the presentation state itself, unless the macro is invoked from the Blending Sequence (0070,0402) in the Presentation State Blending Module, in which case it will be explicitly specified.
>Referenced Image Sequence (0008,1140) 1 The set of images and frames to which the Presentation applies. These shall be of the Study defined by Study Instance UID (0020,000D) and the Series defined by Series Instance UID (0020,000E). One or more Items shall be included in this sequence. The referenced SOP Class shall be the same for all Images in any Item of this Referenced Series Sequence (0008,1115).
>>Include Image SOP Instance Reference Macro, Table 10-3

C.11.12 Presentation State Shutter Module

Table C.11.12-1 contains Attributes that specialize Attributes in other Modules included in a Presentation State.

Table C.11.12-1PRESENTATION STATE SHUTTER MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Shutter Presentation Value (0018,1622) 1C A single grayscale unsigned value used to replace those parts of the image occluded by the shutter, when rendered on a monochrome display. The units are specified in P-Values. Required if the Display Shutter Module or Bitmap Display Shutter Module is present. Note: The requirement in this module is type 1C which overrides the type 3 in the Display Shutter Module.
Shutter Presentation Color CIELab Value (0018,1624) 1C A color triplet value used to replace those parts of the image occluded by the shutter, when rendered on a color display. The units are specified in PCS-Values, and the value is encoded as CIELab. See C.10.7.1.1. Required if the Display Shutter Module or Bitmap Display Shutter Module is present and the SOP Class is other than Grayscale Softcopy Presentation State Storage. Note: The requirement in this module is type 1C, which overrides the type 3 in the Display Shutter and Bitmap Display Shutter Modules.

C.11.13 Presentation State Mask Module

Table C.11.13-1 contains Attributes that specialize the use of masks in a Presentation State.

Table C.11.13-1PRESENTATION STATE MASK MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Mask Subtraction Sequence (0028,6100) 1C Required if Mask Module is present. Only a single Item shall be included in this sequence. Applicable Frame Range (0028,6102) shall not be included in the Sequence Item. See C.7.6.10 for a complete definition of the Attributes in the Items of this Sequence other than Mask Operation(0028,6101) and Applicable Frame Range (0028,6102). Notes: 1. This Sequence is replicated here in order to specify one Item, additional conditions on Mask Operation (0028,6101) and to forbid Applicable Frame Range (0028,6102). 2. The role of Applicable Frame Range (0028,6102) is replaced by Referenced Frame Number (0008,1160).
>Mask Operation (0028,6101) 1 Type of mask operation to be performed Enumerated Values: AVG_SUB TID See C.7.6.10.1 for further explanation. Note: The requirement in this module is for Enumerated Values which override the requirements of the Mask Module.
>Contrast Frame Averaging (0028,6112) 1C Specified the number of contrast frames to average together before performing the mask operation. Required if Mask Frame Numbers (0028,6110) specifies more than one frame (i.e. is multi-valued). Note: The requirement in this module is conditional and overrides the optional requirements of the Mask Module.
Recommended Viewing Mode (0028,1090) 1C Specifies the recommended viewing protocol(s). Enumerated Value: SUB = for subtraction with mask images Required if Mask Subtraction Sequence (0028,6100) is present. Note: The requirement in this module is type 1C and an Enumerated Value is specified which override the requirements of the Mask Module.

C.11.14 Presentation State Blending Module

Table C.11.14-1 contains Attributes that describe the identification of two sets of grayscale images and the grayscale transformations to be applied to them, for the purpose of blending.

Table C.11.14-1PRESENTATION STATE BLENDING MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Blending Sequence (0070,0402) 1 A Sequence of Items, one identifying and describing transformations upon a set of underlying grayscale images, and the other identifying and describing transformations upon a set of superimposed grayscale images. Two Items shall be included in this sequence See C.11.14.1.1.
>Blending Position (0070,0405) 1 Whether or not the contents of the Item represent the superimposed or underlying image set. Enumerated Values: SUPERIMPOSED UNDERLYING
>Study Instance UID (0020,000D) 1 Unique identifier for the Study that contains the images, which may differ from the Study in which the presentation state is contained.
>Include Presentation State Relationship Macro Table C.11.11-1b
>Include Modality LUT Macro Table C.11-1b 1b if a Modality LUT is to be applied to referenced image(s)
>Softcopy VOI LUT Sequence (0028,3110) 1C Defines a sequence of VOI LUTs or Window Centers and Widths and to which images and frames they apply. No more than one VOI LUT Sequence containing a single Item or one pair of Window Center/Width values shall be specified for each image or frame. One or more Items shall be included in this sequence. Required if a VOI LUT is to be applied to referenced image(s).
>>Referenced Image Sequence (0008,1140) 1C Sequence of Items identifying images that are defined in the enclosing Item of the Blending Sequence (0070,0402), to which this VOI LUT or Window Center and Width applies. One or more Items shall be included in this sequence. Required if the VOI LUT transformation in this Item does not apply to all the images and frames in the enclosing Item of the Blending Sequence (0070,0402).
>>>Include Image SOP Instance Reference Macro Table 10-3
>>Include VOI LUT Macro Table C.11-2b
Relative Opacity (0070,0403) 1 A value from 0.0 to 1.0 indicating the relative opacity of the pixels of the superimposed image, where 1.0 means that pixels of the superimposed image completely replace the pixels of the underlying image, and 0.0 means that the pixels of the underlying image completely replace the pixels of the superimposed image. See PS 3.4 for a detailed description of the blending operation.
Referenced Spatial Registration Sequence (0070,0404) 3 A reference to Spatial Registration Instances that may be used to register the underlying and superimposed images. One or more Items are permitted in this sequence. Note: A Spatial Registration Instance may identify registration between frames of reference, or between explicitly identified images. In the latter case, the list of images referenced by the Presentation State, not the list of images referenced by the Spatial Registration Instance, are to be blended.
>Include ‘Hierarchical SOP Instance Reference Macro’ Table C.17-3

