low dpi versus high dpi printing.Continued.

[Anonymous]

Anonymous wrote:
> ...
>  I printed both using lp -o Quality=600GrayscaleK
>  imageA600.pdf and lp -o Quality=600GrayscaleK
>  imageA72.pdf,and the quality of the printed
>  images are approximately identical.So different
>  image resolutions and information in the 2 pdfs
>  should generate different quality printed images.
>  So,is there in Ghostscript,CUPS etc. something that
>  interpolates automatically low resolution images
>  to match the -o Quality=600GrayscaleK option
>  we specified in the command line?

What driver are you using with CUPS?  If you are using a Foomatic,
then you are running into a well-known problem with Foomatic,
namely that the PostScript filtering it does resamples images to
72 DPI...
The fix is to just use the vendor's PPD file instead - you'll get
the same printer support without all of the problems with Foomatic.


The printed output looks more like 600dpi printing
rather than 72 dpi printing.I use the hpijs driver with
the PPD from www.linuxprinting.org.Anyway,the CD that
came with my HP Deskjet 3325 doesn´t have an autonomous
PPD file.For testing differences I did:

       lp -o Quality=300DraftGrayscaleK imageA72.jpg
       and
       lp -o Quality=300GrayscaleK imageA72.jpg

and there are visible differences.In the first the
dots are more visible than in the second.So,if the
Postscript filtering (in my case) did resample the
images from 600dpi to 72dpi,the printed quality with

       lp -o Quality=600GrayscaleK imageA600.jpg
  or   lp -o Quality=600GrayscaleK imageA600.pdf

is very interesting.