Edge detection with Sobel
14 views (last 30 days)
Show older comments
Hi, I am trying to execute an image processing project with sobel edge detection technique. I want to write a function edgy that takes an orginal input image and process an output image. Both the input and output are grayscales images which means they are matrices of date structure unint8 values. However, whenever i run the code given below by calling the function edgy to give output edg as given in the code below, the fucntion call returns errors. Please what is the problem with the code? Any advice on the bug in this code is appreicated. Thank you
function edg=edgy(A)
C=double(A);
B=uint8(C)
edg=imshow(B)
[i,j]=size(C)
for i=1:size(C,1)-2
for j=1:size(C,2)-2
%Sobel mask for x-direction:
Gx=((2*C(i+2,j+1)+C(i+2,j)+C(i+2,j+2))-(2*C(i,j+1)+C(i,j)+C(i,j+2)));
%Sobel mask for y-direction:
Gy=((2*C(i+1,j+2)+C(i,j+2)+C(i+2,j+2))-(2*C(i+1,j)+C(i,j)+C(i+2,j)));
%The gradient of the image
%B(i,j)=abs(Gx)+abs(Gy);
C(i,j)=sqrt(Gx.^2+Gy.^2);
end
end
0 Comments
Accepted Answer
Image Analyst
on 2 Jan 2021
I made a few improvements. This seems to work fine:
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
clear; % Erase all existing variables. Or clearvars if you want.
workspace; % Make sure the workspace panel is showing.
format short g;
format compact;
fontSize = 15;
fprintf('Beginning to run %s.m ...\n', mfilename);
grayImage = imread('cameraman.tif');
subplot(2, 1, 1);
imshow(grayImage);
edg = edgy(grayImage);
subplot(2, 1, 2);
imshow(edg, []);
fprintf('Done running %s.m.\n', mfilename);
function edg = edgy(originalImage)
[rows, columns, numberOfColorChannels] = size(originalImage);
% Convert to gray scale if necessary
if numberOfColorChannels == 3
originalImage = rgb2gray(originalImage);
end
C = double(originalImage);
Gx = zeros(rows, columns);
Gy = zeros(rows, columns);
for row = 1 : rows - 2
for col = 1 : columns - 2
%Sobel mask for x-direction:
Gx=((2*C(row+2,col+1)+C(row+2,col)+C(row+2,col+2))-(2*C(row,col+1)+C(row,col)+C(row,col+2)));
%Sobel mask for y-direction:
Gy=((2*C(row+1,col+2)+C(row,col+2)+C(row+2,col+2))-(2*C(row+1,col)+C(row,col)+C(row+2,col)));
%The gradient of the image
%B(i,j)=abs(Gx)+abs(Gy);
C(row,col)=sqrt(Gx.^2+Gy.^2);
end
end
edg = C;
end
More Answers (1)
Image Analyst
on 1 Jan 2021
Why not just call conv2() with the proper kernel??? Why do it manually like that?
3 Comments
Muniba
on 22 Jan 2024
I have followed the same code but get an error as Undefined function 'edgy' for input arguments of type 'uint8'.
Image Analyst
on 22 Jan 2024
See Also
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!