calculating percentages of a given value in a radiance .pic

And here is one of the many possible standard Radiance tools ways:

pvalue -h -H -o -b -df input.pic | rcalc -if -of -e '$1=1;$2=if(179*$1-THRESHOLD,1,0)' | total -if2

You need to set THRESHOLD to the desired luminance value (in cd/m^2). This will give you two numbers, the ratio of which is the percentage you seek. If you want to do it all on the command line, you can add:

  > rcalc -e '$1=100*$2/$1'

to the end of the pipe.

Best,
-Greg

···

From: "Marija Velickovic" <[email protected]>
Date: October 20, 2008 3:42:28 AM PDT

Hi,

I suppose you can use some of standard Radiance tools for that, but here is another way we use.

In Raddisplay http://deluminaelab.com/en/raddisplay_details.html program you can create falsecolor image from your original radiance image. If you define false color palette with 2 colors - one has value 0 and another value you want to use as a threshold, and open Statistiques dialog, you'll have percent for each color in the tablle. You can also define the palette with more colors, for various threshold values.

Hope this helps,
Marija
De Luminae.

2008/10/20 Galen Burrell <[email protected]>
Hi All,
I have a radiance .pic with lux values calculated using rpict -i. Is there a way to calculate the percentage of the pixels that are at or above a specified value?
Thanks,
Galen