how to compute edge from gradient in an image?

gradient of and image is gradient(f)=[∂f/∂x, ∂f/∂y]=[fx,fy] θ=arctan (fy / fx) ,|| f||gives the magnitude. The angle for edges is θ=arctan (-fx/ fy) We know,edges are perpendicular to gradient ,but how to calculate edges with angle and magnitude in matlab.

                         please help........

Answer 1

[Image Analyst]

Did you look in the help? Do you have the Image Processing Toolbox? Did you see imgradient() and imgradientxy()?