[filmscanners] RE: Archiving and when to sharpen(was:Color spaces for differentpurposes)

["Laurie Solomon" <laurie@advancenet.net>]

>Since JPEG is lossless and TIFF is not, this is to be expected.
Don't you have this reversed?  My understanding is that JPEG is lossy while
TIFF with LZW is lossless.

-----Original Message-----
From: filmscanners_owner@halftone.co.uk
[mailto:filmscanners_owner@halftone.co.uk]On Behalf Of Anthony Atkielski
Sent: Monday, June 10, 2002 4:05 PM
To: laurie@advancenet.net
Subject: [filmscanners] Re: Archiving and when to sharpen(was:Color
spaces for differentpurposes)


Mac writes:

> Contrary to what Anthony Atkielski wrote,
> I have NEVER seen a LZW Tiff come out larger
> than an uncompressed one, regardless of exact
> pixel content.

Real-world photographic images rarely come out larger after compression, but
I can generate such an image in about 30 seconds in Photoshop.  I did that
just now and got one that is 20% larger after compression.

> I have also never seen a compressed TIFF
> come out equal to or smaller than a JPEG
> at the same pixel dimensions, regardless of
> how how the quality setting of the JPEG.

Since JPEG is lossless and TIFF is not, this is to be expected.

> The only time I've seen a compressed file come
> out larger than a non-compressed one
> is when using .zip on a JPEG.

JPEGs are virtually incompressible to begin with, which is why attempts to
losslessly compress them further will often produce larger files.

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