Binarising Camera Images for OCR

  • Authors:
  • Christopher Dance

  • Affiliations:
  • -

  • Venue:
  • ICDAR '01 Proceedings of the Sixth International Conference on Document Analysis and Recognition
  • Year:
  • 2001

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Abstract

Abstract: In this paper we describe a new binarisation method designed specifically for OCR of low quality camera images: Background Surface Thresholding or BST. This method is robust to lighting variations and produces images with very little noise and consistent stroke width. BST computes a "surface" of background intensities at every point in the image and performs adaptive thresholding based on this result. The surface is estimated by identifying regions of low-resolution text and interpolating neighbouring background intensities into these regions. The final threshold is a combination of this surface and a global offset. According to our evaluation BST produces considerably fewer OCR errors than Niblack's local average method while also being more runtime efficient.