Dither-quantized signalling for color television
First Claim
Patent Images
1. A television transmitter includingmeans for resolving a colored input picture into plural component pictures;
- means for representing each component picture by a plurality of video signals, the amplitude of each signal varying substantially in proportion to component intensity in successive picture elements arranged in a predetermined scanning sequence;
means for combining one of said video signals with predetermined dither to obtain a first sum;
means for approximating with plural quantizing levels separate successive samples of the first sum;
means for combining another video signal with predetermined dither to obtain another sum;
means for approximating with two quantizing levels samples of said other sum; and
means for generating and transmitting quantized composite samples wherein the magnitude of a composite sample corresponds to an approximated sample of the first sum and its algebraic sign corresponds to an approximated sample of the other sum.
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Abstract
One or more of the video components of prior art are quantized coarsely before being sent to a receiver. To prevent perceptible loss of picture information and to minimize visible artifacts, suitable ordered dither is added before a component is quantized. The transmitted signal is preferably also sampled at the transmitter and resampled and requantized in the receiver for combatting noise and distortion. Some forms of the invention are compatible with prior art receivers. Other forms provide compressed digital signalling and coarsely quantized pulse-amplitude modulation.
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Citations
21 Claims
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1. A television transmitter including
means for resolving a colored input picture into plural component pictures; -
means for representing each component picture by a plurality of video signals, the amplitude of each signal varying substantially in proportion to component intensity in successive picture elements arranged in a predetermined scanning sequence; means for combining one of said video signals with predetermined dither to obtain a first sum; means for approximating with plural quantizing levels separate successive samples of the first sum; means for combining another video signal with predetermined dither to obtain another sum; means for approximating with two quantizing levels samples of said other sum; and means for generating and transmitting quantized composite samples wherein the magnitude of a composite sample corresponds to an approximated sample of the first sum and its algebraic sign corresponds to an approximated sample of the other sum. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Means for transmitting plural component signals of color television by discrete pulses including
means for sampling a first component signal to obtain a series of primary pulses having like polarity relative to a reference; -
means for sampling a second component signal to obtain a series of secondary pulses, some positive and some negative relative to a reference; means for pairing the secondary pulses with at least some of the primary pulses; means for generating an output pulse corresponding to each pair, the output pulse magnitude corresponding to that of the primary pulse and the polarity having one algebraic sign when the secondary pulse is positive and the opposite sign when said secondary pulse is negative; whereby, in the series of output pulses, successive polarities represent the second component signal quantized with only two amplitude levels and successive magnitudes represent the first component signal. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. Means for recovering separately a luminance signal and two chrominance signals from a series of positive and negative pulses characterized by successive magnitudes representing said luminance signal, by successive polarities in one interleaved fraction of pulses representing one chrominance signal, and by successive polarities in another interleaved fraction representing the second chrominance signal;
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rectifier means removing chrominance effects from the luminance component represented by pulse magnitudes; two-level quantization means removing luminance effects from the interleaved chrominance signals represented by pulse polarities; and demultiplexing means separating the interleaved quantized chrominance signals from each other. - View Dependent Claims (15)
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16. An improved recording and playback system for color television including
means for representing the television signal by plural signal components including a luminance component and at least one chrominance component; -
means for modifying at least the luminance component by adding ordered dither; means for pulse-amplitude modulating the sum of said luminance component and said dither and for restricting the pulse amplitudes to plural discrete levels whereby said pulses are quantized; means for representing a chrominance component, including any dither modification thereof, by quantized samples restricted to two values of amplitude; means for combining quantized pulses representing luminance with quantized samples representing chrominance in composite pulses wherein the magnitude of a composite pulse represents a luminance sample and the algebraic sign represents a chrominance sample; means for recording said composite pulses and for playing back the represented signal components; means for requantizing samples of the played-back luminance component to reduce possibly accumulated noise and distortion; and means for displaying the color television picture corresponding to the played-back signal components, including the requantized luminance component. - View Dependent Claims (17)
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18. A recording system for color television comprising
means for representing a color television signal by plural components, including a luminance component and a chrominance component; -
means for modifying at least the luminance component by adding ordered dither; means for representing the modified luminance component by quantized samples restricted to several discrete amplitudes; means for representing a chrominance component, including any modifications due to dither, by quantized samples restricted to two values of amplitude; means for producing a composite signal corresponding to positive and negative pulses wherein the magnitude of a pulse corresponds to a quantized luminance sample and the algebraic sign corresponds to a quantized chrominance sample; and means for storing said composite signal on a medium to produce a record.
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19. An improved record having stored thereon a composite signal comprising luminance and chrominance signals sufficient for playback of color television;
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wherein the improvement consists of storing a luminance signal restricted to several discrete amplitude levels and a chrominance signal restricted to two amplitude levels, at least one of said signals including ordered dither; the stored signal corresponding to a series of positive and negative pulses wherein the magnitude of a pulse represents a luminance sample quantized with several possible amplitudes and the algebraic sign represents a chrominance sample quantized with two possible amplitudes. - View Dependent Claims (20)
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21. A receiver for plural video signals transmitted as a sequence of composite samples restricted to specific levels of amplitude;
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means for generating a sequence of binary samples corresponding to algebraic sign in a sequence of said composite samples; means for generating a sequence of other samples restricted to a plurality of specific values corresponding to quantized absolute magnitudes in a sequence of said composite samples; and means for displaying a color television picture including a picture component corresponding to said binary samples and a picture component corresponding to said other samples.
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Specification