JPH03217190A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To output a positive color video signal rich in gradation by controlling the change of an amplification factor for a chrominance signal amplifier, the inversion of a phase for a sub carrier, the inversion of a phase for a luminance signal and the change of amplification factors for the chroma signal amplifier and a luminance signal amplifier by generating a control signal from a positive/ negative control part. CONSTITUTION:A positive/negative changeover switch 33 is operated and the control signal is inputted from a negative/positive control part 32 to chroma signal amplifiers 4, 5 and 6 so as to lower the amplification factors of the above amplifiers. A sub carrier SC 90 and the phase of the SC are respectively inverted and outputted. An inverted/not-inverted amplifier 26 is switched to an inverted amplifier, inverts a luminance signal Y and inputs it to a luminance signal amplifier 29. The amplification factors of a chroma signal amplifier 28 and the luminance signal amplifier 29 are increased and the luminance signal and the chroma signal are amplified and outputted with the high amplification factor in comparison with the positive case. At a mixing circuit 30, the luminance signal Y and the chroma signal are mixed and outputted as the positive color video signal while adding color burst and synchronization.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a solid-state imaging device such as a color video camera using a solid-state imaging device.

[Conventional technology]

Conventionally, in solid-state imaging devices such as color video cameras, the configuration of models that can capture negative images such as negative films in addition to normal positive image capture and obtain positive color video signals from the negative signals has been classified as follows. The configuration is shown in the block diagram in Figure 2.

That is, light from an object passes through a lens 1, an aperture 2, forms an image on a solid-state image sensor 3, is photoelectrically converted, and is then sent to amplifiers 4, 5, .
6 is amplified and input to the video processing section A to produce a color difference signal (B-
Y). (.RY) and a luminance signal are formed and input to the encoder section B, where the color difference (.RY) and the luminance signal are formed and input to the encoder section B.
The RY) and (B-Y) signals are modulated by subcarriers SC and SC90 orthogonal to each other, and are superimposed on the luminance signal Y to form a color video signal. When a negative film or the like is captured, subcarriers, SC, and SC90 are used to modulate the image in order for the monitor to project the image as a positive image.
The color difference signal is modulated by inverting the phase of Y, and the luminance signal Y is also inverted and superimposed to output a color video signal.

FIG. 3 is a schematic explanatory diagram of an example of color parsing of a color image, in which (a) is a normal positive image, (b) is a normal positive image, and (a) is a normal positive image.
When the image is inverted, (C) shows the same inversion as when a negative film image is taken, and (d) shows the same inversion as when a negative film image is imaged with the aperture opened.

[Invention or problem to be solved]

However, in the conventional example described above, when capturing an image of a negative film or the like, the color video camera signal processing circuit usually performs various characteristics based on a positive image, which is a general subject.
For example, gain settings such as gamma γ, black and white, clip, and amplifier are provided. In general, the difference in brightness of a subject on a negative film is smaller than that of a general subject, so when photographing a subject on a negative film on a monitor, the image will look like this, as shown in Figure 3 (C). If the output level decreases and the image becomes dark, or if you open the aperture to make the image brighter as shown in Figure 3(d), the linearity may collapse, making it impossible to obtain a brightness level with the desired linearity. The problem was that I couldn't do it.

The present invention solves the above-mentioned problems of the prior art, and aims to provide a solid-state imaging device that can obtain an appropriate positive color video output from a negative image such as a negative color in addition to a normal positive image. do.

[Means to solve the problem]

