Deemphasis & Subsequent reemphasis of high-energy reversed-spectrum components of a folded video signal
First Claim
1. Circuitry for generating a response to a video signal in which the level of higher-amplitude components of said video signal in an upper-frequency band thereof is increased relative to components of said video signal in a lower-frequency band thereof, said circuitry comprising:
- means for generating separated responses to the lower-frequency and upper-frequency bands of said video signal;
a coring circuit for generating a cored response to the separated response to the upper-frequency band of said video signal;
level-boosting means for boosting the level of said cored response by a scaling factor, thereby to generate a boosted cored response; and
means for additively combining said boosted cored response with the separated response to the lower-frequency band of said video signal, thereby to generate said response to said video signal with the level of higher-amplitude components of said video signal in said upper-frequency band thereof increased relative to components of said video signal in a lower-frequency band thereof.
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Abstract
A system for reproducing a luminance signal from a medium containing a previously recorded luminance signal with a high-frequency portion thereof compressed in dynamic range includes a circuit for recovering that luminance signal from the medium. Filtering is done to separate the low-frequency and compressed-in-dynamic-range high-frequency portions of the recovered luminance signal from each other. A corer responds to the separated compressed-in-dynamic-range high-frequency portion of the recovered luminance signal to provide a cored high-frequency portion with expanded dynamic range and reduced noise. The level of the cored high-frequency portion with expanded dynamic range and reduced noise is then boosted by a predetermined amount to compensate for energy losses during the compression of the dynamic range and added back to the low-frequency portion of the recovered luminance signal to reproduce a full-band luminance signal with at least partially restored dynamic range for high-frequencies and without readily visible high-frequency noise.
38 Citations
16 Claims
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1. Circuitry for generating a response to a video signal in which the level of higher-amplitude components of said video signal in an upper-frequency band thereof is increased relative to components of said video signal in a lower-frequency band thereof, said circuitry comprising:
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means for generating separated responses to the lower-frequency and upper-frequency bands of said video signal; a coring circuit for generating a cored response to the separated response to the upper-frequency band of said video signal; level-boosting means for boosting the level of said cored response by a scaling factor, thereby to generate a boosted cored response; and means for additively combining said boosted cored response with the separated response to the lower-frequency band of said video signal, thereby to generate said response to said video signal with the level of higher-amplitude components of said video signal in said upper-frequency band thereof increased relative to components of said video signal in a lower-frequency band thereof. - View Dependent Claims (2, 3, 4, 5, 6, 7, 12)
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8. Circuitry for generating a response to a video signal in which the level of higher-amplitude components of said video signal in an upper-frequency band thereof is increased relative to components of said video signal in a lower-frequency band thereof, said circuitry comprising:
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means for separating said upper-frequency band of said video signal; a coring circuit for coring the separated upper-frequency band of said video signal, thereby to generate a cored response thereto; and means for additively combining said cored response with said video signal, thereby to generate said response to said video signal with the level of higher-amplitude components of said video signal in said upper-frequency band thereof increased relative to components of said video signal in said lower-frequency band thereof. - View Dependent Claims (9, 10, 11)
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13. Circuitry for generating a response to a video signal in which the level of higher-amplitude components of said video signal in an upper-frequency band thereof is reduced relative to components of said video signal in a lower-frequency band thereof, said circuitry comprising:
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means for separating said lower-frequency and upper-frequency bands of said signal; means for rectifying the separated upper-frequency band of said video signal, thereby to generate a rectified upper-frequency response; means for baseline clipping said rectified upper-frequency response for generating a control signal; means for generating a multiplier signal having an amplitude that varies in response to said control signal, growing smaller with increase in said control signal and growing larger with decrease in said control signal; means for multiplying the separated upper-frequency band of said video signal by said multiplier signal, thereby to generate a product signal; and means for additively combining said product signal with the separated lower-frequency band of said video signal, thereby to generate said response to said video signal in which the level of higher-amplitude components of said video signal in an upper-frequency band thereof is reduced relative to components of said video signal in a lower-frequency band thereof. - View Dependent Claims (14, 15, 16)
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Specification