How to calculate Window width and center of DICOM image from VOILut tag

Question

在dicom图像文件中不包括WW和WC / WL，但是存在VOI Lut标签，我想从中计算WW和WL

Answer 1

A VOI LUT is typically used for non-linear transformations of the pixel data, ie for transformations which can not be expressed by specifying WL/WW. For that reason, it is impossible to calculate WL/WW from VOI LUT.

[EDIT]: To be even more clear:

WL/WW is limited to linear transformations of the grayscales. So the difference between the mapped value of x and (x+1) is equal to the difference of the mapped value of y and (y+1).

This does not count for the VOI LUT module which was introduced to allow for non-linear transformations of the grayscales. That is, no assumptions can be taken about the correllation of mapped values (x, x+1), (y, y+1). VOI LUT can be used to define any weird curve for mapping gray values.

"any weird curve" can obviously not be approximated by a strictly linear function. For that reason, it is possible to express WL/WW by VOI LUT but not vice versa.