How to calculate Gradient 'direction' (not magnitude) of image along x and y axis in matlab?

Question

我使用了imgradientxy（）;但是它给出了-600这样的值。我需要在两个方向上分别在-180至180.范围内的角度值。

Answer 1

The values are 0 and 90. The gradient is calculated in the X and Y direction by imgradientxy() as you may infer from its name.

However the gradient in a point is defined by:

and you can do [Gx,Gy]=imgradientxy(img) .

That means that your total gradient (not the "directional gradient", which is what Gx and Gy are) is a vector. the (Gxi,Gyi) vector in point i .

To calculate the modulus and angle of a vector is a straightforward algebra thing:

The modulus, magnitude, euclidean norm or however you preffer to call it is:

m=norm([Gx,Gy]);

And the angle:

theta=atan(Gy/Gx); %radians
theta=atand(Gy/Gx); %degrees