[Radiance-general] Composing multiple radiance images

[Lars O. Grobe]

Hi Giovanni!
> I am not performing any filtering but maybe there is something happening
> behind the scenes...
> I simply set up a job generating 9 images using rad and then a simple
> pcompos line to tile them together
>
> 	pcompos -a 3 test00*.pic>  composite.pic
>
> is this offering more insights?
rad will typically call pfilt

1) to filter down resolution (at any quality setting not equal to LOW) 
to achieve antialiasing as well as
2) to apply a useful exposure (at any quality setting).

If you want to assemble the filtered images, you should set a common 
exposure value to all of them. See the manpage of rad, where the 
EXPOSURE variable is explained as well as how to find a suitable value.

You can also simply keep the unfiltered images as generated by rpict. 
You could then assemble the raw images and filter the complete, 
assembled mosaic. Tell rad to keep the unfiltered images by specifying a 
name pattern using the RAWFILE variable. Again, the details are 
explained in the manpage of rad.

If you want to read numerical values from filtered images, usually the 
-o option are of help. This gives you access to the original pixel 
values by reversing the exposure mapping performed by e.g. pfilt. See 
e.g. the manpage of pvalue.

Cheers, Lars.