C.11.14.1 Presentation State Blending Module Attributes

C.11.14.1.1 Blending Sequence

The Blending Sequence (0070,0402) Attribute is used to identify two sets of images, one to be superimposed upon the other.

The sets of images and any subset of the frames therein in the case of multi-frame images are identified by Study, Series, SOP Instance and Frame Number. In the case of a Segmentation image, the subset of segments is identified by the attribute Referenced Segment Number (0062,000B) in the Referenced Image Sequence (0008,1140) invoked in the Presentation State Relationship Macro.

This module specifies no explicit relationship (such as pairing or ordering) between the sets of images and frames defined in the first item for the underlying images, and the second item for the superimposed images. This module does not define how the images are spatially related, and what re-sampling, if any, needs to be performed before the images are blended for rendering.

Notes: 1. The images in the two sets may share the same Frame of Reference, in which case the rendering application can spatially relate the two sets of images based on their Image Position (Patient) (0020,0032) and Image Orientation (Patient) (0020,0037) Attributes.

Alternatively, a Spatial Registration SOP Instance may exist that relates either two different Frames of Reference, or two sets of images identified by UID and frame.

Whilst the two sets of images may already be spatially co-registered and oriented in the same plane, or even be sampled at the same in-plane and between-plane resolution, this will frequently not be the case.

See PS 3.4 for behavioral requirements that apply to Storage SOP Classes using this Module.

2. The underlying image for a superimposed Segmentation image need not be the source image for the segmentation.

C.11.15 ICC Profile Module

Table C.11.15-1 contains Attributes that identify and describe an ICC Profile.

Table C.11.15-1ICC PROFILE MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
ICC Profile (0028,2000) 1 An ICC Profile encoding the transformation of device-dependent color stored pixel values into PCS-Values.

C.11.15.1 Attribute descriptions

C.11.15.1.1 ICC Profile

The ICC Profile (0028,2000) Attribute encodes an ICC Input Device Profile that encodes the transformation of device-dependent color stored pixel values into PCS-Values.

Notes: 1. Only Input Device profiles are encoded, since display and output device profiles are not interchanged in DICOM, though they may be used internally within display and output devices, for example when they are calibrated.

2. Since the version of the ICC Profile is encoded within the profile itself, no additional version information is encoded in the ICC Profile Module.

The following constraints on the encoding of the ICC Profile shall be observed:

Notes: 1. In the case of a PCS of CIELab, the profile will contain an N-component LUT-based AtoB0Tag, since three-component matrix based transformations are only possible with a PCS of CIEXYZ. A three-component matrix based transformation might be used to define a well-known rather than device-specific profile for such spaces as sRGB.

2. Selection of a PCS of CIELab or CIEXYZ within the ICC profile does not impact the DICOM encoding, since all color management systems support both.

The following constraints on the encoding of the ICC Profile are recommended:

Notes: 1. The rendering intent specifies how rendering will take place when the ICC Input Profile is linked with another Profile for the purpose of display.

2. A perceptual rendering intent implies that AtoB0Tag and BtoA0Tag tags will be present in the profile. The AtoB0Tag allows mapping from the input values to the PCS. The BtoA0Tag allows mapping from the PCS to the input values, though this is not required for the color rendering pipeline defined in PS 3.4.

Note: See the discussion of white point in PS 3.4.

C.11.16 Structured Display Module

Table C.11.16-1 describes the attributes of the Structured Display Module.

Table C.11.16-1

Structured Display Module Attributes

Attribute Name Tag Type Attribute Description
Include Content Identification Macro Table 10-12
Number of Screens (0072,0100) 1 The number of screens for this Structured Display. If SOP Class UID (0008,0016) equals 1.2.840.10008.5.1.4.1.1.131 (Basic Structured Display), the value shall be 1.
Nominal Screen Definition Sequence (0072,0102) 1 Sequence of items that describes the set of screens for this Structured Display. The number of items shall equal the value of the Number of Screens (0072,0100) attribute. One or more Items shall be included in this sequence. Note: The Basic Structured Display IOD limits this Sequence to one Item.
>Include Screen Specifications Macro Table C.23.2-2
Icon Image Sequence (0088,0200) 3 This icon image is representative of the structured display. Only a single item is permitted in this sequence.
>Include ‘Image Pixel Macro’ Table C.7-11b See C.7.6.1.1.6 for further explanation.
Structured Display Background CIELab Value (0072,0420) 3 A value in which it is recommended that Structured Display background (i.e., the area outside of Image Boxes) be rendered on a color display. The units are specified in PCS-Values, and the value is encoded as CIELab. See C.10.7.1.1.
Empty Image Box CIELab Value (0072,0421) 3 A value in which it is recommended that empty Image Boxes be rendered on a color display. The units are specified in PCS-Values, and the value is encoded as CIELab. See C.10.7.1.1.

