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

[Bertrik Sikken]

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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?

As far as I know, xsane automatically calculates and downloads a gamma
table for brightness / contrast / gamma if the backend advertises it.

Bertrik

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