Re: filmscanners: File format

["Alan Tyson" <AlanTyson@bknowl.freeserve.co.uk>]

No-one has commented on the difference between my results
 a bit of lace jpegged 10 times), posted on 30Mar, and
Henk's image of a letter on a plain background, similarly
treated. I can assure folk that I saved each image under a
new name and only *then* closed it before reloading it.

Is it perhaps that jpeg is specially suited to
'photographic' images, and not to areas of single solid
colours with sharp edges like Henk's image? The latter is
rare in photographic images, and lossless gif does an
excellent compression job on that sort of thing anyway.

Would someone who understands the maths of jpeg compression
care to comment and suggest reasons for the discrepancy,
please?

Or maybe Henk's and my results need repeating, like cold
fusion and life on Mars?

Alan T


----- Original Message -----
From: Hugo Gävert <hugo@cc.hut.fi>
To: <filmscanners@halftone.co.uk>
Sent: Monday, April 02, 2001 12:44 PM
Subject: Re: filmscanners: File format


Come on guys, what happens when you save with jpeg or any
other
compression that loses data? You save the file, the
compression algorithm
desides what information can be thrown away, and then saves
it......