Delta E Colour Calculator

Intro

Most humans generally perceive a Delta E value of less than 0 as the same colour. Pantone swatches used by designers and printers for colour matching are produced by Pantone within a Delta E of 2.0. Read more about colour difference

This calculator returns a value of colour difference using the ‘00 or ‘76 Delta E formula.

Project Outline

I created this module with the plan to test against a dataset supplied by the University of Rochester. This was to make sure my code and maths worked as expected. I created code to create the tests needed from the dataset supplied.

Big thanks to Jamie Y for the maths help and guidance!

I chose Delta E 2000 because I’ve always liked the science behind colour and light; along with the fact I had worked in the print industry for 15 years. I started working on this in JavaScript years ago, but I found that Bruce Lindbloom had done the same on his site, so decided to see if I could do this in Python.

Features

Built and tested using poetry, unittest and Travis CI

Using: Python with the builtin math module and testing using unittest.

Features:

Colour Difference Calculator using the Delta E 2000 & 1976 formulas

Addendum

It has come to my attention that the ColorMath Library for Python has a Delta E implementation (see here). Yet as this was my first foray into building something myself in python. I am still going to keep this project up on PyPi. I am also not sure if they would pass the Rochester data-set, or if that is even the best benchmark.

Installation (using pip)

> pip install deltae

Example Usage

import deltae

# Takes CIELAB values as a dictionary:
Lab1 = {'L': 50.00, 'a': 2.6772, 'b': -79.7751}
Lab2 = {'L': 50.00, 'a': 0.00, 'b': -82.7485}

# Get the DeltaE 1976 Formula of 2 Lab Values:
deltae.delta_e_1976(Lab1, Lab2)

# Get the DeltaE 2000 Formula of 2 Lab Values:
deltae.delta_e_2000(Lab1, Lab2)