SI effectiveness evaluation

  • Side information is corrected with parity bits to produce the decoded WZ frame
  • Intuitively, the most the SI “is similar” to the original image, the less parity bits are needed
  • Traditionally, PSNR between SI and WZF has been used to evaluate the SI quality
  • However it is easy to build some toy example where two iso-PSNR images requires a very different number of correction bits

si_quality_example

Questions: why PSNR is not always reliable? Can we find better metrics?
Applications: Hash-based DVC systems, Witsenhausen-Wyner video coding systems, …
New framework for metric comparison based on end-to-end RD performance
Proposed metrics:

SIQ: logarithmic of the cumulated value of an arbitrary power of the error
HSIQ: logarithmic measure of the Hamming distance

SIQ and HSIQ improves wrt PSNR both theoretical and practical effectiveness measures (Hash-based system: 20% rate reduction)
PSNR works well for homogenous errors and start failing for large but spatially concentrated errors

Mon blog professionnel d'enseignant/chercheur de Telecom-ParisTech