Plot gradient magnitudes of a colour image in matlab

I would like to plot gradient magnitudes of an color image in matlab. Precisely saying i want the gradient in my x-axis and the log of probability densit开发者_C百科y on my y axis. i would request if someone can help me out. Thanks

These are the steps you'll need to figure out (I'm not going to write code for you, because I haven't got Matlab at home, and because I'm lazy):

1. Convert your image to grayscale.
2. Determine a suitable finite-difference approximation to the gradient operator.
3. Apply the finite-difference kernel using conv2.
4. Take the abs of the result.
5. Use hist to calculate a histogram.
6. Plot the result, converting as appropriate with log, or semilogy.