Gradient edge detection

1. What is gradient in edge detection?
2. How image gradient is used for edge detection?
3. What is the difference between edge direction and gradient direction?
4. Which algorithm is best for edge detection?

What is gradient in edge detection?

An image gradient is a directional change in the intensity or color in an image. The gradient of the image is one of the fundamental building blocks in image processing. For example, the Canny edge detector uses image gradient for edge detection.

How image gradient is used for edge detection?

The gradient can be defined as the change in the direction of the intensity level of an image. So, the gradient helps us measure how the image changes and based on sharp changes in the intensity levels; it detects the presence of an edge.

What is the difference between edge direction and gradient direction?

The "true" edge point is the point at which slope is steepest along the gradient corresponding to the edge of an object. The gradient will be steepest when it is perpendicular to the edge of the object.

Which algorithm is best for edge detection?

Canny edge detection algorithm (Canny, 1986) known as optimal edge detection algorithm and the most commonly used edge detection algorithm in practice.