C. Optical Path Attribute Descriptions

C. Optical Path Sequence and Optical Path Identifier

The Optical Path Sequence (0048,0105) shall include an Item for every optical path used in the acquisition of the current image.

For single frame images that do not include the Multi-frame Functional Groups Module, this Sequence shall include only one Item.

For images that use the Multi-frame Functional Groups Module, the optical path associated with each frame is identified by reference to the Optical Path Identifier (0048,0106) of this Sequence (see Optical Path Identification Sequence (0048,0207) in Section C. The Optical Path Sequence may include Items for defined optical paths that are not referenced by any frame.

For Whole Slide Microscopy Image LOCALIZER images (see C. and C.8.12.7), all the optical paths associated with referenced images shall be described in Items of this Optical Path Sequence. The optical path associated with each referenced frame is identified in the Referenced Image Navigation Sequence (0048,0200) by reference to an Optical Path Identifier (0048,0106) of this Sequence. The Optical Path Identifiers used in the LOCALIZER image do not have to be identical to those used in the referenced images.

Notes: 1. For example, each of four referenced images may use a different optical path (color), and within each of those image SOP Instances the single Optical Path Sequence Item is identified as “1”, although the meaning of optical path “1” is different for each image. The LOCALIZER, however, must include all four optical paths with distinct identifiers “1”, “2”, “3”, and “4”.

2. The Optical Path Identifier is not necessarily numeric; it is a string of up to 16 characters (VR SH).

C. Illumination Type Code Sequence

Illumination Type Code Sequence (0022,0016) specifies the type of illumination of the imaging target. This attribute may include multiple Items, as some techniques may involve multiple methods, or some method identifiers may not be completely descriptive.

Note: For example, this attribute might include two items, (111741, DCM, “Transmission illumination”) and (111748, DCM, “Differential interference contrast”) to indicate “Transmission DIC”.

The type of illumination often prescribes the set of optical path components such as filters and prisms, and their arrangement in the optical path.

Note: For instance, phase contrast illumination will utilize a condenser annulus and a phase contrast plate; this may be indicated by an item (111747, DCM, “Phase contrast illumination”) in this attribute, but with no further specification in the filters and lenses identification attributes.

C. Light Path and Image Path Filter Type Stack Code Sequences

In some optical imaging methods, e.g., epifluorescence, there may be a single light path with its associated imaging components that is used in both illumination/excitation of the imaging target and in the transmitted/emitted path to the imaging sensor. In this case, the optical components are to be specified in the Image Path Filter Type Stack Code Sequence (0022,0018).

C. ICC Profile

ICC Profile (0028,2000) provides the transform for mapping stored color pixel values into ICC standard color Profile Connection Space (PCS). For MONOCHROME2 pixels that have a preferred color rendering through the Palette Color Lookup Table Sequence (0048,0120), this attribute provides a mapping of that preferred RGB color rendering into PCS. The ICC Profile shall follow the requirements specified in Section C.