Transparently decompressing data in archive to allow greater compression later

Posted by Vi. on Super User See other posts from Super User or by Vi.
Published on 2011-05-10T14:06:02Z Indexed on 2012/11/06 23:05 UTC
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compression

I have, for example, filesystem image which have some compressed files (with weak compression such as gzip), for example, manpages or archives with the same uncompressed content nearby.

How to pre-filter the data to "expand" compressed data to plain form (to re-compress it with strong compression) and then post-filter after decompression to restore original "semi-compressed" image? SHA-1 match is advices but not strictly required (but the resulting image must work, e.g. re-compressed files should not grow too much, be decompressible etc.)

Like improving compression ratio by reversing weak compression algorithms.

Are there programs for this?

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