Prewitt滤波器实现Matlab

Question

我正试图在Matlab中实现Prewitt滤波器。我知道Matlab已经有这种过滤器，但我需要自己编写代码。下面是我的代码，唯一的问题是，在过滤结束时，我得到一个明亮的图像，而不是看到边缘。 我使用Prewitt过滤器的可分性属性来实现过滤器。有任何想法吗？我非常感谢你的帮助。

%% 3x3 Prewitt Filter 
close all 
imageIn = imread('images/Bikesgray.jpg'); 

imageGx = zeros(size(imageIn)); 
imageGy = zeros(size(imageIn)); 
imageOut = zeros(size(imageIn)); 

ny = size(imageIn, 1); 
nx = size(imageIn, 2); 
average = 3; 

imshow(imageIn); 

u = []; 
v = []; 

tic 
%Compute Gx 
%For every row use the mask (-1 0 1) 
for i = 1:ny 
    u = imageIn(i,:); 
    v = zeros(1, nx); 
    for k = 2:nx-1 
     v(k) = (uint32(-1*u(k-1))+uint32(0*u(k))+uint32(u(k+1))); 
    end 
    v(1) = (uint32(-1*u(2))+uint32(0*u(1))+uint32(u(2))); 
    v(nx) = (uint32(-1*u(nx-1))+uint32(0*u(nx))+uint32(u(nx-1))); 
    imageGx(i,:) = v; 
end 
%For every column use the mask (1 1 1) 
for j = 1:nx 
    u = imageGx(:,j); 
    v = zeros(ny, 1); 
    for k = 2:ny-1 
     v(k) = (uint32(u(k-1))+uint32(u(k))+uint32(u(k+1))); 
    end 
    v(1) = (uint32(u(2))+uint32(u(1))+uint32(u(2))); 
    v(ny) = (uint32(u(ny-1))+uint32(u(ny))+uint32(u(ny-1))); 
    imageGx(:,j) = v; 
end 
%Compute Gy 
%For every row use the mask (1 1 1) 
for i = 1:ny 
    u = imageIn(i,:); 
    v = zeros(1, nx); 
    for k = 2:nx-1 
     v(k) = (uint32(u(k-1))+uint32(u(k))+uint32(u(k+1))); 
    end 
    v(1) = (uint32(u(2))+uint32(u(1))+uint32(u(2))); 
    v(nx) = (uint32(u(nx-1))+uint32(u(nx))+uint32(u(nx-1))); 
    imageGy(i,:) = v; 
end 
%For every column use the mask (1 0 -1) 
for j = 1:nx 
    u = imageGy(:,j); 
    v = zeros(ny, 1); 
    for k = 2:ny-1 
     v(k) = (uint32(u(k-1))+uint32(0*u(k))+uint32(-1*u(k+1))); 
    end 
    v(1) = (uint32(u(2))+uint32(0*u(1))+uint32(-1*u(2))); 
    v(ny) = (uint32(u(ny-1))+uint32(0*u(ny))+uint32(-1*u(ny-1))); 
    imageGy(:,j) = v; 
end 

toc 

figure 
imshow(imageGx, [0 255]); 

figure 
imshow(imageGy, [0 255]); 

%Compute the magnitude G = sqrt(Gx^2 + Gy^2); 
imageOut(:,:) = sqrt(imageGx(:,:).^2 + imageGy(:,:).^2); 
figure 
imshow(imageOut, [0 255]); 

Answer 1

解决方案非常明显，但花了我一些时间弄清楚。 我所做的只是将uint32更改为int32，并确保在将值从uint32更改为int32后执行操作（例如，乘以-1）。

Answer 2

这太糟糕了，你没有使用convn（卷积），因为加权和只是尖叫它。 简而言之，你通过在图像矩阵上使用convn来生成Gx,Gy，使用合适的内核，如wikipedia