How can I multiply matrix of vectors by matrix?

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Viktor 2013-3-2

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I have an RGB image, which is [width, height, 3] array. How can I multiply every pixel ([R, G, B] vector) by matrix (this is conversion RGB -> YIQ, but without rgb2ntsc function)? Also, it should be done without any loops.

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Answer 1

Brian B 2013-3-2

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编辑：Brian B 2013-3-2

在 MATLAB Online 中打开

Not without loops, but hiding them inside bsxfun...

 M = rand(140,160,3); % image data
 T = randn(3);        % transformation matrix, [y; i; q] = T*[r; g; b]
 TM = cat(3, sum( bsxfun(@times, M, reshape(T(1,:), 1, 1, [])), 3), ...
             sum( bsxfun(@times, M, reshape(T(2,:), 1, 1, [])), 3), ...
             sum( bsxfun(@times, M, reshape(T(3,:), 1, 1, [])), 3));