New blank and alignment detection method
Closes #376
This MR:
- Implements a new method for misalignment detection before pregrading is applied. This is done by thickening the student image, and checking if it fully covers the reference image.
- Implements a new method for blank answer detection. This is done by thickening the reference image, and calculating the amount of pixels in the student image that are not covered by the thickened reference image.
- Adds tests for the blank and alignment detection method
- Saves realigned images at a fixed image size, the same as the reference image
- Refactors the
reference_image
function.