# Re: SANE frames

Oliver Rauch (oliver.rauch@Wolfsburg.DE)
Mon, 16 Aug 1999 17:27:04 +0200

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Stephen Williams wrote:

> oliver.rauch@Wolfsburg.DE said:
> > May be we should add a generic n-channel frame format
> > (SANE_FRAME_N_CHANNELS or dthg like that) and put the numbers of
> > frames and a list with the name/types of the frames into the parameter
> > block.
>
> This reminds me. Some of the scanners I'm working on not only generate
> compressed images, but can have multiple images per page. I'm thinking
> for example of one document scanner that can, for each page, produce
> all at once:
>
> up to 8 color images
> up to 8 gray images
> up to 8 binary images
>
> Not to mention backside images as well. Each image can have different
> characteristics (i.e. JFIF color/gray, TIFF G4 binary) and dimensions.
> In particular, the scanner supports windows with these different properties
> and their own scan area. An aware application needs to be able to find
> out that these images are from the same page. Ideas?
>
> This is not so pressing to me as the application being able to select
> compressed frame formats (and blocking formats it can't handle) but
> someone should be thinking of these things.
>
> I know, I'm a pest on this list:-)
>

Hi Stephen,

the sane standard defines that you get one image for one call of SANE_START.
The suggestion I made with the n channel frame format is for ONE image
that consist of different frames - eg the RGB + IR channel we are discussing on
this list. This does not work for multi images!

We would have to add an extension to the standard for multiple image scans.
This could be done by a new function:
sane_set_scan_selection()
and a definition how the multiple images are read, eg by calling
sane_start several times but the backend produces all images
at the first call and sends one image for each call of sane_start.

But I am not sure if that is really necessary for sane.

Bye
Oliver

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