Showing papers on "Inter frame published in 1992"

Efficient multiframe Wiener restoration of blurred and noisy image sequences

Abstract: Computationally efficient multiframe Wiener filtering algorithms that account for both intraframe (spatial) and interframe (temporal) correlations are proposed for restoring image sequences that are degraded by both blur and noise. One is a general computationally efficient multiframe filter, the cross-correlated multiframe (CCMF) Wiener filter, which directly utilizes the power and cross power spectra of only N*N matrices, where N is the number of frames used in the restoration. In certain special cases the CCMF lends itself to a closed-form solution that does not involve any matrix inversion. A special case is the motion-compensated multiframe (MCMF) filter, where each frame is assumed to be a globally shifted version of the previous frame. In this case, the interframe correlations can be implicitly accounted for using the estimated motion information. Thus the MCMF filter requires neither explicit estimation of cross correlations among the frames nor matrix inversion. Performance and robustness results are given. >

Image signal band compressing system for digital video tape recorder

Abstract: The image signal band compressing method employs a three-dimensional motion compensating technique, an intraframe and an interframe processes which are alternatively executed. The transfer rate of the intraframe to the interframe is set to 4:1 in a unit of fixed length. The intraframe process is defined such that the present frame image data is compressed in a variable length compressing manner by way of two-dimensional discrete coding transform. The interframe process is defined such that motion data is estimated by comparing the present frame and the preceding frame, the present frame is expected on the basis of the motion data and the difference data between the motion compensated image data and the present frame data.

Interframe motion predicting method and picture signal coding/decoding apparatus

Abstract: An interframe motion predicting method for prediction of the motion in a bidirectionally predictive-coded frame from an intra-coded frame and a predictive-coded frame, predicts the motion in another bidirectionally predictive-coded frame from the preceding bidirectionally predictive-coded frame and the predictive-coded frame. A picture signal coding apparatus executes orthogonal transformation of a picture signal, then quantizes the transformed data, and codes the data thus quantized. The apparatus includes a local decoder for the quantized data; first and second memories for storing the decoded picture data of an intra-coded or bidirectionally predictive-coded frame, and a predictive-coded frame respectively; a predictive picture generator for generating a predictive picture of a second bidirectionally predictive-coded frame; and a difference calculator for calculating the difference between the predictive picture and the original picture signal corresponding thereto. A picture signal decoding apparatus includes inverse multiplexer for separating the coded data into interframe predictive error data and vector coded data; a decoder for generating decoded picture data on the basis of such error data; first and second memories for storing the decoded picture data of the intra-coded frame and the predictive-coded frame respectively; a predictive picture generator for generating a predicted picture of a second bidirectionally predictive-coded frame; and a frame switching selector for selectively rearranging the decoded picture data in the order of reproduction.

System and method for frame differencing video compression and decompression with frame rate scalability

Abstract: A system and method of compressing original video data expressed in a plurality of digitally coded frames which enable decompression and playback of resulting compressed video data at one of a plurality of frame rates while maintaining temporal fidelity of the frames displayed. Compression includes selecting a plurality of rate streams for the compressed video data, including a highest rate stream including all of the frames of the original video data and a lowest rate stream including a subset of regularly spaced frames of the original video data. Then the initial frame in the original video data is spatially compressed and the resulting compressed data placed in the compressed video data. The initial frame is also saved as a base frame for all rate streams for subsequent temporal compression of the original video data. As frames are retrieved from the original video data in sequence, temporal compression based on frame differencing techniques between the retrieved frame and the base is carried out, with difference frames being stored to the compressed video data. Each difference frame is placed in the resulting compressed video data for later decompression and reproduction.

Method and apparatus for communicating compressed digital video signals using multiple processors

Abstract: Digital video signals are processed by a plurality of independently operating processors to provide data for transmission in a compressed, motion compensated form. A video image frame area is divided into a set of subframes. The set of subframes is systematically shifted such that the individual subframes progressively cycle across and wrap around the video image frame area. For each successive video frame, video image data bounded by each of the different subframes is independently compressed using motion estimation to reduce data redundancy among the successive frames. The motion estimation is limited for each subframe of a current video frame to areas of a previous video frame that were bounded by the same subframe in the previous frame. In an illustrated embodiment, the set of subframes is shifted once for each successive video frame, and each subframe includes a refresh region whereby the video image frame area is progressively refreshed as the subframes are shifted thereacross. Receiver apparatus for use in decoding the independently processed subframe data is also disclosed.