Therefore, the solid-state imaging device according to the present invention includes a solid-state imaging device that photoelectrically converts a subject image and outputs a color signal, a color signal amplifier that can change the degree of amplification that amplifies the color signal, and the color signal amplifier. a video processing section that inputs a color signal from the video processing section to form a color difference signal, inputs the color difference signal from the video processing section and a subcarrier from a subcarrier generation circuit and outputs a chroma signal, and outputs a chroma signal from the video processing section; an encoder section that inputs the luminance signal and outputs the luminance signal via an inverting/non-inverting amplifier that selects whether to invert or non-invert the luminance signal; and an amplification factor that inputs and amplifies the chroma signal and the luminance signal from the encoder section. A changeable chroma signal amplifier and a luminance signal amplifier, and a mixing circuit that inputs and mixes output signals from the chroma signal amplifier and luminance signal amplifier, adds burst and sync, and outputs a video signal; A solid-state imaging device comprising the subcarrier generation circuit that generates subcarriers with a phase difference and is invertible, and a negative/positive control unit, the negative/positive control unit issuing a control signal, changing the amplification degree of the color signal amplifier;
Inversion of the phase of subcarriers output from the subcarrier generation circuit and having a phase difference of 90 degrees from each other, inversion of the phase of the luminance signal input to the luminance signal amplifier, and the amplification degree of the chroma signal amplifier and the luminance signal amplifier. Furthermore, in the configuration described above, the negative/positive control section issues a control signal to lower the amplification degree of the color signal amplifier, and the subcarrier generation circuit outputs the signals at 90 degrees to each other. The phase of the subcarrier with a phase difference of The above object is achieved by a configuration characterized in that it captures an image and outputs a positive color video signal.

[Effect]

With the above configuration, the solid-state image sensor performs photoelectric conversion,
The signal is input to a video processing section to form a color difference signal, and is input to an encoder section and a mixing circuit to form and output a normal color video signal.

Then, a control signal is issued from the negative/positive control section to lower the amplification degree of the color signal amplifier, and the phase of the subcarriers output from the subcarrier generation circuit, which have a phase difference of 90 degrees from each other, is inverted and sent to the encoder section. The phase of the luminance signal input to the luminance signal amplifier is inverted, the amplification degree of the chroma signal amplifier and the luminance signal amplifier is increased, the negative film is imaged, and an appropriate positive color video signal is output.

〔Example〕

An embodiment of a solid-state imaging device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of one embodiment. Reference numeral 1 denotes a lens optical system that forms an image on an image sensor that is a subject, 2 a diaphragm that adjusts the exposure amount, and 3 a solid-state image sensor that converts the subject image formed by the lens optical system into an electrical signal. 4
, 5.6 are color signal amplifiers capable of changing the amplification degree for amplifying the color signals separated into three types, R, G, and B, output from the image pickup device. Reference numeral 7 denotes a switch circuit that configures the luminance signal Y by switching the three types of color signals R, G, and B amplified by the color signal amplifiers 4, 5, and 6. The outputs of the color signal amplifiers 8, 9, and 10 and the output of the switch circuit 7 are input to the video processing section A.

8.9.10 of the video processing section is a clamping circuit that inputs and clamps three types of amplified color signals to determine the DC level of the signal.

Reference numeral 11 denotes a clamp circuit that clamps the luminance signal Y formed by the switch circuit 7 and determines the DC level. 12
is a variable amplifier that varies the amplitude level of a clamped R (red) signal. l3 is an amplifier that amplifies the clamped G (green) signal, and 14 is an amplifier that amplifies the clamped B (green) signal.
Blue) is a variable amplifier that varies the amplitude level of the signal. 15 is an amplifier for amplifying the clamped brightness signal Y; Reference numerals 16, 17, 18, and 19 are gamma processing circuits that perform gamma processing and planking processing on each of the R, G, and B signals and the luminance signal Y. 20 is a gamma processing circuit 18, 17 .
This is a matrix circuit that receives the color signals R, G, and B processed in 18 and performs matrix calculations to form color difference signals of (B-Y) and (R-Y). Matrix circuit 2
0 and the output from the gamma processing circuit 19 are input to the encoder section B.

21 and 22 of encoder section B are color difference signals (B-Y). (
RY) clamp circuit clamps the DC level (
electric potential) can be determined. 23 is a clamp circuit for the luminance signal Y, which determines the DC level. 24 and 25 are modulators, each of which receives SC90 from 31 subcarrier generation circuits.
, SC having a phase difference of 90' from each other is also input, and modulates the color difference signals (B-Y) and (R-Y).

Reference numeral 26 denotes an inverting/non-inverting amplifier for the luminance signal Y, which inverts the luminance signal Y according to a control signal from the negative/positive control section 32 or outputs it as it is in positive phase. 27 is modulator 2
4. A mixer that mixes the respective modulated color difference signals at 25.

