sliding window
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How to apply a 3x3 sliding window for an image while the pixel in the center of the window should have the mean value of the window.
回答（3 个）
Ben Mitch
2011-5-22
I think you're after filter2(). Try
mn = filter2(ones(3), im);
5 个评论
Gova ReDDy
2011-5-22
Jan
2011-5-23
Read "doc filter2". I assume you need a further normalization: "filter2(ones(3)/9, im)".
Ben Mitch
2011-5-25
assuming your image comes from a file (if not, the process is much the same)...
im = imread('my_image.png');
im = double(im);
im = mean(im, 3); % convert to greyscale, if is RGB
b = ones(3)/9;
im = filter2(b, im);
imshow(im);
if you need to work in RGB rather than greyscale, you could use something like...
for d = 1:3
im(:, :, d) = filter2(b, im(:, :, d));
end
Gova ReDDy
2011-6-11
Image Analyst
2011-6-12
But that's exactly what Ben, Jan, and Sean de's code does! Did you look up the help for filter2()? It is basically conv2() (which is highly optimized) with the 'same' option. (I always use conv2 rather than filter2.) Write a test with a small image to convince yourself.
Jan
2011-6-11
1 个投票
What is "the next 3x3 position"? Will the resulting picture have a width and size reduced by 3? If so, this can achieve the calculation efficiently: FEX: BlockMean
2 个评论
Gova ReDDy
2011-6-12
Image Analyst
2011-6-12
Patan, how many times do we have to say it. CONV2 AND IMFILTER WILL DO WHAT YOU'RE ASKING!!!!
Sean de Wolski
2011-5-25
Imean_window = conv2(double(I),ones(3)/9,'valid');
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