Align scanned image to form

Discussions about image processing and document imaging.
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Joined: Mon Jul 30, 2018 4:54 pm

Align scanned image to form

Post by ksuppan » Mon Jul 30, 2018 4:59 pm

We have anchors on all 4 corners on each of our forms.
Our current OCR/OMR software can recognize these and align the image (rotation and position transforming) accordingly.
Is this possible with GdPicture.NET? There is the FindAnchor method, of course, but
1. it doesn't align the image itself, but only returns the translation of the coordinates
2. it doesn't take into account an eventual rotation caused by the scanning process. (or does it? I can imagine the OMR recognition process be compromized a lot by this) I also can't find any method that can tell me the rotation error by finding an anchor.

We also have timing lines for the OMR boxes. Maybe those aren't needed in modern OMR SDKs, or is there a way to use them with GdPicture.NET to enhance the quality of the OMR recognition even more?

Best regards

Posts: 269
Joined: Sun Sep 02, 2012 7:30 pm

Re: Align scanned image to form

Post by Cedric » Thu Jan 17, 2019 1:18 pm


I strongly suggest that you go through the dedicated documentation we have about this: ... ition.html
This, I believe, should shed some light on how the translation should be handled.

Now, for the rotation compensation, you might want to pre-process the candidates before running them to OCR/OMR which includes deskew and noise pollution if applicable, all these are part of what we call "Document Clean-Up" and there is also a dedicated documentation that explains it here: ... mages.html

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