Title :
Variable projection for near-optimal filtering in low bit-rate block coders
Author :
Tsaig, Y. ; Elad, M. ; Milanfar, P. ; Golub, G.H.
Author_Institution :
Dept. of Comput. Sci., Stanford Univ., CA, USA
Abstract :
Recent work on block-based compression for low bit-rate coding has shown that employing a block coder within a sampling scheme where the image is downsampled prior to coding (and upsampled after the decoding stage) results in superior performance compared to standard block coding. We explore the use of optimal decimation and interpolation filters in this coding scheme. We show that the problem of finding optimal filters for a general, unknown, "black-box" coder can be written as a separable least squares problem in two sets of variables. We then elegantly solve this optimization problem using the Variable Projection method. The experimental results presented clearly exhibit a significant improvement over existing approaches.
Keywords :
block codes; filtering theory; image coding; image sampling; least squares approximations; optimisation; block-based compression; image coding; image sampling scheme; interpolation filter; low bit-rate block coder; low-pass filter; near-optimal filtering; optimization; separable least square; variable projection method; Block codes; Code standards; Decoding; Filtering; Filters; Image coding; Image sampling; Interpolation; Least squares methods; Optimization methods; Block coders; deblocking; separable least squares; variable projection;
Journal_Title :
Circuits and Systems for Video Technology, IEEE Transactions on
DOI :
10.1109/TCSVT.2004.839980