Files with the extension .ITHMB are media files utilised by the 'Apple iPOD'. .ITHMB files are most commonly picture files in a thumbnail format specific to the iPOD and they can be very difficult to open within an alternative operating systems.
.ITHMB picture files are 16-bit uncompressed raw picture files that tend to be very large in size. The reason for the uncompressed nature of the .ITHMB picture files is thought to be due to the lack of processing power available to the iPOD that would be required to decompress archived picture files and the extra power consumption needed for the process that would have drained users batteries faster.
A .ITHMB image file is made up of four images of different resolutions designed to be displayed on different screen sizes.