Selective tint correction circuits

Claim 2

In a communications system for the reception and transmission of signals having phase information representative of a first set of conditions and amplitude information representative of a second set of conditions, said signal further containing a reference signal of a frequency and phase necessary to demodulate said information contained therein, in combination therewith, apparatus for performing demodulation about a predetermined phase angle when said signals possess phase information in the vicinity of, but different from, said predetermined phase angle, comprising, a. means having one input responsive to said reference signal and a second input responsive to said signals to provide at an output Thereof a control signal when said signals have said phase in the vicinity of, but different from, said predetermined phase angle, b. gating means responsive to said signals and said control signal, to cause said signals to appear at an output thereof during the presence of said control signal, c. combining means responsive to said gated signals and said reference signals to vectorially add said gated signal to said reference signal to provide a new reference signal, d. demodulating means responsive to said new reference signal and said signals to provide at an output thereof demodulated signals having demodulated information derived at a phase angle substantially equal to said predetermined phase angle.

Claim 3

In a color television system for the reception or transmission of a color television signal including a color reference subcarrier signal containing frequency and phase information necessary to demodulate chrominance signals contained in said television signal and having a phase representing the hue, and an amplitude representing the saturation of colors present in a scene, said system including color demodulators responsive to said chrominance signals and a color reference signal to provide at outputs thereof color difference signals containing information proportional to the hue and saturation of said colors contained in said scene, in combination therewith, apparatus for performing hue control for such color signals having hues representative of flesh tones, comprising, a. first means having one input responsive to said color reference signal and a second input responsive to said chrominance signals to provide at an output thereof a control signal when said chrominance signals have a phase in the vicinity of, but different from, that representative of flesh tones, b. selectively operative means responsive to said chrominance signal and said control signal to permit chrominance signal to appear at an output thereof during the presence of said control signal, c. means responsive to said reference signal and coupled to said output of said selectively operative means to combine said permitted chrominance signal with said reference signal to provide a new reference signal which, when applied to one of said color demodulators, will cause said demodulators to provide color signals at said output predominantly representative of the hue associated with flesh tones.

Claim 4

In a color television system for the reception or transmission of a color television signal including a color reference subcarrier signal containing frequency and phase information necessary to demodulate chrominance signals contained in said television signal and having a phase representing the hue, and an amplitude representing the saturation of colors present in a scene, said system including color demodulators responsive to said chrominance signals and a color reference signal to provide at outputs thereof color difference signals containing information proportional to the hue and saturation of said colors contained in said scene, in combination therewith, apparatus for performing hue control for such color signals having hues representative of flesh tones, comprising, a. first means having one input responsive to said color reference signal and a second input responsive to said chrominance signals to provide at an output thereof a control signal when said chrominance signals have a phase in the vicinity of, but different from, that representative of flesh tones, b. selectively operative means responsive to said chrominance signal and said control signal to permit chrominance signal to appear at an output thereof during the presence of said control signal, c. means responsive to said reference signal and coupled to said output of said selectively operative means to combine said permitted chrominance signal with said reference signal to provide a new reference signal which, when applied to one of said color demodulators, will cause said demodulators to provide color signals at said output predominantly representative of the hue associated with flesh tones.

Claim 5

The apparatus according to claim 2 wherein said first means comprises: a. a phase detector circuit having one input responsive to said chrominance signals and a second input responsive to said color reference signal to provide a control signal at an output thereof when said chrominance signals have a phase in the vicinity of, but different from, that representative of flesh tones.

Claim 6

The apparatus according to claim 2 wherein said selectively operative means comprises: a. second means having first and second input terminals and an output terminal and adapted to conduct signal from said first terminal to said output terminal upon the application of said control signal to said second terminal, b. means coupling said second terminal to said first means for applying said control signal thereto, c. limiter means coupling said chrominance signals to said first terminal, for providing thereat an amplitude limited chrominance signal, d. third means coupling said output terminal of said second means to said color demodulator means for shifting the phase of said reference signal as applied to at least one of said demodulators during the presence of said control signal, and in accordance with said limited chrominance signal applied to said first terminal of said second means.

Claim 7

The apparatus according to claim 4 wherein said third means includes, a. a phase shifting network coupling said output terminal of said second means to said color demodulator means for providing a predetermined additional phase shift for said limited chrominance signal beforE application thereof to said color demodulator means.

