3x3 matlab中的平均过滤器 [英] 3x3 Average filter in matlab

问题描述

我编写了使用3x3平均滤波器来平滑图像的代码，但是输出很奇怪，几乎都是黑色的。这是我的代码。

I've written code to smooth an image using a 3x3 averaging filter, however the output is strange, it is almost all black. Here's my code.

function [filtered_img] = average_filter(noisy_img)
    [m,n] = size(noisy_img);
    filtered_img = zeros(m,n);
    for i = 1:m-2
        for j = 1:n-2
            sum = 0;
            for k = i:i+2
                for l = j:j+2
                    sum = sum+noisy_img(k,l);
                end
            end
            filtered_img(i+1,j+1) = sum/9.0;
        end
    end
end

我调用函数如下：

img=imread('img.bmp');
filtered = average_filter(img);
imshow(uint8(filtered));

到目前为止我在代码逻辑中看不到任何错误，如果有人，我会很感激可以发现问题。

I can't see anything wrong in the code logic so far, I'd appreciate it if someone can spot the problem.

推荐答案

假设你正在使用灰度图像，你应该用以下内容替换内部的两个for循环： / p>

Assuming you're working with grayscal images, you should replace the inner two for loops with :

filtered_img(i+1,j+1) = mean2(noisy_img(i:i+2,j:j+2));

它会改变什么吗？

编辑：别忘了将它重新转换为uint8 !!

don't forget to reconvert it to uint8!!

filtered_img = uint8(filtered_img);

编辑2：你的代码无效的原因是因为总和的饱和度为255，即uint8的上限。 mean 似乎可以防止发生这种情况

Edit 2: the reason why it's not working in your code is because sum is saturating at 255, the upper limit of uint8. mean seems to prevent that from happening

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