On Jan 19, 8:57 pm, John Navas wrote:
On Sat, 19 Jan 2008 07:09:48 -0800 (PST), Sachin Garg
wrote in
:

On Jan 19, 1:38 pm, Ron Hunter wrote:
JPEG and 'losless' are really mutually exclusive terms.
The whole idea of JPEG compression is to achieve high compression rates
(6:1 or better), by discarding information not required for satisfactory
image quality, and then applying a standard compression technique, such
as LZW with Huffman, to the result. Leaving out the lossy step results
in dramatically reduced compression. Not worth bothering with.

You are correct that JPEG is lossy. These tools apply further lossless
compression on jpeg files.

Think of it as something similar to using zip.

I think his point is that lossy compression isn't a good choice for
archival storage in the first place.

Ah, I thought he misunderstood what these tools do :-)

But anyway, that mostly depends on what one wants more (quality and
ability to do good post-processing, or just small good-enough files)
and most of the time we just don't get the choice (most cameras do
jpeg only).

In general however, I agree that loss should be avoided wherever
possible.

Sachin Garg [India]
www.sachingarg.com | www.c10n.info