Piecewise linear digital signal processor as for digital video vertical detail processing
First Claim
1. Apparatus for processing a digital video signal, comprising:
- means for applying a digital signal capable of exhibiting positive and negative values;
means responsive to said digital signals for producing a signal corresponding to the absolute value of said digital signal;
a source of reference value, XR1 ;
means responsive to the absolute value of said digital signal and said reference value XR1 for producing a signal corresponding to the difference values therebetween;
a polarity discriminator responsive to said difference values for passing difference values of one polarity only;
a polarity inverting circuit having an input port and an output port and being responsive to the polarity of digital signal samples occurring at the means for applying digital signal, for selectively inverting the polarity of signal samples applied to its input; and
means for coupling said polarity discriminator to the input port of said polarity inverting circuit, wherein the output signal from the polarity inverting circuit is a symmetrically processed signal functionally dependent upon the reference value XR1.
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Abstract
In processing comb filtered video signals it is desirable to separate lower frequency vertical detail signal from comb filtered chrominance and recombine it with the comb filtered luminance signal. System response is enhanced if the vertical detail is non-linear processed before it is recombined with luminance. To core, peak and pare digital vertical detail signal, the signal is passed through an absolute value circuit and then applied to a first signal combiner wherein a first reference value is subtracted from the magnitudes of the input signals. The differences are applied to a polarity discriminator which passes difference values of only one polarity. The one polarity differences are scaled and applied to one input port of a signal combining circuit. The one polarity differences are also applied to a third signal combining circuit wherein a second reference value is subtracted from the one polarity differences to produce a double difference value. The double difference value is applied to a second polarity discriminator which couples one polarity double difference values to a second input port of the second signal combining circuit, the output of which exhibits a piecewise linear, non-linear transfer characteristic.
14 Citations
18 Claims
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1. Apparatus for processing a digital video signal, comprising:
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means for applying a digital signal capable of exhibiting positive and negative values; means responsive to said digital signals for producing a signal corresponding to the absolute value of said digital signal; a source of reference value, XR1 ; means responsive to the absolute value of said digital signal and said reference value XR1 for producing a signal corresponding to the difference values therebetween; a polarity discriminator responsive to said difference values for passing difference values of one polarity only; a polarity inverting circuit having an input port and an output port and being responsive to the polarity of digital signal samples occurring at the means for applying digital signal, for selectively inverting the polarity of signal samples applied to its input; and means for coupling said polarity discriminator to the input port of said polarity inverting circuit, wherein the output signal from the polarity inverting circuit is a symmetrically processed signal functionally dependent upon the reference value XR1. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Apparatus for processing a digital video signal comprising:
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means for applying a digital video signal; means for applying first and second reference values; means responsive to said digital video signal for producing a signal corresponding to the absolute values of the magnitude thereof; first and second threshold/polarity discriminator means having respective reference signal input ports, respective signal input ports and respective output ports, said means each providing output signals of one polarity only and only for applied input signals that exceed respective applied reference signal values; respective means for coupling the signal input port and the reference signal input port of the first threshold/polarity discriminator means to the absolute value means and the means for applying said first reference value respectively; respective means for coupling the signal input port and the reference signal input port of the second threshold/polarity discriminator means to the output port of the first threshold/polarity discriminator and the means for applying said second reference value respectively; signal scaling means having signal input and output ports, said signal scaling means having its input port coupled to the output port of the second threshold/polarity discriminator means; signal combining means (46) having first and second input ports coupled respectively to the output port of said signal scaling means and the output port of the first threshold/polarity discriminator means, and having an output terminal at which processed digital signal is available. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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18. Apparatus for processing a digital video signal which exhibits positive and negative values, comprising:
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an input bus for applying said digital video signal; a source of a reference value, XR1 ; means coupled to said input bus and said source for passing a single polarity signal corresponding to differences between the magnitude of said digital video signal and said reference value; a polarity inverting circuit having an input port and an output port and responsive to the polarity of digital video signal samples occurring at said input bus, for selectively inverting the polarity of signal samples applied to its input port; and means for coupling the input port of the polarity inverting circuit to said means for passing a single polarity signal, wherein output signal from the polarity inverting circuit is symmetrically processed relative to signal polarity, and is functionally dependent upon the reference value XR1.
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Specification