4.16.4.2.2.1 Display of Digital X-Ray, Mammo and Intra-Oral Images
For the “For Presentation” variant of the Digital X-Ray Image,the Digital Mammography Image, and the Digital Intra-oralX-Ray Image, the Image Display or Imaging Document Consumer actorshall have both the capability to apply all the transformationsspecified by the VOI LUT Sequence (0028,3010) and the capabilityto apply all the transformations specified by the Window Width(0028,1051)/Window Center (0028,1050)/VOI LUT Function (0028,1056)attributes in the DX Image Module as selected by the user fromthe choices available (e.g., guided by Window Center/WidthExplanation (0028,1055) or LUT Explanation(0028,3003).

If VOI LUT Function (0028,1056) is absent, then Window Width(0028,1051)/Window Center (0028,1050) shall be assumed to bethe parameters of a linear window operation. VOI LUTFunction (0028,1056) values of “SIGMOID” and “LINEAR” shall besupported.

The Image Display or Imaging Document Consumer shall supportthe application of LUT Data (0028,3006) in items of the VOILUT Sequence (0028,3010) regardless of the Value Representation(i.e., the DICOM standard allows either OW or US Value Representation).

The Image Display or Imaging Document Consumer actor must alsosupport pixel rendering according to the Grayscale StandardDisplay Function (GSDF) defined in DICOM 2007 PS 3.14, becausethe output values of these images are always P-Values.

If the DICOM image is referenced by other DICOM composite objects,such as Grayscale Softcopy Presentation States, it is optionalfor the Image Display or Imaging Document Consumer to actuallyretrieve and display/apply these objects."

4.16.4.2.2.1.1.4 Image Contrast Adjustment
As described in 4.16.4.2.2.1 Display of Digital X-Ray, Mammographyand Intra-Oral Images, the Image Display shall provide the user withthe ability to select amongst the available window and VOI LUTchoices available in the image object.

Subsequent to the initial application of the chosen contrasttransformation, the Image Display actor shall allow the user toadjust the contrast without reverting to a purely lineartransformation:

- If the chosen contrast transformation is a lookup table, thenthe Image Display shall allow the input value of the lookup table tobe stretched and translated so as to give the affect of adjustingcontrast and brightness whilst applying the same general shape asthe curve encoded in the lookup table. To provide feedback to theuser, the “window width” can be reported as the adjusted range ofinput values to the LUT, and the “window center” can be reportedas the center value of that range.

- If the chosen contrast transformation is a sigmoid shaped VOILUT Function parameterized by the window center and width, thenthe Image Display shall allow the window center and width valuesto be adjusted and a sigmoid function reapplied.

If a Pixel Padding Value (0028,0120) only is present in the imagethen image contrast manipulations shall be not be applied to thosepixels with the value specified in Pixel Padding Value (0028,0120).

If both Pixel Padding Value (0028,0120) and Pixel Padding RangeLimit (0028,0121) are present in the image then image contrastmanipulations shall not be applied to those pixels with valuesin the range between the values of Pixel Padding Value (0028,0120)and Pixel Padding Range Limit (0028,0121), inclusive. 

https://groups.google.com/g/comp.protocols.dicom/c/T4jL5_n2sLI?pli=1

https://compgroups.net/comp.protocols.dicom/voi-lut-questions/2998577

https://www.ihe.net/uploadedFiles/Documents/Radiology/IHE_RAD_TF_Rev16.0_Vol2_FT_2017_08_04.pdf