Color television encoding and decoding system

Claim 2

Apparatus for encoding color information from a scene onto a photosensitive surface comprising: a first grating in the optical path between the scene and the photosensitive surface having alternate stripes each transmitting a different color whose projections onto the photosensitive surface produce equal response for white light from the scene; and a second grating, in substantially the same plane as the first grating, having alternate stripes of a different spatial frequency than those of the first grating, each transmitting a different color whose projections onto the photosensitive surface produce equal response for white light from the scene where at least one of the stripes of the second grating has a color different from any of those of the first grating and the colors of the stripes of the first and second gratings are such that the heat frequency grating pattern formed by the optical product of the first and second gratings has a polarity independent of the color of the scene.

Claim 3

Apparatus as cited in claim 1 wherein the first grating has alternate stripes of two of the subtractive color primaries and the second grating has alternate stripes of two of the subtractive color primaries, where one of the subtractive color primaries of the second grating is common to one of those of the first grating, whereby the heat frequency grating pattern amplitude is modulated by the color absorbed by the subtractive color primary common to the first and second grating.

Claim 4

Apparatus as cited in claim 2 wherein the first grating has alternate stripes colored cyan and magenta and the second grating has alternate stripes colored yellow and magenta whereby the beat frequency grating pattern is amplitude modulated by the green light in the scene.

Claim 5

Apparatus as cited in claim 1 including an overall color filter in the optical path between the scene and the photosensitive surface whose color transmission characteristic provides that the projections of the alternate stripes of the first and second gratings will each have equal response for white light from the scene on the photosensitive surface.

Claim 6

Apparatus as cited in claim 1 wherein the stripes of the first grating are parallel to those of the second grating and the ratios of the spatial frequencies of each grating to that of the difference frequency between the two gratings are integers.

Claim 7

Apparatus as cited in claim 1 where the alternate stripes of at least one of the two gratings are dissimilar in width whereby a second harmonic component is generated.

Claim 8

Apparatus as cited in claim 1 wherein the first grating stripes and the second grating stripes make different angles with the vertical whereby the visibility of the beat frequency grating pattern is reduced.

Claim 9

Apparatus as cited in claim 7 wherein the beat frequency grating pattern is diagonal and, when scanned in a television system, provides a reversed polarity on alternate scan lines at each horizontal position.

Claim 10

Apparatus as cited in claim 8 wherein the first grating pattern is diagonal and when scanned in a television system, provides a reversed polarity on alternate scan lines at each horizontal position, and the second grating pattern is vertical.

Claim 11

Apparatus fOr decoding the color scene information encoded on a recording surface, where a first color difference component amplitude modulates a first grating, a second color difference component amplitude modulates a second grating, and a color component of constant polarity amplitude modulates the beat frequency grating formed by the first and second grating, comprising: means for scanning the recording surface whose output signal is a composite signal representative of the color scene information; a low-pass filter whose input is the composite signal and whose output is a luminance signal; a first filter means whose input is connected to the coomposite signal and whose output is a first modulated color difference signal; a first detector means whose input is connected to the first modulated color difference signal and whose output is the absolute value of the first color difference signal; switching means whose input is connected to the output of the first detector means and whose output provides either polarity of the absolute value of the first color difference signal in response to a first control signal; a second filter means whose input is connected to the composite signal and whose output is a second modulated color difference signal; a second detector means whose input is connected to the second modulated color difference signal and whose output is the absolute value of the second color difference signal; switching means whose input is connected to the output of the second detector means and whose output provides either polarity of the absolute value of the second color difference signal in response to a second control signal; third filter means whose input is connected to the composite signal and whose output provides one or more components of a modulated heat frequency signal whose amplitude is modulated by a constant polarity color signal; and means for utilizing components of the modulated heat frequency signal for generating the first and second control signals whereby the proper polarities of the first and second color difference signals will be provided.

