[mapserver-users] 8 bit versus 24 bit output in MapServer 6.x

[Richard Greenwood]

All -

I've have always used 8 bit GIFs because they are generally the
smallest. I serve a rural area with flaky internet and I do a good bit
with mobile, so size is more important to me than pixel-perfect.
Since MapServer 6.0 I have found 8 bit output (GIF or PNG) to be much
more buggy than 24 bit output. Bugs that I have been able to isolate
and report have been fixed very quickly by the devs, but I'm
struggling with a couple now that are sporadic and that I can not
shrink down to a reproducible bug report. I see the same issues in
Windows and Linux. I'm running 6.0.3 on both. So:
1. What image format are people generally using? Am I stuck in the
past with 8 bit images? Should I just go with 24 bit and not worry
that my images are several times larger?
2. My general sense is that the root of the issues I'm seeing are in
the shift from GD to AGG. Are PC256 PNGs generated by GD or AGG?
3. Any general advise for 8 bit output? For GIF is use the default (I
don't define an OUTPUTFORMAT block) for PNG I do define an
OUTPUTFORMAT block and use IMAGEMODE PC256.

The two issues that I'm struggling with right now are that my label
colors change as I pan and zoom, and that the HATCH fill pattern
extends outside of its polygons. In both cases switching from an 8 bit
output to a 24 bit output resolves the issue.

Thanks,
Rich

-- 
Richard Greenwood
richard.greenwood at gmail.com
www.greenwoodmap.com