Some expensive projectors have a wall shot button that white balances automatically. i.e. You see a sequence of colors flash for approximately five seconds while the sensor measures the conditions of the projection surface and adjusts the image.
IF you don’t have that feature, you can eyeball it with selective color or try my auto w/b.
I wrote a project a while back that will automatically remove tints of any color. It also works on incorrect camera settings and old film.
1. just record the projected image on the yellow wall with a camcorder then import and replace the video in the project. It has optional furthur tweaking on master control sliders. (important! Stretch it to the exact size!)
2. copy and paste all layer 6’s effects onto your final out comp. The remove tinting effects will now proactively remove themselves before it’s even projected onto the wall.
auto white balance shadow.aep
ae cs3.zip
https://www.mediafire.com/download.php?5vkfg7ash7tgvj7