C.11.17 Structured Display Image Box Module

Table C.11.17-1 describes the attributes of the Structured Display Image Box Module.

Table C.11.17 -1 Structured Display Image Box Attributes

Attribute Name Tag Type Attribute Description
Structured Display Image Box Sequence (0072,0422) 1 The image display boxes defined in the display environment, together with the reference to the image to be displayed in each Image Box. One or more Items shall be included in this sequence.
>Display Environment Spatial Position (0072,0108) 1 Exactly four dimensionless floating point values, in the range 0.0 to 1.0, indicating the rectangular coordinate position of the Image Box within the Display Environment. Note: For the Basic Structured Display with a single screen, the Display Environment is coextensive with the screen defined in the Nominal Screen Definition Sequence (0072,0102). See Section C.11.17.1.1
>Image Box Number (0072,0302) 1 An integer that is unique across all Items of the Structured Display Image Box Sequence (0072,0422) that identifies the Image Box.
>Image Box Layout Type (0072,0304) 1 Type of layout of the Image Box. The types are primarily distinguished by their interaction technique. Defined Terms: STACK: a single rectangle containing a steppable single frame, intended for user-controlled stepping through the image set, usually via continuous device interaction (e.g., mouse scrolling) or by single stepping (mouse or button click). CINE: a single rectangle, intended for video type play back where the user controls are play sequence, rate of play, and direction. SINGLE: a single rectangle, intended for images and objects with no defined methods of interaction. Note: This value may also be used for non-image objects, such as waveforms and SR documents.
>Image Box Overlap Priority (0072,0320) 3 If this Image Box overlaps in spatial position with others, this attribute indicates the layer of this Image Box in relation to the others. The value shall be a positive integer in the range 1 to 100, where 1 = top and 100 = bottom. If this attribute is not present, then the expected behavior is not defined.
>Display Set Horizontal Justification (0072,0717) 3 Indicates direction in which to horizontally justify the image within an Image Box that is not the same shape (aspect ratio) as the image. Enumerated Values: LEFT CENTER RIGHT Note: Typically used in mammography display applications in which images from the patient’s left and right are displayed “back to back”, rather than centered.
>Display Set Vertical Justification (0072,0718) 3 Indicates direction in which to vertically justify the image within an Image Box that is not the same shape (aspect ratio) as the image. Enumerated Values: TOP CENTER BOTTOM
>Preferred Playback Sequencing (0018,1244) 1C Describes the preferred playback sequencing for the Image Box. Overrides any Preferred Playback Sequencing (0018,1244) value in the image objects being displayed. Required if the value of Image Box Layout Type (0072,0304) is CINE. Enumerated Values: 0 = Looping (1,2…n,1,2,…n,1,2,….n,…) 1 = Sweeping (1,2,…n,n-1,…2,1,2,…n,…) 2 = Stop (1,2…n)
>Recommended Display Frame Rate (0008,2144) 1C Recommended rate at which the frames of a multi-frame image shall be displayed, in frames/second. Shall have a value greater than zero. Overrides any Recommended Display Frame Rate (0008,2144) value in the image objects being displayed. Required if the value of Image Box Layout Type (0072,0304) is CINE and if Cine Relative to Real-Time (0072,0330) is not present.
>Cine Relative to Real-Time (0072,0330) 1C A positive dimensionless floating point numeric factor equal to playback rate divided by acquisition rate. Required if the value of Image Box Layout Type (0072,0304) is CINE and if Recommended Display Frame Rate (0008,2144) is not present. Note: The acquisition rate may change within the image object, as specified in Frame Time Vector (0018,1065).
>Initial Cine Run State (0018,0042) 1C Defined Terms: STOPPED RUNNING Required if the value of Image Box Layout Type (0072,0304) is CINE.
>Start Trim (0008,2142) 2C The frame number of the first frame of the multi-frame image to be displayed in a CINE Image Box. Required if the value of Image Box Layout Type (0072,0304) is CINE.
>Stop Trim (0008,2143) 2C The Frame Number of the last frame of the multi-frame image to be displayed in a CINE Image Box. Required if the value of Image Box Layout Type (0072,0304) is CINE.
>Referenced First Frame Sequence (0072,0427) 2C Reference to the initial frame in a stack to be displayed in this image box. If value is not present, the first image frame to be displayed is not defined by the Standard. Zero or one Item shall be included in this sequence. Required if the value of Image Box Layout Type (0072,0304) is STACK.
>>Include ‘Image SOP Instance Reference Macro’ Table 10-3
>Referenced Image Sequence (0008,1140) 2C Reference to the Image SOP Instances, or frames from multi-frame Image SOP Instances, to be displayed in this Image Box. Zero or more Items shall be included in this sequence. Required if Referenced Presentation State Sequence (0008,9237), Referenced Stereometric Instance Sequence (0008,1134), and Referenced Instance Sequence (0008,114A) are not present. See C.11.17.1.2.
>>Include ‘Image SOP Instance Reference Macro’ Table 10-3 Note: The order of frames identified in the Referenced Frame Number (0008,1160) attribute affects ordering in STACK Image Box Layout. See C.11.17.1.2.
>>Referenced Presentation State Sequence (0008,9237) 1C Reference to a Softcopy Presentation State SOP Instance to be applied to the referenced image. Only a single Item shall be included in this sequence. Required if presentation controls are to be applied to the image or image frame before rendering in the Structured Display.
>>>Include ‘SOP Instance Reference Macro’ Table 10-11
>Referenced Presentation State Sequence (0008,9237) 1C Reference to a Softcopy Presentation State SOP Instance whose referenced images are to be displayed in the Image Box using the presentation controls of the referenced SOP Instance. Only a single Item shall be included in this sequence. Required if Referenced Image Sequence (0008,1140), Referenced Stereometric Instance Sequence (0008,1134), and Referenced Instance Sequence (0008,114A) are not present. See C.11.17.1.2.
>>Include ‘SOP Instance Reference Macro’ Table 10-11
>Referenced Instance Sequence (0008,114A) 1C Reference to a non-image SOP Instance (e.g., waveform, SR, encapsulated document) whose content is to be displayed in the Image Box. Only a single Item shall be included in this sequence. Required if Referenced Presentation State Sequence (0008,9237), Referenced Stereometric Instance Sequence (0008,1134), and Referenced Image Sequence (0008,1140) are not present. See C.11.17.1.3.
>>Include ‘SOP Instance Reference Macro’ Table 10-11
>Referenced Stereometric Instance Sequence (0008,1134) 1C Reference to a Stereometric SOP Instance whose referenced images are to be displayed in the Image Box. Only a single Item shall be included in this sequence. Required if Referenced Presentation State Sequence (0008,9237), Referenced Instance Sequence (0008,114A), and Referenced Image Sequence (0008,1140) are not present. See C.11.17.1.4.
>>Include ‘SOP Instance Reference Macro’ Table 10-11
Image Box Synchronization Sequence (0072,0430) 1C Description of synchronized display between two or more Image Boxes. Required if synchronized display is specified between Image Boxes. One or more Items shall be included in this sequence.
>Synchronized Image Box List (0072,0432) 1 Multi-valued list of two or more Image Box Number (0072,0302) values. Indicates that the display of multiple image frames within the specified Image Boxes are synchronized. Referenced Image Boxes shall be of same Image Box Layout Type (0072,0304). An Image Box Number value may appear in only one Image Box Synchronization Sequence (0072,0430) item.
>Type of Synchronization (0072,0434) 1 Type of synchronization between Image Boxes. Defined Terms: FRAME POSITION TIME PHASE See C.11.17.1.5.

