Patent EP0579319A2 successfully refreshed from Google Patents.
EP0579319A2
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EP
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Tracking moving objects
Assignee: Philips Electronics UK Ltd
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Filing: 1993-07-08
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Granted: —
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Expires: 2013-07-08
Abstract
Abstract A method of tracking an object in a sequence of picture frames comprises inputting motion vectors (100) and segmenting the picture into areas of uniform motion (101). For the initial frame (1027) the object is located (103) either automatically or manually and its centroid and motion vector are calculated (104). For each subsequent frame (105) motion vectors (100) are input and the frame is segmented into areas of uniform motion (101). The forward motion vector of the object is calculated (120) and used to project the centroid of the object from the previous frame onto the present frame (106). The object is then grown round the projected centroid (107) by allocating areas similar to areas of the object in the previous frame and which together produce a centroid close to the projected centroid to a set of areas which define the object. A rectangle may then be drawn around the object (109) which may be used in a coding arrangement to define areas of different resolution. Backward motion vectors of the areas within the set are then calculated (110) and used to determine the similarity of areas in the next frame. Apparatus for performing the method is disclosed particularly in relation to tracking a head for videophone communications.
Inventors
- 👤 Dimitrios c/o Philips Elecxtronics Thanassas
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 12:28
CPC Classifications
G; G01; G01S; G01S3/00; G01S3/78; G01S3/782; G01S3/785; G01S3/786; G01S3/7864; G01S3/7865; G06; G06T; G06T7/00; G06T7/20; G06T7/223; G06V; G06V10/00; G06V10/20; G06V10/24; H; H04; H04N; H04N19/00; H04N19/50; H04N19/503; H04N19/51; H04N19/537; H04N19/543; H04N19/60; H04N19/61; G06T2207/00; G06T2207/10; G06T2207/10016; H04N19/20
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
172 words
A method of tracking an object in a scene represented as a sequence of picture frames captured by a camera for display on a display device, the method comprising the steps of: a) segmenting the image in an initial frame into areas having uniform motion, b) locating the object in the initial frame and finding its centroid and motion vector, c) projecting the centroid of the object onto the next frame using the motion vector to define a new position of the object centroid, d) segmenting the image in the next frame into a number of areas having uniform motion, e) finding those areas of the image similar to areas of the object in the previous frame and which together produce a centroid close to the projected centroid to produce a new object, f) calculating the size and motion vector of the new object, g) projecting the new position of the object centroid onto the succeeding frame using the motion vector of the new object, and h) repeating steps d) to g).
Claim 2
Dependent Claim
21 words
A method as claimed in Claim 1 in which in step c) and step f) a forward motion vector is calculated.
Claim 3
Dependent Claim
21 words
A method as claimed in Claim 1 or Claim 2 in which backward motion vectors are used to segment the images.
Claim 4
Independent Claim
33 words
A method as claimed in any preceding claim in which in step e) the factors determining similarity are the size, position, and magnitude and direction of motion of the areas to be compared.
Claim 5
Independent Claim
15 words
A method as claimed in any preceding claim wherein the object is a human head.
Claim 6
Dependent Claim
17 words
A method as claimed in Claim 5 including the step of constructing a rectangle around the head.
Claim 7
Independent Claim
133 words
A method as claimed in any preceding claim in which the segmenting steps comprise the steps of i) comparing motion vectors of two adjacent blocks of pixels, ii) assigning the blocks of pixels to the same area if the difference between their motion vectors is within a given threshold, iii) repeating steps i) and ii) for each block of pixels adjacent to a block of pixels within the area until all adjacent blocks of pixels have been examined and no further blocks of pixels are incorporated into the area, iv) selecting two further adjacent blocks which are not included within the area and repeating steps i) to iii) to create a further area of uniform motion, and v) repeating step iv) until all blocks within the picture frame are allocated to an area.
Claim 8
Dependent Claim
164 words
Apparatus for tracking an object in a scene represented as a sequence of picture frames captured by a camera for display on a display device, the apparatus comprising means for segmenting the image in an initial frame into areas having uniform motion, means for locating the object in the initial frame and finding its centroid and motion vector, means for projecting the centroid of the object onto the next frame using the motion vector to define a new position of the object centroid, means for segmenting the image in the next frame into a number of areas having uniform motion, means for finding those areas of the image similar to areas of the previous frame and having a centroid close to the projected centroid to produce a new object, means for calculating the size and motion vector of the new object, and means for projecting the new position of the object centroid onto the succeeding frame using the motion vector of the new object.
Claim 9
Dependent Claim
20 words
Apparatus as claimed in Claim 8 in which the segmenting means use the backward motion vectors of the pixel blocks.
Claim 10
Dependent Claim
22 words
Apparatus as claimed in Claim 8 or Claim 9 in which the projecting means uses the forward motion vector of the object.
Claim 11
Dependent Claim
36 words
Apparatus as claimed in any of Claims 8 to 10 in which similarity of areas is determined by taking into account the relative size, position, and magnitude and direction of motion of the areas being compared.
Claim 12
Dependent Claim
18 words
Apparatus as claimed in any of Claims 8 to 11 in which the object is a human head.
Claim 13
Dependent Claim
15 words
Apparatus as claimed in Claim 12 comprising means for constructing a rectangle around the head.
Claim 14
Dependent Claim
87 words
Apparatus as claimed in any of Claims 8 to 13 in which the segmenting means comprises means for comparing motion vectors of two adjacent blocks of pixels, means for assigning the blocks of pixels to the same area if the difference between their motion vectors is less than a given threshold, means for recursively considering all blocks of pixels adjacent to blocks of pixels within the same area until all adjacent blocks of pixels have been examined and no further blocks have been incorporated into the area.
Claim 15
Dependent Claim
88 words
A videophone terminal comprising a camera, a display unit and a codec wherein the codec is arranged to transmit picture information over a communication link of a given bandwidth and includes means for quantising different areas of each picture frame at a different resolution wherein object tracking apparatus as claimed in any of Claims 8 to 14 is arranged to control the codec such that the area of the picture frame containing the tracked object is transmitted at a higher resolution than the rest of the picture frame.
References Cited (Backward Citations)
No citation records indexed.
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