Chrominance Signals Research Articles

Polyphase FIR filters for the demodulation of chrominance signals

The author presents an estimation scheme and its polyphase finite-duration impulse-response (FIR) filter implementation for the demodulation of composite chrominance signals into color difference components such as in-phase and quadrature-phase components. A decoding scheme with three-tap polyphase FIR filters is presented. The least square error estimators, which estimate the chrominance components, are derived and their performance analyzed. The composite video signal is reviewed and the digitization of the video signal is described. The author formulates the demodulation of the digitized video signal as an estimation problem. A polyphase FIR filter implementation of the resultant estimators for the chrominance components is then described. >

New multiplex/separation schemes for telecine images

NTSC-compatible signal processing schemes are proposed for telecine images. In these schemes, luminance, chrominance, and higher-resolution signals are multiplexed at the transmitter side and separated without crosstalk at the receiver side. The proposed schemes are based on the technique of grouping several scanlines which are synchronized with the film frames. A new 2-3-3-2 film-frame sequence format and a five-line-grouping technique are proposed so that the original film frames can be reproduced easily at the receivers. Simulation results show the effect of picture improvement. >

重層塗布型媒体の電磁変換特性

Double layered magnetic coating media were made in order to obtain excellent electromagnetic conversion characteristics in wide frequency range. Video luminance signal is recorded only from a tape surface to 0.3μm in depth. However, video chrominance signal is reorded ranging from a tape surface to 0.6 μm in depth. By utilizing these characteristics, high coercivity magnetic particles which are suitable for recording high frequency signals, are able to be used for the upper layer. However, these characteristics are affected by the thickness of the upper layer and the coercive force of each layer. Therefore these values should be decided carefully considering recording depth of each of each signal.

搬送色信号スペクトルの広がりを考慮した動き適応型ＹＣ分離回路

搬送色信号スペクトルの広がりを考慮した動き適応型ＹＣ分離回路

The PFWM Fiber-Optic Transmission System for HDTV

A new pulse-analog technique has been developed for the transmission of high-definition TV (HDTV) component signals on an optical fiber: pulse frequency and width modulation (PFWM). With this technique, three component signals are multiplexed into one pulse train in which the frequency is varied in proportion to the amplitude of the luminance signal and width, alternately, to the amplitude of two chrominance signals. This results in a compact and low-cost HDTV transmisssion system. The PFWM fiber-optic transmission system and its performance are described in this article. Experiments show that this system transmits HDTV component signals and two PCM audio signals over 20-km single-mode fiber and employs a 1.3-μm laser diode (LD) and a germanium-avalanche photodiode (Ge-APD).

Recent Technical Developments in the S-VHS VCR for Broadcasting and Professional Applications

S-VHS frequency spectrum allocations for luminance and chrominance signals on video recording, resultant performance, and comparison with the U-SP format are reviewed briefly. Technical considerations leading to selection of oxide tape and ferrite heads for S-VHS recording are discussed, and Y/C video signal transmission and its benefits are described. Treated in more detail are some of the innovative video processing techniques recently developed to achieve significant picture performance improvements in professional S-VHS VCRs and peripheral products. These specific techniques include a unique three-line adaptive comb filter to separate luminance and chrominance components from a composite NTSC video signal; a chrominance enhancement technique developed by Faroudja Laboratories and adapted for use with S-VHS, which significantly restores chroma bandwidth lost during record/playback without degradation of signal-to-noise ratio; an adaptive comb filter technique that supplements phase-shift video processing to improve adjacent track chrominance crosstalk cancellation; and a Y/C digital noise-reduction system designed to significantly improve chrominance as well as luminance signal-to-noise ratio.

