无嵌入函数的5X5滤波器的图像滤波

Question

我试图修改代码(Implementing IMFILTER in matlab)，用5X5高斯滤波器过滤图像。有些地方不对劲，但我找不到。

     gauss_kernel = fspecial('gaussian',5,2);
        function [result] = evc_filter(input, kernel)


        rsize = size(input);

        r = zeros(rsize);

        original=padarray(input,[2,2]);

        for i = 3:rsize(1)+2
            for j = 3:rsize(2)+2           
                temp = original(i-2:i+2,j-2:j+2) .* kernel;
                r(i-2,j-2) = sum(temp(:));
            end
        end
result=r;
end

如果我用imshow显示图片，如果使用imfilter函数，它看起来就不一样了。有人能帮忙吗？

Answer 1

首先，将图像转换为双倍，然后执行其余的过程。参见下面的示例代码：

function imfilt()
img = imread('one.jpg');
img = double(img);
[r,c,z] = size(img);
pad = 4;
nimg = zeros(r+pad,c+pad,z);
nimg(pad/2+1: r+pad/2, pad/2+1: c+pad/2,:) = img;
h = fspecial('gaussian',5,2);

res = zeros(r,c,z);
for i = pad/2+1 : r+pad/2
    for j = pad/2+1 : c+pad/2
        tmp = nimg(i-pad/2:i+pad/2,j-pad/2:j+pad/2,1).*h;
        res(i-pad/2,j-pad/2,1) = sum(tmp(:));
        tmp = nimg(i-pad/2:i+pad/2,j-pad/2:j+pad/2,2).*h;
        res(i-pad/2,j-pad/2,2) = sum(tmp(:));
        tmp = nimg(i-pad/2:i+pad/2,j-pad/2:j+pad/2,3).*h;
        res(i-pad/2,j-pad/2,3) = sum(tmp(:));
    end
end

imshow(uint8(res),[]);
end