[Radiance-general] extracting brightness values from picture

[Greg Ward]

As I said, you can also select a region in ximage and use the 'l' key  
to get luminance that way.  And to correct a missing conversion  
factor in my luminance calculation using a mask, the command should  
have read:

         ra_ppm -r mask.ppm \
                  | pvalue -h -H -pG -df \
                  | rlam -if - "\!pvalue -h -H -o -b -df result.pic" \
                  | rcalc -if2 -of -e 'cond=$1-.5;$1=179*$2' \
                  | total -if -m

-Greg

> From: "Prasanta Bhattarai" <bhattarai at simcenter.org>
> Date: January 7, 2008 6:48:17 AM PST
>
> Thanks Greg & Rob for your quick response.
>
> I am using radiance on Linux and I am relatively a new user (both
> radiance & Linux). I'm sure it's going to take some time for me to
> understand Greg's syntax and be able to use it. So for now, I will try
> to find a Mac and do calculations on photosphere.
>
> Thank You so much.
>
> Prasanta