Convert bmp to ithmb Online: bmp2ithmb
You can use Tom's Editor to easily convert images from
Microsoft Windows bitmap .BMP to iPod Thumbnail
Tom's Editor is a free, online image manipulation and converter program.
Go to Tom's Editor
Format created by Microsoft for their Windows and OS/2 operating systems. Images can be compressed or not.
ITHMB are thumbnails used by various Apple devices. At first these images were used by iPhods but now can be found on iPhones and iPads.