Smooth chroma quantization curve for Daala

This video is a before and after comparison of continuously varying the chroma quantization offset on still images from the subset1 corpus. The curve has been fitted to minimize the mean of per-pixel CIEDE2000 color distance. A tightly fitted curve was found by global optimization and relaxed to a simple function of similar shape. Daala is the code-name for a new video compression technology. The effort is a collaboration between Mozilla Foundation, Foundation and other contributors.