detect circle and dfferentiate location for each answer

i want to detect location of answer and separate image for each answer. http://i1108.photobucket.com/albums/h404/abdulhadi3/College-Admin-Survey.png

Answer 1

[Ingo]

Since there's no answer so far, I'll give it a try.

Assuming you at least approximately know the coordinates of the circles (which you do, if the scan is good), I would just count non-white pixels or calculate some sort of color average within a certain area around them. The one with the most non-white pixels or with the "highest blackness" should be the chosen answer then.

With "non-white" pixels I mean, that the difference of the pixel to white is bigger than a certain treshold (because in the scan, the pixels are not perfectly white).

You could also segment the picture into black and white first, that would make the recognition easier/better, I guess.

Then again, this is just an idea.

Answer 2

[Abdul]

can you give the code in matlab?please...