Claim 12

Apparatus fOr decoding the color scene information encoded on a recording surface, where a first color difference component amplitude modulates a first grating, a second color difference component amplitude modulates a second grating, and a color component of constant polarity amplitude modulates the beat frequency grating formed by the first and second grating, comprising: means for scanning the recording surface whose output signal is a composite signal representative of the color scene information; a low-pass filter whose input is the composite signal and whose output is a luminance signal; a first filter means whose input is connected to the coomposite signal and whose output is a first modulated color difference signal; a first detector means whose input is connected to the first modulated color difference signal and whose output is the absolute value of the first color difference signal; switching means whose input is connected to the output of the first detector means and whose output provides either polarity of the absolute value of the first color difference signal in response to a first control signal; a second filter means whose input is connected to the composite signal and whose output is a second modulated color difference signal; a second detector means whose input is connected to the second modulated color difference signal and whose output is the absolute value of the second color difference signal; switching means whose input is connected to the output of the second detector means and whose output provides either polarity of the absolute value of the second color difference signal in response to a second control signal; third filter means whose input is connected to the composite signal and whose output provides one or more components of a modulated heat frequency signal whose amplitude is modulated by a constant polarity color signal; and means for utilizing components of the modulated heat frequency signal for generating the first and second control signals whereby the proper polarities of the first and second color difference signals will be provided.

Claim 13

Apparatus as cited in claim 10 wherein the means for utilizing the modulated heat frequency signal comprises: a first sampler whose sampled signal input is the first modulated color difference signal and whose sampling signal input is the modulated heat frequency signal; a first storage means whose input is connected to the output of the first sampler and whose output is the first control signal; a second sampler whose sampled signal input is the second modulated color difference signal and whose sampling signal input is the modulated heat frequency signal; and a second storage means whose input is connected to the output of the second sampler and whose output is the second control signal.

Claim 14

Apparatus as cited in claim 11 including shaping means whose input is the modulated heat frequency signal and whose output is a constant amplitude pulse sequence which is the sampling signal input to the first and second samplers.

Claim 15

Apparatus as cited in claim 10 including: detector means whose input is the modulated heat frequency signal and whose output is the constant polarity color signal; a first comparator having as inputs the constant polarity color signal and the absolute value of the first color difference signal; means for overriding the first control signal with a positive indicating control signal output from the first comparator when the amplitude of the absolute value of the first color difference signal exceeds that of the constant polarity color signal; a second comparator having as inputs the constant polarity color signal and the absolute value of the second color difference signal; and means for overriding the second control signal with a positive indicating control signal output from the second comparator when the amplitude of the absolute value of the second color difference signal exceeds that of the constAnt polarity signal.

Claim 16

Apparatus as cited in claim 10 wherein the third filter means includes: a first heat frequency filter for extracting a first heat frequency signal derived from the product of the fundamental components of the first and second gratings; and a second heat frequency filter for extracting a second heat frequency signal derived from the product of the second harmonic component of the first grating and the fundamental component of the second grating.

Claim 17

Apparatus as cited in claim 14 wherein the means for utilizing components of the beat frequency signal comprises: a first mixer having as inputs the first and second beat frequency signals of putting out a first reference signal whose frequency is the sum of the first and second beat frequency signal frequencies; a second mixer having as inputs the first reference signal and the first beat frequency signal for putting out a second reference signal whose frequency is the sum of the first reference signal frequency and the first beat frequency signal frequency; a first synchronous detector, whose inputs are the first modulated color difference signal and the first reference signal, whose output provides the first control signal; and a second synchronous detector, whose inputs are the second modulated color difference signal and the second reference signal, whose output provides the second control signal.

Claim 18

Apparatus as cited in claim 10 wherein the means for utilizing the modulated heat frequency signal includes: a detector whose input is the modulated heat frequency signal and whose output is the constant polarity color signal; and a subtractor to subtract the constant polarity color signal from the luminance signal whose output is the weighted sum of the first and second color difference signals.

