how to compute gradients of image using gradient() in matlab2010

im=imread('31.png');
im=rgb2gray(im);
[gx,gy]=gradient(im);

gx1=fft(radon(log(abs(fft2(diff(gx))))));
gy1=fft(radon(log(abs(fft2(diff(gy))))));

gxy=gx+gy;
imshow(gxy);

getting error while computing gradient(im);

[Thorsten]

Please post the error message.

Answer 1

[David Young]

As Thorsten says, you should always post the error message. But here's a guess at what might help:

im=imread('31.png');
im=rgb2gray(im);
im = im2double(im);
[gx,gy]=gradient(im);

This converts the image array to a class which gradient can handle. It also rescales the values to the range 0-1, which improves code portability and makes subsequent display simpler.