Recognize Black patterns appearing on the four corners of the image ios using opencv or some other technique

Question

I am stuck with a problem that is how to recognize some patterns in image.

the image is the image of paper which is pure white and the patterns are in four corners

Answer 1

Maybe this question is helpful for you, especially the link to the Tennis Ball Recognizing Tutorial seems to be pretty much what you are looking for.

Regarding how to use OpenCV on iOS you might want to take a look at OpenCV-iOS and Computer Vision with iOS.