CIECAM 97 Implementation

Parameters

Our CIECAM 97 implementation is based on the IDL implementation publicly available (courtesy of Mark Fairchild). It's functionality includes conversion between XYZ and JCh or QMh (both color appearance / perceptual quantities). XYZ is the commonly used color coordinate reference. JCh represents lightness-chroma-hue, and QMh represents brightness-colorfulness-hue. JCh and QMh are very closely related.

Other parameters used in the conversion include:

	xyzw	- reference white in XYZ colorspace
	LA	- absolute adapting luminance
	c 	- impact of surround
	Nc	- chromatic induction factor
	FLL	- lightness contrast factor
	Yb	- background relative luminance (same units as xyzw)
	D	- discounting the illuminant

Slightly more detailed descriptions of each of the above parameters can be found in the CIECAM 97 final spec.

MATLAB code

ciecam_jc.m XYZ -> JCh
ciecam_qm.m XYZ -> QMh
inv_ciecam_jc.m JCh -> XYZ
inv_ciecam_qm.m QMh -> XYZ