Direction scalability of adaptive directional wavelet transform: An approach using block-lifting based DCT and SPIHT
Direction scalability of adaptive directional wavelet transform: An approach using block-lifting based DCT and SPIHT
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DOI：
10.1109/iscas.2010.5537992
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发表时间：
2010-08
期刊：
影响因子：
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通讯作者：
Yuichi Tanaka;Madoka Hasegawa;Shigeo Kato;Taizo Suzuki;M. Ikehara
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文献类型：
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作者：
Yuichi Tanaka;Madoka Hasegawa;Shigeo Kato;Taizo Suzuki;M. Ikehara
自适应方向小波变换是传统二维小波变换在图像编码中的有效替代方案。它能够自适应地变换图像沿着对角线方向以及传统的垂直/水平方向。然而，其需要将变换方向信息传输到解码器侧。对于非常低比特率的图像编码，方向信息的比特预算降低了重构图像质量。本文提出了一种构造变换方向可分级码流的方法。我们利用的事实是，由变换方向索引产生的矩阵仍然包含原始图像的特征。该矩阵通过基于块提升的DCT变换，然后通过SPIHT编码以产生可伸缩比特流。我们的方法是有效的非常低的比特率的图像编码，并与不可伸缩的中高比特率的一个。
Adaptive directional wavelet transform is an effective alternative of the traditional 2-D wavelet transform for image coding. It is able to transform an image adaptively along diagonal orientations as well as conventional vertical/horizontal directions. However, it requires to transmit transform direction information to the decoder side. For image coding at very low bitrates, the bit budget of the direction information degrades a reconstructed image quality. In this paper, a method to construct a scalable bitstream for transform directions is presented. We utilize the fact that the matrix yielded by transform direction indices still contains the original image characteristics. The matrix is transformed by a block-lifting based DCT, then encoded by SPIHT to yield a scalable bitstream. Our method is effective for very low bitrate image coding, and is comparable to the non-scalable one for middle-to-high bitrates.