[Radiance-general] getting pixel value at x,y

[Lars O. Grobe]

> 	pcomb -o captured.pic \
> 		| pcompos -x ${box_width} -y ${box_height} - -${left} -${lower} \
> 		| pvalue -h -H -df | total -if3 -m
> 
> The initial pcomb command is necessary to apply the exposure values  
> correctly.  If you want luminance (rather than radiance) output, use:

I actually thought that I could use the -o option calling pvalue
instead. What is the difference between pcomb -o my.pic | pvalue and
pvalue -o my.pic?

Thank You again, Lars.