[sane-devel] test backend: 1 bit RGB data for grid pattern

abel deuring a.deuring@satzbau-gmbh.de
Wed, 25 Sep 2002 22:28:09 +0200

Oliver Schwartz wrote:
> Hi,
> On Wednesday 25 September 2002 21:05, Henning Meier-Geinitz wrote:
>>On Wed, Sep 25, 2002 at 11:16:15AM -0700, David Mosberger-Tang wrote:
>>>  Oliver> I think that makes sense.  When a backend really does
>>>  Oliver> support this then it can send it as 8 bit rgb image.
>>>Do we know for a fact that there are no high-speed devices out there
>>>that produce, say, dithered 1-bit data?  If not, inflating the storage
>>>and bandwidth requirements for such devices by a factor of 8 seems
>>>like a non-trivial issue.
>>The older Mustek SCSI scanners could send 1 bit per color RGB so there
>>are devices that can. 
> The Snapscan scanners also support 1 bit per color. You can even send your own 
> dither matrix to the scanner. (In theory, that is. I never quite got it to 
> work.) However, the backend will expand the data to 8 bit/color, so original 
> problem does not appear in the snapscan backend.

Same with Sharp scanners and the Sharp backend. The scanners can produce 
1 bit/sample RGB data, but the backend expands that to 8 bit/sample, 
because [x]scanimage did not write useful output files, at least at the 
time, when I implemented the 1 bit mode.