img2sixel: Image converter to dec sixel graphics

SYNOPSIS

img2sixel [ -options ] imagefiles

img2sixel [ -options ] < imagefiles

DESCRIPTION

img2sixel convert JPEG/PNG images into DEC SIXEL image format.

COMMAND-LINE OPTIONS

img2sixel has the following command-line options:

-7, --7bit-mode

generate a sixel image for 7bit terminals or printers (default).

-8, --8bit-mode

generate a sixel image for 8bit terminals or printers.

-p COLORS, --colors=COLORS

specify number of colors to reduce the image to (default=256).

-m FILE, --mapfile=FILE

transform image colors to match this set of colorsspecify map.

-e, --monochrome

output monochrome sixel image. this option assumes the terminal background color is black.

-i, --invert

assume the terminal background color is white. make sense only when -e option is given.

-u, --use-macro

use DECDMAC and DEVINVM sequences to optimize GIF animation rendering.

-g, --ignore-delay

render GIF animation without delay.

-d DIFFUSIONTYPE, --diffusion=DIFFUSIONTYPE

choose diffusion method which used with color reduction.

DIFFUSIONTYPE is one of them:

auto -> choose diffusion type automatically (default)

none -> do not diffusion

fs -> Bill Atkinson's method

atkinson -> Floyd-Steinberg method

jajuni -> Jarvis, Judice & Ninke

stucki -> Stucki's method

burkes -> Burkes' method

-f FINDTYPE, --find-largest=FINDTYPE

choose method for finding the largest dimention of median cut boxes for splitting, make sense only when -p option (color reduction) is specified.

FINDTYPE is one of them:

auto -> choose finding method automatically (default)

norm -> simply comparing the range in RGB space

lum -> transforming into luminosities before the comparison

-s SELECTTYPE, --select-color=SELECTTYPE

choose the method for selecting representative color from each median-cut box, make sense only when -p option (color reduction) is specified.

SELECTTYPE is one of them:

auto -> choose selecting method automatically (default)

center -> choose the center of the box

average -> caclulate the color average into the box

histgram -> similar with average but considers color histgram

-c REGION, --crop=REGION

crop source image to fit the specified geometry.

REGION should be formatted as '%dx%d+%d+%d'.

-w WIDTH, --width=WIDTH

resize image to specified width.

WIDTH is represented by the following syntax:

auto -> preserving aspect ratio (default)

<number>% -> scale width with given percentage

<number> -> scale width with pixel counts

<number>px -> scale width with pixel counts

-h HEIGHT, --height=HEIGHT

resize image to specified height.

HEIGHT is represented by the following syntax

auto -> preserving aspect ratio (default)

<number>% -> scale height with given percentage

<number> -> scale height with pixel counts

<number>px -> scale height with pixel counts

-r RESAMPLINGTYPE, --resampling=RESAMPLINGTYPE

choose resampling method used with -w or -h option (scaling).

RESAMPLINGTYPE is one of them:

nearest -> Nearest-Neighbor method

gaussian -> Gaussian filter

hanning -> Hanning filter

hamming -> Hamming filter

bilinear -> Bilinear filter (default)

welsh -> Welsh filter

bicubic -> Bicubic filter

lanczos2 -> Lanczos-2 filter

lanczos3 -> Lanczos-3 filter

lanczos4 -> Lanczos-4 filter

-q QUALITYMODE, --quality=QUALITYMODE

select quality of color quanlization.

QUALITYMODE is one of them:

auto -> decide quality mode automatically (default)

high -> high quality and low speed mode

low -> low quality and high speed mode

-l LOOPMODE, --loop-control=LOOPMODE

select loop control mode for GIF animation.

auto -> honer the setting of GIF header (default)

force -> always enable loop

disable -> always disable loop

RELATED TO img2sixel…

sixel(5) sixel2png(1)

AUTHORS

img2sixel is maintained by Hayaki Saito. We imported whole code of stbi-1.41, written by Sean Barrett and its contributers, for loading PNG/JPEG images, and imported some code from pnmquant.c (netpbm library) for image quantization.

COPYRIGHT

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

THANKS

This software derives from the following implementations.

stbi-1.41

This software includes stbi-1.41 (stb_image.h), a public domain JPEG/PNG reader.

https://github.com/nothings/stb

pnmquant.c (netpbm library)

The implementation of median cut algorithm for color quantization in quant.c is imported from pnmcolormap included in netpbm library.

http://netpbm.sourceforge.net/

pnmcolormap was derived from ppmquant, originally by Jef Poskanzer.

Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation. This software is provided "as is" without express or implied warranty.

monosixel (arakiken's tw)

The pattern dither algorithm implemented in quant.c is imported from monosixel/main.c in arakiken's tw "sixel" branch.

https://bitbucket.org/arakiken/tw/branch/sixel

This tool is written by Araki Ken, and we regard it as a derivative of. original tw, created by Sho Hashimoto.

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

sixel 2014-3-2

some part of converters/loader.c are derived from kmiya's "sixel" original version (2014-3-2).

http://nanno.dip.jp/softlib/man/rlogin/sixel.tar.gz

It is written by kmiya@culti.

He distributes it under very permissive license which permits useing, copying, modification, redistribution, and all other public activities without any restrictions.

He declares this is compatible with MIT/BSD/GPL.

REFERENCES

resize.c (ImageMagick)

We added some resampling filters in reference to the line-up of filters of MagickCore's resize.c.

http://www.imagemagick.org/api/MagickCore/resize_8c_source.html

CONTRIBUTORS

Araki Ken (@arakiken),
Iwamoto Kouichi (@ttdoda)
Kazuhiro YOSHIKAWA (@yoshikaw)

BUGS

Send bug-reports, fixes, enhancements to [email protected].

img2sixel (1)