| rgb2ntsc - converts from RGB to YIQ colorspace |
YIQ = rgb2ntsc(RGB) |
| RGB |
| A RGB image (M x N x 3) in 0-1 range or a RGB colormap (M x 3) in 0-1 range |
| YIQ |
| A YIQ image (M x N x 3) in 0-1 range or a YIQ colormap (M x 3) in 0-1 range |
| rgb2ntsc(RGB) converts an RGB image or colormap from RGB to YIQ colorspace. The YIQ model is used in NTSC and European TV's. It is useful for b&w and color compatibility, since the cromaticity (I and Q) and luminance (Y) are conveniently isolated. rgb2ntsc(RGB) uses the following operation to convert each RGB triplet: |
! Y ! ! 0.299 0.587 0.114 ! ! R !
! I ! = ! 0.596 -0.274 -0.322 ! * ! G !
! Q ! ! 0.212 -0.523 0.311 ! ! B !
|
initial_dir = PWD;
chdir (SIPDIR + 'images');
rgb = imread('tru.jpg'); // RGB colorspace, 0-1 range
imshow(rgb);
yiq = rgb2ntsc(rgb); // YIQ colorspace, 0-1 range
yiq(:,:,2) = yiq(:,:,2) /4; // Decrease chromaticity
yiq(:,:,3) = yiq(:,:,3) /4;
rgb = ntsc2rgb(yiq);
imshow(rgb);
chdir(initial_dir);
|
| Ricardo Fabbri <rfabbri@if.sc.usp.br> |
| The latest version of the Scilab Image Processing toolbox can be found at |
| http://siptoolbox.sourceforge.net |
| ntsc2rgb, im2gray |