you sir are crazy that can not be done with shity onboard video. even if that would make on board video very expensive!
The real world is composed of transparent, translucent, and opaque objects. Alpha blending is a technique for adding transparency information for translucent objects. It is implemented by rendering polygons through a stipple mask whose on-off density is proportional to the transparency of the object. The resultant color of a pixel is a combination of the foreground and background color.
Typically, alpha has a normalized value of 0 to 1 for each color pixel.
new pixel = (alpha)(pixel A color) + (1 - alpha)(pixel B color)