Hi, On Wednesday 25 September 2002 21:05, Henning Meier-Geinitz wrote: > Hi, > > 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 storag= e > > 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.=20
The Snapscan scanners also support 1 bit per color. You can even send you= r own=20 dither matrix to the scanner. (In theory, that is. I never quite got it t= o=20 work.) However, the backend will expand the data to 8 bit/color, so origi= nal=20 problem does not appear in the snapscan backend. > But I have never seen the benefit. I mean, 2 > "colors", black and white are ok. 256 (or more) also. But 8? Ok, > that's like CGA (?). > > What to do with these images? I mean, it's RGB so it can't be "lineart > + some IR stuff". IMHO it only makes sense if the scanner does some sort of dithering. The=20 dithered image may be send to a raster printer directly. This will save y= ou=20 the conversion / dithering on the host PC. In such a case, 1 bit/colour m= ay=20 make sense. Regards, Oliver
