Showing papers on "Inter frame published in 1988"

Method and apparatus for low bit-rate interframe video coding

Abstract: An improved low bit-rate interframe video encoder is disclosed of the type known as a hybrid coder. A hybrid coder achieves image compression by using a two-dimensional signal transformation on blocks of differential pel data in the forward loop of a DPCM coder. The transform coefficients of each block are then quantized and entropy coded for transmission. Coding efficiency is in part determined by the size of the transform block. Larger blocks are more bit efficient because of the lower quantity of overhead data required, but require a complex transformer hardware implementation. In addition, larger blocks produce annoying block distortion. The disclosed coder has the advantages of both large and small block size division of the video image. In the disclosed coder, after differential combination (307) with a corresponding block from the previous frame, each m×m block of pel data is sub-divided (309) into smaller n×n (n

Picture coding and decoding apparatus using vector quantization

Abstract: An interframe video data coding and decoding apparatus utilizes a differential amplitude suppression circuit in combination with a block encoder and a motion detector to non-linearly suppress amplitude values of interframe differential block data based on a motion detection threshold value determined by an encoding control circuit. The determined threshold value is based on the amount of encoded data being stored in a transmission buffer memory. The suppressed amplitude differential block data is added to corresponding blocks in a frame memory to update the contents of the frame memory during each frame of input video data. In another embodiment, vector quantization encoders are utilized to transmit a motion vector index with encoded frame differential data. In yet another embodiment, a time integral circuit integrates a continuous input video signal series by frame and writes the integrated frame signal into one of two frame memories, while interframe coding is performed on data stored in the other frame memory. Two transmission buffers are provided so that transmission can occur simultaneously with writing of the encoded interframe data into the buffer, by alternating switched connections of the two buffers.

Three dimensional sub-band coding of video

Abstract: A novel coding scheme has been developed which is based on multidimensional subband coding. The digital video signal is filtered and sub-sampled in all three dimensions (temporally, horizontally and vertically) to yield the subbands, from which the input signal can be losslessly reconstructed in the absence of coding loss. The subbands can be more efficiently coded than the input signal in terms of compression and quality, because the restricted information in each band allows well-tailored encoding. The computational complexity of this coding scheme compares favorably to DCT with interframe prediction and inter/intra frame DPCM. The scheme has an architectural structure suitable for parallel implementation, and it yields high compression with sustained good quality. >

Two algorithms for taking advantage of temporal coherence in ray tracing

Abstract: The basic ray-tracing algorithm is adapted to make ray-tracing faster for the production of motion pictures. Two algorithms are presented. The image space temporal coherence algorithm takes advantage of the fact that motion picture images do not change very much from frame to frame. The reprojection algorithm uses information about the object space saved from the previous frame to accelerate the processing of the current frame. The reprojection algorithm is used when the viewpoint of the current frame is changed by a small amount from the viewpoint of the previous frame.

Encoding of LPC spectral parameters using switched-adaptive interframe vector prediction (speech coding)

Abstract: An efficient, low-complexity method called switched-adaptive interframe vector prediction (SIVP) has been developed for linear predictive coding (LPC) of spectral parameters in the development of low-bit-rate speech coding systems. SIVP utilizes vector linear prediction to exploit the high frame-to-frame redundancy present in the successive frames of LPC parameters. When SIVP is combined with scalar quantization, it has been found that the LPC parameter bit rate required to achieve high-quality synthetic speech is only 1300 b/s. With vector quantization, the bit-rate can be reduced even further (to 1000 b/s) without introducing any perceivable quantization noise in the reconstructed speech. >

s9.9 ENCODING OF LPC SPECTRAL PARAMETERS USING SWITCHED-ADAPTIVE INTERFRAME VECTOR PREDICTION?

