this implements a very simple distortion correction following The Double Sphere Camera Model Vladyslav Usenko, Nikolaus Demmel and Daniel Cremers.
input the input imageoutput the output image after applying lens distortioncenter move the center of the projectionscale scale the image larger or smallersquish0 the radius of one of the spheressquish1 the other radius used for the mappingca red some fake chromatic aberration correction, just scales the red image planeca blue some fake chromatic aberration correction, just scales the blue image plane