Model-based edge reconstruction for low bit-rate wavelet-compressedimages
Guoliang Fan; Wai-Kuen Cham
Circuits and Systems for Video Technology, IEEE Transactions on
Volume 10, Issue 1, Feb 2000 Page(s):120 - 132
Digital Object Identifier 10.1109/76.825866
Summary:At low bit rates, wavelet-based image coding is superior to most
traditional block-based methods in terms of visibility and severity of
coding artifacts in coded images. However, the compressed images still
suffer from obvious distortions around sharp edges, which are
perceptually objectionable. In order to improve the image quality for
low bit-rate wavelet-based image coding, we proposed a model-based
edge-reconstruction algorithm for recovering the lossy edges in coded
images. Our approach applies a general model to represent varieties of
edges existing in an image. Based on this model, the edge degradation
process due to quantization errors of wavelet coefficients is analyzed
with the characterization of two kinds of artifacts at edges. We develop
two operations, model-based edge approximation and Gaussian smoothing,
to reconstruct distorted edges by reducing both artifacts respectively.
The proposed method is able to improve the image quality in terms of
both visual perception and image fidelity (peak signal-to-noise ratio)
for most images coded by wavelet-based methods at low bit-rates
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