I have a 2D matrix which has the size 65536 × 1, if I want to convert it to a 3D in MATLAB, first I should convert it to a 256 × 256, and then that 256 × 256 into an 3D.
Can anyone help me with that?
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Rody Oldenhuis
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user3223551
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1How is it supposed to work? 6656*3 = 19968 elements, whereas 256*256 = 65536 elements!? To change dimensions, use `reshape` – tim Jan 22 '14 at 13:01
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sry, I made a mistake, the input matrix is 65536*1 – user3223551 Jan 22 '14 at 13:08
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...and how big do you want the 3D matrix to be? – Rody Oldenhuis Jan 22 '14 at 13:08
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256*256*256, I guess.. I have a gray image and I'm trying to change it to a rgb image – user3223551 Jan 22 '14 at 13:12
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someone said I could use: rgbimage = grayimage(:,:,[1 1 1]); but I dont know how to use it – user3223551 Jan 22 '14 at 13:13
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Ah...it makes a lot more sense now. You just want to convert a greyscale image into an RGB image. Why don't you just ask that? :) – Rody Oldenhuis Jan 22 '14 at 13:17
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possible duplicate of [Convert grayscale value to RGB representation?](http://stackoverflow.com/questions/835753/convert-grayscale-value-to-rgb-representation) – Rody Oldenhuis Jan 22 '14 at 13:17
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yes, but I've wrote my program codes, and there's just one last step remaining and that's the question I asked :) – user3223551 Jan 22 '14 at 13:21
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To convert your greyscale image (that somehow has been vectorized) into an RGB image, just copy the greyscale intensities into the RGB layers:
%// first, reshape
img = reshape(img, 256, 256);
%// then, copy
img = repmat(img, [1 1 3]);
Rody Oldenhuis
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@user3223551: I've updated my answer to meet your demands. For future reference, this is a typical example of an [XY problem](http://meta.stackexchange.com/questions/66377/what-is-the-xy-problem); please ask about your *original* problem, not about problems you encounter during your attempt to solve your original problem. Include your attempted solution, and why that fails. – Rody Oldenhuis Jan 22 '14 at 13:21