Working-1NL 04/10/2023
Examples of CommonVideo Compression Artifacts
Nigel Lee
Video Quality Analysis Work
05 Aug 2013
Working-2NL 04/10/2023
• Visibility of underlying block encoding structure– Caused by coarse quantization, with different quantization
applied to neighboring blocks• More visible in smoother areas of picture
Block Distortion(Blocking, Blockiness, Pixelation)
Working-3NL 04/10/2023
• Special case of blocking noise along diagonal or curved edges; here, blocking distortion looks like staircase
Staircase Noise
Working-4NL 04/10/2023
• Reduction in sharpness of edges, spatial details– Caused by quantization/truncation of high-frequency
transform (DCT/DWT) coefficients during compression• More noticeable around edges, textured regions
Blurring (Fuzziness, “Unsharpness”)
Working-5NL 04/10/2023
• Colors of contrasting hue/saturation bleed across sharp brightness boundaries, looks like “sloppy painting”
– Caused by chroma subsampling• Worse in images with high color detail
Color Bleeding (Smearing)
Original
Compressed
Working-6NL 04/10/2023
• Haziness, shimmering, blotchy noise around objects/edges– Varies from frame to frame, like mosquitos flying around
person’s head
Mosquito Noise (Gibbs Effect)
Working-7NL 04/10/2023
• Halo surrounding objects and edges– Caused by quantization/truncation of high-frequency transform
(DCT/DWT) coefficients during compression• Doesn’t move around frame-to-frame (unlike mosquito noise)
Ringing (Echoing, Ghosting)
Working-8NL 04/10/2023
• Looks like random noise process (snow); can be grey or colored, but not uniform over image
– Caused by quantization of DCT coefficients
Quantization Noise
