I just loaded a single image into PTGui, but the compression sliders in the Panorama Editor window seem to have no effect. I guess this feature only works with stitched images (?)
Well, I'm using PTGuiPro 9.0.3 and they definitely do
compress a single image. Exactly how this compression is distributed I haven't yet had time to evaluate.
Meanwhile I'm off to add some barrel distortion on a few landscape shots to see how much improvement I can make to my amateur efforts. Maybe this is the key to where I've been falling short. Perhaps add a bit of ca for an interesting "halo" effect and a little blur to take the edge of that disturbing sharpness
A quick test reveals that (rectilinear projection mode) compressing the h axis stretches the v axis at the same time. Not, as far as I can see, in proportion to the amount of h compression. Although I haven't tried dialling in random amounts of V axis compression to compensate, I'd say PRGui is useless for correcting this form of distortion.
I'd love to find a solution other than DxO - although it seems that I'm the only person bothered by the volume anamorphosis effect...