Ubuntu Manpage: chafa - Character art facsimile generator

NAME

       chafa - Character art facsimile generator

SYNOPSIS

       chafa [OPTION...] [IMAGE...]

DESCRIPTION

       chafa is a command-line utility that converts image data, including animated GIFs, into
       graphics formats or ANSI/Unicode character art suitable for display in a terminal. It has
       broad feature support, allowing it to be used on devices ranging from historical
       teleprinters to modern terminal emulators and everything in between.

       You can specify one or more input files, but the default behavior is slightly different
       with multiple files -- for instance, animations will not loop forever when there is more
       than one input file.

GENERAL OPTIONS

       -h, --help
           Show a brief help text.

       --version
           Show version, feature and copyright information.

OUTPUT ENCODING

       -f, --format format
           Set output format; one of [iterm, kitty, sixels, symbols]. The default is iterm, kitty
           or sixels if the connected terminal supports one of these, falling back to symbols
           ("ANSI art") otherwise.

       -O num, --optimize num
           Compress the output by using control sequences intelligently [0-9]. 0 disables, 9
           enables every available optimization. Defaults to 5, except for when used with "-c
           none", where it defaults to 0.

       --relative bool
           Use relative cursor positioning [on, off]. When on, control sequences will be used to
           position images relative to the cursor. When off, newlines will be used to separate
           rows instead for e.g. 'less -R' interop. Defaults to off.

       --passthrough mode
           Graphics protocol passthrough [auto, none, screen, tmux]. Used to show pixel graphics
           from within multiplexers. Defaults to auto, which will enable passthrough if the Kitty
           terminal is detected along with one of the supported multiplexers. Other combinations
           must be enabled manually; use with the -f option to select the appropriate graphics
           protocol.

       --polite bool
           Polite mode [on, off]. Inhibits escape sequences that on rare occasions may confuse
           the terminal or other programs. Defaults to off.

SIZE AND LAYOUT

--align ALIGN
Align images in viewport. The following alignments are understood: left, right, top,
bottom, hcenter, vcenter, center. Two orthogonal alignments can be separated by a
comma, e.g. "center,right". The meaning of "center" depends on context, and defaults
to "hcenter" if ambiguous. "center,center" will center along both axes.

Centering vertically makes sense when used together with "--clear", or possibly as
part of a scheme where the cursor is pre-positioned at the top-left corner of the
view, or a subview when used with "--relative on".

-C bool, --center bool
Center images horizontally in the view [on, off]. Defaults to off. This option is
deprecated; use "--align center" instead.

--clear
Clear screen before processing each file.

--exact-size mode
Try to match the input's size exactly [auto, on, off]. When on, this will override
other sizing options and produce output images at the exact pixel size of the inputs.
In auto mode, scaling will be avoided (in exchange for padding) if the output size is
equal to or slightly bigger than the input. When off, padding will never be added, and
the image is scaled to fit the containing cell extent. Defaults to auto.

--fit-width
Fit images to the view's width, potentially exceeding its height.

--font-ratio width/height
Target font's width/height ratio. Can be specified as a real number or a fraction.
Defaults to 1/2. This will only be applied in symbol mode.

--margin-bottom num
When terminal size is detected, reserve at least this many rows at the bottom as a
safety margin. Can be used to prevent images from scrolling out. Defaults to 1.

--margin-right num
When terminal size is detected, reserve at least this many columns on the right-hand
side as a safety margin. Defaults to 0.

--scale num
Scale image, respecting terminal's maximum dimensions. 1.0 approximates original pixel
dimensions. Specify "max" to use all available space. Defaults to 1.0 for pixel
graphics and 4.0 for symbols.

-s widthxheight, --size widthxheight
Set maximum output image dimensions in columns and rows. By default this will be equal
to the view size (see --view-size).

--stretch
Stretch image to fit output dimensions; ignore aspect. Implies --scale max.

--view-size widthxheight
Set the view size in columns and rows. By default this will be the size of your
terminal, or 80x25 if size detection fails. If one dimension is omitted (by providing
a size of e.g. 80x or x25), it will be set to a reasonable approximation of infinity.

ANIMATION AND TIMING

       --animate bool
           Whether to allow animation [on, off]. Defaults to on. When off, will show a still
           frame from each animation.

       -d, --duration seconds
           Time to show each file, in seconds. Defaults to zero for still images and for
           animations when multiple files are specified. If a single animation is specified,
           defaults to infinite, or "inf". Animations will always be played through at least
           once, even if duration is e.g. zero. See the "Duration" section for more.

       --speed speed
           Set the speed animations will play at. This can be either a unitless multiplier
           (fractions are allowed), or a real number followed by "fps" to apply a specific
           framerate.

       --watch
           Watch a single input file, redisplaying it whenever its contents change. Will run
           until manually interrupted or, if --duration is set, until it expires.

COLORS AND PROCESSING

--bg color
Background color of display (color name or hex). Partially transparent input will be
blended with this color. Color names are based on those provided with X.Org. Defaults
to black.

-c mode, --colors mode
Set output color mode; one of [none, 2, 8, 16/8 16, 240, 256, full]. The 240-color
mode is recommended over the 256-color one, since the lower 16 colors are unreliable
and tend to differ between terminals. 16-color mode will use aixterm extensions to
produce 16 foreground and background colors. The 16/8 mode allows for 8 colors plus
another "bright" 8 colors in the foreground implemented with the "bold" escape
sequence. 2-color mode will only emit the ANSI codes for reverse color and attribute
reset, while "none" will emit no escape sequences at all.

