Video signal noise characteristics with regard to scanning method

The evaluation of a television system is finally verified through the subjective assessment of the picture quality on a display. A system evaluation method has been studied in terms of the picture quality degraded by random noise added through a transmission line, using a weighted signal-to-noise ratio considering the human visual characteristics, and an unweighted signal-to-noise ratio, that is, a physical signal-to-noise ratio. In this paper, the relation between the quantity of random noise added through the transmission line and the quantity of random noise on a display is provided in a television system using either an interlace scanning method or a progressive scanning method, and the change in noise characteristics through an interlace-to-progressive scanning conversion is analyzed. Furthermore, the change in noise characteristics mediated by the human visual system is investigated, and finally, these studies and analyses are verified through subjective assessment     

On line-free and flicker-free television reproduction

In conventional television systems, picture scanning in vertical and temporal directions is usually very defective with regard to the sampling theorem. In this paper some deficiencies such as aliasing, line-structure distortion, line flickering, and large-area flickering are investigated with regard to their dependence on the inter-lacedpicture-scanning process. The three-dimensional reconstruction filtering of the sampled picture is especially analyzed with respect of the viewer's perception. Furthermore, it will be shown that in connection with a new concept of picture scanning published earlier [1], [2], a flat-field reproduction without any 25/30-Hz flicker can be achieved by vertical filtering only. This is true even though the final reproduction by the monitor is performed with interlace. The vertical filtering can then be optimized in the sense of maximum picture sharpness and resolution with negligible ringing as well. Practical results are given in this paper.This research was supported by the German Ministry of Research and Technology. Parts of this paper have been presented at the 1983 International Symposium on Circuits and Systems, Newport Beach.     

Simplified 6.3 Mbit/s Codec for Video Conferencing

A color TV codec with a 6.3 Mbit/s transmission bit-rate has been simplified by a newly developed coding method. This method is the combination of a 4-to-1 dot interlace system and 4 bit/pel DPCM. A digital filtering technique for reducing coding distortion is also employed. In comparison with an interframe codec having the same transmission bit-rate, the amount of codec circuitry is halved. Subjective tests were performed to investigate the coded picture quality. It was found that this codec can present acceptable pictures for video conferencing, and that the picture quality for rapidly moving subjects is the same as that of the interframe codec operating at the same bit-rate. A video conferencing system via a digital satellite link has been constructed for experiments by employing this codec. The experiments showed that the satellite link has a sufficiently low transmission error rate for the coded pieture transmission. Moreover, it has been proved that transmission delay does not pose any problems for normal conferences.     

Character Display on a CRT

Character fonts on raster scanned display devices (e.g., the home television receiver) are usually represented by arrays of bits and displayed as a matrix of black and white (or color) dots. In VIDEOTEX systems, due to the limitations on bandwidth, number of scanning lines, and the interlace of the broadcast television standard, each frame is allowed to contain about 21 rows of 40 characters each; each character occupying a rectangular area of 12 picture elements by 20 lines. The character sets that have traditionally been used in VIDEOTEX systems, have not used the multilevel display capabilities of the television receiver. Due to interlace, this results in flicker at every sharp color vertical transition. In this note, we show how the multilevel capabilities of a television receiver can be used by nonlinearly filtering the characters generated by a conventional VIDEOTEX character generator such that each vertical transition is made less sharp. Although the characters are more blurred due to filtering, the apparent resolution of the display is increased allowing smaller fonts to be used. Flicker is reduced to a large extent, thus, decreasing the fatigue due to prolonged viewing of the display. A font occupying 9X16 rectangular area per character is proposed. It results in about 65 percent more characters per 'page-screen' compared to the present VIDEOTEX system. The hardware required for such nonlinear filtering is minor, since, storage of multilevel intensities of the characters is not required due to local processing at the receiver.     

半导体激光主动成像雷达扫描成像实验

对激光主动成像雷达做了一些初步的理论与实验研究,建立了一个半导体激光扫描成像演示系统,利用雷达距离方程计算了系统的最大作用距离,并在实验室做了成像实验.在实验室内获得了10帧/s、每帧32行的轮廓像,且成像质量较高.     