Abstract: LPC spectral parameter encoding is often a challenging task in the development of low bit-rate speech coding systems. An efficient, low complexity method called Switched-Adaptive Interframe Vector Prediction (SIVP) has been developed for this purpose. SIVP utilizes vector linear prediction to exploit the high frame-to-frame redundancy present in successive frames of LPC parameters. When SIVP is combined with scalar quantization, we have found that the LPC parameter bit-rate required to achieve high-quality synthetic speech is only 1300 bits per second. With vector quantization, the bit-rate can be reduced even further (to 1000 hits per second) without introducing any perceivable quantization noise in the reconstructed

Method for recording and/or reproducing digitally coded signals with interframe and interframe coding

Abstract: A method for recording and/or reproducing digitally coded video signals A frame sequence is coded in such a way that an intraframe coded picture having a fixed or variable block length is recorded at the beginning A fixed number of interframe coded pictures follow The block length of the interframe coded pictures can be both fixed and variable A cutting begins with and ends before an intraframe coded picture

A load balancing technique for video signal processing on a multicomputer type DSP

Abstract: To extract full performance from a multicomputer digital signal processing (DSP) system, the development of a viable load balancing technique is considered indispensable. The authors describe a task allocation and control methodology for image signal processing, such as is used in a low-bit rate (e.g. 64-kb/s) motion picture coding system. On a massive homogeneous multicomputer-type DSP system, the following approaches increase system performance substantially: (1) task scheduling with interframe prediction; (2) layered large-grain data flow; and (3) predefined local reassignment of processing. The effects of these various methods are examined in the context of a low bit rate motion picture codec with motion compensation and vector quantization application. >

A finite state/frame difference interpolative vector quantizer for low rate image sequence coding

Abstract: A finite-state vector quantizer (VQ) suitable for both intraframe and interframe coding is presented. Interblock and interframe memory is expressed through a state variable driven by an improved classifier which keys on the intensity gradients of a block's neighbours and its own interframe motion. A bilinear interpolator reduces the energy of foreground residuals encoded by the quantization, improving edge rendition and limiting blocking artifacts. Background blocks are vector predictive coded using simple frame differencing and codebooks built with a gradient design algorithm. The codec at 0.4 bit/pixel outperforms a similar but non-finite-state intraframe VQ at 1.0 bit/pixel by 4 dB. >

Adaptive Schemes For Motion-Compensated Coding

Abstract: Several variations on the popular motion-compensated interframe block-coding schemes are proposed. The idea behind these schemes is to handle each image block with a different parameter and/or algorithm based on the contents of that individual block. They are extensions of the basic nonadaptive algorithm and are designed to reduce the coding bit rate and to improve the reconstructed picture quality. Our goal in this paper is to explore the potential merits offered by these adaptive techniques. Three schemes are described in this paper: (1) adaptive block-size motion compensation and coding, (2) multiple-transform coding, and (3) DOT and cluster (pel-domain) hybrid coding. Similar to many other adaptive algorithms, each of the above schemes has a number of parameters that need to be chosen carefully for optimum performance. We make no such exhaustive attempt, rather the results presented here are based on a limited set of experiments using a few preselected parameters. However, we find that the experiments conducted still provide us with some insights into issues concerning the adaptive image-sequence coding schemes, such as, the performance versus complexity issue.

Motion detector for video signals including a novel line comparison processing scheme

Abstract: A motion vector suitable for motion-compensated prediction in an inter-frame differential video coder is derived by comparison of each block of a current frame and with shifted corresponding region of a previous frame with the regions of the previous frame. Rather than dealing with each block in turn, the apparatus carries out all comparisons involving a line n of the video signal before commencing comparisons involving n+p (where p is the number of lines encompassed by a block).

Method and circuit arrangement for establishing frame synchronisation in a time-division multiplex system

Abstract: For time-division multiplex frame structures previously used, an imitation frequency of less than one per frame can be calculated for a predetermined frame alignment word (12 bits). Assuming a frame structure which is built up with octets, an imitation frequency of greater than nine per frame is obtained for an 8-bit frame alignment word. It is the object of the invention to establish fast and reliable frame synchronisation for such frame structures having an imitation frequency of greater than one. For this purpose, all bit patterns which correspond to the frame alignment word are first determined in a search mode for the duration of one time frame, and an information item on their position in time is in each case stored. In a following comparison mode, it is determined for the duration of the next time frame, in each case at the times stored, whether a frame alignment word is again present. The respective yes/no result is evaluated for establishing frame synchronisation.