In sixel mode, "full" will dynamically generate a 256-color palette for each image or
animation frame. The other modes refer to built-in palettes. "none" and "2" are
interchangeable and will use the specified foreground/background colors (see --fg and
--bg).

If left unspecified, an optimal default will be chosen based on the current
environment.

--color-extractor extractor
Method for extracting color from an area; one of [average, median]. Median normally
produces crisper output, while average may perform better on noisy images. Defaults to
average.

--color-space cs
Color space used for quantization; one of [rgb, din99d]. Defaults to rgb, which is
faster but less accurate.

--dither type
Type of dithering to apply during quantization. One of [none, ordered, diffusion].
"Bayer" is a synonym for "ordered", and "fs" (Floyd-Steinberg) is a synonym for
"diffusion".

--dither-grain widthxheight
Dimensions of grain used when dithering. Specified as width x height, where each can
be one of [1, 2, 4, 8] pixels. One character cell is by definition 8 pixels across in
both dimensions. Defaults to 4x4 in symbol mode and 1x1 in sixel mode.

--dither-intensity intensity
Intensity of dithering pattern. Ranges from 0.0 to infinity, with 1.0 considered
neutral. Lower values tend to reduce the amount of dithering done, while higher values
increase it. In practice, values higher than 10.0 are unlikely to produce useful
results.

--fg color
Foreground color of display (color name or hex). Together with the background color
specified by --bg, this specifies the terminal's palette in color modes 2 and none.
Color names are based on those provided with X.Org. Defaults to white.

--invert
Invert video. For display with bright backgrounds in color modes 2 and none. Swaps
--fg and --bg.

-p bool, --preprocess bool
Image preprocessing [on, off]. Defaults to on with 16 colors or lower, off otherwise.
This enhances colors and contrast prior to conversion, which can be useful in
low-color modes.

-t threshold, --threshold threshold
Threshold above which full transparency will be used [0.0 - 1.0]. Setting this to 0.0
will render a blank image, while a value of 1.0 will replace any transparency with the
background color (configurable with --bg).

RESOURCE ALLOCATION

       --threads num
           Maximum number of CPU threads to use. If left unspecified or negative, this will equal
           available CPU cores.

       -w num, --work num
           How hard to work in terms of CPU and memory [1-9]. 1 is the cheapest, 9 is the most
           accurate. Defaults to 5.

EXTRA OPTIONS FOR SYMBOL ENCODING

       --fg-only
           Leave the background color untouched. This produces character-cell output using
           foreground colors only, and will avoid resetting or inverting the colors.

       --fill symbols
           Specify character symbols to use for fill/gradients. Defaults to none. Usage is
           similar to that of --symbols; see below.

       --glyph-file file
           Load glyph information from file, which can be any font file supported by FreeType
           (TTF, PCF, etc). The glyph outlines will replace any existing outlines, including
           builtins. Useful in symbol mode for custom font support or for improving quality with
           a specific font. Note that this only makes sense if the output terminal is using a
           matching font. Can be specified multiple times.

       --symbols symbols
           Specify character symbols to employ in final output. See below for full usage and a
           list of symbol classes.

EXIT STATUS

       chafa will return 0 on success, 1 on partial failure or 2 on complete failure (including
       when invoked with no arguments).

       Status   Meaning
       0        Success
       1        Some files failed to display
       2        All files failed to display

SYMBOLS

       Accepted classes for --symbols and --fill are [all, none, space, solid, stipple, block,
       border, diagonal, dot, quad, half, hhalf, vhalf, inverted, braille, technical, geometric,
       ascii, legacy, sextant, wedge, wide, narrow]. Some symbols belong to multiple classes,
       e.g. diagonals are also borders.

       You can add specific characters with the letter "u" followed by a hexadecimal code point,
       e.g. "ue080", or a range of code points by separating the first and last index by "..",
       e.g. "u100..u200".

       Symbol sets can also be specified as a string of UTF-8 characters in square brackets, e.g.
       [abcd]. To include a closing bracket in the set, escape it with a backslash.

       You can specify a list of classes separated by commas, or prefix them with + and - to add
       or remove symbols relative to the existing set. The ordering is significant.

       The default symbol set is block+border+space-wide-inverted for all modes except "none",
       which uses block+border+space-wide (including inverse symbols).

DURATION

       In order to accommodate both interactive use and batch processing, an animation's duration
       is determined according to a few simple rules:

        1. If one or more --duration arguments are present, the final instance is respected and
           applied to every file.

        2. Otherwise, if there's a controlling terminal attached (indicating there's an
           interactive session), and only a single file argument is provided, and that file is an
           animation, it will have infinite duration.

        3. Otherwise (no controlling terminal, multiple files, file is a still image), duration
           will be zero, causing animations to play once and then stop.

EXAMPLES

       chafa in.gif
           Show a potentially animated GIF image in the terminal. If this is an animation, it
           will run until the user generates an interrupt (typically ctrl-c). All parameters will
           be autodetected based on the current environment.

       chafa -c full -s 200 in.gif
           Like the above, but force truecolor output that is 200 characters wide and calculate
           the height preserving the aspect of the original image.

       chafa -c 16 --color-space din99d --symbols -dot in.jpg
           Generate 16-color output with perceptual color picking and avoid using dot symbols.

       chafa -c none --symbols block+border-solid in.png
           Generate uncolored output using block and border symbols, but avoid the solid block
           symbol.

AUTHOR

       Written by Hans Petter Jansson[2] <hpj@hpjansson.org>.

NOTES

        1. Chafa homepage
           https://hpjansson.org/chafa/

        2. Hans Petter Jansson
           https://hpjansson.org/