A luminance signal amplifier 29 amplifies the luminance signal input from the encoder section B, and the amplification degree can be switched to a set value by a control signal from the negative/positive control section 32. 28 is a chroma signal amplifier that amplifies the chroma signal, which is a color signal modulated and mixed in the encoder section B;
Similarly to the luminance signal amplifier No. 29, the amplification degree can be switched to a set value by a control signal from the negative/positive control section 32. 30 is a mixing circuit that mixes the luminance signal Y and the chroma signal C, adds burst and sync, and outputs it to the outside as a color video signal.

31 are subcarriers SC with a phase difference of 90° from each other.
, SC90 is generated.

Reference numeral 32 denotes a negative/positive control unit that controls switching between negative and positive signal processing. Reference numeral 33 denotes a negative/positive changeover switch which is switched when changing between taking a positive image of a general subject and taking a negative film image.

Next, the operation of the embodiment image pickup apparatus having the above configuration will be explained.

First, the operation when the subject is a general subject, that is, a positive image will be explained. An optical system including a lens 1 and an aperture 2 forms an image of a subject on an image sensor 3 as a positive image. The signal is then decomposed into three types of color signals, R, G, and B, and output, and amplified to a specific setting value by the color signal amplifier 11 4.5.6.

Note that the amplification degrees of the color signal amplifiers 4, 5.6 are normally set based on a positive image of a general subject. In other words, the circuit processing is set so that the final color video output is 1 mVp-p (when terminated at 75Ω) when the output value of the image sensor is XmV. Then, the switch circuit 7 switches the three types of color signals R, G, and B to form the luminance signal Y, and the clamp circuits 8, 9, and 10.11 clamp the R, G, B, and Y signals. Determine the DC potential level. Amplifiers 13 and 15 amplify the color signal G (green) and the luminance signal Y to set values and output them.

The variable amplifiers 12.14 are gain adjustment amplifiers for R and B color signals, and perform white balance adjustment. Gamma processing circuits 16, 17 and 18, 19 process each signal R, G, B, Y.
γ (gamma) processing and planking processing are performed on the color signals R, G, and B, which are input to the matrix circuit 20 to form color difference signals (B-Y) and (R-Y).
2 It is input to the encoder section along with No. 2 Y. Then, it is clamped by clamp circuits 21, 22, and 23, and the DC level is determined. The color difference signals are modulated by subcarriers in modulators 24 and 25. The modulated color difference signals are mixed by a mixer 27, amplified to a set value by a chroma signal amplifier 28, and input to a mixing circuit 30. Further, the luminance signal Y is inputted from the gamma processing circuit 19 to the clamp circuit 23 and then to the inverting/non-inverting amplifier 26, which operates as a non-inverting amplifier, that is, it is output as it is in positive phase to the luminance signal amplifier 29. is amplified to the set value and sent to mixing circuit 3.
0 and mixed with the chroma signal and also the color burst . A sync signal is added and output as a color video signal.

Next, an explanation will be given of the operation when the subject is a negative film, that is, a negative image is captured and a positive image is output.

A negative image is formed on the image sensor 3. Then, the negative/positive changeover switch 33 is activated, and a control signal is inputted from the negative/positive control section 32 to the color signal amplifiers 4, 5.6 to lower the amplification degree of the amplifiers. Further, a control signal is input from the negative/positive control unit 32 to the subcarrier generation circuit 31, and the phases of the subcarriers SC90 and SC are inverted and outputted. The modulators 24 and 25 are supplied with subcarriers SC90 whose phase is reversed from that of the object to be photographed.
, SC are input, modulated, mixed by a mixer 27, and input to a chroma signal amplifier 28. The inverting/non-inverting amplifier is switched to an inverting amplifier by a control signal from the negative/positive control unit 32, and inverts the luminance signal Y and inputs it to the luminance signal amplifier 29. Chroma signal amplifier 28. The brightness signal amplifiers 29 have their amplification degrees increased by control signals from the negative/positive control section 32, and amplify and output the brightness signals and chroma signals with higher amplification degrees than in the case of positive signals. In the mixing circuit 30, the luminance signal Y and the chroma signal C
, add color burst and sync, and output as a positive color video signal.

