JPH04122988A - Electronic image input device - Google Patents

Abstract

PURPOSE:To enable automatic white balance adjustment by outputting a stored control signal corresponding to a certain specific light source and controlling the gain of a gain control amplifier when an arithmetic control part judges that the deviation of the color of a subject from the integral value output of a color signal integration circuit. CONSTITUTION:The arithmetic control part 6 performs the automatic white balance adjustment by performing control so that the mean value of a video signal in longer than a specific period indicates gray. Further, signals generated by integrating an R, a G, and a B signal before the gain control for longer than a specific period by color signal integration circuits 8a, 8b, and 8c are inputted to the control circuit 6 and the color deviation of the subject is decided with the input data. When the control part 6 judges that the color of a projected subject deviates greatly to red, the control signal corresponding to the specific light source of the subject stored in a memory 6b is outputted to gain control amplifiers 3a and 3b to perform the white balance adjustment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electronic imaging device having an automatic white balance adjustment function using an imaging lens transmitted light method (hereinafter referred to as TTL method).

(Prior Art) Fig. 2 is a block diagram showing a conventional electronic image input device of this type.A light image of a subject captured in a solid-state image sensor (hereinafter referred to as CCD) is photoelectrically converted into R, G, and , B color signals, double correlation sampling is performed by the CDS circuit 2, and clocking noise is removed.
, B color signals are outputted and supplied to the process circuit 4 through a plurality of gain control amplifiers 3a and 3b shown in 3, where the R, G, and B color signals are combined with the luminance signal Y and the color difference signal R-. Converted to Y, B-Y. Furthermore, these signals are modulated by the encoder circuit 5 and output as a video signal.

By the way, the auto white balance operation in this device takes advantage of the premise that on a numerical screen, the average spectral reflectance of all subjects becomes gray. The configuration is such that automatic white balance control is performed so that the integrated value becomes gray.

Next, the white balance system will be explained with reference to the same figure, and the color difference signals R-Y, B- obtained by the process circuit 4
Y is integrated by the color difference signal integration circuits 7a and 7b, for example, for one field period, and then processed by the microcomputer 6.
a, it is manually operated by the arithmetic control section 6 having a memory 6b. In the arithmetic control section 6, control voltages VR, V are applied to the control amplifier 3 as control signals for controlling the gains of the gain control amplifiers 3a, 3b based on the input integral value data.
a and 3b, and by controlling the output levels of the color signals R and B, the integral value of the color difference signals R-Y and B-Y is made smaller, that is, for example, the value of the video signal for one field period is reduced. White balance is adjusted by controlling the image to either the average value or gray.

[Invention or problem to be solved]

However, in the above conventional example, the data for performing auto white balance is TTL type auto white balance, or the video signal is obtained from the subject image captured by the CCD 1, so it is difficult to capture a special subject, e.g. For subjects that are entirely red, in principle, white balance cannot be performed. That is, the cause is
This is because the average value of the video signal from the above-mentioned subject, for example, during one field period does not turn gray.

To give a specific example, when auto white balance is performed when an original made of black or red paper is displayed on the entire screen, the arithmetic control unit 6 controls the image of the red subject to appear gray. The image displayed on the monitor ends up being an extremely different color from the red that Nisu actually sees.

To counter this, a separate sensor system such as external photometry is required, which is complicated in configuration and handling, and is also expensive.

This invention was made in order to eliminate the shortcomings of the above-mentioned prior art, and it is difficult to obtain an appropriate auto white balance with the TTL auto white balance method. The object of the present invention is to provide an electronic image manual device capable of automatic white balance.

(Means for Solving the Problem) Therefore, an electronic image input device according to the present invention includes a solid-state image sensor that converts an optical image of a subject into an electrical signal and outputs a plurality of color signals, and a solid-state image sensor that converts an optical image of a subject into an electrical signal and outputs a plurality of color signals. a gain control amplifier that controls output and adjusts white balance; a process circuit that inputs the color signal and outputs a luminance signal and a plurality of color difference signals; and a plurality of color difference signal integrals that integrate the color difference signals over a specific period of time. a plurality of color signal integration circuits that integrate the color signal before human input into the gain control amplifier for a specific period or more; and a control signal that inputs the integral value output of the color difference signal to control the gain of the gain control amplifier. an electronic image input device comprising: an arithmetic control unit that outputs an integral value of the color difference signal when the arithmetic control unit determines that the color bias of the subject is large based on the integral value output of the color signal integration circuit; Instead of controlling the gain of the gain control amplifier based on the value output, the configuration is characterized in that white balance adjustment is performed by outputting a memorized control signal corresponding to a specific light source to control the gain of the gain control amplifier. This aims to achieve the above objectives.

