Automatic detection of fluorescent flicker in video images
First Claim
1. A method for detecting the presence of flicker in video images comprising:
- obtaining a set of luminance data from each sampled image field of the video images;
analyzing the set of luminance data to obtain a digital number characterizing a brightness characteristic of the set of luminance data;
compiling a time-series of digital numbers over multiple sets of luminance data of multiple sampled image fields;
performing a frequency analysis on the time-series of digital numbers to provide a first signal indicative of frequency components of the time-series of digital numbers in a flicker frequency band and a second signal indicative of the frequency components of the time-series of digital numbers in a non-flicker frequency band;
computing a first spectral energy signal and a second spectral energy signal based on the first signal and the second signal respectively;
computing a ratio of the first spectral energy signal to the second spectral energy signal, the ratio being a flicker detect indicator signal;
accumulating multiple flicker detect indicator signals from multiple time-series of digital numbers, the accumulated flicker detect indicator signals having values greater than a first threshold; and
generating a flicker present signal when the number of accumulated flicker detect indicator signals is greater than an entry value.
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Abstract
A method for detecting the presence of flicker in video images includes obtaining luminance data from sampled image fields and analyzing the luminance data to obtain a digital number characterizing the brightness of the luminance data. Frequency analysis is performed on a time-series of digital numbers collected over multiple sampled image fields to provide a signal indicative of the spectral energy at a flicker frequency band and a signal indicative of the spectral energy at a non-flicker frequency band. A ratio of the two spectral energy signals is computed as the flicker detect indicator. Multiple flicker detect indicators are accumulated to generate a flicker present signal. In one embodiment, the flicker detect indicator is accumulated only when the ratio has a value greater than a first threshold and the flicker present signal is asserted only when the number of flicker detect indicator signals accumulated exceeds an entry value.
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Citations
20 Claims
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1. A method for detecting the presence of flicker in video images comprising:
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obtaining a set of luminance data from each sampled image field of the video images; analyzing the set of luminance data to obtain a digital number characterizing a brightness characteristic of the set of luminance data; compiling a time-series of digital numbers over multiple sets of luminance data of multiple sampled image fields; performing a frequency analysis on the time-series of digital numbers to provide a first signal indicative of frequency components of the time-series of digital numbers in a flicker frequency band and a second signal indicative of the frequency components of the time-series of digital numbers in a non-flicker frequency band; computing a first spectral energy signal and a second spectral energy signal based on the first signal and the second signal respectively; computing a ratio of the first spectral energy signal to the second spectral energy signal, the ratio being a flicker detect indicator signal; accumulating multiple flicker detect indicator signals from multiple time-series of digital numbers, the accumulated flicker detect indicator signals having values greater than a first threshold; and generating a flicker present signal when the number of accumulated flicker detect indicator signals is greater than an entry value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification