Active process: intentionally reducing high-bit footage (10-bit, RAW) to lower bit depth — for compatibility, delivery, storage. Must be controlled with dither to minimize artifacts.
You're sitting in the grading suite with a 10-bit DPX sequence from the camera—but your client wants a ProRes 422 HQ for the editing suite, and archiving should be done using 8-bit LUT cubes. Quantizing is the controlled process of deliberately reducing these higher-quality files to lower bit depths. It's not about loss in an emotional sense, but about planned digital reduction.
The practice: When you quantize from 10-bit to 8-bit, you reduce the color information per channel from 1,024 possible values to 256. That sounds brutal, but with the right tools, the visual quality remains stable. The trick lies in dithering—you deliberately add noise before quantizing to avoid banding artifacts. Without dither, you'll see posterization effects, especially in gradients and sky areas. With dither, the eye is fooled; the grain masks the jumps between quantization levels. In editing software like Resolve or Premiere, you usually work with this process automated—but during export, you have to make a conscious choice: ordered dither for technical files, error-diffusion dither for final deliverables where quality counts.
On set or later in post: RAW material from RED or ARRI often comes as a logarithmic 12-bit sequence. For real-time playback, you quantize to 8-bit Log or rec.709 so the monitor doesn't crash. This isn't destructive as long as you archive the original bits. But for the final DCP or mastering for streaming—here, quantizing is a one-way ticket. You have to decide: Will it be 8-bit or 10-bit? For cinema, you often need 12-bit TIFF or DPX. For Netflix, usually 10-bit H.265. Each format step forces you into a moment of quantization.
The most common mistake: Quantizing without dither and then wondering why the final grading master looks like a poster. Or: quantizing too early in the workflow—if you're already at 8-bit, you can't go back to 10-bit quality, even if you need color correction. Always work from top to bottom, never from bottom to top. Bit depth is a one-way street—lower it only when you absolutely must, and do it with care.