Illuminated (alpha) gunsights require to bmp files ...
The blahblah_alpha.bmp is 128x128 pixel
grayscale image. This is where the actual gunsight is created.
The blahblah.bmp file is a 128x128 RGB image filled with the color that you want the gunsight to be.
What happens is that anything drawn in the _alpha.bmp that is white to shades of grey is where the color will bleed thru.
So pure white will allow 100% of the color to bleed thru, while the graduated shades of white (grey) will allow percentages of the color to bleed thru. Black allows no color to bleed thru.
I have a bunch of alpha sights on my FTP site ...
http://ftp://AcesHigh:AcesHigh@slapshot.homeftp.nettry those. The AeroReviSights.zip contains most of the popular sights converted to alpha ... excellent work by Aero.
I made one of my own using one of Aero's as the template.