OMR SHEET SCANNER AND GRADER

Now that we understand the basics of OMR, let’s build a computer vision system using Python and OpenCV that can read and grade bubble sheet tests. In our project , we combine 3 techniques: Building document scanner Sorting the outlines Perspective transform to get top-down view Python to Store the correct answer keys in a dict . Used Canny edge detection for detecting the edges in the document and Gaussian blur for reducing high frequency noise OpenCV has the way to get the top-down view of the image. Used that methodology to get the top-down view. Used Otsu’s thresholding method for thresholding. Determined the bubbles using the aspect ratio of approx one (1) for it’s bounding rect- angle. Used bitwise operations and masking to find the filled in bubble using the amount of shaded pixels in the bubble.