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Patent

Hue correction system

TLDR
In this paper, a pair of color demodulators demodulate along wide angle axes of reduced included angle in the flesh tone region, and a third demodulator generates a proportional correction signal which is subtracted from a demodulated B-Y color difference signal to correct for errors in the green and cyan regions caused by wide angle demodulation.
Abstract
In the chroma channel of a color television receiver, a pair of color demodulators demodulate along wide angle axes of reduced included angle in the flesh tone region. A third demodulator, in response to the presence of green and cyan hues in a chroma signal, generates a proportional correction signal which is subtracted from a demodulated B-Y color difference signal to correct for errors in the green and cyan regions caused by wide angle demodulation.

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Citations
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Patent

Color signal enhancing cirucit for improving the resolution of picture signals

TL;DR: In this paper, a color-signal enhancing circuit consisting of a pair of high-pass filters, a control circuit, and a combination of first and second gain controllers is described.
Patent

Automatic hue corrector apparatus and method with a capability to correct wide angle demodulator hue signal distortion created in response to predominantly green hue environments

TL;DR: In this paper, color distortion created in non-standard decoding matrices is corrected by sensing potential differences between hue representative signals and applying correction potentials representative of these potential differences to color representative signals experiencing the greatest distortion.
Patent

Gated automatic tint control circuit

TL;DR: In this article, a gated automatic tint control circuit is used to enhance the flesh tones of reproduced images in a color television receiver using a chrominance signal source and a phase shift network coupled to a reference oscillator signal source.
Patent

I-phase fleshtone correction system using R-Y, G-Y and B-Y color difference signal demodulators

TL;DR: In this article, a locally regenerated chrominance subcarrier signal is phase shifted to produce R-Y, G-Y and B-Y phase subcarriers, which are applied to respective color difference signal demodulators.
Patent

Hue adjustment circuit

TL;DR: In this article, a hue adjustment circuit for adjustment of a color difference signal by addition, subtraction, and multiplication of hue correction components (sin alpha, cos alpha) generated from a sub-carrier signal and an R-Y, B-Y signal is presented.
References
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Patent

Method and apparatus for modifying electrical signals

J Slusarski
TL;DR: A correction circuit for providing natural looking flesh color in a color television apparatus which uses plural color outputs such as RY, B-Y, and G-Y to constitute the color signal is described in this article.
Patent

Color modification apparatus for a color television system

TL;DR: An apparatus for modifying the displayed appearance of preselected colors presented on a color television screen without changing the appearance of other colors in the same picture is described in this article. But it is not shown in this paper.
Patent

Color shifting circuit for a color television display apparatus

TL;DR: In this article, a color shifting circuit for a color television circuit was proposed, in which a carrier is quadrature modulated with the aid of color difference signals whereafter the phase modulation thus obtained is deepened with the assistance of a phase multiplier circuit while means are present for substantially maintaining the amplitude modulation obtained and in which the obtained signal of the deepened phase modulation is demodulated along a number of demodulation axes so as to obtain new color difference signal signals.
Patent

Color emphasis circuit for tv receivers

Mctaggart J
TL;DR: In this paper, the color signal is applied through a diode to the base of a transistor having a threshold between the peak voltage appearing at the base with no color signal present and the peak voltages appearing in the presence of a color signal in phase with the reference signal, which is then added back to the original color signal to provide the enhanced color signal.