Log images have become very popular since today every digital cinema camera manufacturer offers a log output option. But log images look weird and require completely different math operations than normal linear images so they must be converted to linear before working with them – most of the time. This article reveals the advantages of log images, how they work, and how to work with them.
We saw in Part 2, the Real World, how scenes can have an enormous dynamic range that far exceeds our cameras. The inevitable result of this is the camera must clip the scene at its maximum brightness level, so we will explore solutions to that clipping. Film, on the other hand, does a soft clip at the shoulder of the film response curve that is far more elegant. Cameras also perceive color differently than our eyes and those differences must be understood and accounted for. Cameras also introduce their own digital idiosyncrasies to the image such as rolling shutter and digital noise due to their electro-optical design. This too must be understood that we may compensate for them in our work.
The visual effects color pipeline starts in the real world, of course. The light from surfaces and light sources are captured by cameras and travels a data path through several “spaces” to the movie screen. The challenge for visual effects is that the real world presents color and light in a totally different way that far exceeds the capacity of our display devices so a degraded version of the original scene must be carefully managed in order to deliver the most realistic version of the original scene to the audience. The real world is not a “color space” in the color science sense, but instead is presented here as the “World Space” where our entire VFX pipeline begins.