(Function) With the above configuration, the solid-state image sensor converts the optical image of the subject into an electrical signal and outputs multiple color signals, and the gain control amplifier controls the color signal output to adjust the white balance and process the image. It inputs into a circuit and outputs a luminance signal and multiple color difference signals.

Then, the color difference signals are integrated over a specific period of time by a plurality of color difference signal integration circuits and inputted to the arithmetic control section, and the arithmetic control section outputs a control signal for controlling the gain of the gain control amplifier.

Furthermore, the color signal integration circuit integrates the color signal before human input into the gain control amplifier over a specific period of time and outputs it to the arithmetic control section. When it is determined that this is the case, instead of controlling the gain of the gain control amplifier based on the output of the integral value of the color difference signal, a memorized control signal corresponding to the specific light source is output and the gain of the gain control amplifier is controlled to control white. Since balance adjustment is performed, it is possible to perform appropriate white balance control using the TTL method even when the screen is a red-colored subject.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, an electronic image input device according to the present invention will be explained using examples.

FIG. 1 is a block diagram showing an embodiment of the present invention, in which blocks that are the same as or correspond to those of the conventional example are designated by the same reference numerals.

1 is a CCD that photoelectrically converts the image of the subject, 2 is a CCD
1.Clocking noise is removed from the signal obtained by <C
DS circuit. 3a and 3b are gain control amplifiers whose gains are controlled by control signals from the arithmetic control section 6, which control the signal output levels of the R color signal and the B color signal to perform white balance adjustment.

4 is a process circuit that inputs R, G, and B color signals and outputs a luminance signal Y and color difference signals RY and B-Y. 5 is an encoder circuit which inputs the luminance signal Y and the color difference signals R-Y and B-Y and outputs a video signal.

6 is an arithmetic control unit having a microcomputer 6a and a memory 6b. 7a and 7b are color difference signal data detection circuits, and in the embodiment, they are color difference signal integration circuits that integrate the color difference signals R-Y and B-Y over a specific period or longer, respectively.

Reference numerals 8a, 8b, and 8c are color signal data detection circuits, and in this embodiment, they are color signal integration circuits that integrate the R2O and B color signals output from the CDS circuit 2 and before being input to the gain control amplifiers 3a and 3b over a specific period. be. Note that the above-mentioned specific period is a period in which an image sufficient to represent the average color value of the subject can be formed, and is a period shorter than one field.

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

The image electrical signal photoelectrically converted by CCD 1 is
The S circuit 2 outputs R, G, and B color signals from which doubly correlated sunblink and clock noise have been removed. R1B color signal is Kane control amplifier 3a, 3b
The G color signal is directly input to the process circuit 4, where the RlG and B color signals are combined with the luminance signal Y and the color difference signal R-.
Y.

It is converted to B-Y. Furthermore, these signals are modulated by the encoder circuit 5 and output as video signals.

In the white balance system, the color difference signals R-Y and B-Y output from the process circuit 4 are integrated over a specific period by color difference signal integration circuits 7a and 7b, respectively, and the arithmetic control unit 6
is input. The arithmetic control section 6 changes the gains of the gain control amplifiers 3a, 3b based on the input data to change the signal amounts of the R signal and B signal, using control signals VFl and VI.
, are output to the gain control amplifiers 3a and 3b, and are controlled so that the integral values of the color difference signals R-Y and B-Y become smaller. That is, white balance adjustment is performed by controlling the average value of the video signal over a specific period to become gray.

Further, signals obtained by integrating the R2O and B color signals before gain control over a specific period of time by color signal integration circuits 8a, 8b, and 8c are input to the calculation control unit 6, and the color of the subject is determined by this input data. Determine the bias.

For example, if the subject is entirely red, the integrated R color signal will be extremely large compared to the other B and G color signals, so the color of the displayed subject will be heavily biased towards red. If the arithmetic control unit 6 determines that the R
Then, the white balance control that takes white balance by changing the color signal ± output level of the B color signal is canceled, and instead of that, the cleaning control unit 6 performs control corresponding to the subject C specific light source stored in the memory 6b. White balance adjustment is performed by outputting the signal to gain control amplifiers 3a and 3b.

