Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Austin 
Franklin" <darkroom@i...> wrote:
> Hi Roy,
> 
> > In the print
> > facility for OS X, Linux, and other Unix systems the file
> > is resampled in PIXELS to the resolution that you pick for
> > DOTSpi.  I.e. the first step in getting a 1440x720 DPI print
> > is to get a 1440x720 PPI raster that is then processed into
> > ink dots.
> 
> Do you have any references that elaborate on this?

www.cups.orgs has lots of documentation.  see the
programmers manual for "cups raster data" and
cups raster header.

I just spent the last couple of weeks looking at these
raster files and writing code to process them for quadtones.
Yes, they are huge: 8x10 x 1440x720 x 3 (for RGB) is
about 250MB.  Fortunately, they are processed on the
fly so the total size is never there.

gimp-print is one of systems that read these raster files
and print to hundreds of printers.   See documentation at:
gimp-print.sourceforge.net  --  this has dithering info as
well.

Roy

> 
> > I've read documents from Epson (but I'm not sure where)
> > that as least implied that the desktop drivers typically
> > resample to 720 PPI before dithering.
> 
> I have not heard that...of course, any more info you have on 
this, I'd
> certainly like to see.

I t  must have been referenced on one of these groups,
but unfortunately I can't find it.

> 
> Regards,
> 
> Austin