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

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)); 

[Walter Roberson]

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

[Jonathan Harris]

It was originally .tif but resaved it as jpeg

Answer 1

[Walter Roberson]

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.

[Jonathan Harris]

Thank you it worked sir. Will look out for that in the future.