At some point, I&#x27;m hoping to get enough of this to solve this problem: you&#x27;ve taken a picture of, say, the Mona Lisa in its rectangular frame, but because of crowds you weren&#x27;t in line with dead center, instead you were 5 meters back, 1 meter high, and 2 meters to the side, and not even pointed at the center.  Your photo now contains some quadrangle that is a <i>projection</i> of the rectangle.  I&#x27;d like to tag the four corners and have an algorithm map the photo to its original rectangle - I intuit there&#x27;s enough information in the photo and the four tagged points, given that the original is actually a rectangle.