First go from RGB to XYZ and then from XYZ to LUV. These will not be the actual values unless you calibrate/standardize your system - they will merely be estimated "book formula" values that will not necessarily be accurate as they would be, say, if you measured your emitting light source with a radiometer.
You can try first converting the image color from L*a*b* color space to RGB color space using "lab2rgb" and then you can convert it from RGB color space to hue, saturation(chroma), and value (HSV) color space using "rgb2hsv".
Looks right to me. Just realize that any lab or luv or any other colorspace values you get from "book formulas" are not going to be the same as the "true" values you'd get from a spectrophotometer or spectroradiometer. This is because your system is not calibrated and it assumes the values are sRGB which is not true.
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