Claim 8

In a color television receiver for the reception of a color television signal including a color reference subcarrier signal containing frequency and phase information necessary to demodulate chrominance signals contained in said television signal and having a phase representing the hue and an amplitude representing the saturation colors present in the transmitted scene in combination therewith, apparatus for performing dynamic hue control for such color signals having hues representative of flesh tones comprising, a. first means responsive to said chrominance signals to provide a control signal when said chrominance signals have a phase in the vicinity of, but different from, that representative of flesh tones, b. gating means responsive to said chrominance signals and said control signal to provide at an output thereof said chrominance signals only during the presence of said control signal, c. means coupled to said gating means and responsive to said color reference subcarrier signal to combine the gated chrominance signal with said color reference subcarrier signal to provide at an output thereof another color reference signal of different phase than that received, and d. demodulating means having a first input responsive to said another color reference signal and a second input responsive to said chrominance signals to provide at an output thereof a color signal containing information proportional to the hue and saturation of said colors transmitted in said scene and such information being displayed predominantly at flesh tone for the presence of said control signal.

Claim 9

In a color television receiver for the reception of a color television signal including a color reference subcarrier signal containing frequency and phase information necessary to demodulate chrominance signals contained in said television signal and having a phase representing the hue and an amplitude representing the saturation colors present in the transmitted scene in combination therewith, apparatus for performing dynamic hue control for such color signals having hues representative of flesh tones comprising, a. first means responsive to said chrominance signals to provide a control signal when said chrominance signals have a phase in the vicinity of, but different from, that representative of flesh tones, b. gating means responsive to said chrominance signals and said control signal to provide at an output thereof said chrominance signals only during the presence of said control signal, c. means coupled to said gating means and responsive to said color reference subcarrier signal to combine the gated chrominance signal with said color reference subcarrier signal to provide at an output thereof another color reference signal of different phase than that received, and d. demodulating means having a first input responsive to said another color reference signal and a second input responsive to said chrominance signals to provide at an output thereof a color signal containing information proportional to the hue and saturation of said colors transmitted in said scene and such information being displayed predominantly at flesh tone for the presence of said control signal.

Claim 10

In a color television receiver for the reception of a color television signal including a color reference subcarrier signal containing frequency and phase information necessary to demodulate chrominance signals contained in said television signal and having a phase representing the hue, and an amplitude representing the saturation of colors present in a transmitted scene, in combination therewith, apparatus for performing automatic hue control for such color signals having hues representative of flesh tones, comprising, a. color difference demodulators responsive to said chrominance signals and said color reference signal to provide at outputs thereof color difference signals containing information proportional to the hue and saturation of said colors contained in said transmitted scene, b. matrix means coupled to the outputs of said demodulators to provide a control signal when said control difference signals matrix about a predetermined phase axis in the vicinity of, but different from, that representative of flesh tones, c. means coupled to said matrix means and responsive to said control signal to shift the phase of said reference signal as applied to at least one of said demodulators in a direction to provide color difference signals at said outputs which matrix predominantly at the phase associated with flesh tones.

Claim 11

In a color television receiver for the reception of a color television signal including a color reference subcarrier signal containing frequency and phase information necessary to demodulate chrominance signals contained in said television signal and having a phase representing the hue, and an amplitude representing the saturation of colors present in a transmitted scene, in combination therewith, apparatus for performing automatic hue control for such color signals having hues representative of flesh tones, comprising, a. color difference demodulators responsive to said chrominance signals and said color reference signal to provide at outputs thereof color difference signals containing information proportional to the hue and saturation of said colors contained in said transmitted scene, b. matrix means coupled to the outputs of said demodulators to provide a control signal when said control difference signals matrix about a predetermined phase axis in the vicinity of, but different from, that representative of flesh tones, c. means coupled to said matrix means and responsive to said control signal to shift the phase of said reference signal as applied to at least one of said demodulators in a direction to provide color difference signals at said outputs which matrix predominantly at the phase associated with flesh tones.

Claim 12

In a color television system for the reception or transmission of a color television signal including a color reference subcarrier signal containing frequency and phase information necessary to demodulate chrominance signals contained in said television signal and having a phase representing the hue, and an amplitude representing the saturation of colors present in a scene, said system including color demodulators responsive to said chrominance signals and a color reference signal to provide at outputs thereof color difference signals containing information proportional to the hue and saturation of said colors contained in said scene, in combination therewith, apparatus for performing hue control for such color signals having hues representative of flesh tones, comprising, a. a limiter circuit having an input responsive to said chrominance signals to provide at an output terminal thereof amplitude limited chrominance signals, b. phase detecting means having one inpUt responsive to said color reference signal and a second input responsive to said amplitude limited chrominance signals to provide a variable control voltage at an output thereof when said chrominance signals have a phase in the vicinity of, but different from, that representative of flesh tones, c. first means having one input responsive to said control signal and a second input responsive to said limited chrominance signals to provide at an output thereof a variable amplitude chrominance signal having said amplitude proportional to the magnitude of said variable control signal, d. means coupled to said first means and responsive to said color reference signal for combining said chrominance signal with said reference signal to provide at an output another reference signal at a phase in accordance with the phase and amplitude of said variable amplitude chrominance signal, e. means for applying said another reference signal to at least one of said color demodulators to cause said demodulator to provide color signals at said output predominantly representative of the hue associated with flesh tones.