Claim 19

Apparatus as cited in claim 16 including: a first adder for adding the positive absolute value of the first color difference signal to the positive absolute value of the second color difference signal; a second adder for adding the positive absolute value of the first color difference signal to the negative absolute value of the second color difference signal; a third adder for adding the negative absolute value of the first color difference signal to the positive absolute value of the second color difference signal; a fourth adder for adding the negative absolute value of the first color difference signal to the negative absolute value of the second color difference signal; multiple comparator means whose outputs are the subtractor output and the output of the first, second, third and fourth adders; means for generating a positive indicating first control signal and a positive indicating second control signal when the subtractor output substantially equals that of the first adder output; means for generating a positive indicating first control signal and a negative indicating second control signal when the subtractor output substantially equals that of the second adder output; means for generating a negative indicating first control signal and a positive indicating second control signal when the subtractor output substantially equals that of the third adder output; and means for generating a negative indicating first control signal and a negative indicating second control signal when the subtractor output substantially equals that of the fourth adder output.

Claim 20

Apparatus as cited in claim 17 including: a sampler whose sampled input is the first modulated color difference signal and whose sampling input is the modulated heat frequency signal; a storage means connected to the output of the sampler; and means for overriding the first control signal output of the multiple comparator with the stored output of the sampler when the second adder output and the third adder output substantially equals the subtractor output.

Claim 21

Apparatus as cited in claim 17 including: a mixer whosE inputs are components of the modulated heat frequency signal consisting of a first component derived from the product of the fundamental components of the two gratings and a second component deriving from the product of the second harmonic of the first grating and the fundamental of the second grating, and whose output is a reference signal whose frequency is the sum of the frequencies of the modulated heat frequency signal components; a synchronous detector whose inputs are the first modulated color difference signal and the reference signal; and means for overriding the first control signal output of the multiple comparator with the output of the synchronous detector when both the second adder output and the third adder output substantially equal the subtractor output.

Claim 22

Apparatus as recited in claim 16 including: a sampler whose sampled input is the first modulated color difference signal and whose sampling input is the modulated heat frequency signal; storage means connected to the output of the sampler whose stored output is the first control signal; a second subtractor for subtracting the first color difference signal from the output of the subtractor whose output is the second color difference signal; and means for utilizing the output of the second subtractor as the second control signal.

Claim 23

Apparatus as cited in claim 20 including: a comparator whose inputs are the constant polarity color signal and the absolute value of the first color difference signal; and means for overriding the stored sampler output with a positive industry first control signal when the comparator indicates that the amplitude of the absolute value of the first color difference signal exceeds that of the constant polarity color signal.

Claim 24

Apparatus as cited in claim 16 including: A mixer whose inputs are components of the modulated heat frequency signal consisting of a first component derived from the product of the fundamental componets of the two gratings and a second component derived from the product of the second harmonic of the first grating and the fundamental of the second grating, and whose output is a reference signal whose frequency is the sum of the frequencies of the modulated heat frequency signal components; a synchronous detector whose inputs are the first modulated color difference signal and the reference signal and whose output is the first control signal; a second subtractor which subtracts the first color difference signal from the output of the subtractor whose output is the second color difference signal; and mean for utilizing the output of the second subtractor as the second control signal.

Claim 25

Apparatus as cited in claim 22 including: a comparator whose inputs are the constant polarity signal and the absolute value of the first color difference signal; and means for overriding the synchronous detector output with a positive indicating control signal from the comparator output when the amplitude of the absolute value of the first color difference signal exceeds that of the constant polarity color signal.

Claim 26

Apparatus as cited in claim 10 wherein the third filter means has a bandwidth less than that of the first and second filter means.

Claim 27

Apparatus as recited in claim 10 including a delay line whose time delay is substantially the time of one scanning line wherein the composite signal is connected to the input of the delay line, and the input and output of the delay line are combined in a subtractor whose output is connected to the third filter means whereby the modulated heat signal is enhanced.

Claim 28

Apparatus as cited in claim 25 wherein the input and output of the delay line are further combined in a second subtractor whose output is connected to the first filter means whereby the first modulated color difference signal is enhanced.

Claim 29

Apparatus as recited in claim 25 wherein the input and output of the delay line are combined in an adder whose output is connected to the second filter means whereby the second modulated color difference signal is enhanced.

Claim 30

Apparatus as recited in claim 25 wherein the input and output of the delay line are combined in an adder whose output is connected to the low pass filter whereby the modulated heat frequency signal and the first color difference signal are attenuated in the luminance signal.

