'\" t
.\"     Title: cjxl
.\"    Author: [FIXME: author] [see http://www.docbook.org/tdg5/en/html/author]
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 04/07/2024
.\"    Manual: \ \&
.\"    Source: \ \&
.\"  Language: English
.\"
.TH "CJXL" "1" "04/07/2024" "\ \&" "\ \&"
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.nh
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.\" * MAIN CONTENT STARTS HERE *
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.SH "NAME"
cjxl \- compress images to JPEG XL
.SH "SYNOPSIS"
.sp
\fBcjxl\fR [\fIoptions\fR\&...] \fIinput\fR [\fIoutput\&.jxl\fR]
.SH "DESCRIPTION"
.sp
cjxl compresses an image or animation to the JPEG XL format\&. It is intended to spare users the trouble of determining a set of optimal parameters for each individual image\&. Instead, for a given target quality, it should provide consistent visual results across various kinds of images\&. The defaults have been chosen to be sensible, so that the following commands should give satisfactory results in most cases:
.sp
.if n \{\
.RS 4
.\}
.nf
cjxl input\&.png output\&.jxl
cjxl input\&.jpg output\&.jxl
cjxl input\&.gif output\&.jxl
.fi
.if n \{\
.RE
.\}
.SH "OPTIONS"
.PP
\-\-container=\fI0|1\fR
.RS 4
0 = Do not encode using container format (strip Exif/XMP/JPEG bitstream reconstruction data)\&.1 = Force using container format (default: use only if needed)\&.
.RE
.PP
\-\-jpeg_store_metadata=\fI0|1\fR
.RS 4
If \-\-lossless_jpeg=1, store JPEG reconstruction metadata in the JPEG XL container (for lossless reconstruction of the JPEG codestream)\&.(default: 1)
.RE
.PP
\-d \fIdistance\fR, \-\-distance=\fIdistance\fR
.RS 4
Max\&. butteraugli distance, lower = higher quality\&. 0\&.0 = mathematically lossless\&. Default for already\-lossy input (JPEG/GIF)\&. 1\&.0 = visually lossless\&. Default for other input\&. Recommended range: 0\&.5 \&.\&. 3\&.0\&. Mutually exclusive with \-\-quality\&.
.RE
.PP
\-q \fIquality\fR, \-\-quality=\fIquality\fR
.RS 4
Quality setting (is remapped to \-\-distance)\&. Range: \-inf \&.\&. 100\&. 100 = mathematically lossless\&. Default for already\-lossy input (JPEG/GIF)\&. Other input gets encoded as per \-\-distance default\&. Positive quality values roughly match libjpeg quality\&. Mutually exclusive with \-\-distance\&.
.RE
.PP
\-e \fIeffort\fR, \-\-effort=\fIeffort\fR
.RS 4
Encoder effort setting\&. Range: 1 \&.\&. 9\&. Default: 7\&. Higher number is more effort (slower)\&.
.sp
Recognized effort settings, from fastest to slowest, are:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
1 or \(lqlightning\(rq
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
2 or \(lqthunder\(rq
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
3 or \(lqfalcon\(rq
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
4 or \(lqcheetah\(rq
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
5 or \(lqhare\(rq
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
6 or \(lqwombat\(rq
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
7 or \(lqsquirrel\(rq (default)
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
8 or \(lqkitten\(rq
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
9 or \(lqtortoise\(rq
.RE
.RE
.PP
\-\-brotli_effort=\fIB_EFFORT\fR
.RS 4
Brotli effort setting\&. Range: 0 \&.\&. 11\&. Default: 9\&. Higher number is more effort (slower)\&.
.RE
.PP
\-\-faster_decoding=\fI0|1|2|3|4\fR
.RS 4
Favour higher decoding speed\&. 0 = default, higher values give higher speed at the expense of quality
.RE
.PP
\-p, \-\-progressive
.RS 4
Enable progressive/responsive decoding\&.
.RE
.PP
\-\-premultiply=\fI\-1|0|1\fR
.RS 4
Force premultiplied (associated) alpha\&.
.RE
.PP
\-\-keep_invisible=\fI0|1\fR
.RS 4
Force disable/enable preserving color of invisible pixels (default: 1 if lossless, 0 if lossy)\&.
.RE
.PP
\-\-group_order=\fI0|1\fR
.RS 4
Order in which 256x256 groups are stored in the codestream for progressive rendering\&. Value not provided means
\fIencoder default\fR, 0 means
\fIscanline order\fR, 1 means
\fIcenter\-first order\fR\&.
