Showing papers on "Inter frame published in 1991"

Hierarchical entropy coded lattice threshold quantization encoding method and apparatus for image and video compression

Abstract: A method and apparatus for encoding interframe error data in an image transmission system, and in particular in a motion compensated image transmission system for transmitting a sequence of image frames from a transmitter (8) to a receiver (21), employ hierarchical entropy coded lattice threshold quantization (46) to increase the data compression of the images being transmitted. The method and apparatus decimate (502) an interframe predicted image data and an uncoded current image data (504), and apply hierarchical entropy coded lattice threshold quantization encoding (506) to the resulting pyramid data structures. Lossy coding is applied on a level-by-level basis for generating the encoded data representation of the image difference between the predicted image data and the uncoded original image. The method and apparatus are applicable to systems transmitting a sequence of image frames (or other pattern data, such as speech) both with and without motion compensation.

Subband coding algorithms for video applications: videophone to HDTV-conferencing

Abstract: Various subband coding schemes are developed for high compression video coding applications. These schemes are based on two distinct interframe subband models. Both models are compared and show that they perform equally under certain conditions. The first model, which is relatively less complex but operates at full speed, was considered for video conferencing applications at lower rates. The second model, however, due to its generic structure which operates at a reduced speed, was found to be suitable for high quality video applications. As a result, a CCITT compatible video coding scheme for HDTV conferencing is developed. For the best performance, the higher frequency bands were coded with a combination of interframe differential pulse code modulation (DPCM) and direct PCM. >

Predictive block-matching motion estimation for TV coding. II. Inter-frame prediction

Abstract: For pt.I, see ibid., vol.37, no.3, p.97-101 (1991). A predictive block-matching motion estimation scheme was implemented for efficient video code design. The scheme is based on the so-called inertia effect of natural video scenes and takes advantage of the motion vectors obtained in the previous frames. The benefits from this prediction process are threefold. First, the searching area is greatly reduced, and so is the computational complexity. Second, the motion vector overhead information is reduced since motion vectors are decorrelated by the prediction process. Finally, the motion vectors estimated from this procedure are more realistic since it reflects the real physical phenomena. These advantages were also demonstrated by simulation results including the coded data rate, displaced frame difference entropy, motion vectors, and reconstructed signal-to-noise ratio. Only a simple prediction model was implemented; further results in more general autoregressive (AR) modes are still under study. >

Temporally adaptive filtering of noisy image sequences using a robust motion estimation algorithm

Abstract: A motion-compensated noise suppression algorithm that employs temporally adaptive filtering along motion trajectories is proposed for image sequences. Filtering is performed via linear minimum mean square error (LMMSE) point estimation. Motion trajectories are determined using a recent motion estimation algorithm, which is capable of performing very well at low signal-to-noise ratios (SNRs). The results suggest that the proposed method is far superior to methods that incorporate implicit or explicit motion compensation, especially in cases of low SNR and/or significant interframe motion. >

Multilayer universal video coder

Abstract: A video coder is disclosed which codes the digital pel values of a video signal in such a manner that different levels of picture quality, i.e. resolution, are available to users. The coder uses a two-dimensional quadrature-mirror filter (103) to decomposes the input into plural subbands. The baseband lowest horizontal-lowest vertical frequency subband is coded using a hybrid DCT/DPCM coder (104) that is compatible with a proposed CCITT standardized codec. The output of this coder is a layer 1 signal which is available to subscribers who desire only low-quality video service. The other subbands are coded using an interframe DPCM coder (108, 109, 110, 111) for those subbands in which the filtered samples in the subband represent horizontal or vertical edge variations in the video frame, or an intraframe PCM coder (116, 117) for those subbands in which the filtered samples in the subband represent diagonal variations. Other layer signals are formed by combining the outputs of selected of the interframe and intraframe codes. A user subscribing to increasing number of signal layers is able to reconstruct a signal of increasing quality.

