color-diff

Disclaimer: This project aims to be a 1:1 port of Markus Ekholm's great color-diff library which is written in Javascript (hence the occasional untypical naming convention).

Implements the CIEDE2000 color difference algorithm, conversion between RGB and LAB color and mapping all colors in palette X to the closest color in palette Y based on the CIEDE2000 difference.

Installation

color-diff is available on maven central. It works on JDK 8 and later. Use the following snipped in your pom.xml to add it as a dependency:

<dependency>
    <groupId>com.dajudge.color-diff</groupId>
    <artifactId>color-diff</artifactId>
    <version>0.0.4</version>
</dependency>

If you're using gradle then you'll want something like this:

buildscript {
    repositories {
        mavenCentral()
    }
}

dependencies {
    compile 'com.dajudge.color-diff:color-diff:0.0.4'
}

color-diff has no transitive dependencies, so you won't face any compatiblity issues.

Build / Tests

If you want to build it yourself just checkout the source and run the following command:

./gradlew clean build

Tests are implemented in JUnit 5 and run with the build.

Usage

ColorDiff.closest(color, palette, bc)

Returns the closest color. The parameter bc is optional and is used as background color when the color and/or palette uses alpha channels.

RgbColor color = new RgbColor(255, 1, 30);

List<RgbColor> palette = Arrays.asList(
        new RgbColor(255, 0, 0), // red
        new RgbColor(0, 255, 0), // green
        new RgbColor(0, 0, 255)  // blue
);

RgbColor closestMatch = ColorDiff.closest(color, palette);
assertEquals(new RgbColor(255, 0, 0), closestMatch); // red

The result above is obvious, but ColorDiff.closest() could deal with more complicated cases.

ColorDiff.furthest(color, palette, bc)

Returns the most different color. The parameter bc is optional and is used as background color when the color and/or palette uses alpha channels.

RgbColor color = new RgbColor(255, 255, 255); // white

List<RgbColor> palette = Arrays.asList(
        new RgbColor(0, 0, 0),      // black
        new RgbColor(255, 255, 255) // white
);

RgbColor furthestMatch = ColorDiff.furthest(color, palette);
assertEquals(new RgbColor(0,0,0), furthestMatch); // black

The result above is obvious, but ColorDiff.furthest() could deal with more complicated cases.

ColorDiff.map_palette(palette1, palette2)

Returns a mapping from the colors in palette1 to palette2.

RgbColor

RgbColor is type containing 3 properties: R, G, B, such as:

RgbColor color = new RgbColor(255, 1, 0);

There is an optional (i.e. nullable) property A, which specifies the alpha channel between 0.0 and 1.0.

RgbColor colorWithAlpha = new RgbColor(255, 1, 0, .5);

Each RGBA-color is transformed into a RGB-color before being used to calculate the CIEDE2000 difference, using the specified background color (which defaults to white).

Authors

Original Javascript version by Markus Ekholm

Java port by Alex Stockinger

License

3-clause BSD. For details see COPYING.