Yes, I have heard that there are certain new versions of JPEG
that are virtualy or completely lossless, but you will not see compression
ratios on the scale of +20:1 as usual but more like 2:1. From what I
understand in that mode it is employing run lenght encoding as already
used in IFF, so I wonder if there would be a problem in compressing
something twice and not seeing any artifacting. I also doubt that your
run of the mill Amiga Jpegger is that up to date and supports these new
options, but then again SOMEONE out there may have already implemented
these latest and greatest features and not told us about it.
There have also been difficulties with JPEG compressors
being incompatible with each other in PC land, but that may be a thing of the
past.
The biggest problem happens if you go beyond the maybe acceptable 2:1 ratio.
I would hate to be the client who's (for once), perfectly shot greenscreens
are JPEGED, so that when the compositor goes to intigrated them, his comps
get's this really neat black outline around everything, from the compression
artifacts and narrowing of color space. Not to mention the subtle motionblur,
glows and everything else that goes out the window. Or what's even more fun is that your already narrow color space of 24-bit get's crunched to hell and when you are about to do some color correction and you start clipping because you
run out of information on the top and bottom end.
In my opinion jpegging your work is really not a great idea. You might be
able to get away with it if you pursue this as a hobby, but if you are
doing any kind of professional work, let alone film work, it doesn't sound