How does camera firmware obtain lens distortion correction parameters?

Question

I use an Olympus MFT system and one thing I notice is that for most Zuiko MFT lenses there is significant barrel distortion as seen in the raw images. However, if you look at the jpg's, often they have little or no distortion, so apparently it is getting corrected automatically by the camera firmware.

Does the camera (1) just guess at the distortion pattern and apply the same one to every jpg, or (2) does it have some way to detect the lens and have individual distortion correction patterns for particular lenses that it knows about, or (3) does it have some way to detect the distortion by analyzing the image itself and correcting it by image analysis?

Answer 1

Micro Four Thirds (MFT) is a vendor-neutral platform that standardizes the information communicated between camera and lens. Lenses can inform the attached camera body some of their chromatic aberration (CA), lens distortion, and and vignetting characteristics. This allows for an MFT body to do in-camera lens corrections.

Aside from the obvious reasons of high-interoperability as a platform goal, this also allows lens makers to not have to solve such distortions and aberrations optically in the lens. This allows for lighter, less complex, and less expensive lenses.

References:

• Olympus and Panasonic compatibility, In-camera lens correction (apotelyt.com)
• A distorted view? In-camera distortion correction (dpreview.com article)
• Olympus Lens Distortion Correction Does Not Exist??? (dpreview.com discussion thread)

Answer 2

(4) it communicates with MFT lenses and gets told about their distortion parameters.