The actor lost the shirt, so we had to switch to a white turtleneck for all other scenes. This is like an 8 second scene, and all I want to do is just invert the blacks, it will save me a reshoot. I've tried luma key, chroma key, change to color, and none of it works worth a damn. I just can't key out the blacks. Nothing comes close. Luma key has had the best results but it wants to take big chunks of the vest out. Pieces that are obviously red/maroon.
In general, the Extract effect is the most useful for qualifying a luma range. You may still need to at least roughly rotoscope, too, though.
Also, simply inverting the darkest range won't help -- that will also invert the shadows on the shirt, making them highlights instead. I'm not sure you'll have enough detail in the shot to stretch the range and keep the shadows. Re-shooting may ultimately be your easiest option.
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