Data compression method and apparatus in which quantizing bits are allocated to a block in a present frame in response to the block in a past frame

Abstract: A digital input signal is compressed to provide a compressed output signal in a manner which prevents pre-echo, a common defect of data compressors The digital input signal is divided in time into frames, and into at least one block of data in each frame The frames include a past frame preceding a present frame Block floating is applied to the data in the block in each frame Quantizing bits are adaptively allocated to the data in the block in the present frame in response to the block in the past frame Finally, the resulting quantized data is added to the compressed output signal In a first variation, a signal energy or an allowable noise level is determined for the block in each frame A word length is determined for the block in each frame in response to the determined signal energy or allowable noise level of the block The quantizing bits are allocated to the data in the block in the present frame in response to the word length for the block in the past frame In a second variation, a signal energy in the block in each frame is determined, and quantizing bits are adaptively allocated to the data in the block in the present frame in response to an interpolation between the signal energy for the block in the present frame and for the block in the past frame

A look at the MPEG video coding standard for variable bit rate video transmission

Abstract: The MPEG video coding standard for the transmission of variable-bit-rate video on asynchronous transfer mode (ATM)-based broadband ISDN is examined. The focus is on its use for real-time transmission of broadcast-quality video. The impact of two key parameters, the intraframe to interframe picture ratio and the quantization index that are defined in the standard, on the bit rates per frame was studied. These parameters can be used to control video sources depending on the state of the network. Also, as opposed to previous work which looks only at bit rates per frame, the bits generated per macroblock are studied. This is the basic MPEG coding unit. By packetizing these bits, insight was obtained into the cell arrival process to a network for a MPEG video source. >

Gridlocked method and system for video motion compensation

Abstract: A method and system for video motion compensation (21) in which an overall interframe motion vector is divided into a relative block motion vector and a subblock motion vector. Image reconstruction is achieved by adjusting the delay between the synchronization pulse and the start of the pixel data according to the subblock motion vector, and accessing stored data from memory (42) according to the relative block motion vector. Accessing memory in a block-quantized format ensures that page mode accesses are confined to the same memory row.

System and method for frame-differencing based video compression/decompression with forward and reverse playback capability

Abstract: A process for coding a plurality of compressed video data streams in a time ordered sequence. Each compressed data stream includes coding of frame to frame differences of a video segment, which are represented as a compressed M×N exclusive-OR plane of pixel change values and location displacement control values for an output pointer into a decompressed video frame. By coding frame to frame differences in an exclusive-OR values, the replay process is made bidirectional, allowing for both forward and reverse playback of the video segment.

Prioritized transmission of variable bit rate MPEG video

Abstract: The traffic characteristics of an MPEG coder which generates a high-priority and a low-priority bit stream are studied. The prioritization scheme for the coder assigns components of the data stream to each priority level based on the value of a parameter B. Statistics of both high- and low-priority cells for a pure intraframe and a mixed interframe/intraframe coder are presented. In particular, the probability mass functions on a cells per slice basis of the high-priority and low-priority component for various values of B are shown. Statistics gathered from this type of prioritization scheme can be applied in several ways for network design and operation. >

Standards conversion of digital video signals

Abstract: An input digital video signal is converted to an output digital video signal having a different frame rate and a different number of pixel lines per frame. A first series of progressive scan format frames is formed from the input signal. Then a second series of frames is formed from the first series of frames using motion compensated temporal interpolation between successive frames of the first series in producing at least some of the frames of the second series so as to provide the difference in frame rate. Before or after the second series of frames is formed, vertical spatial interpolation is performed so as to provide the difference in the number of pixel lines per frame.

