Shape Context — is a scale & rotation invariant shape descriptor.
Pretty good explanation of Shape Context (Slides, if not retrieval Check HERE)
Shape Context descriptor and fast characters recognition (py code, PDF if not retrieval)
MatLab code for Shape Context
https://www2.eecs.berkeley.edu/Research/Projects/CS/vision/shape/sc_digits.html
https://kyamagu.github.io/mexopencv/matlab/ShapeContextDistanceExtractor.html