EP0660327A2
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EP
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Method and apparatus for detecting abrupt and gradual scene changes in image sequences
Assignee: AT&T Inc
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Filing: 1994-12-01
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Granted: —
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Expires: 2014-12-01
Abstract
Abstract A method is capable of detecting both abrupt and gradual scene changes. Consecutive frames of an image sequence (e.g., a video program) are first acquired and digitized. The images are subdivided into a plurality of rectangular regions. Block matching is performed between the current frame and the Dth previous frame to determine match signals that represent the likelihood that the regions of the first frame contain visual information substantially similar to respective matching regions of the second frame. The match signals are ordered beginning with the match signals defining the best match and ending with the match signals defining the worst match. The first S match signals are selected and averaged together, to obtain an instantaneous match (IM) signal. S is user definable and is greater than zero and less than or equal to the number of regions into which each frame is divided. The IM signal provides a criteria for determining whether the first frame belongs to a scene different from the second frame. Finally, a scene change is indicated when the IM signal meets certain decision criteria.
Inventors
- 👤 Behzad Shahraray
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 04:29
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/68; G; G11; G11B; G11B27/00; G11B27/02; G11B27/031; G06; G06T; G06T7/00; G06T7/20; G06T7/223; G06T7/231; G11B27/10; G11B27/19; G11B27/28; H04N19/00; H04N19/10; H04N19/134; H04N19/142; H04N19/169; H04N19/179; H04N19/80; H04N19/85; H04N19/87; H04N5/00; H04N5/14; H04N5/144; H04N5/147; G06T2207/00; G06T2207/10; G06T2207/10016; G11B2220/00; G11B2220/60; G11B2220/65
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
168 words
A method of determining scene changes in a sequence of visual information-bearing frames, comprising the steps of: (a) dividing a first frame into a first plurality of regions and a second digitized frame into a second plurality of regions that respectively correspond in location to the first plurality of regions; (b) block-matching the regions to produce regional match signals that represent a likelihood that the regions of the first frame contain visual information substantially similar to respective matching regions of the second frame; (c) ordering the regional match signals beginning with the match signals defining a best match and ending with a match signal defining the worst match; (d) selecting and averaging together a predetermined number of the best regional match signals, to obtain an instantaneous match (IM) signal, said IM signal providing a criteria for determining whether the first frame represents a scene different from a scene represented by the second frame; and (e) indicating a scene change when the IM signal meets a predetermined decision criterion.
Claim 2
Dependent Claim
45 words
The method of claim 1 wherein said first and second frames define a first pair of frames and further comprising the step of: (f) repeating steps (a)-(d) a plurality of times for a sequentially chosen plurality of pairs of frames of a sequence of frames.
Claim 3
Dependent Claim
25 words
The method of claim 2 further comprising the step of temporally filtering a plurality of IM signals before the step of indicating a scene change.
Claim 4
Dependent Claim
23 words
The method of claim 3 in which the filtering step comprises the step of subtracting a constant noise value from the IM signal.
Claim 5
Dependent Claim
36 words
The method of claim 4 wherein the step of temporally filtering the IM signals comprises the step of temporally filtering the IM signals with an infinite-impulse-response digital filter having a variable gain and a range limiter.
Claim 6
Dependent Claim
28 words
The method of claim 3 further comprising the step of varying the gain during the step of temporally filtering the IM signals in response to a predefined condition.
Claim 7
Dependent Claim
21 words
The method of claim 6 wherein the predefined condition is a function of a regional match signal and a motion vector.
Claim 8
Dependent Claim
31 words
The method of claim 1, 3 or 7 wherein the regional match signal is a ratio of a minimum block matching error to an average value of the block matching error.
Claim 9
Independent Claim
239 words
A method of determining scene changes in a sequence of visual information-bearing frames, comprising the steps of: (a) digitising at least first and second frames of the sequence; (b) dividing the first frame into a first plurality of regions and the second frame into a second plurality of regions respectively corresponding in location and size to the first plurality of regions of the first frame; (c) block-matching by (i) determining values of a first match distance between a first region of the first plurality of regions and a plurality of regions of the same size as said first region within a portion of the second frame encompassing the corresponding region in the second frame; and (ii) finding a minimum value among said values, said minimum value corresponding to the location of a matching region of the second frame that is defined relative to the location of the corresponding region in the second frame, said matching region being a region of the second frame most likely to contain visual information substantially similar to the first region of the first frame; (d) calculating an average value of all the values of the match distance and normalizing the minimum value of the match distance by dividing said minimum value by said average value to obtain a normalized minimum value, said normalized minimum value representing the likelihood that the matching region contains information substantially similar to the first region of the first frame.
Claim 10
Dependent Claim
44 words
The method of claim 9 further comprising the step of: generating a motion vector from the minimum value, said motion vector equalling a distance defined by the location of the matching region relative to the location of the corresponding region of the second frame.
Claim 11
Dependent Claim
48 words
The method of claim 1 wherein the first frame is divided into K regions and further comprising the step of: (e) repeating steps (c) and (d) for each of said K regions to obtain K minimum values and K normalized minimum values respectively corresponding to the K regions.
Claim 12
Dependent Claim
89 words
The method of claim 11 further comprising the steps of: (f) ordering by magnitude the K normalized minimum values, beginning with the smallest normalized minimum value and ending with the largest normalized minimum value; (g) calculating an instantaneous match (IM) signal having a value determined by selecting and averaging together the first S of the K ordered normalized minimum values, where S <= K and is user definable, said IM signal providing a criteria for determining whether the first frame belongs to a scene different from the second frame.
Claim 13
Dependent Claim
95 words
The method of claim 12 wherein said first and second frames define a first pair of frames and further comprising the steps of: (h) repeating steps (a)-(g) a plurality of times for a sequentially chosen plurality of pairs of frames of the sequence in place of the first pair of frames to calculate a plurality of values of the IM signal such that said IM signal provides a criterion for determining whether a frame of one of the pairs of frames belongs to a scene different from the other frame of the pair of frames.
Claim 14
Dependent Claim
92 words
The method of claim 13 further comprising the step of: (i) preselecting an upper threshold value and a lower threshold value of the IM signal such that a change in the value of the IM signal to a value below the lower threshold value after having been above the upper threshold value at a previous time corresponds to a scene change at the point in the sequence between the pair of frames at which the IM signal changed from the value above the upper threshold value to below the lower threshold value.
Claim 15
Dependent Claim
17 words
The method of claim 9 wherein said first and second frames are consecutive frames in the sequence.
Claim 16
Dependent Claim
19 words
The method of claim 9 wherein said first and second frames are spaced apart a predetermined number of frames.
Claim 17
Dependent Claim
49 words
The method of claim 13 further comprising the step of temporally filtering said IM signal with a digital filter having a variable gain to generate a cumulative match signal, said cumulative match signal providing a criterion for determining whether a scene change has occurred over a plurality of frames.
References Cited (Backward Citations)
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