Image quality correcting system for use with an imaging apparatus

Claim 2

An imaging apparatus which develops a corrected luminance signal and color difference signals of an image subject comprising: optical lens means for receiving image light emitted from said image subject in order to provide received image light; color filter means, coupled to said optical lens means, for filtering said received image light; photo-electric conversion means, coupled to said color filter means, for converting the filtered image light into electrical image signals; pre-amplifier means, coupled to said photo-electric conversion means, for amplifying said electrical image signals; color separator means, coupled to said pre-amplifier means, for separating said amplified electrical image signals into red, green and blue color signals; white balance adjustment means, coupled to said color separator means, for adjusting the amplitude levels of said red, green and blue color signals; matrix circuit means, coupled to said white balance adjustment means, for converting said amplitude adjusted red, green and blue color signals into a luminance signal and color difference signals; luminance signal correction means, coupled to said matrix circuit means, for outputting a corrected luminance signal in accordance with an input-output non-linear amplification factor in response to an input luminance signal intermediate a minimum and maximum luminance level, corresponding to a darkest and lightest luminance state, respectively, and for outputting said minimum and maximum luminance levels in response to an input luminance signal corresponding to said darkest and lightest state, respectively, in order to extend and emphasize an intermediate input luminance signal; and color difference correcting means, having fixed amplification factors, coupled to said matrix circuit means, for outputting corrected color difference signals that are subject to signal extension.

Claim 3

The imaging apparatus of claim 1, wherein said luminance signal correction means comprises: attenuating means, coupled to said matrix circuit means, for attenuating the amplitude of an input luminance signal by a predetermined factor in order to output an attenuated luminance signal; non-linear amplifying means, coupled to said attenuating means, for amplifying said attenuated luminance signal by a preset amplification factor to provide a non-linearly amplified luminance signal; inverter means, coupled to said non-linear amplifying means, for inverting said non-linearly amplified luminance signal; first adder means, coupled to said matrix circuit and said inverter means, for adding said input luminance signal and said inverted non-linearly amplified luminance signal to provide a first added output; and second adder means, coupled to said circuit means and said first adder means, for adding said input luminance signal and said first added output, to provide said corrected luminance signal as an output.

Claim 4

The imaging apparatus of claim 2, wherein said attenuating means attenuates said input luminance signal by a predetermined factor 1/k 1 and said non-linear amplifying means amplifies an attenuated luminance signal corresponding to an input luminance signal of said minimum and maximum luminance levels by a factor of k 1 and an intermediate input luminance signal by a factor less than k 1 .

Claim 5

A luminance signal correcting circuit for developing a corrected luminance signal extended and emphasized in an intermediate portion between a preset minimum luminance level and a preset maximum luminance level, corresponding to a darkest and lightest luminance state respectively, of an input-output non-linear amplification characteristic comprising: attenuating means for attenuating the amplitude of an input luminance signal by a predetermined factor to output an attenuated luminance signal; non-linear amplifying means, coupled to said attenuating means, for amplifying said attenuated luminance signal according to a predetermined amplification factor to output a non-linear amplified luminance signal; inverter means, coupled to said non-linear amplifying means, for inverting said non-linear amplified luminance signal to output an inverted luminance signal; first adder means, coupled to said inverter means, for adding said input luminance signal and said inverted luminance signal to output a first added signal; and second adder means, coupled to said first adder means, for adding said input luminance signal and said first added signal to output said corrected luminance signal.

Claim 6

A luminance signal correcting circuit for developing a corrected luminance signal extended and emphasized in an intermediate portion between a preset minimum luminance level and a preset maximum luminance level, corresponding to a darkest and lightest luminance state respectively, of an input-output non-linear amplification characteristic comprising: attenuating means for attenuating the amplitude of an input luminance signal by a predetermined factor to output an attenuated luminance signal; non-linear amplifying means, coupled to said attenuating means, for amplifying said attenuated luminance signal according to a predetermined amplification factor to output a non-linear amplified luminance signal; inverter means, coupled to said non-linear amplifying means, for inverting said non-linear amplified luminance signal to output an inverted luminance signal; first adder means, coupled to said inverter means, for adding said input luminance signal and said inverted luminance signal to output a first added signal; and second adder means, coupled to said first adder means, for adding said input luminance signal and said first added signal to output said corrected luminance signal.

