Henning Meier-Geinitz wrote:
>
> Hi,
>
> On Tue, Oct 03, 2000 at 02:48:56PM +0200, Oliver Rauch wrote:
> > as far as I know there is no 1 bit color frame or image format defined.
> > I can imagine how this would look like in 3 pass scanning mode,
> > but there is (as far as I know) no interleaved RGB 1 bit format.
>
> You may be right concerning image formats (like pnm, tiff, ...). The SANE
> standard explicitly allows this case (->byte interleaved).
>
> > May be we should use the 8 bit format for it.
>
> Definitely. If somebody really needs 1-bit color ...
The scanners supported by the Sharp backend can produce 1 bit RGB data,
and the backend supports the scan mode. But it expands the 1 bit data
into 8 bits, because [x]scanimage simply copies the data received from
the backend into the output, with a PNM header in front. And a RGB
format with 1 bit per colour is apparently not supported by the "PNM
programs", at least in the format delivered by the Sane programs.
Therefore, I suggest, that the Sane standard should simply state that
RGB data should have at least 8 bits per colour. A smaller bit depth is
hardly of an use at a time, where you can buy a 20 GB hard disk for
$200, so the only thing needed is a clarification of the standard.
(BTW, what happens, if [x]scanimage receives RGB data with, say, 12 bit
per colour? Is such a format handled properly by PNM programs or Gimp?)
Abel
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