TIFF Tag MD ColorTable
|33447 (hex 0x82A7)
Used to specify the conversion from 16bit to 8bit in the Molecular Dynamics GEL file format.
Since the display is only 9bit, the 16bit data must be converted before display.
8bit value = (16bit value - low range ) * 255 / (high range - low range)
Assuming n values, these are their meanings:
value 0 = lowest possible
value 1 = low range
value n-2 = high range
value n-1 = highest possible
If more then 4 values are present, the intermediate values are to be ignored.
Note that this whole scheme may be pretty meaningless. If the application converts the image data as is encoded in the file, to grayscale with whatever bitdepth, using the MD FileTag and MD ScalePixel tags, then next conversion from whatever bitdepth to what is needed for display or other purposes may be the responsibility of an imaging layer that is quite independent from the particular file format. Thus, we feel this tag should be ignored by all but GEL specific applications.