Method for tracking the disappearance of detected logos within digital video signals
First Claim
Patent Images
1. A method of detecting fade in an area of each of a sequence of frames comprising pixels that represent digital video images, comprising:
- calculating a stochastic measure σ
d of the area based on a standard deviation of pixel value differences in at least two frames among the sequence of frames; and
detecting the fade in said area by calculating a difference between the stochastic measure σ
d and a given noise level, such that if the difference 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
27 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:
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calculating a stochastic measure σ
d of the area based on a standard deviation of pixel value differences in at least two frames among the sequence of frames; anddetecting the fade in said area by calculating a difference between the stochastic measure σ
d and a given noise level, such that if the difference is greater than a threshold value then fade is detected. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 25, 27)
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9. A method of detecting fade of a logo in a sequence of digital video frames comprising pixels, comprising:
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(a) for each pixel in a logo area of a current frame; (i) determining a difference between a value of a current pixel and that of a corresponding pixel in a reference frame; (ii) subtracting a mean of a given noise from the said difference and squaring the obtained value; and (iii) generating a sum of the squared differences with the 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 with a level of the given noise characterized by a standard deviation, such that if a difference between the average and the noise standard deviation is greater than a threshold value then fade is detected. - View Dependent Claims (10, 11, 12, 13, 26)
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14. A fade detection system for detecting fade in a logo in each of a sequence of video frames, comprising:
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a detector for detecting the logo in one of the video frames; a logo map generator for generating a map including a pixel pattern corresponding to the video frame, wherein each pixel in the pixel pattern indicates whether the corresponding pixel in the video frame is in the logo; and a logo tracker that detects logo fade by; using the map to select pixels in the logo from the video frame to determine a difference between a value of the current pixel and a value of a corresponding pixel in a reference frame, subtracting a 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 with a given noise level, such that if a difference between the said average and the given noise level 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 one of the frames; a logo tracker that calculates a stochastic measure σ
d of said logo based on a standard deviation of differences in pixel values in at least two of said frames, and detects fade in said logo by comparing σ
d with a given noise level such that if the difference between σ
d and the given noise level is greater than a threshold value then fade is detected. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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Specification