A Hybrid Admissible Distortion Checking Algorithm for the B-Spline-Based Operational Rate-Distortion Optimal Shape Coding

Existing distortion measurement using chord-length parameterization (DMCLP) is fast but results in the extra bit-rate problem. In contrast, the up to date accurate distortion measurement using analytical model (ADMAM) can achieve the smallest bit-rate but is very time consuming. It motivates us to develop a hybrid admissible checking algorithm that can take full use of each advantage. Observing that the value of DMCLP is always no less than that of ADMAM, we develop a hybrid distortion checking algorithm that evokes ADMAM if and only if the DMCLP value of associate contour point exceeds the admissible distortion. Theoretical analyses and experimental results demonstrate that our proposal can save up to 48% execution time compared with the ADMAM checking algorithm while maintains the smallest bit-rate property. Moreover, we discover and explain that its reduced execution time com-pared with the ADMAM checking algorithm is increasing while its extra execution time compared with DMCLP checking algorithm is decreasing toward zero as the admissible distortion increases.