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[filmscanners] RE: JPEG2000/PNG on PS7.0 and PSP8.0

> From: Robert Logan
> Ok, my 1st proper analysis of compression with
> JPEG2000 on a full roll of film. Saving with
> the 'fnord' JP2 plugin in PHotoshop, of 20
> 30Mb-50Mb files, 48 bit scans, and using the
> 'fnord'  Super PNG plugin on the same files
> (and then PNGcrushing them) gives the following
> results.
> Orig TIFF = 850 Mb
> JPEG 2000 = 747 Mb
> PNG/crush = 758 Mb
> The JPEG 2000 is better, over a good analysis,
> and saves the colour profile data too. I will now
> move to archiving totally in JP2 ... after a long
> wait from y2K.

You're going to convert all your TIFFs to JPEG2000 just to save 11% of your
space, and suffer the longer decode times when you view them? Wouldn't it be
easier just to buy a little more disk space?

I intend to convert all my TIFFs to JPEG2000 (as soon as my image cataloger
software, ThumbsPlus, handles the format--RSN), but I'll use 5:1 or 10:1
lossy compression. That provides some meaningful space advantage. All images
from digicams or scanners have noise in them anyway, so the question is
whether the additional error from lossy compression is visible through that
noise. My experience is that it's not, even when magnified. I've even run
tests subtracting the original from the processed version, to see how big
the error is, and whether it looks like noise or shows traces of the image
itself. JPEG2000 is a lot better than JPEG, for a given compression level.


Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com

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