Nec Corporation

Nec Home Electronics, Inc.

Junichi Ohki

Toshio Koga

Mutsumi Ohta

Akihiro Furukawa

Hideto Kunihiro

Yoshihiro Miyamoto

Eri Murata

Hideto Kunhiro

An efficient coding system for interlaced video sequences with forced refreshing capabilities. An input picture of is divided into two fields, a first and a second field. Certain lines or portions of lines in each respective field are designated for forced refreshing, while the non-designated lines are interframe prediction coded. The designated lines of first field are intrafield prediction coded, while the designated lines of the second field are interfield prediction coded. The selection and implementation of the refreshing of the first and second fields is executed by the controller and switching circuitry of the coding system.

Video signal coding method and apparatus

A multiplex transmission method and apparatus for motion picture signals. A transmission line constituted by transmission channels having different carrier frequencies is prepared. One of the transmission channels has a transmission rate almost equal to the long-term average of information generation speeds in encoding an arbitrary motion picture signal. The input motion picture signal is encoded by using inter-frame and intra-frame correlations, and encoded information is output for each image channel. The image channels are related in one-to-one correspondence with the transmission channels having the different carrier frequencies. When an image channel of interest, of the image channels, exhibits a large generated information amount representing the encoded information generation speed within a time interval determined by a predetermined transmission rate of the transmission line in advance, adaptive multiplexing is performed by dividing and distributing the encoded information of the image channel of interest to the transmission channels including the transmission channel of the image channel of interest. The encoded information divided/distributed by the adaptive multiplexing is transmitted for each allocated transmission channel.

Multiplex transmission method for motion picture signals and apparatus

In a transmitting system, a first multiplexer multiplexes first through M-th encoded digital video signals from encoders to produce a primary multiplex signal comprising cells which have channel codes, address codes, and cell data, where M represents an integer greater than two. Each of the cell data represents a part of one of the encoded digital video signals. Each of the channel codes indicates one of the encoded digital video signals. Each of the address codes indicates a position of one of the cell datum. A first demultiplexer demultiplexes the primary multiplex signal to produce first through N-th primary demultiplex signals, where N represents an integer which is less than M and greater than one. A second multiplexer multiplexes the first through the N-th primary demultiplex signals from the first demultiplexer through first through N-th transmitting paths to produce a secondary multiplex signal. A second demultiplexer demultiplexes the secondary multiplex signal datum in response to the channel codes and the address codes to produce the first through the M-th encoded digital video signals.

Transmitting system having transmitting paths with low transmitting rates

Derived from a picture input signal and a motion vector signal in a block matching type motion compensation encoding device, a prediction error signal is quantized by a controllable quantizer into a quantized signal for encoding together with the motion vector signal. Supplied with frame pulses, a controller produces a control signal with a predetermined value for making the quantizer quantize a zero signal instead of the error signal and with a different value for operating the quantizer merely as a forward quantizer. An amount of encoded information is reduced when the predetermined value appears once in two or three frame periods. For smoother movement of a movable part in reproduced pictures, the zero signal is not substituted in each duration in which motion vectors are either greater in magnitude, not identical with a representative vector, or less correlated with corresponding motion vectors in a previous picture for which the zero signal is not substituted. Each duration may be an interval of time during which the error signal has a greater absolute value. The controllable quantizer may be a combination of the forward quantizer and a selector controlled by the control signal to select the zero signal and either the error signal or an output signal of the forward quantizer.