.RE
.PP
\-\-center_x=\fI0\&.\&.XSIZE\fR
.RS 4
Determines the horizontal position of center for the center\-first group order\&. The value \-1 means
\fIuse the middle of the image\fR, other values [0\&.\&.xsize) set this to a particular coordinate\&.
.RE
.PP
\-\-center_y=\fI0\&.\&.YSIZE\fR
.RS 4
Determines the vertical position of center for the center\-first group order\&. The value \-1 means
\fIuse the middle of the image\fR, other values [0\&.\&.ysize) set this to a particular coordinate\&.
.RE
.PP
\-\-progressive_ac
.RS 4
Use the progressive mode for AC\&.
.RE
.PP
\-\-qprogressive_ac
.RS 4
Use the progressive mode for AC with shift quantization\&.
.RE
.PP
\-\-progressive_dc=\fInum_dc_frames\fR
.RS 4
Progressive\-DC setting\&. Valid values are: \-1, 0, 1, 2\&.
.RE
.PP
\-m=\fI0|1\fR, \-\-modular=\fI0|1\fR
.RS 4
Use modular mode (not provided = encoder chooses, 0 = enforce VarDCT, 1 = enforce modular mode)\&.
.RE
.PP
\-j=\fI0|1\fR, \-\-lossless_jpeg=\fI0|1\fR
.RS 4
If the input is JPEG, losslessly transcode JPEG, rather than using reencode pixels\&.
.RE
.PP
\-\-jpeg_reconstruction_cfl=\fI0|1\fR
.RS 4
Enable/disable chroma\-from\-luma (CFL) for lossless JPEG reconstruction\&.
.RE
.PP
\-\-num_threads=\fIN\fR
.RS 4
Number of worker threads (\-1 == use machine default, 0 == do not use multithreading)\&.
.RE
.PP
\-\-num_reps=\fIN\fR
.RS 4
How many times to compress\&. (For benchmarking)\&.
.RE
.PP
\-\-photon_noise=\fIISO3200\fR
.RS 4
Adds noise to the image emulating photographic film noise\&. The higher the given number, the grainier the image will be\&. As an example, a value of 100 gives low noise whereas a value of 3200 gives a lot of noise\&. The default value is 0\&.
.RE
.PP
\-\-dots=\fI0|1\fR
.RS 4
Force disable/enable dots generation\&. (not provided = default, 0 = disable, 1 = enable)\&.
.RE
.PP
\-\-patches=\fI0|1\fR
.RS 4
Force disable/enable patches generation\&. (not provided = default, 0 = disable, 1 = enable)\&.
.RE
.PP
\-\-resampling=\fI\-1|1|2|4|8\fR
.RS 4
Resampling for extra channels\&. Default of \-1 applies resampling only for low quality\&. Value 1 does no downsampling (1x1), 2 does 2x2 downsampling, 4 is for 4x4 downsampling, and 8 for 8x8 downsampling\&.
.RE
.PP
\-\-ec_resampling=\fI1|2|4|8\fR
.RS 4
Resampling for extra channels\&. Default of \-1 applies resampling only for low quality\&. Value 1 does no downsampling (1x1), 2 does 2x2 downsampling, 4 is for 4x4 downsampling, and 8 for 8x8 downsampling\&.
.RE
.PP
\-\-already_downsampled
.RS 4
Do not downsample the given input before encoding, but still signal that the decoder should upsample\&.
.RE
.PP
\-\-epf=\fI\-1|0|1|2|3\fR
.RS 4
Edge preserving filter level, \-1 to 3\&. Value \-1 means: default (encoder chooses), 0 to 3 set a strength\&.
.RE
.PP
\-\-gaborish=\fI0|1\fR
.RS 4
Force disable/enable the gaborish filter\&. (not provided = default, 0 = disable, 1 = enable)\&.
.RE
.PP
\-\-intensity_target=\fIN\fR
.RS 4
Upper bound on the intensity level present in the image in nits\&. Leaving this set to its default of 0 lets libjxl choose a sensible default value based on the color encoding\&.
.RE
.PP
\-x=\fIkey=value\fR, \-\-dec\-hints=\fIkey=value\fR
.RS 4
color_space indicates the ColorEncoding, see Description(); icc_pathname refers to a binary file containing an ICC profile\&.
.RE
.sp
\-\-override_bitdepth=0=use from image, 1\-32=override If nonzero, store the given bit depth in the JPEG XL file metadata (1\-32), instead of using the bit depth from the original input image\&.
