[filmscanners] RE: JPEG2000 > Paul

["Paul D. DeRocco" <pderocco@ix.netcom.com>]

> From: Julian Robinson
>
> I have half-heartedly tried to research JPEG2000 without reaching any
> useful conclusions.  Can you give a reference or a potted summary
> with such
> useful but not readily findable info like what is the outlook for
> JPEG2000?
> how good is it? is it only available for sale or are their free versions?
> if only for sale - how do they expect it to become universal?  etc.
>
> It seems stupid to have standards which are not free because they never
> become standard.  The slowness of uptake and limited public
> knowledge seems
> to support this view.   But maybe JPEG2000 is the exception?
>
> Is the lossless compression worth having, i.e. what is the compression?
>
> Lastly, given you obviously have JPEG2000 (as a PS plugin?), why do you
> save your final images as old jpeg rather than jpeg2000?

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

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