[sane-devel] SANE Color Management

[m. allan noah]

I believe that most backends are doing no transformation at all. Since
most backends are reverse engineered, I think we consider ourselves
lucky just to get image data out of the scanner. If the blacks look
black, and the whites look white, we ship it :)

allan

On Sun, Jul 5, 2020 at 10:38 AM Jürgen Mellinger
<juergen.mellinger at t-online.de> wrote:
>
> Hi,
>
> many SANE backends provide gamma correction options, but I could not find any information about the default color space in which scan data are being sent to sane_read(). I mean, if there is no custom gamma table used, then a backend should be able to use its knowledge about a scanner’s CCD’s gamma value to transform it into a pre-defined color space, such as sRGB, or linear gamma. If there is no such pre-defined color space, then each and every user will have to determine the correct gamma for their each and every scanner, and perform custom gamma correction just to obtain a reasonable image.
>
> From this I suspect that SANE backends indeed transform scanner data into a standard color space. My experience with the genesys backend suggests that it’s linear gamma. But I cannot find any documentation on this issue.
>
> Could someone point me to more information on this topic?
>
> Thank you,
> Jürgen



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