[Radiance-general] Display of time lapse at constant brightness

[ascendilex | Wouter Beck]

Dear Group,

I'm trying to display a series of Radiance renderings as a time lapse
animation.

I convert (pfilt -e +0 -r .6 -x /2 -y /2 filtered) hdr-images via
ra_tiff and the resulting tifs are combined into an animated gif via
(ImageMagick's) convert -delay 200 -quality 100 *.tif time-lapse.gif.

Each image represents a view of an atrium 1 hour apart.
The indirectly lit walls of the room that contains my view point get
displayed darker as the atrium scene brightens up.
In absolute terms one wall has a luminance of 15 cd/m2 at 9:00. That
same wall is 29 cd/m2 at 12:00, yet when displayed (using ximage) it
appears darker.
Exposure times in the headers are of course quite different:
vp-A-092108.00.pic:EXPOSURE=3.008155e+00
vp-A-092112.00.pic:EXPOSURE=3.957302e-01


Basically I want the tone mapping according to a constant (perhaps log)
scale for all images.

How can that be accomplished?
(Looks like falsecolor could do this if it also had a greyscale palette.)

Best regards,

Wouter