Statistically based buffer control policies for constant rate transmission of compressed digital video

Abstract: An investigation of statistically based approaches to the design of buffer control algorithms for interfacing a compressed digital video source to a constant rate channel is presented. As a first step to a quantitative methodology for the design and evaluation of adaptive buffer control algorithms, a detailed statistical characterization of the various encoding modes of an example broadcast quality intra/interframe differential-pulse-code-modulation (DPCM) algorithm is obtained from extensive simulation. The statistics presented include simple measures such as the overall encoded rate distributions for each encoding mode and more detailed intermode and intramode statistics. Two specific adaptive mode control algorithms are proposed. Using simulation over a large sea of representative images, the performance of the proposed statistically based algorithms is compared to that of a conventional buffer-level-based control heuristic which does not require source characterization. >

Concealment of bit error and cell loss in inter-frame coded video transmission

Abstract: Experimental results on error concealment techniques to hide the video quality degradation due to bit errors and cell losses from the viewer's perception are presented. The impact of bit error and cell loss in a hybrid DPCM/DCT (differential pulse code modulation/discrete cosine transform) coding algorithm is described through three different video sequence simulations. Two effective schemes that conceal the information loss caused by bit errors and cell losses based on the information in the previous frame are presented. These error concealment techniques work very well in real-time playback as long as the location of bit error and cell loss is properly detected by the decoder. Impairments caused by a cell loss can be compensated for by simple replenishment in real-time playback. Although motion replenishment performs better in the case of uniformly slow motion, it requires that the network have a priority capability. Impairments due to undetected bit errors cannot be compensated for by any concealment algorithm. >

Interframe-coded output data amount control system

Abstract: A video signal having a group of frames of successive dependent frames and an independent frame following the frames is coded per group of frames, by interframe and intraframe coding, and a data amount of the group is controlled by feedback and feed forward control. A quantization step number for the dependent frames is changed based on a rate of a total data amount of the group and a data amount of the dependent frames for the feedback control. A temporary quantization number of the independent frame is determined for the feed forward control. A data amount predictive value for each blocks in the independent frame is determined by an activity of an image in each blocks and the temporary number of quantization steps. The predictive value is subtracted form the total data amount. A subtraction result for each blocks is accumulated to output a positive compensation amount if the result is a positive amount and a negative compensation amount is a negative amount. The compensation amount is then added to the temporary number of quantization steps to obtain a number of quantization steps for the independent frame. The data amount of the group is thus controlled by quantizing the dependent and independent frames by the numbers of quantization steps of the dependent and independent frames, respectively.

Multi-frame coding of LPC parameters at 600-800 bps

Abstract: Pitch-excited linear predictive coding (LPC) is widely used to code speech at 2400 b/s. The authors describe a method of coding LPC parameters which reduces the required channel bandwidth from 2400 b/s to 600-800 b/s. This method uses a split vector quantizer to code spectral parameters at 18 to 22 b/frame without excessive memory requirements. It also exploits interframe redundancy by block coding the pitch, voicing, and energy parameters, and by selectively interpolating the spectral parameters. When operating at less than 700 b/s, the system achieved as core of 90 for a three-male-speaker DRT (diagnostic rhyme test). >

Secret transmission method of character data in motion picture communication

Abstract: A secret transmission method of character data is presented in this paper when a series of motion pictures are communicated between two stations. Character data are embedded into the codes of image data to be output fromthe interframe DPCM encoder, so as to prevent a third party from reading the message: The received data are normallydecoded to a picture in higher quality and the message is also decoded at the same time if the receiver knows how toembed it. It results in our experiments that the transmission of character data has little effect on picture quality andthe amount of embedded characters will be estimated to be about 20 -' 30% of bits transmitted in each frame, forexample, when SNR is above 30dB. 1. INTRODUCTION A motion picture communication has been developed recently, and several coding algorithms are presented forlow bit-rate video or TV communication1'2. In general, the algorithms for coding and decoding motion pictures arerequired to be more rapid and easier because these must process a lot of data3. The coded data are compressed inhigh rate, but are redundant, yet. Moreover, it is well known that the scrambling and/or ciphering coders4'5 mustbe used to prevent a third party from eavesdropping the multimedia communication. However, motion pictures arerapidly changed (thirty frames are communicated in normal TV system, for example) and we are apt to see only apart of motion objects6. Using these special properties between motion pictures and human ability, we try to embeda message into the output codes of image data in order to reduce the amount of transmission data and increase thedata security. The received data are normally decoded to a picture in higher quality and the message is also decodedat the same time if the receiver knows how to embed it.

