Read the documentation of CircleOS that you can find here:
You will have all the information in the chapter 3 - LCD
CircleOS can display image with the DRAW_SetImage() function.
Several format can be use with this function :
• Raw image (format used with previous CircleOS versions),
• 16-bits BMP image,
• 256 colours BMP image,
• 256 colours BMP image with RLE compression.
When called, the function search the information in the BMP header : a BMP always start with the code
“0x42 0x4d” at the begin of the file, also the bytes number 6 to 9 should be reserved and set to 0. If
those 2 conditions are fitted the data are read as BMP.
You can download and see image feature from Space-Invaders-10.1 example at http://www.stm32circle.com/projects/project.php?id=227