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In addressing today's complex video environment, tackling artifacts or issues that appear with video remains a challenge for many in the industry. In his presentation Examples of Common Video Compression Artifacts, our lead technologist Dr. Nigel Lee identifies some of the various types of artifacts found in today's compressed digital video outputs.
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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