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

["Robert Logan" <bert_logan@btopenworld.com>]

Ok, machine is a PIII840 with 512 megs RAM,
Im using Photoshop 7.0 and Paint Shop Pro 8.0 beta1
as well as some Unix utils for comparison. I installed
the free 'fnordware.com' plugin to get Photoshop to
save JP2, dated 29/01/2003. Fnord also have a 'SuperPNG'
plugin for Photoshop. Its TONS better than the standard
PNG in Photoshop as it allows 48 bit saves, and
compresses far better. Again, lossless (PNG is lossless
only anyway).

I downloaded PSP8 in the hope that it would do a good
compression of my 48 bit TIFF files into either PNG
or JPEG2000 (JP2). I wanted the 16 bit info retained,
and compression to be lossless.

I chose a random file, a 48 bit colour TIFF of 37Mb
size, res of 2500x2500.

Firstly - the fnord plugin is great, it saves 24 bit
and 48 bit JP2 files in both lossy and lossless
formats. It is NOT SLOW. It took 50 seconds to convert
the TIFF into a lossless JP2. I can imagine faster, but
knowing a lot about code optimization, and a lot about
my PIII being dated ... (its a PIII600 overclocked).
Similarly, SuperPNG compression takes about 30 seconds
for the same image to a 48 bit PNG.

The Unix utils I use for archiving my scans (of which I
now have 12000) are ImageMagik - its a command line util
called 'convert' that can transform anything to anything.
It can take a 48 bit TIFF and save as 48 bit PNG etc.
I also used 'pngcrush' - a util to squeeze a lossless
PNG file down through better analysis, savings of 5 to
35% are common. Still lossless!

   Size        Image
37288166 col48bit.tif

26885343 col48bit-unix-crush.png
29145290 col48bit-fnord.png
31816063 col48bit-fnord.jp2

12622821 col24bit-unix-crush.png
12665621 col24bit-fnord.png
12781222 col24bit-psp.jp2
12809609 col24bit-fnord.jp2
13134330 col24bit-psp.png
13205364 col24bit-pshop.png

Analysis.
PSHOP only saves PNG to 24 bit
PSP8.0 only saves PNG to 24 bit
PSP8.0 only saves JP2 to 24 bit
Fnord lets PSHOP save JP2/PNG to 48 bit
Unix utils do PNG to 48 bit
Unix utils, I cant find a good JP2 library!

PNG takes a 48 bit TIFF and reduces it
by about 30% - no colour loss, no compression
loss.

JP2 (fnord) takes a 48 bit TIFF and reduces
it by about 15% - again, no colour loss
and no compression loss.

24 bit saving in PNG/JPG shows a closer
compression capability, but still, PNG saves
to a smaller size a lot more often (my 40 or
so image comparisons have shown me this).

A small note.
Photoshop is CRAP at saving to PNG. For
greyscale images the unix pngcrush can
take a Photoshop PNG and get it 60% smaller!
Unix convert/pngcrush utils do better than all
of the GUI based tools. These utils are available
on Windows too.

Summary - save TIFF to PNG to save archive space.
You lose nothing! Use the fnord plugin, its free,
or purchase a faster one of the JP2 compressors
as the ratio of saving over TIFF can vary for
the image.

Any requests?
And Im not buying the PHotoshops own JP2 plugin
by the sounds of it.
bert

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