Signal Process. Lab., Swiss Federal Inst. of Technol., Lausanne.
IEEE Trans Image Process. 1995;4(4):478-85. doi: 10.1109/83.370676.
We address the problem of the choice of subband filters in the context of image coding. The ringing effects that occur in subband-based compression schemes are the major unpleasant distortions. A new set of two-band filter banks suitable for image coding applications is presented. The basic properties of these filters are linear phase, perfect reconstruction, asymmetric length, and maximum regularity. The better overall performances compared to the classical QMF subband filters are explained. The asymmetry of the filter lengths results in a better compaction of the energy, especially in the highpass subbands. Moreover, the quantization error is reduced due to the short lowpass synthesis filter. The undesirable ringing effect is considerably reduced due to the good step response of the synthesis lowpass filter. The proposed design takes into account the statistics of natural images and the effect of quantization errors in the reconstructed images, which explains the better coding performance.
我们在图像编码的背景下解决子带滤波器选择的问题。在基于子带的压缩方案中出现的振铃效应是主要的不愉快失真。提出了一组新的适用于图像编码应用的两带子带滤波器组。这些滤波器的基本特性是线性相位、完美重建、非对称长度和最大正则性。与经典的 QMF 子带滤波器相比，这些滤波器具有更好的整体性能。滤波器长度的非对称性导致能量更加紧凑，特别是在高通子带中。此外，由于短的低通综合滤波器，量化误差减小。由于综合低通滤波器的良好阶跃响应，不良的振铃效应大大减少。所提出的设计考虑了自然图像的统计特性和重建图像中的量化误差的影响，这解释了更好的编码性能。
