I was wondering are there methods for correcting the whole viewing sphere of a raw fisheye image?
If I understood correctly. The common strategy for removing barrel distortion from fisheye images is first to crop the spherical fisheye image to the rectangular shape and then correct the radial distortion, but then we lose some information from the top and bottom of the original image.
Found this but it makes the fisheye image look blurry and zooming: http://www.tannerhelland.com/4743/simple-algorithm-correcting-lens-distortion/