Denoising fails due to "array dimensions must match binary array op". Picture is 500x500 pixels even.

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Jonathan Harris 2019-4-16

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https://ww2.mathworks.cn/matlabcentral/answers/456801-denoising-fails-due-to-array-dimensions-must-match-binary-array-op-picture-is-500x500-pixels-eve

评论： Jonathan Harris 2019-4-17

circuitboardN.jpg

img = im2double(imread('circuitboardN.jpg'));
imgfft = fftshift(fft2(img));
H5 = zeros(500,500); H15 = H5; H30 = H5; H80 = H5; H230 = H5;
x = 500; y = 500; cx = x/2; cy = y/2;
for i=1:x;
 for j=1:y;
 D(i,j) = sqrt([i-cx]^2 + [j-cy]^2);
 end
end
H5 = exp(-.5*[D/5].^2); H15 = exp(-.5*[D/15].^2);
H30 = exp(-.5*[D/30].^2); H80 = exp(-.5*[D/80].^2);
H230 = exp(-.5*[D/230].^2);
h5 = abs(ifft2(H5.*imgfft)); h15 = abs(ifft2(H15.*imgfft));
h30 = abs(ifft2(H30.*imgfft)); h80 = abs(ifft2(H80.*imgfft));
h230 = abs(ifft2(H230.*imgfft));
figure;
subplot(3,2,1); imshow(imscale01(img)); subplot(3,2,2); imshow(imscale01(h5));
subplot(3,2,3); imshow(imscale01(h15)); subplot(3,2,4); imshow(imscale01(h30));
subplot(3,2,5); imshow(imscale01(h80)); subplot(3,2,6); imshow(imscale01(h230)); 

2 个评论
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Walter Roberson 2019-4-16

Is it truly a grayscale jpg? 99.999% of jpg are rgb even if they look grayscale.

Jonathan Harris 2019-4-17

It was originally .tif but resaved it as jpeg

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Answer 1

Walter Roberson 2019-4-17

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/456801-denoising-fails-due-to-array-dimensions-must-match-binary-array-op-picture-is-500x500-pixels-eve#answer_371092

That .jpg is RGB even though it looks gray. You need to use rgb2gray() on it before you can process it with that code.

I have only ever encountered approximately 5 real grayscale JPEG images, over several decades. All of the rest were either RGB images that looked gray (mostly) or simple demonstrations that it really was possible to create a grayscale JPEG. Grayscale JPEG exist, but four leafed clovers are more common.