[sane-devel] Sane API

Jürgen Mellinger juergen.mellinger at t-online.de
Tue Oct 13 14:20:15 BST 2020

Hi Olaf,

sorry for not being clear about my suggestion. I am aware that various options exist for the user to select hardware gamma correction, and that software gamma correction is discouraged.

However, this is exactly the problem. Without software gamma correction, a frontend is unable to request a certain gamma correction, and cannot choose a gamma correction value suitable for the current operating system, and the current device, or user preferences transferred from a different device. So my suggestion would be to prescribe a software gamma correction option with the values 0 to 2.2, 0 standing for "off". Alternatively, a read-only option "HardwareGamma" could provide the frontend with enough information to implement software gamma correction by itself.


> Am 13.10.2020 um 10:45 schrieb Olaf Meeuwissen <paddy-hack at member.fsf.org>:
> Hi Jürgen,
> Jürgen Mellinger writes:
>> Specifying a gamma value for acquired scan data would greatly add to
>> usability as well.
> That's already in the version 2 draft.  See
>  https://sane-project.gitlab.io/standard/draft-2/api.html#gamma-table-options
>  https://sane-project.gitlab.io/standard/draft-2/api.html#analog-gamma
> Both are for device-side gamma support and the standard discourages
> emulation in the backend of the former and forbids for the latter.
> Hope this helps,
> --
> Olaf Meeuwissen, LPIC-2            FSF Associate Member since 2004-01-27
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