A transformation for the calculation of filter pairs for perfectreconstruction in subband coding with linequincunx subsampling

For a feasible calculation of filters for the subband coding of picture sequences with linequincunx subsampling, a coordinate transformation of the sampling raster is proposed. With the new coordinates, the linequincunx subsampling becomes a simple quincunx subsampling without interlace. This facilitates the mathematical derivation of three-dimensional perfect reconstruction filters     

解码MPEG4视频流中interlace宏块的原理和实现方法

在MPEG4中interlace可以做到宏块级。当宏块使用interlace的方式进行编码的时候，可以结合dct_type，field_prediction，forword_top_field_reference，forword_bot_field_reference等标志来确定interlace宏块的解码方法。     

HDTV standards

An overview of relevant International Radio Consultative Committee (CCIR) activities in the area of high-definition television (HDTV) standardization is presented. The status of the CCIR standards with respect to chromaticity and signal format, picture characteristics, picture scanning characteristic, and analog and digital representation is discussed. It is concluded that the achievement of a single unambiguous parameter set requiring no quality impairing conversions in international program exchange remains doubtful     

基于C P L D技术的码位交织与反交织系统

介绍了数字通信中交织码编码的基本原则,提出了码位交织与反交织系统的实现方案,并用CPLD对系统电路进行了设计集成,仿真结果表明该系统工作稳定,并具有可扩展的灵活性。     

Properties of polarization noise caused by external disturbances insingle-mode fiber transmission systems

The properties of polarization noise caused by external disturbances in intensity modulation/direct detection transmission systems that have polarization-dependent optical devices are analyzed. It is experimentally shown that the noise consists of additive noise and multiplicative noise. The multiplicative noise directly disturbs signals, even if the external disturbance is of a low frequency. The signal to polarization noise ratio easily reaches the ratio at which flickers obstruct the picture in an analog TV transmission system. The polarization noise caused by external disturbances is also discussed. It is shown that disturbances to the fiber can make the maximum noise n ² times greater than the noise caused by a single disturbance, where n is the number of disturbances     

红外图像评价质量研究

按照红外图像的形成过程分析可认为一幅红外图像是由目标图像、背景图像和噪声图像,目标图像和背景图像是红外图像的主体,噪声图像是叠加在红外图像主体上的干扰.文章从红外图像主体能提供的信息量是否丰富、细节是否明显,噪声图像相对图像主体的大小三个方面入手,对红外图像进行质量评价,评价结果与主观评价相一致,具有较好的可比性.     

运动图像的锯齿消除算法研究

针对隔行扫描到逐行扫描转换中出现的运动图像锯齿现象,提出适用于去锯齿的运动检测和基于角度提取的场内插值算法。利用相邻4场运动差值进行运动检测,并结合待插像素相邻行和隔行相关像素点的夹角进行加权平均,提取相关度大的角度点进行场内插值。实验结果表明,算法有效提高了峰值性噪比,也有效降低了均方差,实际图像去锯齿效果良好。     

Bit rate requirements of different HDTV scanning formats

The bit rate required to compress the same content in different HDTV scanning formats to the same level of picture quality is calculated from simulation results. It is shown that the 1080p50 format does not require higher bit rates than the conventional 1080p25 format     

High Definition NTSC Broadcast Protocol

This paper describes a new process referred to as HD-NTSC?. This signal has all the appearances of a conventional NTSC signal, and can be edited, stored, transmitted, and received by conventional NTSC equipment. A receiver constructed to interpret the HD-NTSC protocol will be able to build an ID-NTSC image having substantially improved resolution in both the vertical and horizontal axes for those parts of the imnage that are nearly stationary over time. Those parts of the image exhibiting motion will show resolution equivalent to a conventional top-quality NTSC picture. The HD-NTSC receiver will also display the image at 60 frames per second, eliminating most interlace and flicker defects. An optional technique widens the image aspect ratio and creates bandwidth within the original NTSC standard large enough to transmit a digitally-encoded stereo audio signal to match the improved visual characteristics.     

A 2-million-pixel CCD image sensor overlaid with an amorphoussilicon photoconversion layer

A highly sensitive 2-million-pixel high-definition charge-coupled device (CCD) image sensor was developed that features an overlaid amorphous silicon photoconversion layer on an interline transfer-type CCD scanner. The device is adapted to the 16:9 aspect ratio. 1125 scanning lines and 2:1 interlace high-definition TV system. A dual-channel horizontal CCD register is used to reduce the operating frequency to one half of the 74.25-MHz readout frequency. A horizontal period signal storage memory (1H line memory) is provided between the vertical CCD register and the horizontal CCD register to provide the signal distribution from the vertical CCD to the horizontal CCD register during the 3.77-μs short horizontal blanking interval. This device realized a 1000 TV line horizontal limiting resolution 210 nA/1x high sensitivity. Total random noise was found to be 52 electrons RMS and a 72-dB dynamic range was achieved     

