eRGB Erlang Library API Specification

Version: 0.2.5

Authors: Jeno Jakab.


This documentation contains the eRGB library API specification. It is built to provide easy to use color conversion and manipulations primitives for prospective Erlang projects.

Table of Contents

The eRGB lib

This library was built with the rebar3 Erlang build tool and its code has been structured accordingly to this fact.

The color manipulation API resides in the library color module.


The ergb library can be included in any Erlang app/lib project regardless of the build tool used.

All is needed that the eRGB hex package must be added to the target app/lib dependences.

Adding to rebar3 dependences

{deps, [

Adding to dependences



Usage Examples

% Supported input data color forms:
Color1 = color:from_rgb_hex("#333333").
Color2 = color:from_rgb_hex(0xFF0000).
Color3 = color:from_rgb(115, 38, 38).
Color = color:new(0, 1.0, 0.5).

% Supported color manipulations ...
color:darken(20, Color).
color:darken_in_percent(10, Color).
color:lighten(20, Color).
color:lighten_in_percent(20, Color).
color:saturate(20, Color).
color:saturate_in_percent(20, Color).
color:desaturate(20, Color).
color:desaturate_in_percent(20, Color).

% Mixing colors ...
color:mix(OtherColor, 20, Color). % Mix 20% of other color into this one
color:mix(OtherColor, Color). % 50% by default
color:mix(OtherColor, 20, Color).

% Adjust color hue, saturation, lightness manually
color:set_hue(145.2, Color).
color:set_saturation(0.2, Color).
color:lightness(0.3, Color).

% Supported output formats ...
{0.0, 1.0, 0.5}
{115, 38, 38}

Run eRGB Unit Tests

In order to run the eRGB unit tests, there is necessary to clone the eRGB git repo and run the existing tests.

The test machine requirements:

Cloning the repo and run the unit tests

Create an appropriate test folder on a developer machine having with it rebar3 installed and then run the following commands.
> cd <test-folder>
> git clone
> cd ergb
> rebar3 eunit

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