Temporal domain sub-band video coding with motion compensation

Abstract: Temporal domain subband coding with motion compensation (MC-SBC) is a new technique of interframe data compression in video coding applications. Perfect reconstruction is possible with one-pixel accuracy for motion parameters and a trivial first-order quadrature mirror filter (QMF). With comparable complexity, even this most simple type of MC-SBC outperforms MC prediction (MC-DPCM) techniques when blockwise motion estimation is used. The concept of MC-SBC is generalized to subpixel accuracy of MC and any even-length (odd-order) QMF filters. Motion estimation is performed in a hierarchical forward-backward procedure which gives better SNR and visual performance results than blockwise-independent estimation. The scheme is extremely error resistant due to its nonrecursive structure; the gain over MC-DPCM is remarkably high, especially in layered coding schemes as they are discussed for ATM video applications. Results of MC-SBC and other interframe coding schemes are compared using two different intrafracture schemes in layered and nonlayered coding applications. >

Film-to-video frame image conversion apparatus and method for selectively identifying video fields and frames

Abstract: A film-to-video frame image convertor includes a 3-2 pulldown frame convertor for converting signals representing input film frame images, having a lower associated film frame image rate, to signals representing output video frame images having a higher associated video frame image rate. The output video frame images consist of genuine and simulated video frame images, which correspond to actual input film frame images and multiple input film frame images, respectively, in accordance with a 3-2 film-to-video frame pulldown. Each genuine video frame image consists of two video field images corresponding to two actual film field images from the same film frame image. Each simulated video frame image consists of two video field images corresponding to two actual film field images from different film frame images, with one of the two video field images being a duplicate of a video field image in an adjacent video frame image. Identification signals are selectively inserted into the vertical blanking interval of some of the output video frame images to identify which ones are simulated video frame images containing duplicate video field images. This allows the duplicate video field images to be identified and selectively deleted when the video frame images, having the higher associated video frame image rate, are to be reconverted to film frame images having the lower associated film frame image rate.

Twisted pair ethernet hub for a star local area network

Abstract: A hub in a star local area network (LAN). A single station, called the preferred station, is dynamically selected to perform a transmission. When two or more stations attempt to transmit simultaneously, one currently preferred station goes through, while all others sense collisions. The currently preferred station is dynamically selected by performing a precedence algorithm which is a fairness and deterministic algorithm. If the station receiving from the preferred station also attempts to transmit, then it senses a collision and the hub lets it recover and enable itself for receiving before transmitting the frame. This is done by storing the preferred station frame in an internal small first-in first-out (FIFO) buffer. The hub resends the frame from the FIFO immediately after Inter Frame Spacing (IFS) while the receive station attempts to transmit later. If after a number of attempts the hub does not succeed in transmitting the frame successfully, then the hub generates a collision frame.

Motion compensated resolution conversion system

Abstract: A process is provided for creating a high resolution copy of a target video frame selected from a sequence of video frames, wherein each video frame comprises two interlaced fields. The process comprises the steps of: selecting a single field of the target video frame for resolution enhancement; defining a reference target frame having pixel values assigned from the selected single field; defining an enlarged target frame having pixel locations corresponding to the high resolution copy; assigning pixel values from the selected single field to pixel locations in the enlarged target frame which correspond to pixel locations in the selected single field; assigning estimated pixel values to unassigned pixel locations in the reference target frame; selecting a field from one of the video frames in the sequence of video frames which was not chosen as the selected single field as a first object field; estimating motion vectors extending from the reference target frame to pixels in the first object field; identifying accurate motion vectors; assigning the value of a respective pixel for each motion vector identified as accurate to an enlarged target frame pixel location corresponding to an origination point of the motion vector unless the enlarged target frame pixel location was previously assigned a pixel value; and printing the enlarged target frame. Further provided is printing apparatus for creating a high resolution copy of lower resolution video information.