C.11.17.1 Structured Display Image Box Attribute Descriptions

C.11.17.1.1 Display Environment Spatial Position

The Display Environment Spatial Position (0072,0108) specifies the corners of the Image Box relative to the vertical and horizontal dimensions of the Display Environment, specified as Number of Vertical Pixels (0072,0104) and Number of Horizontal Pixels (0072,0106) in the Nominal Screen Definition Sequence (0072,0102).

See also Section C.23.2.1.1.

Within the Image Box, the image (or the area of the image selected for display by the associated Presentation State SOP Instance) shall be scaled to fit the display area under the constraint that the aspect ratio of the image is maintained.

In rendering the Image Box, the Application Entity may render display controls (such as cine speed control, or stack position indication) either within or outside the specified Display Environment Spatial Position (0072,0108).

C.11.17.1.2 Referenced Image Sequence and Referenced Presentation State Sequence

Image SOP Instances, or frames from multi-frame SOP Instances, to be displayed in an Image Box may be identified either directly by the Referenced Image Sequence (0008,1140), or indirectly through the Referenced Presentation State Sequence (0008,9237).

Referenced Image Sequence (0008,1140) is permitted to be zero length, indicating an empty Image Box.

Note: 1. The recommended display color for an empty Image Box is specified by Empty Image Box CIELab Value (0072,0421).

2. When displaying a standard template such as a dental full mouth series, an empty image box may be used to indicate that the corresponding view was not taken.

If images are identified indirectly through the Referenced Presentation State Sequence (0008,9237), all of the image frames identified in the top level Referenced Series Sequence (0008,1115) attribute shall be displayed. For images identified indirectly through a Blending Presentation State SOP Instance, all the image frames for which the Blending Position (0070,0405) value is UNDERLYING shall be displayed, with the relevant SUPERIMPOSED images blended as necessary.

If images are to be displayed, the number of frames referenced for display shall be consistent with the value of Image Box Layout Type (0072,0304). If the value of Image Box Layout Type is SINGLE, only a single frame shall be referenced, either directly or indirectly; if the value is CINE, only a single multi-frame SOP Instance shall be referenced.

If the value of Image Box Layout Type is STACK, more than one SOP Instance or frame may be referenced, and the frames constitute a stack to be displayed in the Image Box. For frames identified by the Referenced Image Sequence, the order of stepping through the stack shall be the order of Image SOP Instance references in that Sequence. If multiple frames are selected in Referenced Frame Number (0008,1160), those frames shall be stepped through in the order of their listing in that attribute, within the order of display of their Image SOP Instance.

