Can't find functions

[WALP]

havent tried it yet but Effect_Screen_Start()
"Creates an image that shows up on the screen, it must be faded manually. Remember that these must work both on 4:3 and 16:9 aspect ratio"

The function does not seem to use images directly, but through materials, so you will probably need to set one up for your image.
The function also seems to have both a simplified and extended version of itself.