Jpeg XL

I’ve made an experiment with a new image compression format. And i’d like to share it with you, this format is JPEG XL.

I’ve stored in the past on the good old jpeg format for my photo files but recently i’ve heard about jpeg xl. This format is a revolution, it can be lossy or lossless, it can be reversible… If i compress a file in jpeg xl and want to have it back in jpeg, i can with a single command line with no image deterioration. A Jpeg XL file obviously take less space on disk, and is usable on my usual softwares. So i’ve made an experiment.

I’ve taken one image from my photo library and compressed it to three formats :

  • Original is jpeg
  • jpeg with jpegoptim
  • Webp which is my reference for web publication
  • and jpeg XL lossless and lossy

Here are the final results :

Format Compression level File size Perceived quality
Original Jpeg 10% 4.3M Original File
Jpegoptim Same as original 4.1M Same as Original
Webp Lossless 8.7M Same as Original
Webp Quality 90% 2.0M Close to Original
Webp Default (75%) 953K Ok some detail loss
Webp Quality 50% 695K Loss of texture nuances
Jpeg XL Lossless 3.3M Same as Original
Jpeg XL Quality 90% 2M Same as Original
Jpeg XL Quality 75% 907K Close to Original
Jpeg XL Quality 50% 530K Loss of texture nuances

What i’ve noticed during this test is that jpeg XL is really good, by default jpeg XL use a lossless compression and the file is 23% smaller on that test. I’ve also tested to revert it back to jpeg and it is amazing.

I’ve tested the lossy mode and compared it to webp file format :

  • the gain is impressive compared to the original picture size without visual difference at a quality of 90%. At this quality rate the file size between Jpeg XL and Webp is almost the same but visually there is a difference (small but noticeable).

  • At quality 75% jpeg XL performs better in size and visual accuracy.

  • At quality 50% the difference between the two format is really there, they are both bad even if Jpeg XL performs better.

After the experience, i’ve decided to convert all my photos to jpeg XL lossless.

If you’d like to compare the files by yourself, here is a link to the archive with all the files : img_compare.tar



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2024-02-24 17:51 +0100