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Deskew of image and ROI detection

asked 2016-12-22 00:27:21 -0500

Rashmi gravatar image

updated 2016-12-23 00:35:07 -0500

In OMR, if scanned OMR is not in correct position then how can i deskew the image and search exact location of roll number rectangle?i want to extract information from different rectangle based on bubble selection. i need help to sort out this problem.

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answered 2016-12-22 01:08:10 -0500

pi-null-mezon gravatar image

updated 2016-12-22 12:33:29 -0500

You can implement following pipeline:

1) Threshold scan image with Otsu's method (will works better if background will be darker than the blank);

2) Make morphological filtration to reduce the thresholding noise;

3) Find good features by means of goodfeaturestotrack;

4) Find minimal area rectangle for the good features;

5) Perform image rotation and cropping

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@Rashmi he has explained an approach (for which thank you pi-null-mezon) and now expects you to give it a try. This is not a forum where we simply give you the solution, but rather guide you to a decent solution to the problem...

StevenPuttemans gravatar imageStevenPuttemans ( 2016-12-22 08:17:31 -0500 )edit

@Ramshi I have worked on the similar problem some time ago and created dedicated git project, you can simply research the source code

pi-null-mezon gravatar imagepi-null-mezon ( 2016-12-22 12:31:22 -0500 )edit

@pi-null-mezon thank you for the solution.i will try and let you know how it working

Rashmi gravatar imageRashmi ( 2016-12-23 00:34:43 -0500 )edit

@Rashmi by the way, those black rectangles on the blank seems to be good targets for the thresholding, so as a first step you can threshold them instead of whole blank

pi-null-mezon gravatar imagepi-null-mezon ( 2016-12-23 06:23:52 -0500 )edit

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Asked: 2016-12-22 00:27:21 -0500

Seen: 1,807 times

Last updated: Dec 23 '16