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作者是重点研究电视信号帧相关频带压缩法的,也包括动态视觉特性。作为它的一个环节,本文就帧差信号的诸特性进行了若干探讨, 通过实验,确定了其频率包络与频率f的关系,给出了帧差信号模型。当f=0时,其频谱的包络也是0,当f增大,由于存储效应摄象靶面出现模糊时为1/f~2,如果不出现模糊则是1/f。另外,用这个形式计算出了自相关函数。还探讨了帧差信号的固有展开函数形式,说明了采用低通滤波器限制频带的妥善性。其次,从频带压缩的角度考虑,认为帧差信号的短时间特性比统计特性重要,所以对此特性进行了若干次实测。根据帧差信号短时间产生的特点和短时间频谱的特征,证明用比较简单的方法就可以分离出动态模式。最后,利用曾经报导过的视觉特性,对于所分离的动态模式实现视觉的最佳编码。由此证明,帧相关压缩法的压缩率可达到1/3.5。但是,帧间编码方式在接近静止的那种缓慢活动场面,从图象质量上看还有问题,所以在传送高质量图象方面还应重新严格讨论,因为一般在电视节目中,慢动场面的图象质量是非常重要的。
The author focuses on the relevant band compression method for television signal frames, and also includes dynamic visual characteristics. As a part of it, this paper discusses several characteristics of the frame difference signal. Through experiment, the relationship between the frequency envelope and the frequency f is confirmed, and the frame difference signal model is given. The envelope of the spectrum is also 0 when f = 0, 1 / f ~ 2 when f is increased, 1 / f ~ 2 due to storage effect, and 1 / f if no blur occurs. In addition, the autocorrelation function is calculated using this form. The form of the inherent expansion function of frame difference signals is also explored, illustrating the usefulness of band limiting with low-pass filters. Secondly, from the viewpoint of frequency band compression, it is considered that the short-time characteristic of the frame difference signal is more important than the statistical characteristics, so this characteristic has been measured several times. According to the characteristics of the frame difference signal generated in a short time and the characteristics of the short time spectrum, it is proved that the dynamic mode can be separated by a relatively simple method. Finally, using the previously reported visual characteristics, the best visual coding is achieved for the separated dynamic modes. This proves that the compression ratio of the frame-related compression method can reach 1 / 3.5. However, the interframe coding approach is similar to the still-moving slow motion scene, which is problematic in terms of image quality. Therefore, it is necessary to re-discuss strictly the transmission of high-quality images because, in general, in television programs, slow motion scenes The image quality is very important.