Method for tracking the disappearance of detected logos within digital video signals
First Claim
1. A method of detecting fade in an area of each of a sequence of frames comprising pixels that represent digital video images, comprising the steps of:
- calculating a stochastic measure σ
d of said area based on the standard deviation of differences in pixel values in at least two of said frames; and
detecting fade in said area by comparing the stochastic measure σ
d with a given noise level, such that if the difference between σ
d and noise level is greater than a threshold value then fade is detected.
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Abstract
A method and system for sensing disappearance of the previously detected logos in noisy digital video signals. When a video program starts, a short period of time is allowed to initially detect the existence and the location of the logo within the incoming video frames. Once the logo is detected and a logo map is generated, logo tracking senses whether the logo remains in, or disappears from, the video frames. If the logo moves or (partially) changes its intensity, color, pattern, etc., it will be sensed as having disappeared altogether.
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Citations
24 Claims
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1. A method of detecting fade in an area of each of a sequence of frames comprising pixels that represent digital video images, comprising the steps of:
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calculating a stochastic measure σ
d of said area based on the standard deviation of differences in pixel values in at least two of said frames; and
detecting fade in said area by comparing the stochastic measure σ
d with a given noise level, such that if the difference between σ
d and noise level is greater than a threshold value then fade is detected. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of detecting fade of a logo in a sequence of frames comprising pixels that represent digital video images, comprising the steps of:
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(a) for each logo pixel in the current frame;
(i) determining the difference between the value of the current pixel and that of a corresponding pixel in a reference frame;
(ii) subtracting the given noise mean from the said difference and squaring the obtained value; and
(iii) generating a sum of the squared differences with noise mean subtracted for each of a plurality of pixels within the logo area;
(b) generating an average of the sums;
(c) comparing said average to a given noise level represented by STD, such that if the difference between the average and the noise STD is greater than the threshold value then fade is detected. - View Dependent Claims (10, 11, 12, 13)
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14. A fade detection system for detecting fade in a logo in each of a sequence of frames, comprising:
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a detector for detecting the logo in a video frame;
a logo map generator generating a map including a pixel pattern corresponding to the video frame, wherein each pixel in the pattern indicates whether the corresponding pixel in the video frame is in the logo;
a logo tracker that detects logo fade by;
using the map to select pixels of the video frame that are in the logo to, determine the difference between the value of the current pixel and that of a corresponding pixel in a reference frame, subtracting the given noise mean from the said difference and squaring the obtained value, and generate a sum of the squared values for each of a plurality of pixels within the logo area;
generating an average of the sums; and
comparing said average to a given noise level, such that if the difference between the said average and the noise level (STD) is greater than the threshold value then fade is detected. - View Dependent Claims (15, 16)
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17. A fade detection system for detecting fade in a logo in each of a sequence of frames, comprising:
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a detector for detecting the logo in a video signal;
a logo tracker that calculates a stochastic measure σ
d of said logo based on the standard deviation of differences in pixel values in at least two of said frames, and detects fade in said logo by comparing the measure σ
d with a given noise level (STD), such that if the difference between σ
d and the noise level (STD) is greater than the threshold value then fade is detected. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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Specification