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

[Gerhard Jaeger]

On Monday 10 July 2006 21:40, m. allan noah wrote:
> 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?
> 
you might want to have a look @ plustek-usbmap.c, where the brightness &
contrast adjustment isdone for the plustek backend. It's quite simple
and works okay (tm) ;)

HTH
Gerhard