There is only one file type that uses the .KC2 extension:
Kodak DCS200 Camera Raw Image
A KC2 file is a camera raw image created by the Kodak DCS200, an older digital camera first released in 1992. It contains a picture captured by the camera and stores it in a proprietary file format that was created by Kodak.
The KC2 format is old and no longer commonly used. Photographers who take pictures with the Kodak DCS200 are most likely the only users that will come across this file type.
If you have old KC2 files from a Kodak DCS200 camera, you may want to convert them to a format such as JPEG, which can be viewed by standard image viewing software. Software such as ReaConverter from ReaSoft Development can be used for this purpose.
Updated: October 3, 2020