HDR Source and Linearized Working Space

HDR Source and Linearized Working Space

Should you in fact be fortunate enough to have high-bitdepth
source images with over-range values, there are
indisputable benefi ts to working in 32-bit linear, even if
your fi nal output uses a plain old video format that cannot
accommodate these values., the lights are severely clipped by video
space, which is not a problem so long as the image is only
displayed; all of the images look fi ne printed on this page
or displayed on your monitor. Add motion blur, however,
and you see the problem at its most exaggerated; the
points of light should not lose their intensity simply by
being put into motion.

The benefi ts of fl oating point aren’t restricted to blurs,
however; they just happen to be an easy place to see the
difference. Every operation in a compositing pipeline
gains extra realism from the presence of fl oating point
pixels and linear blending.
 features an HDR image on which a simple
composite is performed, once in video space and once
using linear fl oating point. In the fl oating point version,
the dark translucent layer acts like sunglasses on the bright
window, revealing extra detail exactly as a fi lter on a camera
lens would. The soft edges of a motion-blurred object also
behave realistically as bright highlights push through. Without
floating point there is no extra information to reveal, so

the window looks clipped and dull and motion blur doesn’t
interact with the scene properly.