With the above configuration and operation, a normal positive image of a subject can be normally captured. Furthermore, even when imaging negative film, it is possible to obtain a positive image with no signal fluctuation, favorable linearity, and rich gradation without S/N deterioration.
A positive inversion circuit can be constructed relatively inexpensively.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to capture a positive image of a normal subject and output an appropriate positive color video signal.

Furthermore, a control signal is emitted from the negative/positive control section,
Changing the amplification degree of the chrominance signal amplifier, inverting the phase of subcarriers output from the subcarrier generation circuit with a phase difference of 90 degrees from each other, inverting the phase of the luminance signal input to the luminance signal amplifier, and changing the phase of the chroma signal amplifier. By controlling the change in the amplification degree of the luminance signal amplifier, and in detail,
A control signal is issued from the negative/positive control unit to lower the amplification degree of the color signal amplifier, and outputs 1 5 , 3 and 3 from the subcarrier generation circuit are negative/positive changeover switches.

The phases of the subcarriers that have a phase difference of 90 degrees from each other are inverted and input to the encoder section, and the phase of the luminance signal input to the luminance signal amplifier is inverted to increase the amplification of the chroma signal amplifier and luminance signal amplifier. As a result, even when an image of a negative film is captured, it is possible to output a positive color video signal with favorable linear characteristics, low S/N deterioration, and rich gradations without signal distortion, and with rich gradations. Further, it is possible to provide a solid-state imaging device in which the negative/positive inversion circuit can be constructed at relatively low cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment according to the present invention, FIG. 2 is a block diagram of a conventional example, and FIG. 3 is a schematic explanatory diagram of a conventional color par. A is a video processing section, B is an encoder section, 3 is a solid-state image sensor, 4, 5.6 are color signal amplifiers, 26 is an inverting/non-inverting amplifier, 28 is a chroma signal amplifier, 29 is a luminance signal amplifier,
30 is a mixing circuit, 31 is a subcarrier generation circuit, 32 is a negative/positive control 1 6

Claims (2)

[Claims] (1) A solid-state image sensor that photoelectrically converts a subject image and outputs a color signal, a color signal amplifier that amplifies the color signal and can change the degree of amplification, and inputs the color signal from the color signal amplifier and generates a color difference signal. A video processing unit that inputs a color difference signal from the video processing unit and a subcarrier from a subcarrier generation circuit to output a chroma signal, inputs a luminance signal from the video processing unit, and inverts or non-inverts the luminance signal. an encoder section that outputs a luminance signal via an inverting/non-inverting amplifier that selects inversion; a chroma signal amplifier and a luminance signal that input and amplify the chroma signal and luminance signal from the encoder section, each having a variable amplification degree; An amplifier, a mixing circuit that inputs and mixes the output signals from the chroma signal amplifier and the luminance signal amplifier, adds burst and sync, and outputs a video signal, and generates subcarriers having a phase difference of 90 degrees from each other. , and the reversible subcarrier generation circuit;
A solid-state imaging device comprising a positive control section, wherein the control signal is emitted from the negative/positive control section to change the amplification degree of the color signal amplifier, and output signals from the subcarrier generation circuit at a position of 90 degrees from each other. A solid-state imaging device characterized by controlling phase inversion of subcarriers having a phase difference, phase inversion of a luminance signal input to the luminance signal amplifier, and change in amplification degrees of the chroma signal amplifier and the luminance signal amplifier. . (2) In the solid-state imaging device according to claim 1, the negative/positive control section issues a control signal to lower the amplification degree of the color signal amplifier, and the subcarrier generation circuit outputs a
The phase of the subcarriers with a phase difference of 100 degrees is inverted and input to the encoder section, the phase of the luminance signal input to the luminance signal amplifier is inverted, and the amplification degree of the chroma signal amplifier and luminance signal amplifier is increased. A solid-state imaging device characterized by capturing an image of film and outputting a positive color video signal.