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

[m. allan noah]

On Tue, 18 Jul 2006, Bertrik Sikken wrote:

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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.
>

interesting! do you know of a backend that does this? i would like to see 
the option structures which are used... of course, not everyone uses 
xsane, so i might have to steal the code from it :)

allan

> Bertrik
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