Claim 7

The luminance signal correcting circuit of claim 4, wherein said attenuating means attenuates said luminance signal by a predetermined factor 1/k 1 and said non-linear amplifying means amplifies an attenuated luminance signal corresponding to an input luminance signal of said preset minimum and preset maximum luminance levels by a factor of k 1 and an input luminance signal intermediate said preset minimum and preset maximum luminance levels by a factor less than k 1 .

Claim 8

A luminance signal correcting circuit for developing a corrected luminance signal extended and emphasized in an intermediate portion between a preset minimum luminance level and a preset maximum luminance level, corresponding to a darkest and lightest luminance state respectively, of an input-output non-linear amplification characteristic which includes a kinking point intermediate said preset minimum and maximum luminance levels below which said amplification characteristic has a primary gain and above which said amplification characteristic has a secondary gain different from said primary gain, said luminance signal correcting circuit comprising: corrector means, coupled to an input luminance signal, for changing the kinking point of said amplification characteristic in accordance with a first control signal to provide an amplification corrected luminance signal; level shifting means, coupled to said corrector means, for changing a dc bias point of said amplification characteristic in accordance with a second control signal to provide a shifted luminance signal; and high-level selecting means, coupled to said level shifting means, for comparing said input luminance signal and said shifted luminance signal and for outputting the signal of higher level as said corrected luminance signal.

Claim 9

A luminance signal correcting circuit for developing a corrected luminance signal extended and emphasized in an intermediate portion between a preset minimum luminance level and a preset maximum luminance level, corresponding to a darkest and lightest luminance state respectively, of an input-output non-linear amplification characteristic which includes a kinking point intermediate said preset minimum and maximum luminance levels below which said amplification characteristic has a primary gain and above which said amplification characteristic has a secondary gain different from said primary gain, said luminance signal correcting circuit comprising: corrector means, coupled to an input luminance signal, for changing the kinking point of said amplification characteristic in accordance with a first control signal to provide an amplification corrected luminance signal; level shifting means, coupled to said corrector means, for changing a dc bias point of said amplification characteristic in accordance with a second control signal to provide a shifted luminance signal; and high-level selecting means, coupled to said level shifting means, for comparing said input luminance signal and said shifted luminance signal and for outputting the signal of higher level as said corrected luminance signal.

Claim 10

The luminance signal correcting circuit of claim 6 wherein said amplification characteristic includes plural kinking points and gains.

Claim 13

The imaging method of claim 8, wherein said predetermined attenuation factor of said attenuating step is 1/k 1 and wherein an attenuated luminance signal corresponding to an input luminance signal of said preset minimum and maximum luminance levels is amplified by a predetermined amplification factor of k 1 in said amplifying step and an attenuated luminance signal corresponding to an input luminance signal intermediate said preset minimum and maximum luminance levels is amplified by a factor less than k 1 .

Claim 14

An imaging method for providing a corrected luminance signal extended and emphasized in an intermediate portion between a preset minimum luminance level and a preset maximum luminance level, corresponding to a darkest and lightest luminance state respectively, of an input-output non-linear amplification characteristic which includes a kinking point intermediate said preset minimum and maximum luminance levels below which said amplification characteristic has a primary gain and above which said amplification characteristic has a secondary gain different from said primary gain, said imaging method comprising the steps of: changing the kinking point of said amplification characteristic in accordance with a first control signal and amplifying said input luminance signal accordingly to provide an amplification corrected luminance signal; level shifting said amplification corrected luminance signal to change a dc bias point of said amplification characteristic in accordance with a second control signal to provide a shifted luminance signal; comparing said input luminance signal and said shifted luminance signal in order to select the signal of higher level; and outputting said signal of higher level as said corrected luminance signal.

Claim 15

An imaging method for providing a corrected luminance signal extended and emphasized in an intermediate portion between a preset minimum luminance level and a preset maximum luminance level, corresponding to a darkest and lightest luminance state respectively, of an input-output non-linear amplification characteristic which includes a kinking point intermediate said preset minimum and maximum luminance levels below which said amplification characteristic has a primary gain and above which said amplification characteristic has a secondary gain different from said primary gain, said imaging method comprising the steps of: changing the kinking point of said amplification characteristic in accordance with a first control signal and amplifying said input luminance signal accordingly to provide an amplification corrected luminance signal; level shifting said amplification corrected luminance signal to change a dc bias point of said amplification characteristic in accordance with a second control signal to provide a shifted luminance signal; comparing said input luminance signal and said shifted luminance signal in order to select the signal of higher level; and outputting said signal of higher level as said corrected luminance signal.