Frame skip encoding apparatus for moving images

Abstract: In a moving image encoding apparatus, an image signal is converted into a digital image signal by an A/D converter and is stored in frame memory 110 In addition, a movement vector detector 300 detects a movement of the output of the frame memory 110 In an orthogonal transformer 130, a difference signal between a present frame image which is stored in the frame memory 110 and a previous frame image which is stored in a variable delay frame memory 210 is supplied, in which the difference signal is converted by orthogonal transformation The orthogonally transformed transformation signal is quantized into a linear or nonlinear discrete level on the basis of a step width of quantization from a step size controller 600 in a quantizer 140 Then, the quantized data is encoded into a variable length code in a variable length encoder 150 A movement vector detector 300 detects movement of the image by pattern matching processing between the present frame and the previous frame A movement vector/encoding mode judger 310 generates the movement vector 3 and the encoding mode 4 The variable length code is transmitted to the transmission circuit after adding a movement vector 3 and encoding mode 4 In these operations, a frame rate controller 700 controls the processing rate of each frame image in the entire apparatus Frame rate controller 700 calculates a total frame skip number S T which corresponds to the total number of frames that are not transmitted after a frame has been transmitted The total frame skip number S T is calculated by selecting a smaller sum of an externally set signal S min , signal S M which is calculated from the degree of movement compensation and S S which is calculated from the degree of quantization, and an externally set signal S max

Method and apparatus for coding motion pictures utilizing motion compensation

Abstract: An improved motion picture coding scheme is described which provides the benefits of both sub-band coding and motion compensation thereby providing greater degrees of compression than would be obtained using either of these techniques separately. The system generates high and low frequency frames from each pair of frames in the original motion picture. The high frequency represents the difference between the first and second frames of the motion picture. The pixels of the low frequency frame are either the average of two corresponding pixels, one from each of the original frames, or a value derived from a single pixel in the first frame. In the later case, the derived value is chosen to minimize artifacts that could hamper further compression of the low-frequency frame based on sub-band coding.

Interframe predictive coding/decoding system for varying interval between independent frames

Abstract: An efficient coding and decoding system is provided for a moving picture signal having independent and dependent frames. An interval between independent frames is varied in accordance with frame difference or amount of coded data. Predictive error signals are produced by subtracting predictive picture signals based on two of the frames, the interval therebetween thus varied, from picture signals of dependent frames. The predictive error picture signals and picture signals of the independent frames are then coded to produce a coded moving picture signal. When decoding, decoded predictive picture signals and predictive error picture signals are added to each other to reproduce the picture signals of the dependent frames. Decoded picture signals of the independent frames and the reproduced picture signals of the dependent frames are serially outputted to reproduce the original moving picture signal.

Video subband VQ coding at 64 kbit/s using short-kernel filter banks with an improved motion estimation technique

Abstract: A motion compensated interframe prediction (MCIP) coder incorporating short-kernel subband filter-banks with an improved motion estimation technique is described. The coder is based on two-dimensional subband decomposition of the error image obtained after motion compensated interframe prediction. The luminance and chrominance subbands, generated after the decomposition process, form image vectors which are then quantized using vector quantization. The block matching method works well with low velocities and low noise content in the image frames. For a motion compensation estimation algorithm to cope with higher activity image frames, it is important that rapid movements, having high-amplitude motion vectors, are effectively recognized. It is also essential that the motion estimation performance does not degrade due to noise in the previously decoded frame. To achieve this, a combination of phase correlation and block search methods is applied sequentially to a hierarchy of low-pass filtered and subsampled images, while the motion vectors are progressively refined at each step of the process. Details of the proposed coding algorithm and simulation results operating at 64 kbits/s are presented.

Modeling activity in VBR video sources

Abstract: Variable bit-rate (VBR) video sources are significantly characterized by the statistics of ‘scene changes’, which determine the activity exhibited by the pictures. In a source coded with an interframe technique, in fact, this characteristic is related to the length of the emission periods having a very high bit-rate. It therefore represents a fundamental feature in evaluating performance of a network supporting video traffic. In this paper an emission process that is able to fit different activity measurements for VBR video sources characterized by a predefined bit-rate probability density function is introduced. Such a process is based on a suitable linear combination of continuous state autoregressive Markov processes. It is analyzed with respect to its capability to match the actual values of some temporal parameters which have been introduced to characterize the source. Its modeling power is compared with that of a single autoregressive Markov process. In particular is demonstrated that the process introduced here can model faster motion within a scene than a single autoregressive Markov process. Finally a case study is introduced to point out the flexibility of the proposed process.

Predictive Block-matching Motion Estimation Schemes for Video Compression (Digest)

Abstract: A new motion estirrration/compensation scheme for full-motion interframe video compression is proposed in this paper. The scheme is based on prediction of inter-block and inter-frame motion information using minimum absolute difference block matching and hence substantially increases tbe searching and computation efficiency. A comparison is also made widr the "optimal" full motion searching scheme for a standard test sequence.

