[sane-devel] brightness/contrast/gamma LUT ideas?

[m. allan noah]

recent model fujitsu scanners dont have native brightness/contrast/gamma 
support, instead they use an 256x256 or 1024x256 bit look up table to 
convert the raw scan data before 8 bit output.

while it is true that the 8bit square LUT could be done after scanning 
with no data loss, most command line front-ends dont do this, and the 10 
bit lut has 'access' to more data that never gets out of the scanner, so i 
would like to extend the backend to provide at least brightness/contrast 
for these scanners.

i need suggestions or pointers to code that i could use. what things i can 
find are far over my head, but i have a simple brightness adjustment that 
shifts the linear slope of the in-out function up or down, and a crude 
contrast setting that changes the slope of the function around the center 
of the table. i think both of these methods are likely too simplistic.

anyone?

allan

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