Picture Coding

A survey of recent German research in the field of picture coding is presented. The described coding methods are mainly based on extended differential pulse-code modulation (DPCM) techniques. A unified model of a feedback switched quantizer for picture coding is explained. Theoretical results show a 9-dB gain in SNR over that of DPCM. A simple realization is shown. For encoding the 1-MHz videotelephone signals, a two-stage coding system consisting of a two-dimensional DPCM in the first stage and a dot interlaced frame repeating codec in the second stage is described. A DPCM combined with a relevancy detector and runlength coder is used for coding the 5-MHz video signals of a high-resolution videotelephone. A special scanning technique assures compatibility with ordinary videotelephones. Good picture quality is obtained by coding the luminance and chrominance signals of color TV separately with DPCM and switched quantization into a 34 Mbit/s signal.     

Adaptive Scanning Method for Fine Granularity Scalable Video Coding

One of the recent and most significant technical properties can be expressed as “digital convergence,” which is helping lead the technical paradigm into a ubiquitous environment. As an initial trial of realizing a ubiquitous environment, the convergence between broadcasting and telecommunication fields is now on the way, where it is required to develop a scalable video coding scheme for one‐source and multi‐use media. Traditional scalable video coding schemes have, however, limitations for higher stable picture quality especially on the region of interest. Therefore, this paper introduces an adaptive scanning method especially designed for a higher regional‐stable picture quality under a ubiquitous video coding environment, which can improve the subjective quality of the decoded video by most‐preferentially encoding, transmitting, and decoding the top‐priority image information of the region of interest. Thus, the video can be more clearly visible to users. From various simulation results, the proposed scanning method in this paper can achieve an improved subjective picture quality far better than the widely used raster scan order in conventional video coding schemes, especially on the region of interest, and without a significant loss of quality in the left‐over region.     

实时运动检测电视图像内插方式的研究与实现

本文用二维谱分析了现制式广播电视图像的缺陷，研究了用内播法实现逐行扫描或倍行扫描，以使图像得到较大改善。对自适应内播法进行了重点分析，并用硬件实现了该内插方法，得到了较好的主观视觉效果。     

Nonlinear vector error tolerant interpolation of intermediate video images by weighted medians

The conversion of one video standard into another with different field and scan rates is a key feature for modern TV receivers and multimedia video equipment. Therefore, a new vector-based nonlinear conversion algorithm has been developed which applies nonlinear center weighted median (CWM) filters and yields a very good interpolation quality. One of the main properties of this algorithm is vector error tolerance. This property will be derived in this paper and its advantages will be shown. Assuming a 2-channel model of the human visual system with different spatio-temporal characteristics, there are contrary demands for the CWM filters. One can meet these demands by a vertical band separation and an application of the so-called temporally and spatially dominated CWMs. Hereby interpolation errors of the separated channels can be compensated by an adequate splitting of the spectrum. By this means, a very robust vector error tolerant upconversion method can be achieved which significantly improves the interpolation quality. By an appropriate choice of the CWM filter root structures main picture elements are interpolated correctly also if faulty vector fields occur. To demonstrate the correctness of the deduced interpolation scheme picture content is classified. These classes are distinguished by correct or incorrect vector assignment and correlated or noncorrelated picture content. The mode of operation of the new algorithm is portrayed for each class. Whereas for correlated picture content the mode of operation can be shown by object models the operation mode is shown for noncorrelated picture content by the output probability distribution function of the applied CWM filters. The new algorithm has been verified for a 100 Hz upconversion by objective evaluation methods and by comprehensive subjective test series. Within these tests for critical test sequences a gain of about 2 dB PSNR in the objective tests and about 0.4 evaluation grades in the subjective test series could be achieved.     

透过率实时可调的PDP屏滤光膜

利用NiOx薄膜具有优良的电致变色性能,制备了透过率可实时调整的PDP屏滤光膜以提高PDP屏的出光效率,在不同环境照度下获得更好的图像质量。采用扫描电镜(SEM)、X射线衍射仪(XRD)、分光光度计研究了采用磁控溅射法制备的NiOx薄膜中镍的含量对薄膜光电特性的影响。分析测试结果表明:溅射时随着氧分压的提高,氧化镍薄膜的镍含量明显降低;NiOx薄膜中镍原子含量为45%左右时,NiOx薄膜对可见光透过率的调节能力最强,其最高透过率与最低透过率差值达70%。