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jp2a(1) USER COMMANDS jp2a(1)

NAME

jp2a - convert JPEG, PNG and WebP images to ASCII

SYNOPSIS

jp2a [ options ] [ filename(s) | URL(s) ]

DESCRIPTION

jp2a will convert JPEG, PNG and WebP images to ASCII characters. You can specify a mixture of files and URLs.

OPTIONS

-
Read JPEG, PNG and WebP image from standard input
If you don't want to mess with --invert all the time, just use these instead. If you are using white characters on a black display, then use --background=dark, and vice versa.
Frame output image in a border
Use the given characters when producing the output ASCII image. Default is " ...',;:clodxkO0KXNWM".
Use truecolor (or ANSI color if truecolor is not supported) for text output and CSS color for HTML output.
Use a specific color-depth for terminal output. Valid values are: 4 (for ANSI), 8 (for 256 color palette) and 24 (for truecolor or 24-bit color).
Print debugging information when using libcurl to download images from the net.
Use the largest dimension that makes the image fit in your terminal display.
Use terminal display height and calculate width based on image aspect ratio.
Use terminal display width and calculate height based on image aspect ratio.
Use terminal display width and height.
Center image in terminal.
When used with --html and --color, then color each output character's background color. For instance, if you want to use fill-output on a light background, do

jp2a --color --html --html-fill --background=light somefile.jpg --output=dark.html

To do the same on a light background:

jp2a --color --html --html-fill --background=dark somefile.jpg --output=light.html

The default is to have fill disabled.

Flip output image horizontally
Flip output image vertically
Set output height. If only --height is specified, then output width will be calculated according to the source images aspect ratio.
Display a short help text
Converts image to grayscale when using --html or --colors.
Make ASCII output in strict XHTML 1.0. (Will output in HTML for version 2.0.0 and above.)
Make ASCII output in HTML (Living Standard), suitable for viewing with web browsers. This is useful with big output dimensions, and if you want to check the result with a browser with small font.
Make ASCII output in strict XHTML 1.0.
--html-fill
Same as --fill. You should use that option instead.
--html-no-bold
Do not use bold text for HTML output.
--html-raw
Output only the image in HTML codes, leaving out the rest of the webpage, so you can construct your own. (Will use <br> for version 2.0.0 and above instead of <br/>.)
--html-fontsize=N
Set fontsize when using --html output. Default is 4.
--html-title=...
Set HTML output title.
Write ASCII output to given filename. To explicitly specify standard output, use --output=-.
Invert output image. If you view a picture with white background, but you are using a display with light characters on a dark background, you should invert the image.
When converting from RGB to grayscale, use the given weights to calculate luminance. The default is red=0.2989, green=0.5866 and blue=0.1145.
Set output dimension.
Print some verbose information to standard error when reading each JPEG image.
Set output width. If you only specify the width, the height will be calculated automatically.
Print program version.
Sets output dimensions to your entire terminal window, disregarding source image aspect ratio.
Specifies an image gradient above which to shade lines and edges with directional glyphs (such as -/|\). The right value to pick up the edges nicely will depend on the image but might be around 0.5.
Only draw edges, so that the resulting image is like a line drawing or edge detector. This option should be used in conjunction with --edge-threshold so that edges are drawn.

RETURN VALUES

jp2a returns 1 when errors are encountered, zero for no errors.

EXAMPLES

Convert and print imagefile.jpg using ASCII characters in 40 columns and 20 rows:

jp2a --size=40x20 imagefile.jpg

Download an image off the net, convert and print:

jp2a http://www.google.com/intl/en/logos/easter_logo.jpg

Output picture.jpg and picture2.jpg, each 80x25 characters, using the characters " ...ooxx@@" for output:

jp2a --size=80x25 --chars=" ...ooxx@@" picture.jpg picture2.jpg

Output image.jpg using 76 columns, height is automatically calculated from aspect ratio of image.jpg

cat image.jpg | jp2a --width=76 -

If you use jp2a together with ImageMagick's convert(1) then you can make good use of pipes, and have ImageMagick do all sorts of image conversions and effects on the source image. For example:

magick somefile.gif jpg:- | jp2a - --width=80

Check out convert(1) options to see what you can do. Convert can handle almost any image format, so with this combination you can convert images in e.g. PDF or AVI files to ASCII.

jp2a uses a very basic scaling algorithm for every image format except WebP. To get better quality, convert an image to WebP to make use of the scaling built into the libwebp library:

cwebp -quiet image.jpg -o - | jp2a -

Although the default build of jp2a includes automatic downloading of files specified by URLs, you can explicitly download them by using curl(1) or wget(1), for example:

curl -s http://foo.bar/image.jpg | magick - jpg:- | jp2a -

You can pass the --edge-threshold option to highlight the edges of the image, or add the --edges-only option to draw only the edges, to produce a line drawing.

jp2a --edge-threshold=0.5 --edges-only imagefile.jpg

DOWNLOADING IMAGES FROM THE NET

If you have compiled jp2a with libcurl(3), you can download images by specifying URLs:

jp2a https://user:pass@foo.com/bar.jpg

The protocols recognized are ftp, ftps, file, http, https and tftp.

If you need more control of the downloading, you should use curl(1) or wget(1) and jp2a read the image from standard input.

jp2a uses pipe and fork to download images using libcurl (i.e., no exec or system calls) and therefore does not worry about malevolently formatted URLs.

GRAYSCALE CONVERSION

You can extract the red channel by doing this:

jp2a somefile.jpg --red=1.0 --green=0.0 --blue=0.0

This will calculate luminance based on Y = R*1.0 + G*0.0 + B*0.0. The default values is to use Y = R*0.2989 + G*0.5866 + B*0.1145.

PROJECT HOMEPAGE

The latest version of jp2a and news is always available from https://github.com/Talinx/jp2a.

SEE ALSO

cjpeg(1), djpeg(1), jpegtran(1), convert(1), cwebp(1)

BUGS

jp2a does not interpolate when resizing (except for WebP images). If you want better quality, try using cwebp(1) to convert the image to WebP before using jp2a to get correct scaling.

Another issue is that jp2a skips some X-pixels along each scanline. This gives a less precise output image, and will probably be corrected in future versions.

AUTHOR

Christian Stigen Larsen and Christoph Raitzig

jp2a uses jpeglib to read JPEG files. jpeglib is made by The Independent JPEG Group (IJG), who have a page at http://www.ijg.org

jp2a uses libpng to read PNG files. libpng's homepage: http://libpng.org/pub/png/libpng.html

jp2a uses libwebp to read WebP files. libwebp's homepage: https://developers.google.com/speed/webp/

LICENSE

jp2a is distributed under the GNU General Public License v2.

September 22, 2024 version 1.3.0