lossless compression of still images - recommendations?

Karl Auer kauer at biplane.com.au
Sat Feb 18 22:43:20 UTC 2017


On Sat, 2017-02-18 at 21:11 +0000, Colin Law wrote:
> On 17 February 2017 at 21:11, Robert Heller <heller at deepsoft.com>
> wrote:
> > 
> > Use tar+bzip2.
> I thought that the OP meant that he wanted to compress the series of
> images, making use of the fact that they are little changed from one
> image to the next. Much like video is stored.

Because the images are very alike, they should compress exceptionally
well. That's kinda how modern compression works; it looks for recurring
sequences in the data and replaces them with a index numbers
representing those sequences. It stores the sequence once, and the
index many times. Multipass compression looks for metasequences and
does the same with them.

I think the OP will get better compression out of tarring them up
first, then compressing them, because that lets the compression program
look for sequences across the whole set, not just within one image.
However, it would be worth trying both (compress first and tar first).
It would also be worth trying a few different compression programs.

Regards, K.

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