Claim 16

The imaging method of claim 10, wherein said amplification characteristic has plural kinking points and gains.

Claim 17

An image quality correcting system for use with an imaging apparatus which includes a matrix circuit for forming a luminance signal and color difference signals from color signals generated in an imaging device, comprising: luminance signal correcting means for producing with the same linear input-output characteristic an output in response to a luminance signal input for a preset minimum luminance and another output in response to a luminance signal input for a preset maximum luminance and for producing an output in response to a luminance signal input within limits of said preset minimum and maximum luminance levels in accordance with an appropriate nonlinear input-output characteristic having a greater amplification factor than said linear input-output characteristic; and color difference correcting means for amplifying said color difference signals by an appropriate amplification factor, at least a new luminance signal being generated for the luminance signal formed in the matrix circuit, said new luminance signal being nonlinearly extended with the limits of said preset minimum and maximum luminance levels, and new color difference signals being generated by amplification with said appropriate amplification factor.

Claim 18

An image quality correcting system for use with an imaging apparatus which includes a matrix circuit for forming a luminance signal and color difference signals from color signals generated in an imaging device, comprising: luminance signal correcting means for producing with the same linear input-output characteristic an output in response to a luminance signal input for a preset minimum luminance and another output in response to a luminance signal input for a preset maximum luminance and for producing an output in response to a luminance signal input within limits of said preset minimum and maximum luminance levels in accordance with an appropriate nonlinear input-output characteristic having a greater amplification factor than said linear input-output characteristic; and color difference correcting means for amplifying said color difference signals by an appropriate amplification factor, at least a new luminance signal being generated for the luminance signal formed in the matrix circuit, said new luminance signal being nonlinearly extended with the limits of said preset minimum and maximum luminance levels, and new color difference signals being generated by amplification with said appropriate amplification factor.

Claim 19

The image quality correcting system according to claim 12, wherein said appropriate amplification factor of said color difference correcting means is varied in accordance with said nonlinear input-output characteristic.

Claim 22

An image quality correcting system for use with an imaging apparatus comprising: matrix means for forming a luminance signal from color signals obtained by an imaging device; and luminance signal correcting means for producing with the same linear input-output characteristic an output in response to an input luminance signal for a preset minimum luminance and another output in response to an input luminance signal for a preset maximum luminance and for producing an output in response to an input luminance signal within limits of said preset minimum and maximum luminance levels in accordance with an appropriate nonlinear input-output characteristic having a greater amplification factor than said linear input-output characteristic, thereby extending a luminance signal within the limits of said preset minimum and maximum luminance levels, said luminance signal formed in said matrix circuit being supplied to said luminance signal correcting means as said input luminance signal to generate a nonlinearly amplified luminance signal, said luminance signal correcting means comprising first means, coupled to said matrix means, for amplifying and inverting said input luminance signal to generate a first output signal in which amplitude levels of minimum and maximum levels are equal to said preset minimum and maximum levels and wherein amplitude levels therebetween are non-linearly amplified, first adder means, coupled to said matrix means and said first means, for adding said input luminance signal to said first output signal to generate a first added signal, and second adder means, coupled to said matrix means and said first adder means, for adding said input luminance signal to said first added signal to generate said non-linearly amplified luminance signal.

Claim 23

An image quality correcting system for use with an imaging apparatus comprising: matrix means for forming a luminance signal from color signals obtained by an imaging device; and luminance signal correcting means for producing with the same linear input-output characteristic an output in response to an input luminance signal for a preset minimum luminance and another output in response to an input luminance signal for a preset maximum luminance and for producing an output in response to an input luminance signal within limits of said preset minimum and maximum luminance levels in accordance with an appropriate nonlinear input-output characteristic having a greater amplification factor than said linear input-output characteristic, thereby extending a luminance signal within the limits of said preset minimum and maximum luminance levels, said luminance signal formed in said matrix circuit being supplied to said luminance signal correcting means as said input luminance signal to generate a nonlinearly amplified luminance signal, said luminance signal correcting means comprising first means, coupled to said matrix means, for amplifying and inverting said input luminance signal to generate a first output signal in which amplitude levels of minimum and maximum levels are equal to said preset minimum and maximum levels and wherein amplitude levels therebetween are non-linearly amplified, first adder means, coupled to said matrix means and said first means, for adding said input luminance signal to said first output signal to generate a first added signal, and second adder means, coupled to said matrix means and said first adder means, for adding said input luminance signal to said first added signal to generate said non-linearly amplified luminance signal.