Camera zoom/pan estimation and compensation for video compression

Abstract: Most image coding algorithms, like the P X 64 and MPEG-1 standards, use locally derived estimates of object motion to form a prediction of the current frame. But camera motion, such as zooms and pans, which systemically affect the entire frame, is seldom handled efficiently. In this paper, we study the modeling, estimation and compensation of global motion caused by camera zooms and pans, we model the global motion in each frame with just two parameters: a scalar zoom factor and a 2D pan vector. Parameter estimation minimizes the squared prediction error of either the difference frame or the optical flow field. The estimated parameters are then used to construct a zoom/pan compensated prediction of the current frame, upon which some local motion compensation algorithm can then be applied to model object motion. Simulations suggest that these two global motion estimation algorithms are robust and accurate, and that global motion compensation provides a better prediction of the current frame with a potentially large reduction of motion side information.

Multilayer subband-based video coding

Abstract: A motion compensated interframe subband coding algorithm suitable for a wide range of video coding applications is described. In this approach the spectrum of each frame of video signal is first decomposed into smaller frequency bands where each can then be coded accordingly. For the best performance a combination of hybrid DCT/DPCM (discrete cosine transform/differential pulse code modulation), interframe DPCM, and intraframe PCM was considered. To preserve its hierarchical structure each band is coded independently of higher frequency bands but can share information with the lower bands. A simulation was carried out for HDTV sequences. >

Design and performance evaluation of a variable bit-rate (VBR) video compression algorithm for ATM networks

Abstract: The authors present the design and performance evaluation of a robust, DCT-based (discrete-cosine-transform-based) variable-bit-rate (VBR) compression algorithm for use on B-ISDN/ATM networks. The algorithm class under consideration is based on a recent proposal by F. Kishino et al. (1989), intended to provide robust delivery of video under relatively high ATM cell loss conditions. The robust VBR codec is based on separation of subjectively important low-frequency DCT coefficients (for high-priority transport) from the less important high-frequency coefficients (which are sent at a lower priority level). Temporal propagation of error after loss of low-priority ATM cells is avoided by limiting interframe prediction to low-frequency information transmitted in high-priority cells. Several key questions that arise in the design of such an ATM codec are considered, including: (a) the trade-off between total bit-rate and robustness; (b) the influence of the high/low priority boundary parameter on the high-priority and low-priority bit-rates; and (c) performance at the decoder in the presence of ATM channel loss. >

Moving compensation inter-frame coding/decoding method and coder/decoder

Abstract: PURPOSE:To attain coding with less code quantity even to a luminance change caused due to change in a lighting condition by obtaining a moving vector minimizing an absolute sum or power of inter-frame difference except a DC component. CONSTITUTION:A variable delay device 151 applies position correction to a local decoding signal stored in a frame memory 140 in response to a moving vector detected by a moving vector detector 150 and a DC component correction device 152 corrects a DC component correction value detected by the moving vector detector 150 to generate an interframe prediction signal. The moving vector detector 150 eliminates a DC component from a prediction error signal with respect to each trial vector in the detection of a moving vector and compares absolute sums or powers to select a trial vector minimizing the values to be a moving vector and the DC component of the prediction error signal to the trial vector is a DC component correction value. Thus, the luminance change caused in the change of the lighting condition is coded with less coding quantity.

Coding of motion vectors for motion-compensated predictive/interpolative video coder

Abstract: Motion vectors are side information vital to motion-compensated predictive/interpolative interframe video coding algorithms. This paper is concerned with the coding efficiency for this motion information. It is demonstrated that coding differential motion vectors is not always advantageous. An adaptive strategy is thus considered to automatically select the most favorable mode to code the motion information. The effects of video noise to motion estimation and coding are also investigated. A simple linear filtering scheme is used to reduce the noise effects. Simulation results show a significant performance improvement for noisy video by using this simple filtering scheme.

High-definition television signal processing system for transmitting and receiving a television signal in a manner compatible with the present system

Abstract: On the transmission side, a delay unit, an adder, and a subtracter obtain an interframe sum output by calculating, in units of two frames, an interframe average sum of progressive scanning signals each having N scanning lines per frame, and an interframe difference output by calculating, in units of two frames, an interframe average difference related to moving image data. The interframe sum output is band-limited to a band which can be transmitted with a conventional scheme by switching, time expansion, vertical filtering, and first scanning line count conversion, and converted into M scanning lines per frame. The interframe difference output is band-limited to a band effective for resolution improvement of a moving image in a receiver of a conventional scheme by switching, time expansion, vertical filtering, horizontal filtering, and second scanning line count conversion, and converted into M scanning lines per frame. Outputs obtained by first and second scanning line count conversions are input to a sum arithmetic means to generate a first frame signal, and input to a difference arithmetic means to generate a second frame signal. The first and second frame signals are transmitted as an interlace scanning signal of M scanning lines per frame for a central portion thereof.

