Lossless:
ie when you uncompress you get an exact of the original
TIF LZW - compression 5-20% for photo images
PNG - compression 10-40% for photo images
Note that PNG will always be smaller due to
a more efficient algorithm.
Original: 24532 Kb = 2500x3300@24bit
TIF LZW: 20336 Kb = 17% smaller
PNG: 16348 Kb = 33% smaller
Lossy:
ie when u uncompress you get less than the original
but much better compression
JPG@15%: 1440 Kb
JPG@25%: 990 Kb
GIF: 6675 Kb
PNG@8: 5172 Kb
Note that JPG uses 24 bit colour and throws away data
that the human eye/ brain ignores to some extent.
GIF uses a 256 colour indexed system - for photo images
it is terrible. PNG using 256 colour compresses smaller
than GIF due to a more sophistcated algorithm.
Conclusions (please contribute):
TIF LZW is fine, but PNG is a lot better. Both are lossy
but TIF has been around longer, and thus is better
supported. PNG is realtively new, but it is open-source
meaning that any software developer can use its code,
which is freely available ... so if its not there then
complain.
Forget GIF. Its wayyyy too lossy for photo images. For
low colour images (<256) it is fine, but PNG does a
better job than GIF anyway for this type of image.
Most browsers support JPG/GIF/PNG.
PNG offers support for 8/24/48 bit colour, with better
compression than TIF (significantly).
Personally. I store in PNG format on CD, with a nice
auto generated index.html file displaying thumbnail
JPG images which lead to medium size 800xAAA JPG images
and large 1400xAAA images. This gives me a full monitor
view and a web capable view.
bert
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