Compact coder for component color television

A study of predictive coding of component TV signals for compression to transmit at rates that give good picture quality is reported. Designing predictors for minimum mean square prediction error is effective, both for luminance and chrominance signals. Predictors designed in this manner were found to be as good as or better than all other predictors tested. Quantizers designed for minimum mean square system error were primarily used in this study. A programmable testbed was built to permit quick comparisons. Predictors were compared on the testbed using a 2-b quantizer in order to have adequate system error to display visible differences. For simple intrafield coding, component signals compressed for transmission at 30 Mb/s gave about equivalent quality to an NTSC composite signal coded directly for transmission at 45 Mb/s. With 45-Mb/s transmission, component signal coding showed no detectable degradation on close inspection of real pictures. Maximum chrominance changes on test patterns yield visually detectable chrominance slope overload.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A single-chip CMOS analog/digital mixed NTSC decoder

A single-chip CMOS LSI that integrates all analog-to-digital (A/D), digital-to-analog (D/A), peripheral, and digital signal processing circuits necessary for a digital National Television System Committee (NTSC) signal decoder is described. The LSI chip accepts composite NTSC video signals in analog form, digitizes them using the on-chip A/D converter, converts them to component RGB signals, and then converts the signals to analog form by using the on-chip D/A converters. The development of circuits that maximize use of the input digital data is discussed. A 6-b A/D circuit is used to reduce the circuit size. Circuits that help maintain acceptable picture quality despite 6-b resolution were developed. Besides analog NTSC signal input and RGB signal output, the IC can also input and output digital NTSC signals, Y/C (luminance, chrominance) signals, and RGB signals. Applications of the LSI are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

FM recording characteristics of Co-Ni obliquely evaporated tape

The recording and reproducing characteristics of Co-Ni obliquely evaporated (metal evaporated, or ME) tape in video recording were investigated in comparison with metal-particulate (MP) tape using a single-frequency signal and a frequency-modulated (FM) signal. The results indicate that the formation of the circulation magnetization mode is difficult, although in ME tape as in MP tape there is an effective recording depth which is estimated to be a quarter of the recording wavelength in short-wavelength recording. It has been clarified that the lower sideband enhancement and the upper sideband suppression of the reproduced FM signal are reduced as the recording current is increased. The bias recording characteristics were also measured, and it was found that the reproduced voltage of the low-frequency converted chrominance signal does not depend on the gap length of the recording head.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A comparison between the luminance compensation method and other color picture transmission systems

To improve conventional color picture transmission systems, the luminance compensation method is proposed. It compensates the luminance perturbation at the transmitter side that occurs due to changes of the chrominance signal. Incompatible transmission systems show no significant advantages compared to the luminance compensation method.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

色信号のフィールド順次伝送方式におけるＶＳＢ補正可能なデコーダの設計とその画質

色信号のフィールド順次伝送方式におけるＶＳＢ補正可能なデコーダの設計とその画質

Single-Channel Backward-Compatible EDTV Systems

This article describes some methods for adding supplementary information to a compatible NTSC broadcast signal so that an advanced receiver can decode that information to provide improved picture quality (Extended-Definition Television, or EDTV), while a standard NTSC receiver will display an image with minimally visible impairments. In particular, chrominance information is transmitted at one-half the frame rate and alternate frames are used to encode high-definition luminance information in the chrominance signal. This is useful for any EDTV system. A particular design is suggested where some active lines are usurped from the top and bottom of the picture and augmentation information is encoded into this region so that both the EDTV and the NTSC receiver receive similar-looking widescreen pictures, with the EDTV picture containing greater resolution.

A single-chip adaptive DPCM video codec

A differential pulse-code modulation (DPCM) video codec with two-dimensional intrafield prediction and adaptive quantizer is presented. An approach for the arithmetic implementation of the DPCM structure and the design of a test chip, fabricated in a 1.5 mu m CMOS technology, is described. This is the first VLSI realization of a DPCM codec with adaptive quantizer. For the test chip transmitter or receiver mode, application as part of a three-dimensional interframe codec and processing of luminance or chrominance signals are optional. A line buffer and ten different quantizer characteristics are realized on-chip. Correct operation has been verified up to 26 MHz.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

1/2-inch cassette VTR for baseband HDTV signal recording

Technical details are reported for a 1/2-inch cassette videotape recorder (VTR) developed for recording the baseband high-definition TV (HDTV) signal. A recording time of 63 min was achieved by using metal-particle tape and laminated amorphous video heads. The frequency bandwidths used for luminance and chrominance signals were 20 and 7 MHz, respectively. A novel two-channel, three-segment recording method was developed for the purpose. Four-channel digital audio recording with a sampling frequency of 48 kHz and 16-b linear quantization was used. The digital audio signal was recorded on the overlapped area succeeding to the video track by using the same heads used for video recording. >

