DICOM PS3.3 2020b - Information Object Definitions

C.8.12 VL Modules and Functional Group Macros (Current)
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### C.8.12 VL Modules and Functional Group Macros

#### C.8.12.1 VL Image Module

Table C.8-77 specifies the Attributes that describe a VL Image produced by Endoscopy (ES), General Microscopy (GM), Automated-Stage Microscopy (SM), External-camera Photography (XC), or other VL imaging Modalities.

Table C.8-77. VL Image Module Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
Image Type | (0008,0008) | 1 | Image identification characteristics. See Section C.8.12.1.1.6 for specialization.
Photometric Interpretation | (0028,0004) | 1 | Specifies the intended interpretation of the pixel data. See Section C.8.12.1.1.1 for specialization of this Attribute.
Bits Allocated | (0028,0100) | 1 | Number of bits allocated for each pixel sample. Each sample shall have the same number of bits allocated. See Section C.8.12.1.1.2 for specialization of this Attribute. See PS3.5 for further explanation.
Bits Stored | (0028,0101) | 1 | Number of bits stored for each pixel sample. Each sample shall have the same number of bits stored. See Section C.8.12.1.1.2 for specialization of this Attribute. See PS3.5 for further explanation.
High Bit | (0028,0102) | 1 | Most significant bit for pixel sample data. Each sample shall have the same high bit. See Section C.8.12.1.1.2 for specialization of this Attribute. See PS3.5 for further explanation.
Pixel Representation | (0028,0103) | 1 | Data representation of the pixel samples. Each sample shall have the same pixel representation. See Section C.8.12.1.1.3 for specialization of this Attribute.
Samples per Pixel | (0028,0002) | 1 | Number of samples (planes) per image. See Section C.8.12.1.1.4 for specialization of this Attribute.
Planar Configuration | (0028,0006) | 1C | Indicates whether the pixel data are encoded color-by-plane or color-by-pixel. Required if Samples per Pixel (0028,0002) has a value greater than 1. See Section C.8.12.1.1.5 for specialization of this Attribute.
Content Time | (0008,0033) | 1C | The time the image pixel data creation started. Required if the Image is part of a Series in which the images are temporally related. ### Note This Attribute was formerly known as Image Time.
Lossy Image Compression | (0028,2110) | 2 | Specifies whether an Image has undergone lossy compression (at a point in its lifetime). Enumerated Values: 00 Image has NOT been subjected to lossy compression. 01 Image has been subjected to lossy compression. Once this value has been set to 01 it shall not be reset. See Section C.7.6.1.1.5
Referenced Image Sequence | (0008,1140) | 1C | A Sequence that references other images significantly related to this image. One or more Items are permitted in this Sequence. Required if Image Type (0008,0008) Value 3 is present and has a value of "STEREO L" or "STEREO R". May also be present otherwise. See Section C.8.12.1.1.7.
>Include Table 10-3 “Image SOP Instance Reference Macro Attributes” |
>Purpose of Reference Code Sequence | (0040,A170) | 2 | Describes the purpose for which the reference is made. Zero or one Item shall be included in this Sequence.
>>Include Table 8.8-1 “Code Sequence Macro Attributes” | DCID 7201 “Referenced Image Purposes of Reference”.
Window Center | (0028,1050) | 3 | Window Center for display. See Section C.11.2.1.2 for further explanation. Meaningful only if Photometric Interpretation (0028,0004) is MONOCHROME2.
Window Width | (0028,1051) | 1C | Window Width for display. See Section C.11.2.1.2 for further explanation. Required if Window Center (0028,1050) is present.
Image Laterality | (0020,0062) | 3 | Laterality of (possibly paired) body part (as described in Anatomic Region Sequence (0008,2218)) examined. Enumerated Values: R right L left U unpaired B both left and right Shall be consistent with any laterality information contained in Primary Anatomic Structure Modifier Sequence (0008,2230), Anatomic Region Modifier Sequence (0008,2220), and/or Laterality (0020,0060), if present. ### Note Laterality (0020,0060) is a Series level Attribute and must be the same for all Images in the Series, hence it must be absent if Image Laterality (0020,0062) has different values for Images in the same Series. There is no value for median, for which Primary Anatomic Structure Modifier Sequence (0008,2230) or Anatomic Region Modifier Sequence (0008,2220) may be used instead.
Anatomic Region Sequence | (0008,2218) | 1C | Sequence that identifies the anatomic region of interest in this image (i.e., external anatomy, surface anatomy, or general region of the body). Only a single Item shall be included in this Sequence. Required if Number of Frames (0028,0008) is present and Specimen Description Sequence (0040,0560) is absent. May be present otherwise.
>Include Table 8.8-1 “Code Sequence Macro Attributes” | DCID 4040 “Endoscopy Anatomic Regions” is defined for the Video Endoscopic IOD. BCID 4029 “Dermatology Anatomic Sites” is defined for the VL Photographic Image IOD for dermatology applications. BCID is CID 4031 “Common Anatomic Regions” for humans and CID 7483 “Common Anatomic Regions for Animals” for animals.
>Anatomic Region Modifier Sequence | (0008,2220) | 3 | Sequence of Items that modifies the anatomic region of interest of this image One or more Items are permitted in this Sequence.
>>Include Table 8.8-1 “Code Sequence Macro Attributes” | BCID 2 “Anatomic Modifier”. BCID 245 “Laterality with Median” is defined for the VL Photographic Image IOD for dermatology applications.
Include Table 10-8 “Primary Anatomic Structure Macro Attributes” | No CID is defined. These Type 3 Attributes are not appropriate when Specimen Description Sequence (0040,0560) is present, as it includes the Primary Anatomic Structure Macro for each specimen in the image.
Channel Description Code Sequence | (0022,001A) | 3 | Describes the light color used for each channel to generate the image. If Photometric Interpretation (0028,0004) has one of the YBR values, the meaning is for pixel data in an equivalent RGB encoding. ### Note Interpretation and representation of RGB images rely on the assumption that the red channel really contains the red wavelength range of illumination light, the blue channel the blue wavelength range, etc. Some modalities use the RGB Photometric Interpretation as a container representing 3 channels of any illumination wavelength. Shall have the same number of Items as the value of Samples per Pixel (0028,0002). The channels shall be described in the order in which the channels are encoded.
>Include Table 8.8-1 “Code Sequence Macro Attributes” | BCID 4206 “Ophthalmic Channel Description”.
Pixel Spacing | (0028,0030) | 3 | Physical distance in the imaging target (patient or specimen) between the center of each pixel, specified as a numeric pair - adjacent row spacing \ adjacent column spacing, in mm. See Section 10.7.1.3.
Imager Pixel Spacing | (0018,1164) | 3 | Physical distance measured at the front plane of the Image Receptor housing between the center of each pixel. Specified by a numeric pair - row spacing value (delimiter) column spacing value - in mm. In the case of a photographic camera, the front plane is defined to be the focal plane.

