I know how to account for the cone shape of a cup to get the image to go straight, my question is does anyone have a formula that accounts for how the image looks  on the vertical curve. For example, if you place a square on a cylinder and then look at it straight on, depending on the radius of the cylinder and the size of the square, it will look like a rectangle. It will appear to be taller than wide. Anyone have a calculation to compensate for this?