RGB to Lab color space

I want to converte RGB values to Lab, I read that conversion goes between XYZ color space. Ofcourse, I find directly alghorithm in Matlab

labTransformation = makecform('srgb2lab');

labI = applycform(image,labTransformation);

l = labI(:,:,1);

a = labI(:,:,2);

b = labI(:,:,3);

but it shows me values between 0-255 and I need standard values for Lab, L=0-100, a,b=-127+128. Because later I want calculate C and H with a, b values.

Thanks.

Answer 1

[Adam]

Just using

lab = rgb2lab(rgb);

seems to give results in the expected output range. I'm not sure what all the extra work of creating a colour transform gives you, even if it did give the answer you want.

[Ivana]

Thanks, I also found this conversion when I get Lab in uint 8 (0-255) to convert to Lab standard range values: L=L/2,55; a=a-127; b=b-128. I chek this and it realy works, now I will update my algorithm.