Motion capture by a frame: global or local processing?

Abstract: The possibility that frames serve to capture lines within them sc that they appear on a coplanar surface was investigated, using coherence in direction of rotary motion (Gillam, 1972) as a quantitative measure of the coplanarity of frame and internal lines. It was found that perceptual coherence between a pair of lines was greatly increased by surrounding them with a frame, if the frame was perspectivally consistent with the lines. A second experiment showed that this grouping can be attributed to a global effect of the frame and cannot be accounted, for. by local grouping of the internal lines with components of the frame.

Multiplexed transmission system of image data from two or more sources wherein thinning rates are adaptively allocated to respective sources

Abstract: A transmission system is provided having a sender side apparatus, a receiver side apparatus, and a transmission line connecting the sender and receiver side apparatuses. The sender side apparatus provides a selector for receiving image data signals of a plurality of channels in parallel and, frame by frame, selects an image data signal of one of the plurality of channels for each frame. The selector discards the image data signals of the other of the plurality of channels. A coding unit codes the image data signal which is selected for each frame by the selector, by interframe difference coding. A monitoring unit monitor data amounts of interframe differences in the image data signals of the respective channels. A control unit determines which one of said plurality of channels is to be selected by the selector, based on the data amounts of interframe differences in the image data signals of the respective channels, and adaptively controls the selector in accordance with this determination. Channel information is generated indicating the above one of the channels determined by the control unit for each frame. Frame by frame, the image data signal coded by the above coding means is transmitted, together with the above channel information corresponding to the coded image data signal. The receiver side apparatus receives the transmitted image data signal, together with the channel information, and a unit for decodes the received image data signal for each frame.

Inter-frame adaptive prediction encoding system

Abstract: PURPOSE: To supply an inter-frame adaptive prediction encoding system which can prevent the deterioration of picture quality without deteriorating prediction efficiency even if movement changes and the correlation of inter-frame changes and which can reduce an operation amount required for prediction. CONSTITUTION: An encoding part 3 encodes a key frame at a prescribed interval as against a picture signal 1 which is continuously inputted, and a predictor 17 predicts an interpolation frame between the previously encoded key frames by using a preceding frame by two, the preceding frame and subsequent frame. COPYRIGHT: (C)1992,JPO&Japio

Method for estimation of motion in a captured image

Abstract: In this method, in which a motion vector is in each case determined for one block of the recorded frame, which vector presents the motion within the block from one frame to a following frame, first motion vectors will be initially determined independently of one another for in each case one block. The first motion vectors determined are corrected taking into consideration a correlation with motion vectors of adjacent blocks.

A motion vector replenishment video codec for ATM networks

Abstract: A low bit-rate video codec for ATM networks is described. It is based on two-layer coding principles. The base layer comprises the motion vectors plus a strip of interframe coded video data. The remaining video data are coded by a second layer. Transmission of the base layer cells is assumed to be guaranteed. The required guaranteed channel rate can be as low as that needed for a speech signal, such that networks like Orwell can handle them equally. The second layer cells may be lost, if congestion arises. Simulation results demonstrate the performance of the codec for a range of cell loss rates from the second layer.

Method for coding interlace-scanned digital video signal

Abstract: PURPOSE:To obtain a high picture quality by dividing the frame of interlace scanning video signals into small blocks and performing a frame coding process or field coding process on the blocks in accordance with the difference in number of picture elements between two fields in each block. CONSTITUTION:A block division circuit 2 divides an input picture 1 into small blocks of picture element data and interfield difference detection circuit 3 detects the correlation between two fields in each block. When the difference between the two fields is small, namely, when the correlation is high, the block is coded by means of a frame coding process circuit 6 by using a frame coding method by which all lines in the block are successively scanned, accordingly, by using an efficiently designed interframe movement compensating method and intraframe sub-sampling method for color data. When the correlation is low, on the other hand, the block is coded by means of a field coding process circuit 5 by which the detection of intrafield correlation and interfield correlation is intensified.

Predictive block-matching motion estimation schemes for video compression. I. Inter-block prediction

Abstract: A novel motion estimation/compensation scheme for full-motion interframe video compression is proposed. This scheme is based on prediction of interblock motion information by using minimum absolute difference block matching and hence substantially increases the searching and computation efficiency. A comparison is made with the 'optimal' full motion searching scheme for a standard test sequence. The experimental results show that the proposed scheme provides a computationally efficient algorithm in a real-time video communication environment. >