Steve on Image Processing and MATLAB

Concepts, algorithms & MATLAB

Out-of-gamut colors

The set of colors that can be represented using a particular color space is called the gamut. Some L*a*b* color values may be out of gamut when converted to RGB. You know that a converted RGB color is out of gamut when any of its component values is less than 0 or greater than 1.

lab = [80 -130 85];
lab2rgb(lab)
ans =

   -0.6210    0.9537   -0.1926

The negative values demonstrate that the L*a*b* color [80 -130 85] is not in the gamut of the sRGB color space, which is the default RGB color space used by lab2rgb. A different RGB color space, Adobe RGB (1998), has a larger gamut than sRGB. Use the 'ColorSpace' parameter to convert a L*a*b* color to the Adobe color space.

lab2rgb(lab,'ColorSpace','adobe-rgb-1998')
ans =

    0.1234    0.9522    0.1073

Because all the output values are between 0.0 and 1.0 (inclusive), you can conclude that the L*a*b* color [80 -130 85] is inside the Adobe RGB (1998) gamut.




Published with MATLAB® R2015a

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