edge detection : Code sobel

hello,someone correct me this program please.

I=imread('lena.jpg'); 
I=rgb2gray(I); 
[i j]=size(I);
I=double(I)/255; 
level=0.5; 

%carte de gradient
MH= [1 2 1; 0 0 0;-1 -2 -1]; 
GH = conv2 (I, MH); 
figure(1),imshow(GH), title('Contours horizontal'); 
MV= [-1 0 1; -2 0 2; -1 0 1]; 
GV = conv2 (I, MV); 
figure(2),imshow(GV), title('Contours vertical'); 
G=sqrt(GH.*GH + GV.*GV); 
G=im2bw(G,level); 
figure(3),imshow(G), title('Contours global'); 

%direction du gradient
eq=imdivide(GH,GV); 
eq=atan(eq); 
eq= (eq*180)/pi; 
figure(4),imshow(eq),title ('direction gradient'); 

%seuillage et suppression des non maximum locaux
for i =  1  : size(eq,1) 
    j  =  1  : size(eq,2) 
    if level > eq(i,j) 
        eq(i,j) = 0; 
    if  level < eq(i,j) 
        eq(i,j) = 255; 
    end 
    end 
end 
eq = im2bw(eq,level); 
figure(5), imshow(eq)    

[KALYAN ACHARJYA]

Issue?

[malak alexos]

1-deletion of local non-maxima is not correct because i didn't see any different between it and the result of (contours global).

2-the exercice is (Calculate and display a gradient with normalized values ​​between 0 and 255) so i want know if i should always convert the values of image in double and do the devision ( I=double/255)

3- i can do the threshold after calculate the direction of gradient or after magnitude

thanks for help

[Image Analyst]

Try imgradient() and imgradientxy()

[malak alexos]

i dont want to work with function

[Image Analyst]

Why not? Is it your homework assignment? If so, tag it as homework.

[malak alexos]

oook, thanks