Inter-frame encoder

Abstract: PURPOSE: To prevent inter-frame correlation from being reduced due to the leakage of a chrominance component to a luminance component by attaching a frame limiting means to limit an encoding frame to be encoded to the frame with the same phase of a chrominance subcarrier. CONSTITUTION: A television signal inputted to a port 1 is supplied to a Y/C separator 3 via an A/D converter 2, and is separated to a luminance signal and a chrominance signal. Also, a frame synchronizing signal is detected at a synchronism detection circuit 7. A frame limitation circuit 8 generates a signal to limit the frame with the same phase of the chrominance subcarrier, and supplies it to a timing control circuit 9. The opening/closing of a switch 4 is controlled by the timing control circuit 9, and the signal supplied to an encoder 5 is limited to the frame with the same phase of the chrominance subcarrier and issuing an encoding request. COPYRIGHT: (C)1990,JPO&Japio

Inter-frame coding system for image information

Abstract: PURPOSE:To decide validity/invalidity corresponding to the spatial resolution of humane vision and to improve the quality of a picture by weighting the spatial frequency characteristics of an image signal and an inter-frame predictive error signal corresponding to the human vision to variably control a threshold. CONSTITUTION:An image signal processor 8 transforms orthogonally an image signal with the unit of block to transform a two dimensional spatial frequency characteristic, and executes the weighting corresponding to the characteristics of the spatial resolution of the human vision, and calculates the loading power P1 of the image signals in the block. In the meantime, an inter-frame predictive error signals obtained by a subtractor 1 are weighted similarly by an error signal processor 9 to generate a spatial frequency characteristic, and from this characteristic, the loading power P2 of the inter-frame predictive error signal in the block is calculated. A controller 10, in accordance with the values of the loading powers P1, P2, modifies a threshold T1 for the decision of a validity/invalidity decision device 3. As a result, the device 3 can executes a decision on validity/invalidity corresponding to the spatial resolution of the human vision.

Addaptive inter-frame encoding system

Abstract: PURPOSE:To reproduce a faithful animation image by extracting a feature value from a difference signal between an input signal and a frame by means of a characteristic value corresponding to visual time space resolution and adaptively controlling quantization. CONSTITUTION:An input signal and a preframe signal obtained from a frame memory part 5 are applied to a subtractor 4 to form an inter-frame difference signal. The inter-frame difference signal is orthogonally converted by an orthogonal converter 1 and then applied to a quantizer 2 and the quantized output signal is encoded by an encoder 6. The quantized output signal is also applied to a frame memory part 5 and stored as a preframe signal. A feature value is extracted from the input signal and the inter-frame difference signal by a feature value extracting means 3 by means of a characteristic value corresponding to visual time space resolution and the quantizer 2 is controlled based on the feature value so that the visually redundant information is deleted and encoded.

Motion estimation for video bandwidth compression using a heterogeneous pyramid image processing architecture

Abstract: In many image processing contexts there is a requirement for some form of motion estimation. A number of strategies exist, differing in the accuracy and granularity of the motion estimate and in their computational requirements. The simplest and most coarse-grained scheme is 'block' motion estimation, where the current frame is divided into blocks of pixels and for each block an estimate of its most likely motion is computed by reference to a neighbourhood in the previous frame. Such coarse motion estimates are of utility in situations where a fairly approximate but fast trajectory estimate is required. Examples are motion-compensated interframe predictive coders and various aerospace applications. The block motion estimator is simple and amenable to parallel computation, making it feasible for implementation at realtime frame rates. This paper describes the mapping of the block motion estimator on to the lower levels of the Wamick Pyramid Machine (WPM), a heterogeneous pyramid architecture for parallel image processing I understanding which is currently under development at the University of Warwick. The paper describes how the required computations are performed and presents simulated timings. The advantages of the multi-SIMD architecture of the WPM are illustrated.

Inter-frame predictive coding device

Abstract: PURPOSE:To prevent a refresh area from being seen by a user by providing first frame storage parts, from which input picture frames are read out with each divided area as the unit with a preliminarily determined period in accordance with a preliminarily determined order, and second frame storage parts where inter-frame predicted value data is stored and providing a means which selects the output of one of them as a predicted value. CONSTITUTION:First frame storage parts 106 and 110 in which input picture frames are stored as a preliminarily determined number (n) of divided areas ((n) is an integer equal to or larger than one) with a preliminarily determined period and from which stored input picture frames are read out with each divided area as the unit with a preliminarily determined period in accordance with a preliminarily determined order, second frame storage parts 104 and 111 where inter-frame predicted value data is stored, and selecting means 105 and 112 which selects the output of first frame storage parts 106 and 110 or second frame storage parts 104 and 110 as the predicted value are provided. Thus, a refresh part is prevented from being seen by the user.