For a stack whose frames are selected indirectly through an Item of the Referenced Presentation State Sequence, the order of stepping through the stack shall be the order of SOP Instance references in the Referenced Series Sequence (0008,1115) of the referenced Presentation State. For a referenced Blending Softcopy Presentation State, this shall be the Referenced Series Sequence within the Blending Sequence (0070,0402) for which the Blending Position (0070,0405) value is UNDERLYING.

Notes: 1. Display of images using Blending Softcopy Presentation State must use indirect SOP Instance reference through the Referenced Presentation State Sequence (0008,9237) at the top level of Structured Display Image Box Sequence (0072,0422) Item, and cannot use the Referenced Presentation State Sequence within an item of the Referenced Image Sequence (0008,1140).

2. A Blending Presentation State that references a blending of a single underlying frame and a single superimposed frame may be associated with a SINGLE Image Box Layout.

3. A reference to a single display frame, either directly through Referenced Image Sequence or indirectly through Referenced Presentation State Sequence, may be associated with either a STACK or a CINE Image Box Layout as a degenerate case.

4. There is no requirement for the pixel matrix sizes of the images in the stack, or the image display area as selected by referenced Presentation State SOP Instances, to be identical, nor for the referenced images to be of the same SOP Class.

5. Referenced Presentation States are an initial presentation control. The rendering Application Entity might allow a user to interactively enable/disable graphic layers, or change the zoom, rotation, window width / window level, or other presentation controls. Any such Application Entity functionality is beyond the scope of the Standard.

C.11.17.1.3 Referenced Instance Sequence

The Referenced Instance Sequence (0008,114A) references a non-Image SOP Instance, e.g., a Structured Report, Waveform, or Encapsulated Document SOP Instance, to be displayed in the image box. For such object references, the value of Image Box Layout Type (0072,0304) shall be SINGLE, even if displaying the object will require scrolling or paging (e.g., a multi-page encapsulated document).

C.11.17.1.4 Referenced Stereometric Instance Sequence

The Referenced Stereometric Instance Sequence (0008,1134) references a Stereometric SOP Instance, whose Stereo Pairs Sequence (0022,0020) references image pairs to be displayed in the Image Box. The number of image pairs referenced for display shall be consistent with the value of Image Box Layout Type (0072,0304). If the value of Image Box Layout Type is SINGLE, only a single pair of frames shall be referenced by the Stereo Pairs Sequence in the referenced stereometric instance; if the value is CINE, only a single pair of multi-frame SOP Instances shall be referenced; if the value is STACK, one or more pairs may be referenced constituting a stack to be displayed in the Image Box, and the order of stepping through the stack shall be the order of Items in the Stereo Pairs Sequence. The manner in which a stereo pair is rendered is unspecified.

Notes: 1. While the Stereometric IOD allows reference to multiple pairs of multi-frame cine Instances, the CINE Image Box Layout does not support the display of more than one (a “stack” of cines).

2. Display of stereo pairs typically requires specialized hardware (e.g., polarizing filters and shutter glasses).

C.11.17.1.5 Type of Synchronization

Type of Synchronization (0072,0434) specifies the method for synchronizing the display of images in two or more Image Boxes linked through the Synchronized Image Box List (0072,0432).

  1. FRAME: Stepping of frames in one Image Box is synchronized by the stepping of an identical number of frames in the other Image Boxes.

  2. POSITION: Stepping of frames in one Image Box is synchronized by the stepping of frames in the other Image Boxes to effect an identical relative positional offset within the patient based coordinate system. This presumes that the referenced images includes Image Position (Patient) (0020,0032) and Image Orientation (Patient) (0020,0037) attributes, and that the stacks have approximately the same orientation relative to the patient based coordinate system.

  3. TIME: Playback of frames in one Image Box is synchronized by the playback of frames in the other Image Boxes to effect an identical temporal offset from the original displayed frame. This presumes that the referenced images include Frame Time (0018,1063), Frame Time Vector (0018,1065), or Frame Reference DateTime (0018,9151). It also presumes that if the Image Box Layout Type (0072,0304) is STACK, the frames are referenced in a monotonically increasing time order in the stack.

  4. PHASE: Playback of frames in one Image Box is synchronized by the playback of frames in the other Image Boxes to effect an identical phase offset. This presumes that the referenced frames within each referenced Image Box constitute a uniform sampling across a single “cycle”, and that relative position within that cycle is synchronized across all the referenced Image Boxes. For Image Boxes with Image Box Layout Type (0072,0304) value CINE, the set of frames to be displayed as one cycle may be specified either using the Referenced Frame Number (0008,1160) attribute within the Referenced Image Sequence (0008,1140), or if that attribute is not present, using the values of attributes Start Trim (0008,2142) and Stop Trim (0008,2143).

Notes: 1. PHASE may be used, for instance, to synchronize display of images representing a single cardiac cycle.

2. Synchronization of Image Boxes is an initial presentation control. The rendering Application Entity might allow a user to unlink the synchronization, e.g., to navigate to cine frames before the Start Trim (0008,2142) frame or after the Stop Trim (0008,2143) frame. Any such Application Entity functionality is beyond the scope of the Standard.

