https://github.com/tessarin/dither

Small image utility featuring an implementation of the median-cut color quantization algorithm and Floyd-Steinberg dithering in C.
https://github.com/tessarin/dither

c color-quantization dithering dithering-algorithms image-processing libpng png ppm-format

Last synced: about 2 months ago
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Small image utility featuring an implementation of the median-cut color quantization algorithm and Floyd-Steinberg dithering in C.

• Host: GitHub
• URL: https://github.com/tessarin/dither
• Owner: tessarin
• License: mit
• Created: 2017-08-10T22:06:28.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2017-10-09T19:56:55.000Z (about 7 years ago)
• Last Synced: 2024-10-25T08:18:55.257Z (2 months ago)
• Topics: c, color-quantization, dithering, dithering-algorithms, image-processing, libpng, png, ppm-format
• Language: C
• Homepage:
• Size: 398 KB
• Stars: 47
• Watchers: 5
• Forks: 8
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Dither - Color Quantization and Dithering

This is a small program dedicated to reducing the number of colors in an

image. It operates with files in PNG or binary PPM format ([Portable

PixMap][ppm]), and features automatic palette generation (using a median-cut

algorithm) and dithering implemented with the Floyd-Steinberg method.

## Installing

#### On macOS with [Homebrew][brw]

    $ brew install tessarin/core/dither

#### Manual Installation

First, install [`libpng`][lpg]. Running `make` will then compile the program

and generate the documentation (requires Perl). To install, move the

executable and manual files to appropriate directories in your system.

    $ make

    $ mv dither ~/bin

    $ mv dither.1 ~/man/man1

Individual targets can also be specified to only compile the program or to

generate the manual page:

    $ make dither

    $ make doc

## Usage

    $ dither [-p name.size] [-dv] input output

Detailed information about the program options are included in the

[manual][man].

## Features

By default, `dither` will use a 3-bit RGB palette and dithering when

processing an image. Other possible palettes include:

 - Grayscale of any given size

 - Automatic, generated with the given size using a median-cut quantization

   algorithm

 - Custom palette

Dithering on the final image can be disabled and the program can also be used

just to generate a palette.

## Samples

#### Automatic Palette

    $ dither -p auto.32 bird-original.png bird-auto.32.png

![original bird](samples/bird-original.png)

![generated bird](samples/bird-auto.32.png)

#### 1-bit Black & White

    $ dither -p bw flower-original.png flower-bw.png

![original flower](samples/flower-original.png)

![generated flower](samples/flower-bw.png)

#### 50% Gray Test

Generates a perfect checkerboard pattern.

    $ dither -p bw gray-original.png gray-dithered.png

![original gray](samples/gray-original.png)

![dithered gray](samples/gray-dithered.png)

 [ppm]: https://en.wikipedia.org/wiki/Netpbm_format

 [brw]: https://brew.sh

 [lpg]: http://www.libpng.org/pub/png/libpng.html

 [man]: dither.pod