You can use to_framestore with 12-bit clips. When importing 16-bit SGI image files, to_framestore expects to find the 12 bits of data in the 12 most significant bits of each colour component. You can use the -l command line option to tell it to look at the 12 least significant bits instead. These options are most commonly used when working with 16-bit SGI image files originating from an Oxberry film scanner. See About Importing Media Files.