C.11.18 Structured Display Annotation Module

This Module defines Attributes of text annotation that shall be applied to a Structured Display. The text is defined in position and size relative to the Display Environment.

Notes: 1. The text bounding box is specified using the same attribute, Display Environment Spatial Position (0072,0108), that is used for Image Boxes in the Structured Display Module. This attribute uses the coordinates (0.0,0.0) as the bottom left hand corner and (1.0,1.0) as the top right hand corner. In contrast, the image-related text annotations defined in the Graphic Annotation Module in image Presentation State IODs use the attributes Bounding Box Top Left Hand Corner (0070,0010) and Bounding Box Bottom Right Hand Corner (0070,0011), which use the coordinates (0.0,0.0) as the top left hand corner and (1.0,1.0) as the bottom right hand corner.

2. Annotation of regions of interest in images included in the Structured Display, e.g., circling of a feature of interest, may be done with a Presentation State applied to the image in the Structured Display Image Box Sequence (0072,0422) in the Structured Display Image Box Module. This Structured Display Annotation Module provides only for text annotations, typically as used for captions for the Image Boxes or for the Structured Display as a whole.

Table C.11.18-1 describes the attributes of the Structured Display Annotation Module.

Table C.11.18 -1 Structured Display Annotation Attributes

Attribute Name Tag Type Attribute Description
Structured Display Text Box Sequence (0072,0424) 1 Sequence that describes a text annotation. One or more Items shall be included in this sequence.
>Unformatted Text Value (0070,0006) 1 Text data which is unformatted and whose manner of display within the defined bounding box is implementation dependent. See C.11.18.1.1. The text value may contain spaces, as well as multiple lines separated by either LF, CR, CR LF or LF CR, but otherwise no format control characters (such as horizontal or vertical tab and form feed) shall be present, even if permitted by the Value Representation of ST. The text shall be interpreted as specified by Specific Character Set (0008,0005) if present in the SOP Instance. Note: The text may contain single or multi-byte characters and use code extension techniques as described in PS 3.5 if permitted by the values of Specific Character Set (0008,0005).
>Display Environment Spatial Position (0072,0108) 1 Exactly four dimensionless floating point values, in the range 0.0 to 1.0, indicating the rectangular coordinate position within the Display Environment of the bounding box in which Unformatted Text Value (0070,0006) is to be displayed. Note: For the Basic Structured Display with a single screen, the Display Environment is coextensive with the screen defined in the Nominal Screen Definition Sequence (0072,0102). See Section C.11.16.
>Bounding Box Text Horizontal Justification (0070,0012) 1 Location of the text relative to the vertical edges of the bounding box. Enumerated Values: LEFT = closest to left edge RIGHT = closest to right edge CENTER = centered
>Graphic Layer Recommended Display CIELab Value (0070,0401) 3 A value in which it is recommended that Unformatted Text Value (0070,0006) be rendered on a color display. The units are specified in PCS-Values, and the value is encoded as CIELab. See C.10.7.1.1.

C.11.18.1 Structured Display Annotation Attribute Descriptions

C.11.18.1.1 Unformatted Text Value and Display Environment Spatial Position

The Unformatted Text Value (0070,0006) rendered in Display Environment Spatial Position (0072,0108) need not be confined to the specified bounding box.

Notes: 1. An implementation may render text outside the confines of the bounding box if necessary to display all the specified text.

2. Alternatively, an implementation may choose to render the text in a scrolling box, or a link to another fixed or popup window as appropriate.

When the text bounding box overlaps an Image Box (from the Structured Display Image Box Module), the text box has a higher display priority (i.e., it is on top of the image box). The background color of the bounding box is undefined.

Notes: 1. Commonly, the background region of the bounding box around the text will be rendered “transparently”, i.e. the image will be visible, though some implementations may choose to opacify the bounding box behind the text to improve its readability.

2. With a transparent background, for example, an implementation may choose an “exclusive or” style opacification to be sure that the text is discernible over light and dark portions of the image.

The size, font, and rotation of the individual rendered text characters are unspecified.

C.11.19 XA/XRF Presentation State Mask Module

Table C.11.19-1 specifies the Attributes that describe mask operations for a XA/XRF Multi-frame image.

