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I decided to use JPEG 2000 to save disk space on my photo archive a decade ago... huge mistake. [edit] I thought I had the originals backed up on CD, it turns
by mikewarot 4y ago
I decided to use JPEG 2000 to save disk space on my photo archive a decade ago... huge mistake.
[edit] I thought I had the originals backed up on CD, it turns out I didn't.
DigiKam and many other programs don't support them natively.
At some point I'm going to have to write a script and convert them all to normal jpegs.
- melissalobos 4y agoWhy was it a huge mistake? There are decent libraries that support it. Did it just not work with your cloud setup or OS libraries?
- simonh 4y agoCheck the article’s discussion of rendering bugs and implementation incompatibilities.
- melissalobos 4y agoSure those were encountered there, but at least in my experience those are easily avoided. I have had to make test suites for this, and in my experience if you use reasonable libraries things work well.
- alophawen 4y agoAre you suggesting the parent sets up test suites for a cloud solution and call it a day? How would that guarantee safe storage, given the previous discussion of all the broken implementations.
- mindslight 4y agoI was thinking about using JPEG2000 to archive scan masters, because I hate the look of original JPEG artifacts. In the end I decided to go with FLIF to eliminate the "preservation risk" - by being lossless, I can run the output through sha256 to make sure I've gotten all the original bits back. In the event that I regret this decision, I can simply transcode and not feel too bad (as opposed to transcoding from lossless and losing even more quality).
- matja 4y agoImageMagick and GNU parallel happily max-out all cores on my machine and convert a few hundred images per second: find -type f -name '*.jp2' | parallel --xargs --max-args=1 convert {} {.}.jpg
- prvc 4y agoWould be yet another lossy transcode, though.
- acomjean 4y agoYou could convert to png or tiff if you wanted lossless. Jpg at high quality is pretty good for general photo saving if you aren't doing tons of modifications after the fact. I think some editors now save the original and just store the modification steps (Lightroom does this for raw at least.)
- grumbel 4y agoUse JPEG XR, that has a lossless mode and better compression than you would get with .png. Though of course that puts you at risk of using yet another unproven format. Though it seems to be on track to become the JPEG successor from what I understand.
- ars 4y agoConvert them to JPEG XL instead. It seems to be the future widely supported format, and it can loselessly convert back and forth with regular JPEG.
- UberFly 4y agoI don't think you can ever convert to a regular JPEG and the outcome will be lossless. Like Webp ,JPEG XL has a lossless setting but it has to remain there.
- pabs3 4y agoI tried it on my computer. Converting from JPEG to JPEG XL and then back to JPEG gets you a bit-wise identical JPEG file.
- lioeters 4y agoI'm guessing the opposite (XL -> JPEG -> XL) does not work, i.e., "losslessly convert back and forth with regular JPEG".
- pabs3 4y agoJust tried it and JPEG -> XL -> JPEG -> XL is bit-wise identical between the two JPEGs and bit-wise identical between the two JPEG XLs.
- iggldiggl 4y agoI think the issue at hand is that behind the scenes, JPEG XL the image format actually combines three different kinds of image compression algorithms: 1. native JPEG XL lossy compression 2. JPEG lossy compression, but using a more space-efficient storage format than classic JPEG 3. lossless compression The lossless conversion between JPEG XL and JPEG only works with 2). Normally you'd only use 2) for existing JPEG images in order to avoid a lossy re-compression, and use 1) for any freshly-created images because native JPEG XL compression will compress the image data even more efficiently than the JPEG compatibility-mode, though if you've got strong interoperability constraints with clients requiring JPEG data you might possibly want to store even newly created images using sub-format 2) in order to get the ability to losslessly convert back and forth between JPEG XL and JPEG.