1CJXL(1)                                                                CJXL(1)
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NAME

6       cjxl - compress images to JPEG XL
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SYNOPSIS

9       cjxl [options...] input [output.jxl]
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DESCRIPTION

12       cjxl compresses an image or animation to the JPEG XL format. It is
13       intended to spare users the trouble of determining a set of optimal
14       parameters for each individual image. Instead, for a given target
15       quality, it should provide consistent visual results across various
16       kinds of images. The defaults have been chosen to be sensible, so that
17       the following commands should give satisfactory results in most cases:
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19           cjxl input.png output.jxl
20           cjxl input.jpg output.jxl
21           cjxl input.gif output.jxl
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OPTIONS

24       -h, --help
25           Displays the options that cjxl supports. On its own, it will only
26           show basic options. It can be combined with -v or -v -v to show
27           increasingly advanced options as well.
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29       -v, --verbose
30           Increases verbosity. Can be repeated to increase it further, and
31           also applies to --help.
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33       -d distance, --distance=distance
34           The preferred way to specify quality. It is specified in multiples
35           of a just-noticeable difference. That is, -d 0 is mathematically
36           lossless, -d 1 should be visually lossless, and higher distances
37           yield denser and denser files with lower and lower fidelity. Lossy
38           sources such as JPEG and GIF files are compressed losslessly by
39           default, and in the case of JPEG files specifically, the original
40           JPEG can then be reconstructed bit-for-bit. For lossless sources,
41           -d 1 is the default.
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43       -q quality, --quality=quality
44           Alternative way to indicate the desired quality. 100 is lossless
45           and lower values yield smaller files. There is no lower bound to
46           this quality parameter, but positive values should approximately
47           match the quality setting of libjpeg.
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49       -e effort, --effort=effort
50           Controls the amount of effort that goes into producing an “optimal”
51           file in terms of quality/size. That is to say, all other parameters
52           being equal, a higher effort should yield a file that is at least
53           as dense and possibly denser, and with at least as high and
54           possibly higher quality.
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56           Recognized effort settings, from fastest to slowest, are:
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58           •   1 or “lightning”
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60           •   2 or “thunder”
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62           •   3 or “falcon”
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64           •   4 or “cheetah”
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66           •   5 or “hare”
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68           •   6 or “wombat”
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70           •   7 or “squirrel” (default)
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72           •   8 or “kitten”
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74           •   9 or “tortoise”
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EXAMPLES

77           # Compress a PNG file to a high-quality JPEG XL version.
78           $ cjxl input.png output.jxl
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80           # Compress it at a slightly lower quality, appropriate for web use.
81           $ cjxl -d 2 input.png output.jxl
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83           # Compress it losslessly. These are equivalent.
84           $ cjxl -d 0   input.png lossless.jxl
85           $ cjxl -q 100 input.png lossless.jxl
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87           # Compress a JPEG file losslessly.
88           $ cjxl input.jpeg lossless-jpeg.jxl
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SEE ALSO

91       djxl(1)
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95                                  08/10/2023                           CJXL(1)