|Baseline TIFF Tag GrayResponseCurve|
TIFF Tag Reference
TIFF Tag GrayResponseCurve
For grayscale data, the optical density of each possible pixel value.
The 0th value of GrayResponseCurve corresponds to the optical density of a pixel having a value of 0, and so on.
This field may provide useful information for sophisticated applications, but it is currently ignored by most TIFF readers.