Optica Acta International Journal of Optics · 1969 · 12 citations · 10 references
ComputingComputer ScienceColor VisionComputer VisionVisual PerceptionFourier AnalysisFourier OpticsLetter RecognitionNumeral RecognitionOptical Character RecognitionPattern RecognitionCharacter ClassificationNumber ReadingNumeral ReadingSpatial Frequency Analysis
It is possible to determine any Fourier coefficient (spatial frequency) in a real two-dimensional distribution of illumination by allowing the distribution to throw the shadow of a suitably placed grid onto an observation plane, where the contrast of the shadow measures the modulus of the Fourier coefficient and its position measures the phase of the coefficient. A pilot model of a scheme for reading the Arabic numerals 0, 1, …, 9 using only three Fourier coefficients has been set up and run successfully. The possibilities of the method are assessed.
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W. L. Bragg · Nature · 1942 · 64 citations
Pattern Recognition Using Autocorrelation
L. P. Horwitz, Georgia Shelton · Proceedings of the IRE · 1961 · 56 citations