[:fr]Notre article sur l’évaluation de la qualité pour l’information adjacente a été finalement accepté dans IEEE Transactions on Circuits and Systems for Video Technology.
L’idée de base est que l’erreur quadratique moyenne n’est pas une bonne métrique pour mesurer la qualité de l’information adjacente dans un système de codage vidéo distribué. La raison est que cette image n’est pas utilisée pour une prédiction, mais elle est « corrigée » par décodeur de canal, à l’aide d’un certain nombre de bits de parité. Ce nombre de bit et la qualité de la correction affectent les performances finales du système. L’EQM ne prend pas en compte ces phénomènes, et donc des nouvelles métriques ont été proposées.
L’utilisation de ces métriques dans des systèmes de codage vidéo distribué avec « hash » permet de réduire le débit de codage de plus de 25% en moyenne.[:en]Our article about side information effectiveness in distributed video coding has been accepted in IEEE Transactions on Circuits and Systems for Video Technology.
The abstract follows:
The rate-distortion performance of a distributed video coding system strongly depends on the characteristics of the side information. One could naively think that the best side information is the one with the largest PSNR with respect to the original corresponding image. However, previous works have shown that this is not always the case and a reduction of the side information MSE does not always translate into better rate-distortion performance for the complete system. The scope of this paper is to explore a set of metrics other than the PSNR and explicitly designed to classify the side information with respect to its impact on the end-to-end compression performance. A first contribution is to define an experimental framework that can be used to meaningfully compare different metrics for side information evaluation. As a second contribution, our analysis allows to understand why in some cases PSNR-based metrics provide a fairly reliable estimation of the side information quality, while in other cases they do not. This analysis also allows us to introduce a set of new metrics that are better adapted for side information effectiveness evaluation, and that are based on a suitable power of the absolute difference between side information and the original image, or on the Hamming distance between the respective transform coefficients. Besides their theoretical interest, these new metrics can also improve the rate-distortion performance of some distributed video coding systems such as the hash-based ones. We observe improvement up to 74 % rate reduction in a simple study case.[:it]Il nostro articolo sulla valutazione della Side Information per sistemi di codifica video distribuita è stato accettato in IEEE Transactions on Circuits and Systems for Video Technology.[:]