Modeling of motion classified VBR video codecs

Abstract: The authors use a motion adaptive variable-bit-rate (VBR) video codec and propose a motion classified model to represent the characteristics of various classes of motion activities. The codec switches between interframe, motion compensated, and intraframe coding corresponding to low, medium, and high motions and scene changes, respectively. The model captures the motion of various video scenes and the codec structure by providing the statistics of VBR-coded video' traffic through a first-order composite autoregressive process with three motion classes. The parameters of this model are derived from a VBR-coded sample video sequence such that the bit rate distribution and the autocorrelation in bit rates of two successive frames are matched. The validity and accuracy of the model are verified. Using this model, the characteristics of aggregated traffic sources are discussed. >

Low-bit rate interframe video encoder with adaptive transformation block selection

Abstract: An interframe video encoder of the type known as a hybrid coder, combines the advantages of both the interfield and the interframe codings for low bit-rate video transmission. The pel elements of differential block from subtracter are rearranged and the correlation of the rearranged block is estimated. The correlation of the differential block is also provided. And then, one of the differential block and the rearranged block is subjected to two-dimensional transform according to the comparsion of the correlations.

Hybrid coders with motion compensation

Abstract: This paper investigates analytically the effects of motion compensation in a coder based on the observed properties of motion-compensated frame difference (MCFD) signals. The AR(1) processes with a given pixel-to-pixel autocorrelation coefficient will be used to model the intraframe images. For interframe motion, each image is allowed to have both moving and nonmoving parts, with the moving parts executing a range of translational motion. From this mathematical model, the statistical characteristics of MCFD signals are derived. Motion compensation gain, 2-D intraframe transform gain, and hybrid gain are next evaluated to ascertain their suitability for the coding process. Experimental results on the Trevor sequence seem to confirm the model and conform with its analytical results.

Motion-compensated multiframe Wiener restoration of blurred and noisy image sequences

Abstract: A computationally efficient multiframe LMMSE filtering algorithm, the motion-compensated multiframe (MCMF) Wiener filter, for restoring image sequences that are degraded by both blur and noise is proposed. MCMF Wiener filter applies to the cases where each frame of the ideal image sequence can be expressed as a globally shifted version of its previous frame. As opposed to single-frame filtering, the MCMF Wiener filter accounts for interframe (temporal) correlations as well as intraframe (spatial) correlations in restoring a given image sequence. The MCMF filter requires neither the explicit estimation of cross correlations among the frames, nor any matrix inversion. It accounts for the interframe correlations implicitly by using the estimated interframe motion information. The results of an extensive study on the performance and robustness of the proposed algorithm are presented. >

Interframe hierarchical address-vector quantization

Abstract: A new interframe coding technique called interframe hierarchical address-vector quantization (IHA-VQ) is presented. It exploits the local characteristics of a moving image's motion-compensated (via block matching) difference signals by using quadtree segmentation to divide each image into large, uniform regions and smaller, highly detailed regions. The detailed regions are encoded by vector quantization (VQ), and the larger, low-detail regions are replenished from the previous frame, IHA-VQ also exploits the correlation between the small blocks by encoding the addresses of neighboring vectors by using several codebooks of address code-vectors. >

Frame rate conversion of motion picture films for progressive-scan hdtv

Abstract: Frame rate conversion facilitates visual information exchange among systems employing various different frame rates for storage, transmission and display of image video signals. Motion pictures have a temporal rate of 24 frames per second, while most of the conventional video displays and recording devices utilize a rate of 60 fields per second. In the case of high-definition television (HDTV) systems, some proposals in the US require a video rate of 60 frames per second. Up-conversion of motion picture film to 60 frames per second is of importance because programs recorded on motion picture film can be used as high-quality source material for HDTV. In this paper, we address the problem of motion-compensated up-conversion of digitized motion pictures at 24 frames per second to 60 frames per second digital video signals.

Digital video signal with increased motion blur characteristic

Abstract: An input digital video signal representing a series of input frames is processed to produce an output digital video signal representing a series of output frames with an increased motion blur effect. For each output frame at least one intermediate field or frame is produced by motion compensated temporal interpolation between a pair of the input frames. Each output frame is then produced by combining the intermediate field or frame with at least one further intermediate field or frame and/or with one of the respective input frames so that the output frame has an increased motion blur characteristic compared with that of the input frames. Using motion compensated temporal interpolation, a change in frame rate can also be produced as between the input frames and the output frames.