FIG. 2 is a flowchart of the white balance operation described above, and will be explained again with reference to the same figure.

In step S1, control signals V, , VB are set to initial values. In step S2, the color signal 8a before gain control,
The color bias is determined from the integral values of 8b and 8c, and if there is no bias, a white balance calculation is performed in step S3, and control signals V, , V, as the calculation results are outputted to the gain control amplifiers 3a and 3b in step S4. Perform white balance adjustment.

If it is determined in step S2 that the bias is biased, the process proceeds to step S5, and the control signal vR1VB determined in advance and stored in the memory 6b is applied to the gain control amplifier 3a.
, 3b to perform white balance adjustment.

As described above, gain control amplifiers 3a and 3b
By setting the control value to a pre-stored setting value corresponding to the light source, it is possible to obtain a TTL auto white balance adjustment function that can reproduce a red subject in red.

Note that setting values that are stored in advance according to the light source are used when the conditions in which this electronic image input device will be used can be easily predicted.
If a specific light source is attached to illuminate the document table (such as OHP), the gain is set so that colors that are generally considered white appear white when illuminated by that light source. These are the control values VR and R of the control amplifiers 3a and 3b.

Note that the integration periods of the color difference signal integration circuits 7a, 7b and the color signal integration circuits 8a, 8b, 8c are not limited to one field period, but may be two or more field periods. White balance control is possible.

〔Effect of the invention〕

As explained above, according to the present invention, a solid-state image sensor photoelectrically converts an optical image of a subject to output a plurality of color signals, and a gain control amplifier controls the output of the plurality of color signals to adjust white balance. is input to a process circuit and outputs a luminance signal and multiple color difference signals.

Then, the color difference signals are integrated by a plurality of color difference signal integration circuits for a specific period or more, and inputted to the arithmetic control section, which outputs a control signal for controlling the gain of the gain control amplifier.

Furthermore, the color signal integration circuit integrates the color signal before human input into the gain control amplifier over a specific period and outputs it to the arithmetic control section, and the arithmetic control section calculates the color of the subject from the integral value output of the color signal integration circuit. When it is determined that the bias is large, instead of performing white balance control based on the output of the integral value of the color difference signal, the arithmetic control unit outputs a stored control all signal corresponding to a specific light source and adjusts the gain of the gain control amplifier. The white balance is adjusted by controlling the
It is possible to provide an electronic image human-powered device having a TTL auto white balance function that allows for good white balance adjustment even on a color screen without adding a sensor system such as external photometry. .

In particular, it is easy to assume a light source such as an electronic overhead projector (OHP) that is equipped with illumination, and the features of the present invention can be more effectively utilized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a flowchart of white balance operation in the same embodiment, and FIG. 3 is a conventional electronic image human power device having an automatic white balance adjustment function using the LLT method. FIG. 1...Solid-state image sensor 3a, 3b=- Gain control amplifier 4...
---Process circuit 5--Encoder circuit 6--Arithmetic control section a--Microcomputer a--Memory 7a. 7b...Color difference signal data detection circuit (integrator circuit)

Claims (1)

[Claims] A solid-state image sensor that converts an optical image of a subject into an electrical signal and outputs a plurality of color signals, a gain control amplifier that controls the output of the plurality of color signals and adjusts white balance, and a gain control amplifier that inputs the color signal and outputs a plurality of color signals. A process circuit that outputs a luminance signal and a plurality of color difference signals, a plurality of color difference signal integration circuits that integrate the color difference signals over a specific period of time, and a plurality of color signal integration circuits that integrate the color signal before being input to the gain control amplifier over a specific period of time. An electronic image input device comprising a signal integration circuit and an arithmetic control section that inputs an integral value output of the color difference signal and outputs a control signal for controlling the gain of the gain control amplifier, the arithmetic control section comprising: When it is determined that the color bias of the object is large based on the integral value output of the color signal integration circuit, instead of controlling the gain of the gain control amplifier based on the integral value output of the color difference signal, An electronic image input device characterized in that white balance adjustment is performed by outputting a corresponding control signal to control the gain of a gain control amplifier.