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TOPIC: Are images re compressed during format conversion?

Are images re compressed during format conversion? 10 years 1 week ago #398

  • mmalone27
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First off, thank you for such a great piece of software. It has totally changed the way I think about managing digital comics.

I understand that in order to have the tags persist whenever the file is moved to a non-NTFS file system, I should use CBZ files, and change the option allowing the info to be saved to the file. I have a lot of CBR files that I want to convert to CBZ for this, but I noticed that after doing a conversion such as this, the actual file size of the individual jpegs in the archive changes by a few bytes. I know the jpeg file names are changed, but are the files themselves being rewritten and compressed again? I want to do the conversion without loosing image quality. If ComicRack is not altering the jpegs, why is the file size different? I even tried to convert back and forth from cbr to cbz to cbt to cbz to compare each version. I would expect the two CBZ files to be identical, or at least their jpegs to be identical. However, both CBZ files contain jpegs with different file sizes.

So, are any of the conversion processes lossy? If so, which ones are safe, if any? If they are lossy, I'll just extract the original CBR files and create the CBZ files manually.

Thanks for giving my rambling some thought. I did search for the answer first.
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Re:Are images re compressed during format conversi 10 years 1 week ago #404

  • cYo
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currently conversion/saving is recompressing the images. You got that right.

The next release will have conversion/saving between cbr/cbz/cbt without recompressing. Storing/reading from PDF will still go through a recompression - it's PDF :P

Thanks for the hint. I had this for a long time on my agenda but always kinda forgot about it.
Also there will be a nice speed boost when converting/saving eComics :)
Last Edit: 10 years 1 week ago by cYo.
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Re:Are images re compressed during format conversi 10 years 1 week ago #407

  • mmalone27
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Thanks for the info. Keep up the great work!
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Re:Are images re compressed during format conversi 10 years 1 week ago #420

  • mmalone27
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I just saw this was added to the new release. You are awesome!
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Re:Are images re compressed during format conversi 9 years 11 months ago #561

Yeah, just to make it explicit here: there is no recompression anymore (except for PDF format). So, if you want to \"bounce\" between file formats, whenever you come back to the original format, the files will be exactly like the original ones.
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