I like to project our church beamer presentations over my camera image with alpha channel effect.
(both are coming in through the capture input)
The presentations have most of the time black or white backgrounds.
I did some tests with color settings black/white stretch and alpha, but my camera image is always getting lighter or darker and the text is not sharp.
Isn't there are more simple way to filter out the black or white background and project the letters on the camera image?

Chromakey is not working because the text must be displayed over the whole camera image.

Thanks, but I am not making the presentations by myself.
The (guest)speakers are bringing there own presentations.

The beamer output is captured as a video signal, so I've got 2 capture inputs to create this effect.
Should that also be possible with lumakey?

Have you tried picture in picture ?
using the multi-view to place speaker in a sized down window over the text.
Also I have had the speaker stand in front of a Green screen and keyed them over a presentation
While sized and place in an optimal position. then I can fade them up and down as needed.
kind of like a virtual set but with presentation as the background .

I can't edit the presentation.
I've only got the video output of the pc that is showed on the beamer.

btw. The presentation should always be on the foreground, not behind the speaker.


However, I got a nice result now with this settings (for those who are interested):

Beamer image color settings:
white text on black background: Black stretch=0 White stretch=7 Alpha=6
Black text on white background: Black stretch=242 White stretch=234 Alpha=10

Start the lumakey effect with start Overlay (Alpha=128) and effect duration=1000 for a smooth fade effect.