This link might help:
http://www.fortunecity.com/skyscraper/windows/364/bmpffrmt.html
From what I've quickly read there, you should be able to write a BMP loader which gives you direct access to the RGB data. By modifying this data you should be able to change the colour of any given register.
http://www.fortunecity.com/skyscraper/windows/364/bmpffrmt.html
From what I've quickly read there, you should be able to write a BMP loader which gives you direct access to the RGB data. By modifying this data you should be able to change the colour of any given register.