╬ HDR to 8 bit Grading Tip ~ Reclaiming the Shadows ╬
Content courtesy Gordon Laing / Cameralabs
- When rendering 8 bit videos from HDR / 32 bit float projects in Vegas, a narrow band of monochrome quantization noise appears to take over the bottom 5% of RGB color space.
- This also can occur when rendering 8 bit source to a 10 bit container in a float project.
Source: GH5 10 bit 422 Project: 32 bit Float, Video Levels.
8 bit output pipeline
- Spoiler: To skip the tl;dr part, here is the solution to remove the unwanted noise from your 8 bit renders:
Apply the Levels filter to your 32 bit project as such:
- Before:
- After:
- Side by Side:
If we isolate only the added noise by a 10:1 factor, we see from the histogram that it is spurious narrow negative sideband monochrome noise, unrelated to the original 10 bit image integrity. So much for Hogwarts' School of Grading.
- What did we do? We added a nondestructive low block filter, to isolate and precisely remove some unwanted frequencies from the video.
- How did the noise get there? This is the kind of spurious quantization noise that would normally get clipped out of gamut using good integer leveling techniques. In a float project, it sits right alongside the lowest program bits, and lacking fixed endpoints, will be imported right along to the compressed 8 bit space, unless excised first using a technique such as this.
- Conclusion: When rendering 8 bit video from HDR / 32 bit float projects, shadow noise can be reduced and apparent sharpness increased by applying a 0.05 to 0.10 Shadow Mask, using the Levels plugin.
- When rendering from 8 bit projects, regardless of native source depth, there are no differences, and no apparent correction is needed.
In this example, a low cut at 0.088 separated the noise from the signal, preserving the detail while cleaning the shadows.