Paul wrote:
> 
> I'm producing a CD based website for someone who has given me a number of
> bmp files generated by POV-Ray 3.1 for windows. The website has to be
> viewable in a minimum of 16 bit high color, at 800 x 600 resolution and be
> viewable in internet explorer 3.0 from microsoft. Naturally image quality is
> important but it is also important to deliver the images effectively via a
> web browser interface.
> 
> The problem I have is that in order to view the images in internet explorer
> 3.0 (which does not support bmp or png file formats) i'm converting the
> original bmp files to the jpg file format. With a low compression ratio the
> loss in image quality is acceptable. However when i drop my machine's color
> depth down from 32 bit true color to the required minimum of 16 bit high
> color I get color banding or concentric circles on the images.
> 
> I've tried using various image manipulation techniques to reduce the color
> depth without effecting the image quality too seriously, but nothing seems
> to get rid of the color banding or concentric circles without completely
> destroying the pictures. I've also had a play with POV-Ray (since i've been
> given the original files too) but nothing i've tried (including changing the
> render settings and ini files) seems to work.
> 
> I have access to a large collection of image manipulation software such as
> photoshop, paintshop pro etc, but nothing there seems to work either.
> 
> Please help, it's driving me nuts!
> 
> Thanks
> Paul

Why concert to jpg. jpg is only good for 24bit colors. The compression
method will thrash any lower bit depth. Why do you not use "gif" or
"tif" they also compress the image, but they have special 16bit and eveb
8bit modes. So if you convert the images you could directly concert to a
16bit format (with dithering if wished). Photoshop could write such
formats if I'm not mistaken. Or let Pov render to those formats.

Axel

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