Checking the similarity of two 2D images using a checker-board with adjustable tile transparency

This is a part of InSPIRE for checking the similarity of two figures possibly after registration.

This provides the users a way to display moving and fixed images in a checker-board pattern. When alpha1=1 and alpha2=0, this program returns to
usual black and white checker board pattern. Please use:
CheckerboardVariableTileTransparency(square1,square2,0.1,0.5)
to produce the output.fig. The square1.png and square2.png are provided for the test.
The number of the tiles could be modified as needed in the code.