Is your feature request related to a problem? Please describe.
It's a common use case for OMR templates having L shaped markers. This will increase accuracy and success rate for such OMR sheets.

Describe the solution you'd like

• Update the template schema to support "Anchor points" - areas to identify the L shaped markers
• Use morphology(erode/dilate/open+close) to remove noise
• Use canny edges + contour detection to extract the L shaped point and the corner/turning points of each L
• It should not be limited to 4 points, but rather using a rectangular bounding box method which will find an outer bounding box of all the obtained points.
• Lastly, reuse the common code of cropping mechanisms of existing processors to warp the page.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
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