[OSGeo-Discuss] 'lossless' JPEG2000

[Christopher Schmidt]

On Mon, Feb 25, 2008 at 09:04:59PM -0500, Ed McNierney wrote:
> Christopher -
> 
> You will very likely find that using different LZW compression options (particularly setting a small strip size) will slightly degrade compression performance while significantly improving read time.  While I think your test data are valid, they only address one of many possible configurations and I wouldn't necessarily make broad generalizations about LZW from them.
> 
> However, I have generally found that LZW compression for photographic data is indeed not a good choice; I'm surprised you got it to perform as well as you did (in compression).

Yeah, I think we've stumbled back and forth across these numbers before.
I'm aware that they're essentially 'back of the envelope': they weren't
run entirely in isolation, they were only repeated a couple of times
(half dozen rather than an order of magnitude more), they might have
been cached in memory, etc. etc. etc. However, they do seem to serve as
a good 'order of magnitude' measure of size and performance for
compressing aerial imagery based on other similar experiments, and I
have no evidence to seriously discount them, so I'm sticking to them.

Regards,
-- 
Christopher Schmidt
Web Developer