From Personal PC Helpers:
DeskewHelper allows automatic skew detection and correction. Skew detection and correction is a very important problem when an OCR algorithm tries to detect and interpret characters from the source document. Many different solutions have been developed. The stage in which the skew detection takes place also varies from the first to the very last one before the OCR phase. The document structure analysis and character recognition are usually done in several phases: scanning and thresholding, image enhancement, skew detection and correction, segmentation, classification and character recognition. Each step must be completed well enough for the performance of each step must be completed well enough for the performance of the sequence and result to be successful. Steps that follow the skew correction are inefficient if the correction fails.