The Sobel operator, sometimes called Sobel Filter, is used in image processing and computer vision, particularly within edge detection algorithms.
The Sobel operator, sometimes called Sobel Filter, is used in image processing and computer vision, particularly within edge detection algorithms.
It is named after Irwin Sobel, who presented the idea of an "Isotropic 3x3 Image Gradient Operator" at a talk at the Stanford Artificial Intelligence Project (SAIL) in 1968.
Technically, it is a discrete differentiation operator, computing an approximation of the gradient of the image intensity function. At each point in the image, the result of the Sobel operator is either the corresponding gradient vector or the norm of this vector.
The Sobel operator is based on convolving the image with a small, separable, and integer valued filter in horizontal and vertical direction and is therefore relatively inexpensive in terms of computations.
On the other hand, the gradient approximation that it produces is relatively crude, in particular for high frequency variations in the image.
The Kayyali operator for edge detection is another operator generated from Sobel operator.
Wikipedia: http://en.wikipedia.org/wiki/Sobel_operator
