.jpg images are from SGI captured .rgb images after conversion to .ppm,
images were temporally downsampled by factor of 2, deinterlaced, and then
taking only odd fields, and upinterpolating to fullsize
then ptrwarping (radial unwarping), then jpg compression at quality 80.

thus these images are as if taken through a rectilinear lens.
radial warp NaN regions were cropped away