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US 8,571,313 B2Granted
Methods and systems for estimation of document skew in an image
AssigneeSharp Laboratories of America, Inc.
InventorJohn E. Dolan
Life of this patent
Estimating the term…
Abstract
Aspects of the present invention are related to systems and methods for determining a skew angle associated with a document image. According to a first aspect of the present invention, a rotation vector may be estimated for at least one layer in a vertical-edge buffer and a horizontal-edge buffer. According to a second aspect of the present invention, a rotation vector may be estimated directly from the vertical-edge buffer and the horizontal-edge buffer using a fixed-sized, progressively constrained histogram.
Claims7
A system for determining a skew angle associated with a scanned document page, said system comprising:
- a) an edge-buffer generator for generating, from a normalized image associated with a scanned document page, a vertical-edge buffer of vertical edges and a horizontal-edge buffer of horizontal edges;
- and
- b) a constrained-histogram generator for forming a plurality of constrained histograms, wherein said plurality of constrained histograms comprises:
- i) a first constrained histogram of deltas associated with said vertical edges and said horizontal edges at a first baseline length;
- and
- ii) a second constrained histogram of deltas associated with said vertical edges and said horizontal edges at a second baseline length, wherein:
- (1) said first baseline length is less than said second baseline length;
- (2) said first constrained histogram and said second constrained histogram are the same size;
- and
- (3) said second constrained histogram is centered around a first delta determined from said first constrained histogram.
7 more elements
Dependencies are inferred from the claim text.