[Radiance-general] Create constant radiance image

[Greg Ward]

Hi John,

I updated the ximage man page with the current behavior, which is to  
take the peak of the three channels for reporting of radiance.

Cheers,
-Greg

> From: John Mardaljevic <jm at dmu.ac.uk>
> Date: January 6, 2010 11:13:32 AM PST
>
>> There is no agreed-upon weighting for radiance values, only luminance
>
> Of course (duh)!  I get so used to working between irradiance and  
> illuminance using luminous efficacy models that I occasionally  
> forget some of the R(r)adiance basics.  Nonetheless, to avoid  
> confusion in the future, might I suggest an update to the ximage  
> manpage?  Perhaps something like:
>
> <return> 		Display the mean RGB radiance averaged over the area of  
> interest.  [For a single value, the mean seems less arbitrary than  
> the maximum value for any one of the channels.  Otherwise, some  
> indication of what the current behaviour is.]
> l 			Display the photometrically-weighted RGB luminance value in the  
> area of interest. This assumes that the image was correctly computed  
> in terms of luminance.
> Then again, if I'm the only person who's been bamboozled by this,  
> it's probably not worth the mods to the man page.
> -John