Claim 31

Apparatus as recited in claim 10 wherein the first color difference signal represents the difference between two primary colors, the second color difference signal represents the difference between two primary colors where one of the colors is common to one of the colors of the first color difference signal, and the constant polarity color signal represents the primary color common to the first and second color difference signals.

Claim 32

Apparatus recited in claim 29 wherein the first color difference signal represents R-G, the second color difference signal represents B-G and the constant polarity color signal represents G.

Claim 33

Apparatus as recited in claim 10 wherein the recording surface is the photocathode of a television camera tube and the means for scanning the recording surface is the scanned electron beam of the television camera tube.

Claim 34

Apparatus as recited in claim 10 wherein the recording surface is a reproduction of the encoded color scene information and the means for scanning the recording surface is a television camera imaged on the reproduction.

Claim 35

Apparatus as recited in claim 10 wherein the recording surface is a transparency and the means for scanning the recording surface is a flying spot scanner imaged on the transparency with a photocell used to collect the transmitted light.

Claim 36

Apparatus as recited in claim 10 including a matrix circuit whose inputs are the first and second color difference signals and whose outputs are the standard color television signals.

Claim 37

A color television camera having a lens and a photocathode comprising: a first grating in the optical path between the lens and the photocathode having alternate stripes each transmitting a different color and whose projections onto the photocathode produce equal response for white light; a second grating in substantially the same plane as the first grating, having alternate stripes of a different spatial frequency than those of the first grating, each transmitting a different color, whose projections onto the photocathode produce equal response for white light, where at least one of the stripes of the second grating has a color different from any of those of the first grating, and the colors of the stripes of the first and second gratings are such that the beat frequency grating pattern formed by the optical product of the first and second gratings has a fixed polarity; means for scanning the photocathode to produce a composite signal; a low pass filter whose input is connected to the composite signal and whose output is a luminance signal; a first filter means whose input is connected to the composite signal and whose output is a first modulated color difference signal; a first detector means whose input is the first modulated color difference signal and whose output is the absolute value of the first color difference signal; means for providing either polarity of the absolute value of the first color difference signal in response to a first control signal, a second filter means whose input is connected to the composite signal and whose output is a second modulated color difference signal; a second detector means whose input is the second modulated color difference signal and whose output is the absolute value of the second color difference signal; means for providing either polarity of the absolute value of the second color difference signal in response to a second control signal; third filter means whose input is the composite signal and whose output is one or more components of a modulated heat frequency signal; and means for utilIzing components of the modulated heat frequency signal for generating the first and second control signals whereby the proper polarities of the first and second color difference signals will be provided.

Claim 38

A color television camera having a lens and a photocathode comprising: a first grating in the optical path between the lens and the photocathode having alternate stripes each transmitting a different color and whose projections onto the photocathode produce equal response for white light; a second grating in substantially the same plane as the first grating, having alternate stripes of a different spatial frequency than those of the first grating, each transmitting a different color, whose projections onto the photocathode produce equal response for white light, where at least one of the stripes of the second grating has a color different from any of those of the first grating, and the colors of the stripes of the first and second gratings are such that the beat frequency grating pattern formed by the optical product of the first and second gratings has a fixed polarity; means for scanning the photocathode to produce a composite signal; a low pass filter whose input is connected to the composite signal and whose output is a luminance signal; a first filter means whose input is connected to the composite signal and whose output is a first modulated color difference signal; a first detector means whose input is the first modulated color difference signal and whose output is the absolute value of the first color difference signal; means for providing either polarity of the absolute value of the first color difference signal in response to a first control signal, a second filter means whose input is connected to the composite signal and whose output is a second modulated color difference signal; a second detector means whose input is the second modulated color difference signal and whose output is the absolute value of the second color difference signal; means for providing either polarity of the absolute value of the second color difference signal in response to a second control signal; third filter means whose input is the composite signal and whose output is one or more components of a modulated heat frequency signal; and means for utilIzing components of the modulated heat frequency signal for generating the first and second control signals whereby the proper polarities of the first and second color difference signals will be provided.