Movement compensating inter-frame encoder

Abstract: PURPOSE:To cope with the increase of the number of searching points by writing plural blocks including a movement compensating range in plural buffer memories from pre-frame data and simultaneously operating a distortion to the quantity of the movement different in the respective buffers. CONSTITUTION:The preframe data advanced by two block lines from a current frame block is read from a frame data memory 3 and written in the writing block line buffers of the tracking area buffers 28a-28c. Simultaneously, to a searching number of times counting value generated in a searching number of times counter 24, the respectively different quantity of the movement is generated by movement quantity memories 25a-25c and applied to the address value of a reading address counter 29. In respective distortion computing elements 23a-23c, the distortion to the current frame data is obtained. A minimum distortion is obtained in a minimum distortion detector 26 and the quantity of the movement at that time is outputted as a movement vector 5.

Characterization of variable rate inter-frame video coding for ATM-based networks

Abstract: The authors characterize variable-rate interframe video coding for an ATM (asynchronous transfer mode) -based environment, focusing on bursty characteristics of encoded information. Inter-frame DPCM (differential pulse code modulation), motion-compensated DPCM and motion-compensated DCT (discrete cosine transform) are examined. As a useful measure to characterize variable-rate video sources, the coefficient of variation is proposed to supplement conventional distribution and autocovariance. Modeling methods of variable-rate coders using the AR (autoregressive) process and coefficients of variation are introduced. The fitness of each model is evaluated by estimating stochastic multiplexing effects for a simple one-buffer one-server situation. >

Inter-frame decoding system with frame memories for uninterrupted clear video signals

Abstract: A system for decoding a coded inter-frame prediction signal comprises a separating circuit (4) for separating the coded signal into a coded prediction error signal (b k ) and a remainder (r k ). A decoding circuit (5, 6, 7) generates a decoded prediction error signal x k . A first delay circuit (8) provides the decoded signal with a first delay to produce a first delayed signal. An error detecting circuit (11, 13) detects errors in the decoded signal (x k ) and generates an error detection signal which has a high or low level, depending on whether an error has been detected for a given frame. A second delay circuit (10) provides the output of the decoding system with a second delay to produce a second delayed signal. A selecting circuit (14, 9) receives the error detection signal and the first and second delayed signals and selects one of the latter to produce the output of the decoding system.

Inter-frame predictive decoder

Abstract: PURPOSE:To prevent an error in a decoded image even if an interframe predicting decoding error takes place by providing a switching signal generating circuit, 1st and 2nd frame memories and a selector circuit CONSTITUTION:An inter-frame predictive decoding error 13 takes place in three frames x3-x5 of an inter-frame prediction composite signal 12 and the error is lost after the frame x6 and its subsequent frames A frame memory output 14 is delayed for one frame time with respect to the signal 12 and outputted in the order of x1, x2, x3- A switching signal 17 goes to a H level in the normal state and goes to a L level only a frame just after that having the error 13 When the signal 17 is at the H level, a selector circuit 104 selects the output 14 and when at the L level, a frame memory output 16 is selected Thus, when the error 13 takes place, the output 14 of the preceding frame x2 is outputted and when it is lost, the output x6 at that time is outputted as it is Thus, the output 16 is delayed by one frame time and outputted as shown in figure Thus, even when the error 13 takes place, no error is caused in the decoded image

Inter-frame difference transmission system

Abstract: PURPOSE:To attain efficient band compression of a video signal by reading a designated video part as a coordinate reference point and taking difference of the same coordinate of each memory in reading video signals from two frame memories. CONSTITUTION:An analog video signal from a television camera 1 is digitized by an A/D converter 2 and outputted to a changeover switch 3. A write controller 7 controls the changeover timing of the changeover switch 3, outputs a write control signal to frame memories 4, 5 in matching with the changeover timing to apply write alternately at each frame. On the other hand, the analog video signal from the television camera 1 is displayed on a monitor 10 via a video signal processing circuit 9. The operator observes the patternand designates a still picture part by a light pen to read its coordinate reference information, which is given to a controller 8. The read controller 8 reads information from the frame memories 4, 5 based on the coordinate and a signal of moving picture part only is extracted from a subtractor 6.

