Sobel, I. (1978) Neighborhood Coding of Binary Images for Fast Contour Following and General Binary Array Processing. Computer Graphics & Image Processing, 8, 127-135.
https://doi.org/10.1016/S0146-664X(78)80020-3

has been cited by the following article:

• TITLE: Grey Relevancy Degree and Improved Eight-Direction Sobel Operator Edge Detection

  AUTHORS: Yang Yang, Lianxin Wei

  KEYWORDS: Edge Detection, Grey Relevancy, Eight Directions, Sobel Operator

  JOURNAL NAME: Journal of Signal and Information Processing, Vol.12 No.2, April 25, 2021

  ABSTRACT: Edge detection is an important aspect to improve image edge quality in image processing. The purpose of edge detection is to identify the points in digital images with great brightness variation. However, the accuracy of traditional edge detection methods in edge extraction is low. For the actual image, the grey edge is sometimes not very clear, the image also contains noise. The detection result of the traditional Sobel operator is relatively accurate, but the detection result is rough and sensitive to noise. To solve the above problems, this paper proposes an improved eight-direction Sobel operator based on grey relevancy degree, which combines 5 × 5 Sobel operator with a grey relational degree and a new eight-direction grey relevancy method. The results show that this method can detect the useful information of edge more accurately and improve the anti-noise performance. However, the drawback is that the algorithm is not automatic.