cjxl.txt (2875B)
1 cjxl(1) 2 ======= 3 :doctype: manpage 4 5 Name 6 ---- 7 8 cjxl - compress images to JPEG XL 9 10 Synopsis 11 -------- 12 13 *cjxl* ['options'...] 'input' ['output.jxl'] 14 15 Description 16 ----------- 17 18 `cjxl` compresses an image or animation to the JPEG XL format. It is intended to 19 spare users the trouble of determining a set of optimal parameters for each 20 individual image. Instead, for a given target quality, it should provide 21 consistent visual results across various kinds of images. The defaults have been 22 chosen to be sensible, so that the following commands should give satisfactory 23 results in most cases: 24 25 ---- 26 cjxl input.png output.jxl 27 cjxl input.jpg output.jxl 28 cjxl input.gif output.jxl 29 ---- 30 31 Options 32 ------- 33 34 -h:: 35 --help:: 36 Displays the options that `cjxl` supports. On its own, it will only show 37 basic options. It can be combined with `-v` or `-v -v` to show increasingly 38 advanced options as well. 39 40 -v:: 41 --verbose:: 42 Increases verbosity. Can be repeated to increase it further, and also 43 applies to `--help`. 44 45 -d 'distance':: 46 --distance='distance':: 47 The preferred way to specify quality. It is specified in multiples of a 48 just-noticeable difference. That is, `-d 0` is mathematically lossless, 49 `-d 1` should be visually lossless, and higher distances yield denser and 50 denser files with lower and lower fidelity. Lossy sources such as JPEG and 51 GIF files are compressed losslessly by default, and in the case of JPEG 52 files specifically, the original JPEG can then be reconstructed bit-for-bit. 53 For lossless sources, `-d 1` is the default. 54 55 -q 'quality':: 56 --quality='quality':: 57 Alternative way to indicate the desired quality. 100 is lossless and lower 58 values yield smaller files. There is no lower bound to this quality 59 parameter, but positive values should approximately match the quality 60 setting of libjpeg. 61 62 -e 'effort':: 63 --effort='effort':: 64 Controls the amount of effort that goes into producing an ``optimal'' file 65 in terms of quality/size. That is to say, all other parameters being equal, 66 a higher effort should yield a file that is at least as dense and possibly 67 denser, and with at least as high and possibly higher quality. 68 + 69 Recognized effort settings, from fastest to slowest, are: 70 + 71 - 1 or ``lightning'' 72 - 2 or ``thunder'' 73 - 3 or ``falcon'' 74 - 4 or ``cheetah'' 75 - 5 or ``hare'' 76 - 6 or ``wombat'' 77 - 7 or ``squirrel'' (default) 78 - 8 or ``kitten'' 79 - 9 or ``tortoise'' 80 81 Examples 82 -------- 83 84 ---- 85 # Compress a PNG file to a high-quality JPEG XL version. 86 $ cjxl input.png output.jxl 87 88 # Compress it at a slightly lower quality, appropriate for web use. 89 $ cjxl -d 2 input.png output.jxl 90 91 # Compress it losslessly. These are equivalent. 92 $ cjxl -d 0 input.png lossless.jxl 93 $ cjxl -q 100 input.png lossless.jxl 94 95 # Compress a JPEG file losslessly. 96 $ cjxl input.jpeg lossless-jpeg.jxl 97 ---- 98 99 See also 100 -------- 101 102 *djxl*(1)