##### C.8.12.1.1 VL Image Module Attribute Descriptions

###### C.8.12.1.1.1 Photometric Interpretation

Enumerated Values:

MONOCHROME2

RGB

YBR_FULL_422

YBR_PARTIAL_420

YBR_RCT

YBR_ICT

Photometric Interpretation (0028,0004) shall be RGB for uncompressed or lossless compressed Transfer Syntaxes that do not have defined color space transformations, YBR_ICT for irreversible JPEG 2000 Transfer Syntaxes, YBR_RCT for reversible JPEG 2000 Transfer Syntaxes, YBR_PARTIAL_420 for MPEG2, MPEG-4 AVC/H.264 and HEVC/H.265 Transfer Syntaxes and YBR_FULL_422 for JPEG lossy compressed Transfer Syntaxes.

### Note

1. The YBR_FULL Photometric Interpretation (0028,0004), such as might be used with the RLE Transfer Syntax, is not permitted.

2. There is no formal color space defined, hence "false" color applications that encode near-visible light images may be encoded, for example, as RGB.

###### C.8.12.1.1.2 Bits Allocated, Bits Stored, and High Bit

Enumerated Values of Bits Allocated (0028,0100):

8

Enumerated Values of Bits Stored (0028,0101):

8

Enumerated Values of High Bit (0028,0102):

7

###### C.8.12.1.1.3 Pixel Representation

Enumerated Values:

0

###### C.8.12.1.1.4 Samples Per Pixel

Enumerated Values when Photometric Interpretation (0028,0004) is MONOCHROME2:

1

Enumerated Values when Photometric Interpretation (0028,0004) is RGB or YBR_FULL_422 or YBR_PARTIAL_420 or YBR_RCT or YBR_ICT:

3

###### C.8.12.1.1.5 Planar Configuration

This value shall be present if Samples per Pixel (0028,0002) has a value greater than 1.

Enumerated Values:

0

###### C.8.12.1.1.6 Image Type

The Image Type Attribute identifies important image characteristics in a multiple valued Data Element. For Visible Light, Image Type is specialized as follows:

- Value 1 shall identify the Pixel Data Characteristics in accordance with Section C.7.6.1.1.2.

  Enumerated Values:

  ORIGINAL

  DERIVED

- Value 2 shall identify the Patient Examination Characteristics in accordance with Section C.7.6.1.1.2.

  Enumerated Values:

  PRIMARY

  SECONDARY

- Value 3 may be absent, but if present shall identify the members of a stereo pair, in which case Referenced Image Sequence (0008,1140) is used to identify the other member of the pair.

  Enumerated Values:

  STEREO L

    Image is the left image (relative to the observer's left) of a stereo pair acquisition

  STEREO R

    Image is the right image (relative to the observer's right) of a stereo pair acquisition

- Other Values are implementation specific (optional).

###### C.8.12.1.1.7 Referenced Image Sequence

When Image Type (0008,0008) Value 3 is STEREO L or STEREO R, Referenced Image Sequence (0008,1140) shall be used to identify the corresponding SOP Instance of the Stereoscopic acquisition. In this case, either:

- only a single Item shall be present, or

- multiple Items may be present, each with the Purpose of Reference Code Sequence (0040,A170) present, and only the first Item having the Purpose of Reference value (121315, DCM, "Other image of stereoscopic pair").

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DICOM PS3.3 2020b - Information Object Definitions