Nominal Luminance
These images are published under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License . I was recently in a discussion about the Firefly filter in DAZ Studio's Iray renders. Someone seemed to be asking why increasing the Nominal Luminance for the Firefly filter was actually making the scene darker. I say, "seemed to be," because there was some initial confusion over whether we were talking about Luminosity or Nominal Luminance . Anyway, the discussion prompted me to look into what exactly Nominal Luminance is and what it does in the Firefly filter. With a combination of reading and experimentation, I learned quite a lot and want to share it with you here. First you need to understand what a firefly is in the world of 3D rendering. It's basically an artifact of 3D renders where an individual pixel is drawn much brighter than it should. An image with a bunch of these looks a bit like there are fireflies (the insect) loose in the scen...