Ken wrote:

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

My 2 cents : when storage space or file management is an issue, large images
can be converted to JPG with a good compression with little or at least
acceptable loss in quality. The Sony Cybershot digital camera uses it to store
its files on its memory stick and IMHO the result is perfect (we've been using
these files for professional documention). Another example below : the picture
is a detail from a 22 Mb rendering. The left image is from the original
(stored as a 7 Mb PNG). The image on the right is from a jpg compressed with a
1/11 ratio (stored as a 953 kb Jpg). The present combo is a jpg obtained with
the minimum compression available.
You can see the difference if you magnify the jpg image, and even without
magnifying there are visible artifacts (lines belows the lampshade). However,
both the (original) images would be perfectly suitable for printing. And while
the 953 kb JPG file can be sent by email (after taking the proper
precautions), the 7 Mb PNG usually can't... I had to do this some time ago
and, though this was very surprising at first, it made me realize that JPG,
when handled wisely, can save the day.

The day POV supports JPG input, I'll quicky convert the larger image maps
(with the proper compression ratio !!!), because it will make managing the
projects easier (like saving them on CD-ROMs, or transferring them between
machines). I can already do that, but it requires zipping or converting the
files back and forth, which is not very practical (and saving in PNG takes a
while, particularly with large files). However I'll keep storing as PNGs the
final renderings, the small image maps, the few image maps that behave too
strangely in JPG and those with an alpha channel. And yes, I'll still miss
(just a little) a jpeg saving feature in pov, because I think that it would
have been very handy during the test renders (and the possibility of launching
by mistake a week-long final render in JPG format is not worse than any other
mistake I can do at this always febrile and exciting moment).

G.

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