Table C.11.19-1XA/XRF PRESENTATION STATE MASK MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Mask Subtraction Sequence (0028,6100) 1 Defines a sequence that describes mask subtraction operations for Multi-frame Images. One or more items shall be included in this sequence.
>Referenced Image Sequence (0008,1140) 1C A reference to a selected Image. Required if Presentation State Relationship Module references more than one SOP Instance. Only a single item shall be included in this sequence.
>>Include ‘SOP Instance Reference Macro’ Table 10-11
>Mask Operation (0028,6101) 1 Defined Term identifying the type of mask operation to be performed. See C.7.6.10.1 for further explanation.
>Applicable Frame Range (0028,6102) 1C Each pair of numbers in this multi-valued attribute specifies a beginning and ending frame number inclusive of a range where this particular mask operation is valid. Discontinuous ranges are represented by multiple pairs of numbers. Frames in a Multi-frame Image are specified by sequentially increasing number values beginning with 1. If this Attribute is missing in this particular sequence item, then the mask operation is applicable throughout the entire Multi-frame Image, subject to certain limits as described in C.7.6.10.1.1. Each frame shall only be associated with a single Item of this sequence. Required if Mask Operation (0028,6101) equals REV_TID. May be present otherwise.
>Mask Frame Numbers (0028,6110) 1C Specifies the frame numbers of the pixel data used to generate this mask. Frames in a Multi-frame Image are specified by sequentially increasing number values beginning with 1. Required if the Mask Operation (0028,6101) is AVG_SUB.
>Contrast Frame Averaging (0028,6112) 3 Specifies the number of contrast frames to average together before performing the mask operation. If the Attribute is missing, no averaging is performed.
>TID Offset (0028,6120) 2C If Mask Operation is TID, specifies the offset to be subtracted from the current frame number in order to locate the mask frame in TID mode. If Mask Operation is REV_TID, specifies the initial offset to be subtracted from the first contrast frame number. See section C.7.6.10.1.1. If zero length, TID Offset defaults to 1. Required if Mask Operation (0028,6101) is TID or REV_TID.
>Pixel Intensity Relationship LUT Sequence (0028,9422) 1C A sequence of Pixel Intensity Relationship LUTs that specifies a transformation to logarithmic space. One or more items shall be included in this sequence. Required if Pixel Intensity Relationship (0028,1040) is not LOG for frames included in this Item of the Mask Subtraction Sequence (0028,6100).
>>LUT Frame Range (0028,9507) 1 Each pair of numbers in this multi-valued attribute specifies a beginning and ending frame number inclusive of a range where this LUT operation is specified. Discontinuous ranges are represented by multiple pairs of numbers. Frames in a Multi-frame Image are specified by sequentially increasing number values beginning with 1. Note: The specified frame numbers must be a part of the frames where this mask operation is valid.
>>LUT Descriptor (0028,3002) 1 Specifies the format of the LUT Data in this Sequence. See C.11.1.1 and C.7.6.16.2.13.1 for further explanation.
>>LUT Data (0028,3006) 1 LUT Data in this Sequence
>>LUT Function (0028,9474) 1 The transformation function this LUT applies to the stored pixel values. Enumerate Values: TO_LOG
>Pixel Shift Sequence (0028,9501) 1 Sequence containing the pixel shift values for the masks of the specified frame range(s) in the specified region(s). One or more items shall be included in this sequence.
>>Pixel Shift Frame Range (0028,9506) 1 Each pair of numbers in this multi-valued attribute specify a beginning and ending contrast frame number inclusive of a range where this pixel shift is specified. Discontinuous ranges are represented by multiple pairs of numbers. Frames in a Multi-frame Image are specified by sequentially increasing number values beginning with 1. Overlapping frame ranges are not permitted. Note: The specified frame numbers must be a part of the frames where this mask operation is valid.
>>Region Pixel Shift Sequence (0028,9502) 1 Sequence containing the pixel shifts for this frame(s). Only one sub region of this frame(s) shall be specified when the pixel shift is applicable for the full size or a single region of the frame(s). More than one sub region of this frame(s) may be specified when pixel shift is different in different regions. The order of Items in this sequence is significant, see C.11.19.1.2. One or more items shall be included in this sequence.
>>>Mask Sub-pixel Shift (0028,6114) 1 A pair of floating point numbers specifying the fractional vertical [adjacent row spacing] and horizontal [adjacent column spacing] pixel shift applied to the mask before subtracting it from the region of the frame numbers specified by Pixel Shift Frame Range (0028,9506) of this Pixel Shift Sequence (0028,9501) Item. The region is specified by the polygon defined by the Vertices of the Region (0028,9503) attribute. The pixels on the line of the polygon belong to the region. Note: If no pixel shift has to be applied a pair of zero attribute values (0.0\0.0) should be specified. See Section C.11.19.1.1.
>>>Vertices of the Region (0028,9503) 1C Multiple Values where the first set of two values are: row of the origin vertex column of the origin vertex Two or more pairs of values follow and are the row and column coordinates of the other vertices of the polygon region. Each polygon region is implicitly closed from the last vertex to the origin vertex and all edges shall be non-intersecting except at the vertices. See C.11.19.1.2. The upper left pixel of the image has the coordinate 1\1. Required if the pixel shift does not apply to the entire set of pixels of the frames.

C.11.19.1 XA/XRF Presentation State Mask Attributes

C.11.19.1.1 Mask Sub-pixel Shift

A pair of floating point numbers specifying the fractional vertical [adjacent row spacing] and horizontal [adjacent column spacing] pixel shift applied to the mask before subtracting it from the specified region of the contrast frame. The row offset results in a shift of the pixels along the column axis. The column offset results in a shift of the pixels along the row axis. A positive row offset is a shift toward the pixels of the lower row of the pixel plane. A positive column offset is a shift toward the pixels of the left hand side column of the pixel plane.

C.11.19.1.2 Vertices of the Region

Each item of the Region Pixel Shift Sequence (0028,9502) specifies both a region of the contrast frame and a mask pixel shift to be applied during the subtraction of that region.

When the Region Pixel Shift Sequence (0028,9502) contains more than one item, each region of the contrast frame is subtracted by applying the corresponding pixel shift specified in that item.

