cieCAM02inv – frudawski

The cieCAM02inv function determines the colour appearance model parameters of the CIECAM02 inverse model, as in CIE 159:2004. For the forward model, see cieCAM02. Any errors in the data set or in results generated with the Lighting Toolbox are not in the liability of the CIE nor me, see licence.

Usage:

XYZ = cieCAM02inv(cam,wp,cond,La,Yb)

Or:

XYZ = cieCAM02inv(cam,p)

Where:

Parameter	Description
`XYZ`	Is the return vector triplet or matrix of the sample(s).
`cam`	Is the input struct of the colour appearance model: J = lightness C = chroma H = hue quadrature M = colourfulness Q = brightness s = saturation a = corresponding cartesian coordinates: $a_c, a_M, a_s$ b = corresponding cartesian coordinates: $b_c, b_M, b_s$
`wp`	Defines the test illuminant white point, vector triplet [X Y Z].
`cond`	Defines the surround condition: ‘ave’ average surround (default) ‘dim’ dim surround ‘dark’ dark surround
`La`	Is the corresponding luminance of the adapting field, numeric. Default: XYZ(2)/5
`Yb`	Is the corresponding background luminance, numeric. Default: Yb = wp(2)/5
`p`	Is the alternative input struct with several parameters for the inverse model function, see cieCAM02.

Examples

CIECAM02 inverse transformation:

% define parameters
XYZ = [19.31 23.93 10.14];
wp = [98.88 90.00 32.02];
cond = 'ave';
La = 20;
Yb = 18;
% CIECAM02 transfromation
cam = cieCAM02(XYZ,wp,cond,La,Yb);
% change viewing condition
La = 50;
wp = ciewhitepoint('D50').*100;
% inverse transformation
XYZ = cieCAM02inv(cam,XYZ,wp,cond,La,Yb)

Result:

XYZ = 17.809   26.924   23.874

CIECAM02 inverse transformation with CIECAM02 parameter struct:

% define parameters
XYZ = [19.31 23.93 10.14];
wp = [98.88 90.00 32.02];
cond = 'ave';
La = 20;
Yb = 18;
% CIECAM02 transfromation
[cam,p] = cieCAM02(XYZ,wp,cond,La,Yb);
% inverse transformation
XYZ = cieCAM02inv(cam,p)

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