Method and apparatus for shot detection
AssigneeMicrosoft Corporation
InventorsWei Qi, Dong Zhang
Life of this patent
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Abstract
A system identifies an abrupt transition in content between two frames, and determines whether the abrupt transition was caused by a shot boundary between the two frames or by a flashlight event. Identification of the abrupt transition in content includes calculating a difference in light intensity histograms between the current frame and a preceding frame, and comparing the histogram difference to a dynamically determined threshold. Further, an average light intensity based method is used to determine whether the abrupt transition was caused by a shot boundary or by a flashlight event.
Claims27
A method comprising:
- identifying an abrupt transition in average light intensity between two frames;
- and
- determining whether the abrupt transition was caused by a shot boundary between the two frames or by a flashlight event, wherein determining a cause of the abrupt transition comprises:
- calculating a difference in average minimal intensity values between a window of frames preceding the current frame and a window of frames subsequent to the current frame;
- generating a ratio of the average intensity change of the current frame to the calculated difference in average minimal intensity values;
- and
- concluding that the abrupt transition is caused by a flashlight event if the ratio does not exceed a threshold.
A media analysis agent comprising:
- a shot boundary detector to statistically analyze one or more attributes associated with content in video frames to detect abrupt and gradual transitions in the video content indicative of a shot boundary;
- a flashlight detector, responsive to the shot boundary detector, to distinguish abrupt transitions in the video content caused by flashlight events from those caused by actual shot boundaries, to reduce false-positive identification of flashlight events as shot boundaries;
- and
- an adaptive threshold selection module, responsive to the shot boundary detector, to dynamically set one or more thresholds for use in shot boundary identification based, at least in part, on one or more attributes of video content, wherein the adaptive threshold selection module calculates an average and standard deviation of a histogram difference in sliding windows of frames proceeding and subsequent to a current frame, and generates a proposed low threshold value (Ts) and a proposed high-threshold value (Tb) from the average histogram difference.
A computer readable medium storing a plurality of executable instructions which, when executed, implement a media analysis agent to detect shot boundaries resulting from an abrupt or gradual transition in content between frames, and further to distinguish abrupt transitions caused by shot cuts from those caused by flashlight events, wherein the media analysis agent calculates a difference in average minimal intensity values between a first sliding window preceding the current frame, and a second sliding window subsequent to the current frame, and calculates the average intensity change of the current frame, and generates a ratio of the difference in average minimal intensity values to the average intensity change of the current frame.
One or more computer-readable media having stored thereon a computer program that, when executed by one or more processors, causes the one or more processors to:
- calculate a difference in light intensity histograms between two frames;
- compare the histogram difference to a dynamically determined threshold, wherein an abrupt transition is indicated if the histogram difference exceeds the threshold;
- and
- determine whether the abrupt transition was caused by a shot boundary between the two frames or by a flashlight event, wherein to determine a cause of the abrupt transition, the one or more processors:
- calculate a difference in average minimal intensity values between a window of frames preceding the current frame and a window of frames subsequent to the current frame;
- generate a ratio of the average intensity change of the current frame to the calculated difference in average minimal intensity values;
- and
- conclude that the abrupt transition is caused by a flashlight event if the ratio does not exceed a threshold.
An apparatus comprising:
- means for identifying an abrupt transition in average light intensity between two frames, wherein the means for identifying:
- calculates a difference in light intensity histograms between the current frame and a preceding frame;
- compares the histogram difference to a threshold value;
- and means for determining whether the abrupt transition was caused by a shot boundary between the two frames or by a flashlight event, wherein the means for determining:
- calculates a difference in average minimal intensity values between a window of frames preceding the current frame and a window of frames subsequent to the current frame;
- generates a ratio of the average intensity change of the current frame to the calculated difference in average minimal intensity values;
- and
- concludes that the abrupt transition is caused by a flashlight event if the ratio does not exceed the threshold value.
Dependencies are inferred from the claim text.