Interframe/interfield predictive encoding system

Abstract: An interframe/interfield encoding system is for coding an incoming video signal having a successive specific number of dependent frames/fields, and independent frames/fields located anterior and posterior to the dependent frames/fields on a time axis. The system has a predictor for generating prediction errors of the dependent frames/fields by the independent frames/fields and an encoder for coding the independent frames/fields and the prediction errors. The system also has a delay section delays coding the posterior independent frame/field by the specific number of dependent frames/fields on the time axis to the incoming video signal and a controller, responsive to the delaying, controls the encoder to encode the posterior independent frame/field so as to follow the coding of the prediction errors. The posterior independent frame/field, without being delayed, is employed for generation of the prediction errors.

Comparison of motion compensation using different degrees of sub-pixel accuracy for interfield/interframe hybrid coding of HDTV image sequences

Abstract: The bit rates for interfield/interframe hybrid coding of high-definition television (HDTV) image sequences with motion compensation using 1, 1/2, 1/4, and 1/8 pixel accuracy. Three sets of HDTV image sequences with panning, zooming, local motion and different spatial details are tested. The coding performance of bilinear interpolation is compared to Lagrange interpolation for obtaining sub-pixel precision. A means for finding the best matching motion block and obtaining the subpixel image values which dramatically reduces simulation times is discussed. >

Decoding apparatus of a compressed digital video signal

Abstract: Encoded picture data or encoded difference data is decoded by an intraframe decoder. To an adder, zero data is given through a switching circuit at the time of the decoding of intraframe coded data, and when interframe coded data, i.e., difference data is decoded, a decoded value of a previous frame is supplied through the switching circuit. By the adder, the decoded value of the previous frame and the decoded difference value are added to allow the decoding of interframe coding.

Video signal coding

Abstract: A circuit is described for independently producing interframe data and intraframe data from a video signal (VD) and thereafter selecting for output, at an inter/intra selector (12) using coefficient values of orthogonally transformed interframe data and intraframe data, the data permitting the more efficient coding.

Interframe video coding using overlapped motion compensation and perfect reconstruction filter banks

Abstract: Interframe video coders using the discrete cosine transform (DCT) and motion compensation (MC) produce block artifacts in the decoded video at low bit-rates. Results on lapped orthogonal transforms (LOTs) suggest that they can reduce these artifacts. However, LOTs are difficult to use efficiently with motion compensation because of block overlap. The authors propose a new video coding algorithm that forms a natural connection between LOTs and motion compensation using two novel concepts: overlapped motion compensation (OMC) and overlapped macroblocks using frequency domain coefficients. >

Bidirectional motion estimation based on P frame motion vectors and area overlap

Abstract: Some proposed video compression schemes do not send frames in the order they were captured. Such schemes yield bidirectional or B frames: frames that are predicted from past and future frames. When estimating motion vectors for B frames the motion vector field referencing the future to the past frame (the P frame motion vector field) is available. The area overlap (AO) method presented estimates the motion vector fields relating a B frame to past and future frames using the P frame motion vector field. Thus B frame motion vectors need not be sent AO's estimates are scaled versions of P frame motion vectors and therefore have finer resolution. >

Bit allocation and rate control based on human visual sensitivity for interframe coders

Abstract: Video coding standards such as the CCITT H.261 and the ISO 11172 allow substantial freedom in the exact methodology used to allocate bits to different parameters and control the output bit rate. Thus, different standard conforming coders can give different picture quality depending on the bit allocation and rate control strategy used at the encoder. The authors propose a new bit allocation and rate control strategy that is based on some assumptions about the sensitivity of the human visual system to distortion. They use the ISO 11172 standard in their examples, although the strategy is equally applicable to other DCT based interframe coding schemes. The new scheme shows considerable quality improvement over conventional schemes in the informal subjective tests. >

A split-merge parallel block-matching algorithm for video displacement estimation

Abstract: Motion compensation is one of the most effective techniques used in interframe data compression. The authors present a parallel block-matching algorithm for estimating interframe displacement of small blocks with minimum error. The algorithm is designed for a grid architecture to process video in real time. The blocks may have variable size depending on a split-and-merge technique. The algorithm performs a segmentation of the image into regions (objects) moving in the same direction and uses this knowledge to improve the transmission of the displacement vectors. >