Jim Snyder wrote:
[chop]
you can stand a little bit of image quality loss, use ZIP
[chop]
Hmmmm - this email list needs an FAQ - or
some pointers to certain image FAQs on the
web now and again.
Image compression is a rather complex mathematical
process that usually requires some 'dumping' of
image data to gain good compression ratios - thus
these compression schemes are 'lossy'.
Non-lossy compression schemes use LZW type compressors
which are good when there is a lot of replicated data
in a file - but not so good for images that have a
large variation of data components.
The problem with most people is the mixup of file
formats with compression schemes. For example, TIF
can be compressed or uncompressed - it uses LZW
to compress - but two TIF files are still called
XXX.TIF and YYY.TIF even though one is raw data
and one is compressed data. There is no such thing
as an 'LZW' extension - only file formats that use
it.
Ive attached a small HTML doc with some specs.
Not exact, but a guide - if anyone wants to add
formats then do so.
bert
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