C.7.6.16.2.14 Frame Pixel Shift Macro

Table C.7.6.16-15 specifies the attributes of the Frame Pixel Shift Functional Group macro.

Table C.7.6.16-15FRAME PIXEL SHIFT MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
Frame Pixel Shift Sequence (0028,9415) 1 Sequence containing the pixel shift for a number of masks for this frame. One or more items shall be included in this sequence.
>Subtraction Item ID (0028,9416) 1 Identifier of the Subtraction Item in the Mask Subtraction Sequence (0028,6100) to which this pixel shift is associated. See C.7.6.16.2.14.1.
>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 this contrast frame. Note: If no pixel shift has to be applied a pair of zero values should be specified. See Section C.7.6.10.1.2.

C.7.6.16.2.14.1 Subtraction Item ID Description

Subtraction Item ID (0028,9416) specifies the ID of a subtraction operation to which the Mask Sub-pixel Shift (0028,6114) is associated. The Subtraction Item ID is also present in the Mask Subtraction Sequence (0028,6100) to allow this association.

When used as per-frame macro, the Subtraction Item ID (0028,9416) allows to specify different values of Mask Sub-pixel Shift (0028,6114) individually frame by frame, and relate them to a single item of the Mask Subtraction Sequence (0028,6100).

Note: There is no restriction in the number of Subtraction Item ID’s associated to each contrast frame. The same contrast frame may be present in several items of the Mask Subtraction Sequence, each item having a different value of Subtraction Item ID.

When used as shared macro, the Subtraction Item ID (0028,9416) allows to specify one or more values of Mask Sub-pixel Shift that will be applied to all the frames of the Multi-frame image.

Note: Example of usage of Subtraction Item ID in a per-frame macro, see Figure C.7.6.16-8:

In this example of Multi-Frame Image with 3 frames, one Mask Frame (i.e., Frame 1) is applied to the next two frames of the Multi-Frame image (i.e., Frames 2 and 3). Therefore, there is only one item in the Mask Subtraction Sequence, containing its own Subtraction Item ID value (i.e., 100). The Frame Pixel Shift Macro allows to define a Mask Sub-Pixel Shift different for each contrast frame.

First Frame Subtracted: Subtraction of Frame 1 (Mask) to Frame 2, with Sub-Pixel Shift 1.3\2.4

Second Frame Subtracted: Subtraction of Frame 1 (Mask) to Frame 3, with Sub-Pixel Shift 1.9\3.0

[pic]

Figure C.7.6.16-8Example of usage of Subtraction Item ID in a per-frame Macro