CAMBI: Contrast-aware Multiscale Banding Index
This addresses video quality assessment for viewers, particularly on larger displays, but is incremental as it builds on existing perceptual models.
The paper tackled the problem of banding artifacts in videos by developing a no-reference banding index called CAMBI, which predicts banding visibility based on human visual system insights and correlates well with subjective perception.
Banding artifacts are artificially-introduced contours arising from the quantization of a smooth region in a video. Despite the advent of recent higher quality video systems with more efficient codecs, these artifacts remain conspicuous, especially on larger displays. In this work, a comprehensive subjective study is performed to understand the dependence of the banding visibility on encoding parameters and dithering. We subsequently develop a simple and intuitive no-reference banding index called CAMBI (Contrast-aware Multiscale Banding Index) which uses insights from Contrast Sensitivity Function in the Human Visual System to predict banding visibility. CAMBI correlates well with subjective perception of banding while using only a few visually-motivated hyperparameters.