MRW - Konica Minolta Raw Images
Many of Konica Minolta's digital cameras can shoot images in raw format which contains everything its sensor sees.
Convert
If you have macOS 10.4.8 File Juicer will use Apples RAW importer to convert the MRW files to JPEG or TIFF depending on the checkboxes you set in the preferences.
To convert and work with the raw data and convert it to other formats you can also use my other application DoubleTake, iPhoto, Preview or dedicated professional applications like: