RGB2NTSC(1)

NAME
rbg2ntsc - converts from RGB to YIQ colorspace

SYNOPSIS
YIQ = rgb2ntsc(RGB)

PARAMETERS

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

DESCRIPTION
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 !

EXAMPLE
initial_dir = PWD;
chdir (SIPDIR + 'examples');
rgb = imread('tru.jpg');   // RGB colorspace 0-255
imshow(rgb*257);
yiq = rgb2ntsc(rgb);        // YIQ colorspace 0-255
yiq(:,:,2) = yiq(:,:,2) /4; // Decrease chromaticity
yiq(:,:,3) = yiq(:,:,3) /4;
rgb = ntsc2rgb(yiq);
imshow(rgb*257);
chdir(initial_dir);

AUTHORS
Ricardo Fabbri <rfabbri@if.sc.usp.br>

AVAILABILITY
The latest version of the Scilab Image Processing toolbox can be found at

    http://cyvision.if.sc.usp.br/~rfabbri/sip/

SEE ALSO
ntsc2rgb, im2gray