MATLAB: How to detect specific colors

Question

I need to build an application which takes an image of a clothing article and tells whether its colored black,blue, beige, or brown.

I concluded a method to detect whether the color is blue or not by taking the minimum value for each channel and incase the blue has the greater value I could say its a blue article but incase this method got applied on a black clothing article, it may identify it as blue which is wrong.

So how can I differ between these four colors (black,blue,beige,brown)?

Answer 1

Use rgb2lab() to convert your images to LAB color space. Then use it again to find the lab values for your reference colors. Then compute the delta E (color difference) between your image and each of the reference colors. Which ever one is lowest is the color class that pixel belongs to.