[sane-devel] SANE_FRAME_IR

[Benjamin Gordon]

On Wed, Jul 22, 2026 at 11:33 AM Ralph Little <skelband at gmail.com> wrote:

> Hi,
> We have had a question from a developer regarding support for IR from a
> scanner, namely the LS-5000 supported by the coolscan3 backend.
> This device can supply IR but there are a few different ways in which
> this can be delivered to the frontend. The brief discussion is here:
> https://gitlab.com/sane-project/backends/-/merge_requests/937
>
> As I said in that discussion, I believe the SANE_FRAME_IR option (or
> some variant) is the better one to explicitly support it from the SANE
> standard. I assume that this was a proposed extension at some point.
> However, this would mean we would need to ratify a new standard and ask
> frontend developers to support the new features, something that we might
> struggle to do ourselves what with the backlog we currently have.
>
> There are mentioned some other options, such as delivering the IR frame
> as grey in the next frame, which is done currently by another backend,
> and has the advantage of being supported right now.
>
> Views? Any appetite for an update to the SANE Standard? I'm sure there
> are a few things that people would like to add.
>

If there's the possibility of re-opening the standard, I for one would like
to consider a more general handling of frame formats.  All the scanners
that support eSCL these days can return JPEG directly, and some of them can
even return a whole PDF at once.  It would be great for the frontend to be
able to negotiate some sort of passthrough mode instead of decoding these
and then re-encoding in the frontend.

Thanks,
Benjamin
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