Re: your mail

Jean-Baptiste Nivoit (jbnivoit@ix.netcom.com)
Mon, 19 Oct 1998 11:34:38 -0400

On Tue, Oct 20, 1998 at 10:02:03PM +0200, becka@rz.uni-duesseldorf.de wrote:
> Hi !
>
> > i just purchased a Casio QV-11 camera the other day and got
> > load CAM pictures directly into the GIMP). Now i think i read in the
> > SANE doc that JPEG was not supported yet... i don't see the point of
> > translating a JPEG file into a bitmap that SANE can handle, since most
> > often users might convert the result to JPEG in the end anyway..
>
> Yes. If it hasn't been removed, there was an entry in the "TODO" file
> or something that stated that for a while.
Well that might be a good thing (to support other picture format).
Even other formats, more generally, with a fallback default to RGB/24 bits.

> > So here are basically the questions:
> > - how hard is it to write a backend? what's a good place to
> > start (which one is the simplest ?) ?
>
> I once wrote the pnm backend to serve as some kind of reference
> implementation. In your case, this might be a good place to start, as
> effectively the camera is more like an "external image library" than like
> a scanner, so it does make sense to start from the pnm backend.
OK. Well actually, there is a package called QVplay that extracts pictures
from those cameras, and i've started to look at how to modify the code
to fit in a SANE back-end. It's kind of messy, though. But the good part
is that there already is some code in there that extracts the pictures
not a JPEG but YCC, which can then be converted to RGB/24 bits.

> I'd say it isn't too hard, if you have the actual communications code.
> The SANE interface itself is pretty simple, once you have grasped how
> this option stuff works.
Yes, that's what i thought too, that the 'option' thing is a little
weird.

> > - when will there be JPEG support in the SANE interface? i guess
> > other camera (such as the Kodak ones?) also use a format
> > that's close to JPEG...
> We should finally add that.
>
> My idea about adding it would be to increase the version number, which
> can be queried at sane_init() time.
Yes, SANE probably needs something like that.
But i think i went ahead to quickly as far as those QV cameras are
concerned, apparently we can extract YCC image data from them..


jb.
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