The document discusses no-reference algorithms for video quality assessment focused on artifact evaluation in MPEG-2 and H.264 encoding standards. It highlights advancements in encoding techniques and tools, including the impact of blocking and blurring artifacts on video quality. The conclusions emphasize the need for improved artifact detection methods informed by human visual perception.

1. No-Reference Algorithms for Video
Quality Assessment based on
Artifact Evaluation in MPEG-2 and
H.264 Encoding Standards
Juan Pedro López Velasco
Universidad Politécnica de Madrid
Ghent, 31th May 2013
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2. Index
• No-Reference Quality Assessment
• Encoding standards
• Advanced tools
• Work in Artifacts detection:
– Blocking
– Blurring
• Conclusions
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3. No-Reference Algorithms
• NR: Still necessary in environments
with no reference available (internet,
mobiles).
• NR: search for what human eye sees.
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4. Encoding standards
Each standard offers better tecniques
than the previous ones.
• H.263 / MPEG-2
• H.264
• HEVC (in the future)
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5. Artifacts
• Blocking
• Blurring
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6. Advanced Tools
• Improvement in H.264 from MPEG-2
includes:
– Deblocking filter
– Variability in macroblocks size
– Efficiency improvement
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7. Blocking
• Based on gradient detection and
filtering, evaluates the changes in
degree in edges for each
pixel/macroblock.
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8. Advanced Gradient Filter
• Original image (No encoding)
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9. MPEG-2
– Blocking artifact detected in homogeneous
areas.
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10. H.264
• Without deblocking filter
– Blocking artifact detected in homogeneous
areas.
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11. Deblocking filter
• The effience in deblocking is not perfect
in big homogeneous areas.
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12. Blurring
• Based on transforms, such as
Hadamard and distribution of energies,
taking into account the variability of
macroblock size in H.264.
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13. Diagrams of energy
distribution
• Distribution of energies based on
Hadamard coefficient analysis
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14. Conclusions
• Efficiency in detecting artifacts, also in
H.264, based on metrics from MPEG-2
– Necessity of taking into account advances
encoding to improve results:
• Deblocking filter.
• Variability of coefficients /
• The final decision depends on what
human eye see (NR vs. FR).
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15. Thanks for your attention
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