The first four transformations, 'linear conformal' , 'affine ', 'projective' and 'polynomial' are global transformations. In these transformations, a single mathematical expression applies to an entire image. In these transformations, different mathematical expressions apply to different regions within an image. When exploring how different transformations affect the images you are working with, try the global transformations first. Example 'linear conformal' Use this transformation when shapes in the input image are unchanged, but the image is distorted by some combination of translation, rotation, and scaling.
Straight lines remain straight, and parallel lines are still parallel.
2 pairs 'affine' Use this transformation when shapes in the input image exhibit shearing. Straight lines remain straight, and parallel lines remain parallel, but rectangles become parallelograms. 4 pairs 'polynomial' Use this transformation when objects in the image are curved. The higher the order of the polynomial, the better the fit, but the result can contain more curves than the base image.