[gdal-dev] tiff format: compression vs. performance

[Ed McNierney]

Andrey -

I think in my dictionary "quite incompressible" and "10% of source file
size" are the same thing <g>!

Thanks for that observation - it helps show why it's important not to
generalize too much; for some users a 10% savings is important, and for
others it's not worth the trouble.

	- Ed

-----Original Message-----
From: gdal-dev-bounces at lists.osgeo.org
[mailto:gdal-dev-bounces at lists.osgeo.org] On Behalf Of Andrey Kiselev
Sent: Tuesday, January 15, 2008 10:49 AM
To: gdal-dev at lists.osgeo.org
Subject: Re: [gdal-dev] tiff format: compression vs. performance

Ed,

On Tue, Jan 15, 2008 at 10:03:57AM -0500, Ed McNierney wrote:
> You also need to look at the properties of your data, especially if
> you're limiting yourself to uncompressed, PackBits, and LZW-compressed
> TIFFs.  Some data sets (aerial photography) are usually quite
> incompressible using those algorithms.  They're not going to get any
> smaller if you try to compress them, so there's no point in trying.

That depends on what you call a "compression". I think everything that
saves more than 10% of source file size is a good result for my needs.
And you can get such a ratio almost for every photography, just do not
forget to utilize data predictor. In most cases you will get better
ratios. And there is no reason to omit deflate compression. It has worse
performance than LZW, but better compression ratios.

Best regards,
Andrey

-- 
Andrey V. Kiselev
ICQ# 26871517
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