Re: [hylafax-users] Ghostscript Anti-Aliasing For Better Quality Faxes

["A. Kalten" <akalten@xxxxxxxxxxx>]

On Tue, 27 Feb 2007 15:43:52 -0800
Lee Howard <faxguy@xxxxxxxxxxxxxxxx> wrote:

> 
> I also tried the escher.ps Ghostscript examples file, and while without 
> the AlphaBits it looked good, with it the image lost its detail.  In 
> fact, none of the examples files that I tested came out better with 
> -d*AlphaBits=4 used... so I wonder if it's some particular way that the 
> PostScript samples that you're using are being rendered.
> 

Two files for comparison have been uploaded to the following
links.  The PostScript for these files was produced using the
tetex package.  The differences, viewed with either viewfax
or qfaxreader, are not drastic but they are significant.
Characters in the antialiased file are thicker and fuller,
where in the non-antialiased form they tend to be more jagged.

http://firstbooks.biz/test-aa.tif    (with -dTextAlphaBits=4)

http://firstbooks.biz/test-noaa.tif  (without -dTextAlphaBits=4)

These files are produced with the command:

gs [-dTextAlphaBits=4] -sDEVICE=tiffg32d -r204x196 -sPAPERSIZE=letter -sOUTPUTFILE=file.tif file.ps

The Ghostscript version is AFPL 8.54.

The postscript was created with these commands:

latex file.tex
dvips -Pdfaxhigh -t letter -o file.ps file.dvi

I also have been having problems in applying this aliasing
parameter consistently.  Cover sheets, for example, which 
I create with a different process, cause ghostscript to
abort with an error when using the -dTextAlphaBits=4.

Andrew Kalten


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