Comparison of MPEG-2 and AVC coding on synthetic test materials

The resources for evaluation of moving imagery coding include a variety of subjective and objective methods for quality measurement. These are applied to a variety of imagery, ranging from synthetically-generated to live capture. NIST has created a family of synthetic motion imagery (MI) materials providing image elements such as moving spirals, blocks, text, and spinning wheels. Through the addition of a colored noise background, the materials support the generation of graded levels of MI coding impairments such as image blocking and mosquito noise, impairments that are found in imagery coded with Motion Pictures Expert Group (MPEG) and similar codecs. For typical available synthetic imagery, human viewers respond unfavorably to repeated viewings; so in this case, the use of objective (computed) metrics for evaluation of quality is preferred. Three such quality metrics are described: a standard peak-signal-to-noise measure, a new metric of edge-blurring, and another of added-edge-energy. As applied to the NIST synthetic clips, the metrics confirm an approximate doubling [1] of compression efficiency between two commercial codecs, one an implementation of AVC/H.264 and the other of MPEG-2.