MATLAB: How to convert RGB to YUV

Question

hello sir, I am trying to convert an RGB image to YUV, and convert it back to RGB. This is my code:

 %host image

T=imread('……');

M=imresize(T,[512 512]);

I=im2double(M);

figure(1),imshow(I); title('Host Image');

 %separate host image into R G & B components

R=I(:,:,1); figure(2),imshow (R);

G=I(:,:,2); figure(3),imshow(G);

B=I(:,:,3); figure(4),imshow(B);

Y = 0.299 * R + 0.587 * G + 0.114 * B;

figure(5),imshow(Y);

U = -0.14713 * R – 0.28886 * G + 0.436 * B;

figure(6),imshow(U);

V = 0.615 * R – 0.51499 * G – 0.10001 * B;

figure(7),imshow(V);

YUV = cat(3,Y,U,V);

figure(8),imshow(YUV);

R = Y + 1.139834576 * V;

G = Y -.3946460533 * U -.58060 * V;

B = Y + 2.032111938 * U;

RGB = cat(3,R,G,B);

figure(9),imshow(RGB);

The U component of image that Matlab shows me is very dark black and very different from the U component of image i have seen in some paper. what is the correct way of converting into YUV color space ? what is meaning of cat ?

Answer 1

http://www.mathworks.com/matlabcentral/fileexchange/20033-firewire-vision-tools/content/web_CMU1394_VisionTools/_bin/rgb2yuv.m

in this code 128 is added to U and V

cat connects the three matrices R, G, B along the third dimension