I'm trying to figure out if there are any projectors out there that let you load in a custom image overlay, whether on internal memory, or via a USB stick or SD card. I'm working on a classroom display project that requires converting the VGA source signal to a round output. Physically cropping the light output from the projector is not possible (I've tried and it's too soft) so I'm looking for a way to digitally alter the source signal and crop/mask anything outside of the center circle. I've got the following mask image that I can use with chroma keying, but I'm not aware of any current projectors on the market that let you load-in a custom image file to overlay on your source. (I swear that I had a projector that could do this many years ago, but I can't remember what model it was, and my searching isn't yielding any results.)