WO1995024096A1 - Estimation du mouvement - Google Patents

Estimation du mouvement Download PDF

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Publication number
WO1995024096A1
WO1995024096A1 PCT/GB1995/000479 GB9500479W WO9524096A1 WO 1995024096 A1 WO1995024096 A1 WO 1995024096A1 GB 9500479 W GB9500479 W GB 9500479W WO 9524096 A1 WO9524096 A1 WO 9524096A1
Authority
WO
WIPO (PCT)
Prior art keywords
motion vectors
phase correlation
candidate motion
block
video signal
Prior art date
Application number
PCT/GB1995/000479
Other languages
English (en)
Inventor
Rod Thomson
Bruce Devlin
Andrew Major
Original Assignee
Snell & Wilcox Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Snell & Wilcox Limited filed Critical Snell & Wilcox Limited
Priority to AU18538/95A priority Critical patent/AU1853895A/en
Publication of WO1995024096A1 publication Critical patent/WO1995024096A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/14—Picture signal circuitry for video frequency region
    • H04N5/144—Movement detection
    • H04N5/145—Movement estimation
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/20—Analysis of motion
    • G06T7/262—Analysis of motion using transform domain methods, e.g. Fourier domain methods
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
    • H04N19/51—Motion estimation or motion compensation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
    • H04N19/51—Motion estimation or motion compensation
    • H04N19/547—Motion estimation performed in a transform domain

Definitions

  • This invention relates to motion estimation for the purposes of video signal processing.
  • the aim of the process is to measure the movement of objects between two scenes by measuring the correlation of the pixels in the current block against the pixels in the delayed reference block. Where there has been a simple movement within the block, the correlation will be good and there will be a peak in the correlation surface. The position of this peak is found in the peak hunter and this position is a measure of the motion of the object. For example, a peak with zero displacement corresponds to a zero motion or static object within the block. The ability of the system to generate multiple peaks per block allows complex motions to be measured with accuracy.
  • Very large motions can give similar problems to those described for small objects.
  • the object may partly leave the block in question. It will be understood that there are then fewer pixels that contribute to the correlation process than during small movements. The effect of this is to reduce the height of the correlation peak with the result that the measurement of the motion is less precise.
  • the present invention consists in one aspect in a method of motion estimation comprising the steps of dividing an image into relatively large blocks, performing a first level phase correlation between corresponding blocks in successive images to identify candidate motion vectors; dividing each block into relatively small sub-blocks; pre-shifting each sub-block with one or more of the candidate motion vectors for the corresponding block; performing a second level phase correlation between the pre-shifted sub-block and the corresponding sub-block in successive images and identifying motion vectors by selecting from candidate motion vectors in dependence upon said second level phase correlation.
  • the present invention consists in apparatus for motion estimation in a video signal, comprising an input video signal path including frequency domain transform means; a plurality of pre-shift paths each comprising means for pre-shifting by a candidate motion vector selected for that path, frequency domain transform means; phase correlation means for performing a phase correlation between the input video signal and the pre-shifted signal, and means for identifying motion vectors taking into account the pre-shift for that path.
  • the invention builds on the known advantageous properties of phase correlation.
  • the invention proposes the use of a traditional phase correlator to generate vectors for any new or large movements in a scene. These vectors are fed into a second stage phase correlator where they are treated as predictors for a pre-shifting strategy.
  • Figure 1 is a block diagram illustrating, for the purposes of comparison, a phase correlator according to the prior art.
  • FIG. 2 is a block diagram illustrating apparatus according to the present invention.
  • the diagram of Figure 1 shows in block form, the process involved in traditional phase correlation as used in motion estimation.
  • Input video is formed into, say, 64 pixels square blocks in component " IO and two- dimensional Fast Fourier transforms (FFT) then carried out on the blocks in component 12.
  • FFT Fast Fourier transforms
  • a phase correlation is conducted in correlator 14 between the transform and the transform of the signal subjected to one-field delay in delay 16.
  • peaks are located in the correlation surface in peak hunter 20.
  • Motion vectors generated from these peaks in vector generator 22. In the known arrangement, those motion vectors are then assigned in a block matching procedure not shown in the figure.
  • each motion vector from the phase correlation procedure is regarded as a candidate motion vector.
  • Each candidate motion vector stream controls a pre-shifter.
  • an input video signal path 30 comprises a field delay 30, a pre-shift matching delay 34 and a 16 point two-dimensional FFT block 36.
  • Each pre-shift path is completed by an inverse transform block 44, a peak hunter 46 and a vector generator 48.
  • Each pre-shift path produces a block of appropriately filtered pixels displaced by the candidate vector MV, to MV n . If this vector represents the true displacements of the objects in the blocks then the phase correlation process will find a zero vector. If the vector is close to the true vector then the phase correlation process will find a correction to the candidate vector. If there is complex motion within the block then multiple peaks will appear in the correlation sur ace and several vectors could be generated. A poor correlation will indicate that the candidate vector did not represent the movement in that block.
  • the candidate motion vectors (MV r .MV n ) can be generated from a number of sources, including an earlier phase correlation process. These would typically be:-
  • Temporal predictors vectors projected from the previous field/frame/picture which would be used to find small moving objects/accurate high speed vectors and to provide temporal stability to the system
  • Heuristic predictors vectors known to be used in the picture such as zero vectors and global movement (pan/zoom) vectors
  • the "vector generate” block 48 is able to generate motion vectors and side information depending on the application for the motion estimation. Two such applications are standards conversion and compression coding.
  • a projected predictor at the input to the pre-shifter should enable a constant velocity object to be tracked even if the object did not generate a vector in the initial "large block” phase correlation. * The pre-shifting will improve the signal to noise ratio of the phase correlation peaks when the motion vector is large.
  • a confidence measure can be generated for each block by measuring the peak height(s) of the candidate vector. This confidence measure should be vaiid for most of the pixels in this small block and can be used in the picture building algorithm to control the mix of pixels in the standards converted output picture.
  • this requires one vector per block at the output of the motion estimator.
  • this block size is 16 X 16 pixels and the new phase correlation method can be used to measure directly the quality of the motion vectors.
  • the quality of the motion in a block can be directly measured. For example: one single large correlation peak with little noise indicates a simpie translational movement. A block matcher may not produce such a clear result due to noise in the pixel domain. If several vectors are found in the one small bock then the motion can be classed as complex and the block should be coded more carefully.
  • the peak height of the correlation surface can generate a confidence measure for the vector. This can be used in addition to the vector magnitude and a "cost" function associated with coding the vector and block to decide upon the best coding mode.

