Tesseract doesn't deskew the output image. It makes no changes to the output image.
What it does try to do is find a local baseline to account for text that is skewed. I believe it may be capable of finding low order polynomial baselines as well to account for certain distortions. This is strictly a tool to improve OCR results. You can see the results in the output of the "hocr" renderer. Example hocr output for a straight line with no skew: <span class='ocr_line' id='line_1_1' title="bbox 882 131 1656 217; baseline 0 -17; x_size 87; x_descenders 17; x_ascenders 21"> Interpretation in hocr spec of "baseline": https://kba.github.io/hocr-spec/1.2/#propdef-baseline You will get better results if you globally deskew and cleanup the image using other methods such as Leptonica's deskew function. OCRmyPDF is a tool I develop that wraps tesseract. It can perform deskew using Leptonica before it delegates OCR to tesseract. On Sunday, 22 January 2017 15:40:20 UTC-8, Pedro Correia wrote: > > Hi there, > I've been reading Tesseract's code and I've realized that are several skew > estimation functions around. However I am really confused: does Tesseract > actually deskew the image? > Here [1] we find that "The line finding algorithm is designed so that a > skewed page can be recognized without having to de-skew, thus saving loss > of image quality." Does it mean that no deskewing is done? > On the other hand, I've seen some posts around here referring to > Leptonica's deskewing algorithm, even though I couldn't find any call to > it's functions anywhere in Tesseract's code. > So, can anyone explain the real deal to me? > Thanks in advance! > > [1]: > https://github.com/tesseract-ocr/docs/blob/master/tesseracticdar2007.pdf > > -- You received this message because you are subscribed to the Google Groups "tesseract-ocr" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/tesseract-ocr. To view this discussion on the web visit https://groups.google.com/d/msgid/tesseract-ocr/d7ba0ec1-286c-46ad-8f8a-869440bea3c9%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
