I need to reduce the size of my photo library so I naturally want to compress them. Many of them are not quite identical, but still very similar (subsequent shots of the same scene). Is there any compression algorithm that takes advantage of this fact to effectively compress these images? 7zip (LZMA) is useless.
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You might try Paq 8 (fp8_v2.zip). I just tried it myself on 1440 similar PNG images and then again on 111 similar JPG images. Here are the results.
Compression of the PNG files took about 8 minutes and 550 MB of memory when using:
Compression of the JPG files took about 5 minutes and 125 MB of memory when using:
See also: jpg lossless image compression test |
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I would imagine that that the burrows-wheeler transform with an arithmetic coder would be ideal for this given a large enough window. What happens if you configure BZIP2 to use a block size equal to a small run of photos? It'll be slower and take more memory but the compression ratio should skyrocket. And have you tried LZMA with larger block sizes yet? |
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Not that I've seen. Probably the closest thing would be taking several similar JPEGs and putting them into an MJPEG movie. You could also use APNG or animated GIFs for a similar purpose. I'm not sure how well that would work though, and it sounds like you're already talking about movie screencaps, so repacking them into a movie file sounds... counterproductive. Maybe a better way, if you still have the clips that the screens came from, would be to simply find a command line tool that can extract the exact frame for you, copy that unique identifier into a text file someplace, and then you can always easily re-extract the frame when you need it. |
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