[bug-gs] Poor antialiasing with gs-8.10 to gs-8.12

[Harald Anlauf]

Hi,

at low resolutions, the antialiasing in gs-8.10 and later (verified also
to still exist in gs-8.12) is apparently far inferior to the algorithm
in gs-8.00.  Its deficiencies are very noticeable for rotated text or
text positioned along curves.  A good example is program 10 from the
"bluebook" with the font Times replaced by Helvetica.  It is also seen
with the following PostScript file:

-------------8<---------------> cut here <--------------8<--------------
%!PS-Adobe-2.0 EPSF-2.0
%%BoundingBox: 0 0 52 55
%%EndComments

/Helvetica findfont 15 scalefont setfont

0 47 moveto
gsave -45 rotate
(New York) show
grestore

showpage
-------------8<---------------> cut here <--------------8<--------------

Reproduce by:

gs -dTextAlphaBits=4 -dGraphicsAlphaBits=4 \
   -dDEVICEWIDTH=600 -dDEVICEHEIGHT=600 \
   -r144 example.eps

and vary the resolution.  At large resolution (say, 600), gs-8.12 gets
sufficently close to the result of gs-8.00, but not below.  It is
terrible when rendering EPS files to bitmaps...

Cheers,
-Harald