Block matching type motion compensation encoder with controllable

Time-varying picture signals of a plurality of channels are predictively coded by utilizing the interframe correlation and multiplexed at the transmitting side. The signals are separated for each channel, switched and selected for any channel for decoding at the receiving side after transmitted. When the receiving channel is switched over to other channel, a decoding error can occur and a reproduced screen can collapse since the predicting signals do not coincide with each other at the transmitting and receiving sides. Therefore, when the plurality of channels is selectively switched for decoding by using a single decoder, the refresh is repeated at predetermined time intervals in a short period of time by utilizing the intraframe correlation when the coding is carried out at the transmitting side so that, even if the channel is switched, an excellent reproduced screen may be immediately obtained. However, during the refresh, the compression ratio is reduced compared with that of the bit rate when a normal interframe correlation is carried out. Therefore, when the refresh is carried out, the amount of transmitted information for part or all of the channels other than the refreshed channel is compressed and, conversely, the amount of transmitted information for the refreshed channel is increased by the compressed amount and allocated. Thus, even if the channel is switched at the receiving side, the decoded image for the newly selected channel can be promptly reproduced.

Method and apparatus for multiplex transmission of video signals in a

According to a method and apparatus for coding a moving image signal, a change between a current frame and a previous frame is detected in units of blocks obtained by dividing a frame constituted by an input moving image signal into a plurality of pixels. A first valid block map is formed in units of frames by determining valid and invalid blocks on the basis of the detected changes. A first weighting operation of the formed first valid block map is performed. A second weighting operation of a fourth valid block map of the previous frame is performed. A weighted second valid block map is obtained by adding/synthesizing the first and fourth valid block maps respectively subjected to the first and second weighting operations. A third valid block map is obtained by performing predetermined segmentation of the second valid block map. A fourth valid block map is obtained by determining validity of an isolated invalid block in the third valid block map by referring to neighboring blocks. A valid block region of the fourth valid block map is coded.

Method and apparatus for coding moving image signal

In a reproduction system for use in reproducing a still image from a sequence of predictive error signals which is read out of a memory and which is preliminarily processed into a sequence of preliminary processed signals, an intermediate circuit interrupts the preliminary processed signals in response to an external command signal. In the intermediate circuit, the external command signal is resampled by a sequence of frame pulses in a resampling circuit into a resampled signal so as to close a gate circuit. No predictive error signal is sent to an adder circuit during absence of the gate circuit. An identical error signal is repeatedly produced as a sequence of reproduced signals to reproduce the still image.

Reproduction system capable of reproducing a still image by interrupting

In an encoding device including a frame memory for memorizing an input moving picture signal as a memorized moving picture signal frame by frame and an encoding unit for encoding the memorized moving picture signal by using an encoding parameter, a control unit controls the parameter in compliance with a ratio which a moving picture area has relative to a frame picture represented by each frame of the input moving picture signal. The parameter should be fine and coarse when the ratio is small and great, respectively. As usual, a buffer memory of the encoding unit produces an amount signal indicative of an extent to which the buffer memory is full. Preferably, the control unit suspends encoding operation during a succeeding one of two successive frames when the amount signal indicates that the buffer memory became full in a preceding one of the two successive frames. The control unit makes the frame memory keep a frame of the memorized moving picture signal while suspending the encoding operation. If desired, the control unit controls the parameter additionally in compliance with a bit rate at which the encoding unit produces an encoded picture signal.

Control of an encoding parameter according to a ratio of a moving

In an image processing system for use in processing a sequence of image signals carrying a moving image, the image signal sequence is divided into a sequence of partial image signals each of which carries a scene subsequence defined by scene changes. A background signal generator determines a background portion of the moving image by monitoring a whole of each partial image signal and produces a background signal. The background signal is coded by a coder prior to a sequence of error signals resulting from predictive coding of each partial signal. During prediction of the background signal, the error signals may be rendered to zero in the coder. The background signal may be either determined at every picture element or at every block composed of a plurality of picture elements.

Image processing system operable in cooperation with a recording medium

In a recording system, a sequence of image signals obtained from a sequence of images are used to generate and record a sequence of recordable signals on a read only memory. Efficient coding of the received sequence of image signals is carried out through the use of a given parameter which is adaptively and dynamically changed, preferably manually, through a parameter controller acting as the interactive device. The image signals are repeatedly subjected to the efficient coding process. The process uses a sequence of predictive signals to produce coded signals. The predictive signals are displayed on a monitor display device to be monitored by an operator. The operator changes the attributes of the parameter until an optimum image is obtained. The optimum parameter is stored on a magnetic tape. The image signals subjected to the efficient coding enable the production of a sequence of coded image signals which are recorded on the read only memory in synchronism with the optimum parameter, after the optimum image has been obtained.