Consideration on and compensation for violations of the constant luminance principle for EDTV

Evaluation tests of the HDTV system show that a reduction of the chrominance signal bandwidth is possible if gamma correction is performed at the receiver. The number of bits required in the chrominance signals is discussed. For an enhanced television system, the authors propose the use of precompensation methods at the transmitter to improve the picture-quality of highly saturated color pictures. These methods have been adopted in the EDTV (enhanced-definition TV) television system in Japan. The authors also discuss the flarelike reproduction of the black level caused by beam cutoff in the cathode-ray tube (CRT) display and band limitation of the chrominance signals.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A video codec LSI for high-definition TV systems with one-transistor DRAM line memories

A video codec LSI for high-definition television (HDTV) systems has been developed. By using a time-compressed integration encoding technique, it converts a 20.0-MHz bandwidth luminance signal and two 5.0-MHz chrominance signals into a compressed image signal at 48.6-MHz sampling frequency. It is useful in many HDTV application systems, such as 400-Mb/s digital transmission system, a video disk player system, or an analog transmission system. Over 288000 elements, including a 52-kb one-transistor DRAM (dynamic random access memory) line memory specially developed for this LSI, were integrated on a 12.16*12.10-mm/sup 2/ chip. A standard cell layout method and a 1.2- mu m CMOS logic LSI process were used. >

A new multistandard video processor including deflection drive circuits which is controlled by digital process

The authors describe a novel multistandard video processor which uses the counted-down method in the synchronization block. The processor consists of luminance, chrominance and deflection signal processing blocks. The count-down method is used in both the horizontal and the vertical synchronization circuits of the deflection signal processing block. Because a 50/60 identification circuit is installed and the chrominance signal processing block can receive PAL (phase alteration line) and NTSC (National Television System Committee) signals using this video processor and a SECAM (sequential and memory) decoder, it is possible to construct a multistandard system TV receiver. Systematic development work has been done to maximize the performance of the functional blocks and to minimize the number of pins and external components. >

Optical disc system for wideband high definition video signal

An optical video disk system for reproducing high-definition pictures with digital audio was developed, using two-channel recording and playback technology. A 20-MHz-bandwidth luminance (Y) signal and 6-MHz-bandwidth line sequential chrominance (C) signals for the 1125/60 HDTV (high-definition TV) standard were recorded without bandwidth compression. The maximum playback time is 8.4 min per side in a constant-angular-velocity disk rotational mode and can be prolonged to 15 minutes per side in a constant-linear-velocity mode.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A single chip Y/C signal processing IC for VHS VCRs

A single-chip Y/C signal processing IC for VHS VCRs in a compact 54-pin shrink package was made. The chip includes all of the luminance and chrominance signal processors with four internal filters. These filters are automatically adjusted by a chroma-PLL (phase-locked loop). This IC reduces the number of external elements and makes a video circuit smaller and less expensive. The whole block diagram of the IC is shown. >

Adaptive signal processing for digital HDTV 280 Mbit/s transmission

A two-stage coding system for reducing the high data rate of a digital HDTV signal (≈1 Gbit/s) is described. Spatio-temporal subsampling of the interlaced source signal is used in conjunction with an intrafield DPCM of the remaining samples. For the luminance signal two well-known sampling patterns, fieldquincunx and linequincunx, are proposed; both provide a 2:1 subsampling. Prior to subsampling, a digital filter which adapts itself to the movement in the scene, adjusts the three-dimensional spectrum of the television signal to some reduced region supported by the sampling pattern and the properties of the human visual system. Different filter structures are suggested for prefiltering and for interpolation of the missing samples in the receiver. The chrominance signals are horizontally bandlimited before digitization. A modified linequincunx sampling structure is used for subsampling the chrominance signals. Two-dimensional digital prefilters and interpolators are required. Then predictive coding with a fixed quantizer and predictor is applied to the picture elements which remain in the luminance and chrominance paths after subsampling. Sixteen quantization levels are used for the luminance and for each chrominance component to reduce the whole data rate to less than 280 Mbit/s.