Skew correction (deskew)

Most images, scanned in a flatbed scanner or photographed by a digital camera, are slightly skewed.


In order to improve OCR quality, FineReader Engine deskews the image automatically. You may turn off automatic skew correction by setting PrepareImageMode.CorrectSkewMode = 0;

Here is the result sample:


You may find the deskew edge applied in property ImageDocument.SkewAngle.

After the deskew, the coordinates of OCRed text correspond to the deskewed image plane, not to the initial ones. In order to access initial coordinates, use ConvertCoordinates Method of the CoordinatesConverter Object. This method works only if the KeepOriginalCoordinatesInfo property of the PrepareImageMode object is true.

Please note, that the resulting image is larger than the initial one. The extended fields are highlighted by yellow. At the moment, FineReader Engine does not support automatic cropping. 

You may change fields color by altering PrepareImageMode.BackgroundFillingColor property. By default, it's the same as the color of image edges (white or light gray for most cases).

Was this article helpful?

5 out of 19 found this helpful

Have more questions? Submit a request



Please sign in to leave a comment.