Bert wrote:
>Ive attached a small HTML doc with some specs.
>Not exact, but a guide - if anyone wants to add
>formats then do so.
Very good post, Bert, and thank you.
IMO, some of the confusion, vis a vis archiving, is based on "lossy" vs.
"lossless" compression. STM the difference is in how it's to be used. If the
files are going to be uses for public viewing (as mine are, and consistently
have been), then the "lossy" JPEG format is perfectly acceptable, as long as
you keep the JPEG artifacts out of your pictures (you can recognize them by
their "shimmery" off-color pixels, and adjust back if you have a proper
JPEGing program).
If you're going to later do either retouching or large blow-ups, then the
much-higher-sized "lossless" file compressions are what you should use. In
fact, you should probably save in the uncompressed Photoshop (or whatever)
format, "shine" the compression, and just take your lumps with file size.
:-)
Bert's attachment is an excellent guide, and thanks again for the input.
Best regards--LRA
>From: Robert Logan <rl@dmu.ac.uk>
>Reply-To: filmscanners@halftone.co.uk
>To: Filmscanners@halftone.co.uk
>Subject: Re: filmscanners: (anti)compression?
>Date: Tue, 07 Aug 2001 14:31:15 +0100
>
>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
>Filmscanners archive at:
>
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