Claim 13

In a color television system for the reception or transmission of a color television signal including a color reference subcarrier signal containing frequency and phase information necessary to demodulate chrominance signals contained in said television signal and having a phase representing the hue, and an amplitude representing the saturation of colors present in a scene, said system including color demodulators responsive to said chrominance signals and a color reference signal to provide at outputs thereof color difference signals containing information proportional to the hue and saturation of said colors contained in said scene, in combination therewith, apparatus for performing hue control for such color signals having hues representative of flesh tones, comprising, a. a limiter circuit having an input responsive to said chrominance signals to provide at an output terminal thereof amplitude limited chrominance signals, b. phase detecting means having one inpUt responsive to said color reference signal and a second input responsive to said amplitude limited chrominance signals to provide a variable control voltage at an output thereof when said chrominance signals have a phase in the vicinity of, but different from, that representative of flesh tones, c. first means having one input responsive to said control signal and a second input responsive to said limited chrominance signals to provide at an output thereof a variable amplitude chrominance signal having said amplitude proportional to the magnitude of said variable control signal, d. means coupled to said first means and responsive to said color reference signal for combining said chrominance signal with said reference signal to provide at an output another reference signal at a phase in accordance with the phase and amplitude of said variable amplitude chrominance signal, e. means for applying said another reference signal to at least one of said color demodulators to cause said demodulator to provide color signals at said output predominantly representative of the hue associated with flesh tones.

Claim 14

The apparatus according to claim 8 wherein said first means is a modulator circuit comprising, a. first and second transistors each having a base, collector and emitter electrode, b. first and second degenerating resistors coupled in series between said emitter electrodes of said first and second transistors, c. means coupled to the junction between said first and second resistors for applying said limited chrominance signals thereto, d. means coupled to one of said base electrodes of said transistors for applying said control signal thereto, and e. means coupled to one of said collector electrodes for obtaining a chrominance signal therefrom having an amplitude proportional to the magnitude of said applied control signal.

Claim 15

The apparatus according to claim 8 wherein said limiter circuit includes at least one differential amplifier comprising, a. first and second transistors each having a base, collector and an emitter electrode and having their emitter electrodes coupled together, b. a constant current source coupling said emitter electrodes to a point of reference potential, c. means coupled to one of said collector electrodes for providing a load impedance thereat for chrominance signals, d. means coupled to said base electrodes for application thereto of said chrominance signals.

Claim 16

In a color television receiver for the reception of a color television signal including a color reference subcarrier signal containing frequency and phase information necessary to demodulate chrominance signals contained in said television signal and having a phase representing the hue, and an amplitude representing the saturation of colors present in a transmitted scene, in combination therewith, apparatus for performing dynamic hue control for such color signals having hues representative of flesh tones, comprising, a. limiter means responsive to said chrominance signals to provide at an output thereof an amplitude limited chrominance signal, b. first means responsive to said chrominance signals to provide a control signal when said chrominance signals have a phase in the vicinity of, but different from, that representative of flesh tones, c. gating means responsive to said limited chrominance signals and said control signal to provide at an output thereof said limited chrominance signals only during the presence of said control signal, d. means coupled to said gating means and responsive to said color reference subcarrier signal to add said gated chrominance signal to said color reference subcarrier signal to provide at an output thereof another color reference subcarrier signal of a different phase than that received, e. at least one color demodulator having a first input responsive to said another color reference signal and a second input responsive to said chrominance signals to provide At an output thereof a color signal containing information proportional to the hue and saturation of said colors transmitted in said scene and such information being displayed predominantly at flesh tone for the presence of said control signal.

Claim 17

In a color television receiver for the reception of a color television signal including a color reference subcarrier signal containing frequency and phase information necessary to demodulate chrominance signals contained in said television signal and having a phase representing the hue, and an amplitude representing the saturation of colors present in a transmitted scene, in combination therewith, apparatus for performing dynamic hue control for such color signals having hues representative of flesh tones, comprising, a. limiter means responsive to said chrominance signals to provide at an output thereof an amplitude limited chrominance signal, b. first means responsive to said chrominance signals to provide a control signal when said chrominance signals have a phase in the vicinity of, but different from, that representative of flesh tones, c. gating means responsive to said limited chrominance signals and said control signal to provide at an output thereof said limited chrominance signals only during the presence of said control signal, d. means coupled to said gating means and responsive to said color reference subcarrier signal to add said gated chrominance signal to said color reference subcarrier signal to provide at an output thereof another color reference subcarrier signal of a different phase than that received, e. at least one color demodulator having a first input responsive to said another color reference signal and a second input responsive to said chrominance signals to provide At an output thereof a color signal containing information proportional to the hue and saturation of said colors transmitted in said scene and such information being displayed predominantly at flesh tone for the presence of said control signal.