Glen,

 Attached you will find a small jpg image_map (ugly.jpg) and a
rendered image (GBerry.jpg) illustrating the undersirable conseq-
uenses of using .jpg images as an input format. Had the original
image not been compressed in the .jpg format the artifacts you
see in the final result would never have appeared. In this case
I forced the quality to be lower in the jpg before converting to
.tga just to prove my point but it illustrates it well.
 It is not at all unusual to find "texture" sites on the web with
extremly poor quality jpg's but some of them are just attactive
enough that you might attemt to use them anyway. In those cases
I am forced to try to clean them up before converting them to a
format usable by POV-Ray. If POV-Ray were to accept jpgs as input
for image_maps I would still try to clean them up but would still
run the risk of losing quality when I resave them in .jpg format
because the damage done by the jpg compression algorithm is prog-
ressive.

In my opinion the .jpg image format sucks. PNG is a much better
option and POV-Ray already supports it.

-- 
Ken Tyler -  1300+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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Download 'ugly.jpg' (3 KB) Download 'gberry.jpg' (11 KB)

Preview of image 'ugly.jpg'

Preview of image 'gberry.jpg'