Simulated Annealing for Optimisation and Characterisation of Quantisation Parameters in Integral 3D Image Compression

The authors have developed a lossy coding scheme using a 3D discrete cosine transform, for use with integral 3D image data. Correct selection of the step sizes of the uniform symmetric scalar quantisers used in the scheme is crucial to attaining good rate-distortion performance. Imageorientated optimisations have been performed to obtain the quantisation parameters leading to minimum objective distortion of the reconstructed image at given bit rates. Simulated annealing, an optimisation method suitable for complex non-linear problems whose objective functions typically possess many local extrema, is used for this purpose. A model for optimal quantisation is then constructed for general use across an arbitrary bit rate range. This paper describes the integral 3D imaging system which generates the image data used, the coding scheme and the simulated annealing technique. The results of simulations using optimal model-derived quantisation arrays are presented and compared with previous use of fixed quantisation parameters.