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Article:
  JPEG2000: the Killer Image File Format for Lossless Storage
Subject:   PNG vs. JPEG2000
Date:   2003-11-24 20:37:20
From:   kmilburn
There was no intent to be either malicious or
negligent when it came to not mentioning a file format
that is already several generations old. PNG simply
wasn't what the article was about. PNG is also not an
approved standard of the Joint Photographic Experts
Group.


Having said that, you do have a point and I should
have made at least a reference to the older format.
PNG will save lossless images somewhat more
efficiently than JPEG2000 if those images contain
comparatively large numbers of pixels of the same
color (e.g. blue skies or solid color seamless
backgrounds). This is especially the case with web
images that consist largely of a plain or transparent
background.


PNG is also faster when opening a large file than
JPEG2000. However, for the majority of straight
outdoor photos, JPEG2000 files are smaller. JPEG2000
also gives you the option of saving to a much smaller
lossy format, which can be set to a near lossless
level. PNG will only allow you to save as totally
lossless.


JPEG2000's potential advantage, when it comes to using
it for efficient backup storage is due to it's wavelet
compression method (similar to the type of compression
in Genuine Fractals Printshop series). It is said that
this results in a less noisy, smoother edged image
when the file is enlarged. I have not yet seen the
result of extensive tests that would prove this to be
the case, however.


Thanks to all of you for bringing up the subject.
Hopefully, these comments will add some needed
perspective.


Ken Milburn


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