That depends on many factors. Are you talking about dewarping of camera-captured images, or dewarping of flatbed scanned pages? And what purpose do you want to dewarp the images for?
Dewarping of camera-captured images involves projective transforms and taking advantage of the fact that paper is physically constrained and can curl only in certain ways. In addition, camera lenses may be distorting the image as well. We're developing software for doing this as part of the DECAPOD project, but it's still going to take a while until that gets released. Dewarping scanned pages involves compensating for periodic slippage and excentricity in the scanner transport. That's a completely different model. Generally, no simple global model is going to work well for either situation. If this is just for OCR, we're currently integrating layout analysis into OCRopus that can deal with some degree of curvature. With that, you should be able to perform OCR on lightly distorted pages directly without dewarping. Tom On Apr 29, 9:55 am, "Romeyke, Andreas" <[email protected]> wrote: > Hello, > > We need to develop an image dewarping function. We have a working > function to evaluate the distortion. What we need is a transfer > function which maps P(x,y) to P'(x',y') based on a model of typical > distortions of book scans. > > We have experimented with following functions (polynom based), but they > need too many parameters: > > ax + by + c fx + gy + h > x' = -----------, y' = ----------- > 1 + dx + ey 1 + dx + ey > > If we have a look to typical book form, we think something similar to > this would be better: > > b -cx > x' = ax e + d, with a~1, b~0.5, c~1, d~0 > > Do you have another suggestions? Do you have ideas to map y -> y'? > > Thanks for your help... > > Bye Andreas > -- > Andreas Romeyke > - Abteilung Blindenschrift - > Deutsche Zentralbücherei für Blinde zu Leipzig (DZB) > Gustav-Adolf-Straße 7, 04105 Leipzig > Tel: +49 341 7113-..., Fax: +49 341 7113-125 > Internet:www.dzb.de > E-Mail: [email protected] > > -- > -- > Diese e-mail wurde auf Spam und Viren mit Astaro Security Gateway geprueft. > > signature.asc > < 1KViewDownload -- You received this message because you are subscribed to the Google Groups "ocropus" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/ocropus?hl=en.
