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

[Stephen Wasilewski]

Have you tried a ratio of G:B?

-e 'thresh=2' -e
'ro=if(thresh-gi(1)/bi(2),ri(2),ri(1));go=if(thresh-gi(1)/bi(2),gi(2),gi(1));bo=if(thresh-gi(1)/bi(2),bi(2),bi(1))'

I haven't tried this syntax, but I was doing something similar recently and
it worked to use the ratio of two colors rather than an absolute.

Stephen Wasilewski
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On Mon, Feb 29, 2016 at 4:45 PM, Christian Humann <chris at christianhumann.com
> wrote:

> Greetings,
>
> (apologies for the duplicate post which I errantly posted in haste the
> first time by using reply to another subject)
>
> 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
>
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