SKEW DETECTION

摘要

Presented is a skew detection apparatus for estimating a skew angle of a document shown in an image. After a pre-processing step (100), skew is estimated by a first method which uses the alignment of pixels on the boundaries of the document and/or the content o the document (199). This may be an Adapted Quasi-Hough Transform (AQHT). If this first algorighm is not confident in this output, another skew esrimation approach is tried (299), wherein the second method relies in pixels in the interior rather than the boundary o the document content This second method may be Enhanced Piecewise Covering by Parallelograms (EPCP). If the second skew estimate has no sufficiency high confidence value, consistency between the first and second estimates is assessed (300).