.PP
\-I \fIF\fR, \-\-iterations=\fIF\fR
.RS 4
[modular encoding] Fraction of pixels used to learn MA trees as a percentage\&. \-1 = default, 0 = no MA and fast decode, 50 = default value, 100 = all\&.Higher values use more encoder memory\&.
.RE
.PP
\-C \fIK\fR, \-\-modular_colorspace=\fIK\fR
.RS 4
[modular encoding] color transform: \-1=default, 0=RGB (none), 1\-41=RCT (6=YCoCg, default: try several, depending on speed)
.RE
.PP
\-g \fIK\fR, \-\-modular_group_size=\fIK\fR
.RS 4
[modular encoding] group size: \-1 == default\&. 0 ⇒ 128, 1 ⇒ 256, 2 ⇒ 512, 3 ⇒ 1024
.RE
.PP
\-P \fIK\fR, \-\-modular_predictor=\fIK\fR
.RS 4
[modular encoding] predictor(s) to use:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
0=zero,
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
1=left,
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
2=top,
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
3=avg0,
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
4=select,
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
5=gradient,
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
6=weighted,
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
7=topright,
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
8=topleft,
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
9=leftleft,
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
10=avg1,
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
11=avg2,
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
12=avg3,
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
13=toptop predictive average
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
14=mix 5 and 6,
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
15=mix everything\&.
.sp
Default 14, at slowest speed default 15
.RE
.RE
.PP
\-E \fIK\fR, \-\-modular_nb_prev_channels=\fIK\fR
.RS 4
[modular encoding] number of extra MA tree properties to use
.RE
.PP
\-\-modular_palette_colors=\fIK\fR
.RS 4
[modular encoding] Use color palette if number of colors is smaller than or equal to this, or \-1 to use the encoder default\&.
.RE
.PP
\-\-modular_lossy_palette
.RS 4
[modular encoding] quantize to a palette that has fewer entries than would be necessary for perfect preservation; for the time being, it is recommended to set \-\-palette=0 with this option to use the default palette only
.RE
.PP
\-X \fIPERCENT\fR, \-\-pre\-compact=\fIPERCENT\fR
.RS 4
[modular encoding] Use Global channel palette if the number of colors is smaller than this percentage of range\&. Use 0\-100 to set an explicit percentage, \-1 to use the encoder default\&.
.RE
.PP
\-Y \fIPERCENT\fR, \-\-post\-compact=\fIPERCENT\fR
.RS 4
[modular encoding] Use Local (per\-group) channel palette if the number of colors is smaller than this percentage of range\&. Use 0\-100 to set an explicit percentage, \-1 to use the encoder default\&.
.RE
.PP
\-\-codestream_level=\fIK\fR
.RS 4
The codestream level\&. Either
\-1,
5
or
10\&.
.RE
.PP
\-R \fIK\fR, \-\-responsive=\fIK\fR
.RS 4
[modular encoding] do Squeeze transform, 0=false, 1=true (default: true if lossy, false if lossless)
.RE
.sp
\-V \-\-version:: Print encoder library version number and exit\&.
.PP
\-\-quiet
.RS 4
Be more silent
.RE
.PP
\-\-frame_indexing=\fIstring\fR
.RS 4
If non\-empty, a string matching
\fI^(0*|1[01]*)\fR\&. If this string has a
\fI1\fR
in i\-th position, then the i\-th frame will be indexed in the frame index box\&.
.RE
.PP
\-v, \-\-verbose
.RS 4
Increases verbosity\&. Can be repeated to increase it further, and also applies to
\-\-help\&.
.RE
.PP
\-h, \-\-help
.RS 4
Displays the options that
cjxl
supports\&. On its own, it will only show basic options\&. It can be combined with
\-v
or
\-v \-v
to show increasingly advanced options as well\&.
.RE
.SH "EXAMPLES"
.sp
.if n \{\
.RS 4
.\}
.nf
# Compress a PNG file to a high\-quality JPEG XL version\&.
$ cjxl input\&.png output\&.jxl

# Compress it at a slightly lower quality, appropriate for web use\&.
$ cjxl \-d 2 input\&.png output\&.jxl

# Compress it losslessly\&. These are equivalent\&.
$ cjxl \-d 0   input\&.png lossless\&.jxl
$ cjxl \-q 100 input\&.png lossless\&.jxl

# Compress a JPEG file losslessly\&.
$ cjxl input\&.jpeg lossless\-jpeg\&.jxl
.fi
.if n \{\
.RE
.\}
.SH "SEE ALSO"
.sp
\fBdjxl\fR(1)