Histogram-Based Prefiltering for Luminance and Chrominance Compensation of Multiview Video
Histogram-Based Prefiltering for Luminance and Chrominance Compensation of Multiview Video
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DOI：
10.1109/tcsvt.2008.926997
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发表时间：
2008-09
影响因子：
8.4
通讯作者：
U. Fecker;M. Barkowsky;André Kaup
中科院分区：
文献类型：
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作者：
U. Fecker;M. Barkowsky;André Kaup
最近在用多个摄像机记录的视频数据的编码方面已经取得了重大进展。然而，相机视图之间的亮度和色度变化可能使多视图编解码器和基于图像的渲染算法的性能劣化。可以应用直方图匹配算法以在预滤波步骤中有效地补偿这些差异。导出了一个映射函数，该映射函数将失真序列的累积直方图适应于参考序列的累积直方图。如果使用直方图匹配将多视图序列的所有相机视图适配到公共参考，则改善了跨相机视图的空间预测。基本算法以三种方式扩展：映射函数的时间常数计算、RGB颜色转换和全局视差补偿的使用。当时间常数直方图计算和RGB颜色转换相结合时，获得了最佳的编码效果。在这种情况下，在多视图编码之前使用直方图匹配导致编码效率的实质性增益，对于亮度分量高达0.7dB，对于色度分量高达1.9dB。该预滤波步骤可以与基于块的照明补偿技术相结合，该技术修改编码器和解码器本身，特别是与联合视频团队（JVT）的多视图参考软件中实现的方法相结合。当这两种方法相结合时，可以观察到高达0.4 dB的额外编码增益。
Significant advances have recently been made in the coding of video data recorded with multiple cameras. However, luminance and chrominance variations between the camera views may deteriorate the performance of multiview codecs and image-based rendering algorithms. A histogram matching algorithm can be applied to efficiently compensate for these differences in a prefiltering step. A mapping function is derived which adapts the cumulative histogram of a distorted sequence to the cumulative histogram of a reference sequence. If all camera views of a multiview sequence are adapted to a common reference using histogram matching, the spatial prediction across camera views is improved. The basic algorithm is extended in three ways: a time-constant calculation of the mapping function, RGB color conversion, and the use of global disparity compensation. The best coding results are achieved when time-constant histogram calculation and RGB color conversion are combined. In this case, the usage of histogram matching prior to multiview encoding leads to substantial gains in the coding efficiency of up to 0.7 dB for the luminance component and up to 1.9 dB for the chrominance components. This prefiltering step can be combined with block-based illumination compensation techniques that modify the coder and decoder themselves, especially with the approach implemented in the multiview reference software of the joint video team (JVT). Additional coding gains up to 0.4 dB can be observed when both methods are combined.