Abstract

On évalue le mouvement dans un signal vidéo en réalisant une corrélation de phase de premier niveau entre des blocs correspondants, dans des images successives, en vue d'identifier des vecteurs de mouvement candidats; en divisant chaque bloc en sous-blocs relativement petits; en pré-décalant chaque sous-bloc à l'aide d'un ou plusieurs des vecteurs de mouvement candidats; et en réalisant une corrélation de phase de second niveau entre le sous-bloc pré-décalé et le sous-bloc d'entrée.
PCT/GB1995/000479 1994-03-04 1995-03-06 Estimation du mouvement WO1995024096A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU18538/95A AU1853895A (en) 1994-03-04 1995-03-06 Motion estimation

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9404189A GB9404189D0 (en) 1994-03-04 1994-03-04 Motion estimation
GB9404189.4 1994-03-04

Publications (1)

Publication Number Publication Date
WO1995024096A1 true WO1995024096A1 (fr) 1995-09-08

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1995/000479 WO1995024096A1 (fr) 1994-03-04 1995-03-06 Estimation du mouvement

Country Status (3)

Country Link
AU (1) AU1853895A (fr)
GB (1) GB9404189D0 (fr)
WO (1) WO1995024096A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8139883B2 (en) 2008-07-29 2012-03-20 Sony Corporation System and method for image and video encoding artifacts reduction and quality improvement
US8285079B2 (en) 2010-03-19 2012-10-09 Sony Corporation Method for highly accurate estimation of motion using phase correlation
US8363728B2 (en) 2008-04-18 2013-01-29 Sony Corporation Block based codec friendly edge detection and transform selection
US8488007B2 (en) 2010-01-19 2013-07-16 Sony Corporation Method to estimate segmented motion
US8553758B2 (en) 2007-03-02 2013-10-08 Sony Corporation Motion parameter engine for true motion

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0367310A2 (fr) * 1988-09-05 1990-05-09 Philips Electronics Uk Limited Mesure de mouvement d'image

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0367310A2 (fr) * 1988-09-05 1990-05-09 Philips Electronics Uk Limited Mesure de mouvement d'image

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
G. THOMAS: "Television Motion Measurement for DATV and Other Applications", BBC RESEARCH DEPARTMENT REPORT, TADWORTH(GB), pages 1 *
M. ZIEGLER: "Hierarchical Motion Estimation Using the Phase Correlation Method in 140 MBits/s HDTV-Coding.", SIGNAL PROCESSING OF HDTV, II, TURIN (IT), pages 131 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8553758B2 (en) 2007-03-02 2013-10-08 Sony Corporation Motion parameter engine for true motion
US8363728B2 (en) 2008-04-18 2013-01-29 Sony Corporation Block based codec friendly edge detection and transform selection
US8139883B2 (en) 2008-07-29 2012-03-20 Sony Corporation System and method for image and video encoding artifacts reduction and quality improvement
US8488007B2 (en) 2010-01-19 2013-07-16 Sony Corporation Method to estimate segmented motion
US8285079B2 (en) 2010-03-19 2012-10-09 Sony Corporation Method for highly accurate estimation of motion using phase correlation

Also Published As

Publication number Publication date
AU1853895A (en) 1995-09-18
GB9404189D0 (en) 1994-04-20

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