When an item of the sequence does not contain the attribute Vertices of the Region (0028,9503) , the applicable region for that item is the whole contrast frame.

The union of all the regions defined in the Region Pixel Shift Sequence (0028,9502) does not cover necessarily the whole contrast frame, in which case the pixels outside the union of all the regions shall be subtracted with no pixel shift.

If a set of pixels of the contrast frame is contained in more than one region, the applicable pixel shift is the one of the last item with the region that contains this set of pixels, as shown in Figure C.11.19-1.

[pic]

Figure C.11.19-1Applicable pixel shift in case of multiple pixel shift region s

Note: For example, the contrast frames 4 to 10 of a SOP Instance “A” are subtracted to the mask frame 1, the subtraction of the frames 4 to 7 being performed with three different values of mask pixel shift on overlapping rectangular regions: The (row,column) coordinates of the top-left and bottom-right vertices of the regions are 1: (1,1) to (30,60), 2: (10,40) to (50,120) and 3: (20,20) to (70,80). The mask pixel shift to be applied to the pixel (25,50) corresponds to the region 3 because this pixel is contained in the intersection of the three regions (See Figures C.11.19-2 and C.11.19-3).

Mask Subtraction Sequence (0028,6100)
Item 1
>Referenced Image Sequence (0008,1140)
Item 1
>>Referenced SOP Class UID (0008,1150) = 1.2.840.10008.5.1.4.1.1.12.1.1
>>Referenced SOP Instance UID (0008,1155) = UID "A"
>Mask Operation (0028,6101) = AVG_SUB
>Applicable Frame range (0028,6102) = 4\10
>Mask Frame Numbers (0028,6110) = 1
>Pixel Shift Sequence (0028,9510)
Item 1
>>Pixel Shift Frame range (0029,9506) = 4\7
>>Region Pixel Shift Sequence (0029,9506)
Frame Display Shutter Sequence (0018,9472) 1 Sequence of shutter specifications to be applied to groups of frames. One or more Items shall be included in this sequence.
>Referenced Image Sequence (0008,1140) 1C Sequence of Items where each Item provides reference to a selected set of Image SOP Class/SOP Instance pairs that are defined in the Presentation State Relationship Module. One or more Items shall be included in this sequence. Required if shutters in this Item do not apply to all the images and frames listed in the Presentation State Relationship Module.
>>Include ‘Image SOP Instance Reference Macro’ Table 10-3
>Include ‘Display Shutter Macro’ Table C.7-17A.

C.11.21 XA/XRF Presentation State Presentation Module

Table C.11.21-1 specifies the Attributes of a XA/XRF Presentation State Presentation Module.

Table C.11.21-1XA/XRF PRESENTATION STATE PRESENTATION MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Multi-frame Presentation Sequence (0028,9505) 1 Describes for one or more SOP Instances the recommended playback and display preferences. One or more Items shall be included in this sequence.
>Referenced Image Sequence (0008,1140) 1C Sequence of Items where each Item provides reference to a selected set of Image SOP Class/SOP Instance pairs that are defined in the Presentation State Relationship Module. One or more Items shall be included in this sequence. Required if display sequences in this Item do not apply to all the images listed in the Presentation State Relationship Module.
>>Include ‘SOP Instance Reference Macro’ Table 10-11
>Preferred Playback Sequencing (0018,1244) 3 Describes the preferred playback sequencing for a multi-frame image. Enumerated Values: 0 = Looping (1,2...n,1,2,...n,1,2,....n,...) 1 = Sweeping (1,2,...n,n -1,...2,1,2,...n,...)
>Frame Display Sequence (0008,9458) 3 Sequence that specifies the display frame rate of a selected set of frames. The Items are ordered in increasing frame number. The range of the frames may not overlap and the ranges shall be adjacent. One or more items are permitted in this sequence.
>>Start Trim (0008,2142) 1 The Frame Number of the first frame of the set of frames to be displayed in this Item.
>>Stop Trim (0008,2143) 1 The Frame Number of the last frame of the set of frames to be displayed in this Item.
>>Skip Frame Range Flag (0008,9460) 1 A flag indicating that the range of frames in this item may be skipped. Defined Terms: DISPLAY SKIP
>>Recommended Display Frame Rate in Float (0008,9459) 1 Recommended rate at which the frames of this Item should be displayed in frames/second.
>>Recommended Viewing Mode (0028,1090) 2 Specifies the recommended viewing protocol(s). Defined terms: SUB = subtraction with mask images NAT = native viewing of image as stored Note: If an implementation does not recognize the defined term for Recommended Viewing Mode (0028,1090), reverting to native display mode is recommended.
>>Display Filter Percentage (0028,9411) 2 Edge enhancement filter percentage that is recommended by the pixel data creator as filter presetting for display purposes. The value of 100 corresponds to the maximum filter strength that can be applied by a specific application displaying the image.
>>Mask Visibility Percentage (0028,9478) 1C The percentage of visibility of the mask frame during a subtracted display. A value of 0 corresponds to subtracted display, a value of 100 corresponds to un-subtracted display (native). See C.8.19.7.1. Note: The value of 100 is equivalent to Recommended Viewing Mode (0028,1090) having a value of NAT. Required if Recommended Viewing Mode (0028,1090) equals SUB.