deskew

Deskew is a process used in image processing and document analysis to correct the slight rotational misalignment of an image. This misalignment, often referred to as "skew," can occur during the scanning or photography of documents. The goal of deskewing is to rotate the image so that the text lines or other dominant features are perfectly horizontal or vertical.

The process typically involves detecting the dominant angle of rotation in an image. Common methods for detecting this angle include the Hough transform, which can identify lines within the image, or projection profile analysis, which examines the distribution of pixels along different axes. Once the skew angle is estimated, an image transformation is applied to rotate the image by the negative of that angle. This effectively corrects the tilt.

Deskewing is crucial for improving the accuracy of subsequent image processing tasks. For instance, optical character recognition (OCR) software relies heavily on properly aligned text to achieve high recognition rates. Without deskewing, OCR systems may misinterpret characters or struggle to segment lines of text correctly. Similarly, other document analysis applications such as table extraction, form processing, and barcode reading can be significantly hindered by skewed images. The correction ensures that algorithms can reliably analyze the content.