Thanks Paul, that is really useful info. I am keen on anything that
reduces my 50MB files to 5MB with little loss, for all the obvious
reasons. I guess I need to try JPEG2000, and I will, but one last question
on what you said, how slow IS it? I mean, are we talking 1 sec, 10sec,
1minute or more to save a 50MB file? I remember trying Genuine Fractals
and giving it away because it was just too slow.
Julian
>As far as I know, the standard is free, meaning anyone can write a JPEG
>encoder or decoder and sell it. However, it hasn't yet found its way into
>Photoshop, so you need to use a plug-in to load and save JPEG2000 files.
>Perhaps free ones exist, but I haven't seen any. I use LuraWave's, which was
>fairly inexpensive. I seem to recall reading somewhere that Photoshop would
>support it in the next release, but I could be wrong.
>
>As to quality, JPEG2000 gives better quality than regular JPEG for a given
>amount of compression, or better compression for a given quality. It also
>includes the ability to preserve 16 bits per channel. I don't bother with
>the lossless compression because the lossy setting provides greater
>compression, without any artifacts that I can see. I compress by 10x, and if
>I open the TIFF and JPEG2000 images in Photoshop, reduce them to 8bpc
>(because PS doesn't let you do arithmetic on 16bpc images), and subtract
>them, most values differ by 0 or 1, and I can only find the occasional value
>that differs by 2. With regular JPEG compressing by 10x, many values differ
>by 2, and a few by 3 or more, and I lose the ability to save 16bpc files.
>
>After editing, I save as regular JPEG because a) the JPEG2000 plug-in is
>much slower, and b) the image viewer/cataloger I use (ThumbsPlus) has a
>problem reading JPEG2000 files if they contain ICC profiles. Hopefully,
>these are both temporary problems.
>
>--
>
>Ciao, Paul D. DeRocco
>Paul mailto:pderocco@ix.netcom.com
Julian
Canberra, Australia
Satellite maps of fire situation Canberra and Snowy Montains
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