文件名称：Shape-Adaptive Discrete Wavelet Transforms for
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更新时间：2011-03-29 14:41:12
Discrete for Shape-Adaptive Transforms Wavelet
Abstract—This paper presents a shape-adaptive wavelet
coding technique for coding arbitrarily shaped still texture. This
technique includes shape-adaptive discrete wavelet transforms
(SA-DWT’s) and extentions of zerotree entropy (ZTE) coding
and embedded zerotree wavelet (EZW) coding. Shape-adaptive
wavelet coding is needed for efficiently coding arbitrarily shaped
visual objects, which is essential for object-oriented multimedia
applications. The challenge is to achieve high coding efficiency
while satisfying the functionality of representing arbitrarily
shaped visual texture. One of the features of the SA-DWT’s is
that the number of coefficients after SA-DWT’s is identical to the
number of pixels in the original arbitrarily shaped visual object.
Another feature of the SA-DWT is that the spatial correlation,
locality properties of wavelet transforms, and self-similarity across
subbands are well preserved in the SA-DWT. Also, for a rectangular
region, the SA-DWT becomes identical to the conventional
wavelet transforms. For the same reason, the extentions of ZTE
and EZW to coding arbitrarily shaped visual objects carefully
treat “don’t care” nodes in the wavelet trees. Comparison of
shape-adaptive wavelet coding with other coding schemes for
arbitrarily shaped visual objects shows that shape-adaptive
wavelet coding always achieves better coding efficiency than
other schemes. One implementation of the shape-adaptive wavelet
coding technique has been included in the new multimedia coding
standard MPEG-4 for coding arbitrarily shaped still texture.
Software implementation is also available.