Image Undistortion
Radial distortions arise as a result of the shape of the lens.
The lenses of real cameras often noticeably distort the location of pixels near the edges of the imager. This bulging phenomenon is the source of the “barrel” or “fish-eye” effect.
For radial distortions, the distortion is 0 at the (optical) center of the image and increases as we move toward the periphery. In practice, this distortion is small and can be characterized by the first few terms of a Taylor series expansion around r=0.
In general, the radial location of a point on the image will be rescaled according to the following equations :