Human vision combines oriented filters to compute edges.

@article{Georgeson1992HumanVC,
  title={Human vision combines oriented filters to compute edges.},
  author={Mark A. Georgeson},
  journal={Proceedings. Biological sciences},
  year={1992},
  volume={249 1326},
  pages={235-45}
}
The experiments examined the perceived spatial structure of plaid patterns, composed of two or three sinusoidal gratings of the same spatial frequency, superimposed at different orientations. Perceived structure corresponded well with the pattern of zero crossings in the output of a circular spatial filter applied to the image. This lends some support to… CONTINUE READING