HSV = rgb2hsv(RGB);
H = HSV(:,:,1);
R = RGB(:,:,1); G = RGB(:,:,2); B = RGB(:,:,3);
maskH = H < 0.4 | H > 0.6;
R(maskH) = 0; G(maskH) = 0; B(maskH) = 0;
rec = cat(3,R,G,B);
This might not be good enough for your purposes, as it misses some of the streaks on the floor. But the 0.4 and 0.6 were chosen arbitrarily so there is room to tune them. If you
then you can use a data cursor to explore the HSV values of the pixels of interest.