Convert otb to bmp Online: otb2bmp
You can use Tom's Editor to easily convert images from
On-the-air Bitmap .OTB to Microsoft Windows bitmap .BMP.
Tom's Editor is a free, online image manipulation and converter program.
Go to Tom's Editor
On-the-air Bitmap is an image format with extension OTB.
Format created by Microsoft for their Windows and OS/2 operating systems. Images can be compressed or not.