[PD] Pix_levels explanation and Screen Effect for Gem

[IOhannes m zmoelnig]

Peter Forde wrote:
> In Gem, does anyone know how pix_levels works. I just want to kill all
> the reds or greens in a video. I don't understand the floor/ceiling stuff.

if you want to just remove all the greens and reds in the video, why not
texture it on something that has no red/green components (like a
[square] with [color 0 0 1])  - default texturing does a per-channel
multiplication with the underlying color (so if the the channel "red" is
zero for the geo, than the you won't have any red-component in the
displayed image either)
if you want to burn CPU-cycles, you could also use [pix_gain] and set
the gains to "0 0 1"

> 
> Also does anyone know how to do the screen effect, similar to add....?

i don't know what the "screen effect" is.

mfg.asdr.
IOhannes