I used the Panasonic Lumix G Vario 14-42mm f/3.5 -5.6 Asph. / MEGA O.I.S. Lens to take a photo from my balcony.
Here's the original RAW (ORF).
The symptom I am experiencing is that different applications render this image differently, and I am not sure "who is right" and how to fix it.
Here's how Windows 10 Photos renders it: Windows 10 Photos http://philip.mailworks.org/distortion/ORF%20in%20Windows%20Photos.jpg
Looks good. But here's how it looks in Corel AfterShot 2:
You can see some barrel distortion.
I opened this photo in PTGui, which allows me to control the lens parameters.
By default, PTGui considers my lens, 14mm, to be rectilinear, and renders the barrel distortion:
Finally, when I adjust the lens parameter from rectilinear to Full Frame Fisheye, it again looks correct:
It appears that my original image has a significant amount of barrel distortion, why is this lens categorized as rectilinear in PTGui?
More generally, why is there even a drop-down for me to choose between rectilinear and fisheye, given that it's purely a function of focal length, which is already an input? I must be missing something.