Calculate Average around pixel

Question

Dani D 2016-3-12

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/272994-calculate-average-around-pixel

回答： Image Analyst 2016-3-12

Hello, I want calculate average 3*3 around a pixel. but in my code i have a problem. Please view code and help me . Thanks

clear all;
close all;
clc
I=imread('cameraman.tif');
[m , n] = size(I);
newI= uint8(ones(size(I)));
figure;
for i = 1:m
    for j = 1:n
          p = 0;
              sum = 0;
    x = i ; y= j;
    if (x-1 >= 1 && y-1 >= 1)
        p = p+1;
        sum = sum + I(x-1,y-1);
    end
    if (x-1 >=1 )
        p = p  +1;
        sum = sum + I(x-1,y);
    end
    if (x-1 >=1 && y+1 <=n)
            p = p  +1;
        sum = sum + I(x-1,y+1);
    end
      if ( y-1 >=1)
            p = p  +1;
        sum = sum + I(x,y-1);
      end
      if ( y+1 <=n)
            p = p  +1;
        sum = sum + I(x,y+1);
      end
      if (x+1 <=m && y-1 >=1)
            p = p +1;
        sum = sum + I(x+1,y-1);
      end
      if (x+1 <=m )
            p = p  +1;
        sum = sum + I(x+1,y);
        f = I(x+1,y);
      end
      if (x+1 <=m && y+1 <=n)
            p = p  +1;
        sum = sum + I(x+1,y+1);
      end
    newI(i,j) = uint8(sum/p);
      end
       p = 0;
                sum = 0;
  end
  imshow(newI);

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Answer 1

Image Analyst 2016-3-12

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/272994-calculate-average-around-pixel#answer_213349

在 MATLAB Online 中打开

Yes, that's a mess. Like Walter said, use conv2(), or imfilter():

windowSize = 3;
kernel = ones(windowSize);
kernel = kernel / sum(kernel(:));
localAverageImage = conv2(double(grayImage), kernel, 'same');

Now just index any location to get the mean in a square window there. If you want non-square windows, then make some of the elements in the kernel zero to achieve whatever shape you want, like a circle or cross of whatever, but do that before you divide by the sum of kernel otherwise you'll be shifting the average to some other level.