Some simple effects based around changing the image based on luminosity thresholds.
I like the more subtle effects best, I think. I’ve always liked the effect of selectively desaturating an image, and desaturating based on luminosity seems to work well. What would be even cooler would be to be able to desaturate the image based on hue, so you could make an image monochrome, except for a particular colour.
Sorry about the photos of me. It’s not because I’m some kind of egomaniac. It’s more that I’m generally too lazy to use anything other than my laptop’s builtin iSight as an input when I’m developing qcFX.
machines don't care 
I’m certain you can desaturate by hue and with stock patches… It seems like I setup a qtz to do that a year or so ago. I’ll give a look, maybe I’m remembering wrong. I think I set it up so that you just have to pick the color that you want to leave untouched.
Where’s the fun in that, though..?
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Voli Dublino thinks you are right!