Hello,

On https://dicom.offis.de/download/mesa_cpi/release_2004/, a testset of Dicom Images containing SMPTE Patters is available for testing Dicom image display software. This testset was in the past often used on IHE Connectathons..

Refer to mlut_01.dcm, where pixel 127, 280 (col, row) is supposed to have a value of 10% of the max value 255, which I think is 25.5. I would round that to 26, but in the image (as well as in most other images in the test set, pixel value is rounded to 25. Not a big difference, but I could not find anything about this in the Dicom Standard (https://dicom.nema.org/medical/dicom/current/output/chtml/part03/sect_C.11.2.html#sect_C.11.2.1.2).

Refer to vlut_08.dcm, for which the situation is stranger. Refer to table below for pixel values and display values according to the formula in the dicom standard.

Anyone who can shine light on this?

Best regards, Ronald

Original bitmap values

x = 255, y = 127, value = 0
x = 127, y = 280, value = 4
x = 127, y = 230, value = 9
x = 127, y = 180, value = 14
x = 180, y = 180, value = 19
x = 230, y = 180, value = 24
x = 280, y = 180, value = 24
x = 330, y = 180, value = 29
x = 380, y = 180, value = 34
x = 380, y = 230, value = 39
x = 380, y = 280, value = 44
x = 127, y = 127, value = 49

Gray Level = 50,00
Gray Width = 50,00

Converted bitmap values

x = 255, y = 127, value = 000, should be 000
x = 127, y = 280, value = 021, should be 025
x = 127, y = 230, value = 047, should be 051
x = 127, y = 180, value = 073, should be 076
x = 180, y = 180, value = 099, should be 102
x = 230, y = 180, value = 125, should be 127
x = 280, y = 180, value = 125, should be 127
x = 330, y = 180, value = 151, should be 153
x = 380, y = 180, value = 177, should be 178
x = 380, y = 230, value = 203, should be 204
x = 380, y = 280, value = 229, should be 229
x = 127, y = 127, value = 255, should be 255