Possible Duplicate:
Recognize Black patterns appearing on the four corners of the image ios using opencv or some other technique
I want to create a app like shotnote app(basically its camera feature). It is a page scanning app that is used to scan special type of paper.
http://itunes.apple.com/us/app/shot-note/id411332997?mt=8
Refer first two screenshots
You can check the functionality what I am searching in the following video:-
http://www.youtube.com/watch?v=8F_1iu4pDkQ
In my app
The paper background will be white and the pattern will be in black.
What I want is when I take a image from camera then it should match with the pattern (image or mages) and if patterns are present in that captured image then image should be cropped like in the way so that the patterns should appear at the corners of the image.
Basically I need to detect that the patterns are present and after that I want their coordinates so that I can crop the image accordingly.
Patterns you can assume as rectangle or L shape .
I am surfing for this from the last two weeks and still struggling with it.
Please provide me some sample code or some suggestions which I should follow.
Any suggestions would be highly appreciated. Thanks in advance.