From Just Solve the File Format Problem
If, in the first TIFF IFD, the Make or Model tag has a value that begins with "PENTAX", or the Compression code is 65535, it's probably a PEF file.
- http://www.pfpho.com/k5review/raw/ → *.PEF
- Pentax K-5 Review → Sample RAW Images
- Pentax K20D Review → RAW format
- RAW-Samples: Pentax
- http://digikam3rdparty.free.fr/TEST_IMAGES/RAW/ → .../*.pef
- http://digikam3rdparty.free.fr/TEST_IMAGES/HDR/ → *.pef