Recording system for recording on a ROM image signal information which

In an image recording system for use in recording a sequence of coded signals on a recording medium, such as a CD-ROM in response to a sequence of image signals divisible into a succession of frames each of which is subdivided into a plurality of splits, the image signals are selectively subjected to interframe coding and intraframe coding in a coder to be coded into first and second error signals, respectively, under control of a coding control circuit. The intraframe coding may be carried out about a selected split at every frame, at every preselected period, or at predetermined positions of each scene. The second and the first error signals are rearranged into the coded signals by delaying the second error signal relative to the first error signal. Such a second error signal serves to reproduce an initial image on reproducing the coded signals and enables a reverse reproduction, a quick search, a high speed reproduction, and the like in a reproducing system.

Image processing system for recording or reproducing an image signal

A coding system in accordance with the present invention includes a control signal generating circuit for generating a control signal indicative of a quantity of band limitation by calculating a ratio of an area of motion from an input video signal. A band limiter band-limits a transform-coded video signal in response to the control signal. For example, when the picture is stationary or little moved, the transform-coded video signal is not band-limited at all; when the area of motion is medium, high frequency components of a part of the video signal are omitted to cope with an increase in the amount of data generated; and when the area of motion is extremely great, many high frequency components are omitted to accommodate a rash of data. A prediction coding circuit predictively codes the band-limited video signal before the latter is sent out to a transmission path.

Method and system for transform coding of video signals

In an image communication system, an input image sequence is converted into a block-formatted sequence. A data compression signal indicative of the amount of moving blocks in the block-formatted sequence is generated to individually control a plurality of vector quantizers each having a particular frequency band and a memory containing output vectors. The output vectors of each of the vector quantizers is representative of inverse orthogonal transform of a code table of optimum quantized vectors in the particular frequency band, the optimum quantized vectors being orthogonal transform of interframe differential training image sequences. The output vectors is retrievable from the memory as a function of an interframe differential image sequence, or prediction error. Each vector quantizer selects one of the vectors retrieved from the memory which is nearest to the value of the interframe differential image sequence and generates an index signal representative of the selected vector, which index signal is encoded and transmitted to a destination. The outputs of the vector quantizers are processed by inverse vector quantizers to generate a predictive image sequence. The prediction error is detected as a difference between the predictive image sequence and the block-formatted sequence.

Data compression using orthogonal transform and vector quantization

A coding apparatus for a moving object image input signal such as a television signal detects an uncovered background area appearing upon movement of a moving object in the moving object image input signal and encodes an image signal corresponding to the uncovered background area according to intraframe correlation instead of interframe correlation. The coding apparatus includes a noise reduction circuit for decreasing a noise reduction level for the signal corresponding to the uncovered background area.

Coding apparatus for moving object image

On subjecting a digital video signal representative of successive pictures to predictive coding by using correlation between two successive pictures, an estimated result is derived from the digital video signal to represent a degree of correlation between a current picture and a previous picture and is increased with a reduction of the degree. When the estimated result becomes greater than a predetermined threshold value as a result of a drastical change, such as a scene change, from the previous picture to the current picture, a control signal is produced. Furthermore, the digital video signal is separated into a preceding signal part ending at the previous picture and a succeeding part which begins at the current picture. The control signal controls the predictive coding so that the succeeding part be coded with an area of predictive coding of each picture gradually widened with time. The control signal may be supplied to a predictive coder. Alternatively, the control signal may be used to control a frame memory for supplying the digital video signal to the predictive coder with the area gradually widened for the succeeding part. A plurality of threshold levels may be used collectively as the predetermined threshold. The threshold levels are for use in selecting a rate of gradually widening the area.

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Tokyo, Japan

Junichi Ohki