PEF - Pentax Raw Images
File Juicer can extract the JPEG version in the simplest possible way without conversion. You also have the option of using this with File Juicer's Automator action.
This is done the same way File Juicer extracts JPEGs from PowerPoint and Word files. A simple search through the file finds both the low resolution thumbnail and the higher resolution JPEG which is stored inside.
Performance Tip: Uncheck all the formats if File Juicers preferences you don't want to look for, if you know that File Juicer should only search for JPEG files.
To convert and work with the raw data and convert it to other formats you can use dedicated professional applications like: