CIECAM16 Color Appearance Model and CAM16 Uniform ColorSpace for MATLAB

This code is based on the following sources:

1. the article "The development of the CIECAM16 and visualization of its domain and range" by Cheng Gao, Kaida Xiao, Mike Pointer, and Changjun Li in "Color Research and Application" Volume 50 Issue 2, published on the 29th of October 2024.
2. the article "Comprehensive color solutions: CAM16, CAT16, and CAM16-UCS" by Changjun Li, Zhiqiang Li, Zhifeng Wang, Yang Xu, Ming Ronnier Luo, Guihua Cui, Manuel Melgosa, Michael H. Brill, Michael Pointer in "Color Research and Application" Volume 42 Issue 6, published on the 10th of June 2017.
3. the article "Algorithmic improvements for the CIECAM02 and CAM16 color appearance models" by Nico Schlömer, revised on the 14th of October 2021.

This code does not require the Image Processing Toolbox!

This code is based on my CIECAM02 implementation: https://github.com/DrosteEffect/CIECAM02

My goal was to provide functionality as simple as the commonly used CIELab colorspace conversions, whilst providing a much more perceptually uniform colorspace. Note that I replaced calculations with a matrix inverse, e.g. inv(A)*b, with the recommended and numerically more precise \ or /, see: https://www.mathworks.com/help/matlab/ref/inv.html

Quickstart Guide: As Easy As CIELAB!

Many users will want to convert between sRGB and the CAM16 uniform colorspace, just as easily as they might use rgb2lab and lab2rgb. This conversion is easy with these convenience functions (i.e. rgb2jab and jab2rgb):

Jab = sRGB_to_CAM16UCS(rgb)
rgb = CAM16UCS_to_sRGB(Jab)

These use default values that are appropriate for sRGB (D65 illuminant, etc), and the CAM16-UCS colorspace (option to select SCD, LCD, UCS, or UCSHF (Hellwig & Fairchild) colorspaces). Note that the sRGB inputs are MATLAB standard float values 0<=rgb<=1 or integer values 0<=rgb<=intmax(class(rgb)).

Other Conversions

While most users will likely want to convert between sRGB and CAM16 colorspaces, the main functions provide the following conversions:

CIEXYZ_to_CIECAM16()
CIECAM16_to_CIEXYZ()

CIECAM16_to_CAM16UCS()
CAM16UCS_to_CIECAM16()

And for convenience in MATLAB (note that XYZ is scaled so Ymax==1):

sRGB_to_CIEXYZ()
CIEXYZ_to_sRGB()

Test Scripts

Of course there is no point in writing a conversion this complex without testing it thoroughly: test functions check the conversion between CIEXYZ and CIECAM16 and CAM16 J'a'b'. The test values are those referenced in the Python library "colour-science". The test functions are included in this repository.