A Fixed Quality, Variable Rate Finite State Vector Quantizer For Encoding Video Over Packet Networks

Abstract: The advent of packet-switched networks has renewed interest in variable rate video coding schemes which can deliver a specified level of image quality. This paper describes one such scheme, using a variable rate Finite State Vector Quantizer (FSVQ). The codec alternates between an intraframe mode, for encoding foreground (moving) areas, and an interframe mode, for background areas. Separate FSVQs are used for the two modes, each with its own set of super-codebooks. Background blocks having low residual energies are conditionally replenished. The codec maintains a fixed SNR by using sub-codebooks having various numbers of codevectors and dimensions, making it an adaptive multi-rate FSVQ. Image quality is controlled by a set of SNR status variables which dynamically select classes of sub-codebooks. Each status variable is a temporally filtered measure of the SNR in a pre-assigned region of the frame that is updated each frame time. The codec may also be configured to include a rate buffer so that image quality can be degraded in a controlled fashion, should the attached network become congested. Distortion during non-congested operation is maintained to within about 1 dB of the desired value over a range of SNRs up to about 45 dB, with rates as high as 1.5 bpp.

Adaptive Methods Applied To Intra And Interframe Predictive Coding

Abstract: One way to achieve image compression is to use predictive coding schemes. Furthermore, as the signal to process is not stationary, such schemes can even be improved by adopting adaptive strategies. In this paper, it will be proven that it is possible to use a continuous adaptation. The coding protocol can thus be simplified because there is no need to transmit any signal other than the prediction error. The predictor used is a transversal filter with continuously adapted coefficients. To arrive at this, one-dimensional Least Mean Square and adaptive Least Squares are generalized to the special case of digital image processing. The methods described are of great interest and could be applied to many fields other than image coding. A method of adapting the levels of a quantizer to the dynamic range of the two-dimensional signal will also be developed. This is based on a 2D backward estimation of the prediction error variance. The practical implementation of these algorithms will then be analyzed for intraframe and interframe cases. Comparison with a fixed encoder, clearly shows the interest of such techniques. With no excessive computational complexity, we obtain a 40 percent improvement for the distortion by using an LMS -adapted predictor and a three-level adaptive quantizer. The numerous simulations made also give good visual results.

Method and device for encoding moving picture signal

Abstract: PURPOSE:To reduce the amount of generated codes and make encoding efficient while suppressing encoding distortion as to an encoding system which encodes orthogonal transform coefficients between frames by discarding the orthogonal transform coefficient of a current frame if the value of the coefficient is small although the frame difference is large. CONSTITUTION:When the orthogonal transform coefficient of the last frame is large and the orthogonal transform coefficient of the current frame is small, it is decided which orthogonal transform coefficient is discarded so as to suppress the encoding of the value of the orthogonal transform coefficient of the last frame in the encoding of the current frame. At this time, the decision is made by using the value of the orthogonal transform coefficient of an input signal before the interframe difference is calculated. The small orthogonal transform coefficient of the input signal is discarded to determine the coefficient which is discarded regardless of the value of the orthogonal transform coefficient of the last frame and the value of the orthogonal transform coefficient of the last frame is not encoded in the encoding of the current frame, so that the amount of information is reduced correspondingly.

Apparatus for coding/decoding image

Abstract: The correlation between adjacent frames of a moving-picture signal is utilized to code and decode the signal while detecting the motion of each block of an image. There is provided a differential amplitude suppressing circuit which nonlinearly suppresses the amplitude of coded block data of an interframe difference based upon a threshold value for detection of motion. This circuit suppress the amplitude greatly when a detected value of motion is great in order to suppress the increase in the amount of coded data so that the reproduced moving image may be followed more faithfully. When the motion is small, the suppressing characteristics are reduced to improve the subjective quality of image. Further, the image signal sequence is integrated with time for each frame using a time integration circuit, the output of which is stored in a frame memory and read out at the same time. Therefore, the apparatus does not become bulky, and it is possible to eliminate the decrease in coding efficiency and the increase in generation of information by maintening reasonable delay time and proper interframe correlation.