Claim 24

An imaging apparatus which develops a corrected luminance signal and color difference signals of an image subject comprising: optical lens means for receiving image light emitted from said image subject in order to provide received image light; color filter means, coupled to said optical lens means, for filtering said received image light; photo-electric conversion means, coupled to said color filter means, for converting the filtered image light into electrical image signals; pre-amplifier means, coupled to said photo-electric conversion means, for amplifying said electrical image signals; color separator means, coupled to said pre-amplifier means, for separating said amplified electrical image signals into red, green and blue color signals; white balance adjustment means, coupled to said color separator means, for adjusting the amplitude levels of said red, green and blue color signals; matrix circuit means, coupled to said white balance adjustment means, for converting said amplitude adjusted red, green and blue color signals into a luminance signal and color difference signals; and luminance signal correction means, coupled to said matrix circuit means, for outputting a corrected luminance signal in accordance with an input-output non-linear amplification factor in response to an input luminance signal intermediate a minimum and maximum luminance level, corresponding to a darkest and lightest luminance state, respectively, and for outputting said minimum and maximum luminance levels in response to an input luminance signal corresponding to said darkest and lightest state, respectively, in order to extend and emphasize an intermediate input luminance signal, said input-output non-linear amplification factor having plural kinking points intermediate said minimum and maximum luminance levels, below which said amplification factor has primary gains and above which has secondary gains which are unequal.

Claim 25

An imaging apparatus which develops a corrected luminance signal and color difference signals of an image subject comprising: optical lens means for receiving image light emitted from said image subject in order to provide received image light; color filter means, coupled to said optical lens means, for filtering said received image light; photo-electric conversion means, coupled to said color filter means, for converting the filtered image light into electrical image signals; pre-amplifier means, coupled to said photo-electric conversion means, for amplifying said electrical image signals; color separator means, coupled to said pre-amplifier means, for separating said amplified electrical image signals into red, green and blue color signals; white balance adjustment means, coupled to said color separator means, for adjusting the amplitude levels of said red, green and blue color signals; matrix circuit means, coupled to said white balance adjustment means, for converting said amplitude adjusted red, green and blue color signals into a luminance signal and color difference signals; and luminance signal correction means, coupled to said matrix circuit means, for outputting a corrected luminance signal in accordance with an input-output non-linear amplification factor in response to an input luminance signal intermediate a minimum and maximum luminance level, corresponding to a darkest and lightest luminance state, respectively, and for outputting said minimum and maximum luminance levels in response to an input luminance signal corresponding to said darkest and lightest state, respectively, in order to extend and emphasize an intermediate input luminance signal, said input-output non-linear amplification factor having plural kinking points intermediate said minimum and maximum luminance levels, below which said amplification factor has primary gains and above which has secondary gains which are unequal.

Claim 26

The imaging apparatus of claim 16, wherein said luminance signal correction means comprises: corrector means, coupled to said matrix circuit means, for changing the kinking point of said amplification factor in accordance with a first control signal to provide an amplification corrected luminance signal; level shifting means, coupled to said corrector means, for changing a dc bias point of said amplification corrected luminance signal, in accordance with a second control signal, to provide a shifted luminance signal; and high-level selecting means, coupled to said matrix circuit means and said level shifting means, for comparing said input luminance signal and said shifted luminance signal and for outputting the signal with a higher level as said corrected luminance signal.

Claim 27

The imaging apparatus of claim 16, further comprising: variable-gain amplifier means, coupled to said matrix circuit means, for non-linearly amplifying the color difference signals; and gain control means, coupled to said matrix circuit means, said luminance signal correction means and said variable-gain amplifier means, for detecting the time at which said luminance signal correction means performs non-linear amplification on said input luminance signal and for controlling said variable-gain amplifier means to perform non-linear amplification on said color difference signals at that time.