MATLAB: How to convert RGB to CIE Lab color space.

color space conversionImage Processing Toolbox

Is there any difference between these two procedures of rgb to lab conversion.

1. colorTransform = makecform('srgb2lab'); lab = applycform(rgbImage, colorTransform);

2. rgb2lab

makecform('srgb2lab') uses WhitePoint 'ICC' by default. rgb2lab() uses whitepoint 'D65' by default.

https://en.wikipedia.org/wiki/ICC_profile "a 16-bit fractional approximation of D50"

Convert the image to L*a*b* color space using makecform and applycform.

colorTransform = makecform('srgb2lab');
lab = applycform(rgbImage, colorTransform);

To convert from a non-standard RGB color profile to the device-independent XYZ profile connection space, use the following code:

InputProfile = iccread('myRGB.icc');
C = makecform('mattrc',InputProfile.MatTRC, 'direction', 'forward');

Note that this will only work if the ICC profile includes a MatTRC value.