That's what the fixbmpheader.c code does, the mrz99 bitmap format is slightly different to the rgb565 gimp produces. If you run the modified bitmaps through fixbmpheader they should be the correct size.
не могу разобратьÑÑ ÐºÐ°Ðº работать Ñ fixbmpheader.c
I can not understand how to work with fixbmpheader.c