[Radiance-general] Pcomb to mask an area of one image on to another

[Christian Humann]

Greetings,

I’d like to write an expression within pcomb to mask the area of green trees in one  HDR fisheye scene and apply those selected pixels in the same location on a second image (both images are the same resolution).  Here’s an example of what I’m trying to do:
https://gyazo.com/932e7a14d64c35bff1802bcd11acc053

I’m getting close, but just can’t quite get there with the correct syntax using a threshold value for green [ex: -e 'gi(1)-thres*gi(2)’]

Thanks,
Chris