JPH11317960A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply white balance adjustment to two kinds of video signals with different exposure independently. SOLUTION: Two kinds of video signals with different exposure outputted from an image pickup element 101, where a transfer speed of a horizontal CCD is twice, are separated into a long time exposure video signal and a short time exposure video signal in a same timing at a conventional transmission rate and synthesized at a prescribed level. A means 109 that discriminates a bright area and a dark area through the comparison between the long time exposure video signal and the synthesis level, and an area designation means 115 that selects color difference signals for each of the bright and dark areas are used to provide a color difference mean value of the dark area at first to a microcomputer 117, which controls a multiplier 112 so that the mean value is coincident with a reference value thereby adjusting white balance of the dark area. A color difference signal of the bright area is selected based on adjustment end information, and similarly a multiplier 108 that applies gain control to a short time exposure video signal for each pixel is controlled and white balance in the bright area is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus used for a video camera or the like, and more particularly to an image pickup apparatus capable of independently adjusting the white balance of two kinds of video signals having different exposure amounts.

[0002]

2. Description of the Related Art FIG. 3 shows functional blocks of a conventional image pickup apparatus when white balance adjustment is performed on a synthesized signal subjected to dynamic range expansion signal processing. In FIG. 3, a functional block for realizing white balance correction control in a conventional imaging apparatus is an image sensor 1
, A pre-processing unit 2 such as a CDS or AGC, and an A / D converter 3
A time axis converter 4, a separation unit 5 for luminance signal and color signal, a combination unit 6 for luminance signal and color signal, a gradation correction unit 7, a luminance signal composite component and a color signal composite component whose gradation has been corrected , A dynamic range expansion signal processing circuit comprising means for adding
It comprises a means 9 for separating into primary colors of GB, a multiplier 10 for white balance adjustment, a subtractor 11 for creating a color difference signal, a means 12 for modulating the color difference signal with a color carrier, and a means 13 for creating an average value of the color difference signals. It comprises a main signal processing circuit and a microcomputer 14.

The image pickup device 1 can alternately output two kinds of video signals in which the transfer speed of the horizontal CCD is twice the normal speed and the exposure amount is long and short, within one field period. The video signal output from this is CDS, A
After performing preprocessing 2 such as GC, the signal is converted into a digital signal by an A / D converter 3, and a long-time exposure image signal and a short-time exposure image signal at standard speed and at the same timing by a time axis converter 4. Is separated into

When the image sensor 1 is an image sensor for a single-chip color camera using a mosaic color filter,
The two types of video signals having different exposure amounts output from the time axis converter 4 include color modulation components, and when these are combined at a predetermined luminance level, they are separated into a luminance signal and a color modulation component. After separation into a luminance signal and a color carrier component by the filter 5, the synthesis 6 of the luminance signal and the color component is performed.

[0005] The composite component of the luminance signal is subjected to gradation correction by the gradation correction means 7 so that the higher the level (gradation) of the image histogram frequency, the more the contrast is enhanced.
The separated color components are added and sent to the main signal processing circuit.

The white balance adjustment is performed by a main signal processing circuit. The synthesized signal subjected to the dynamic range expansion signal processing is again separated into a luminance signal and a color carrier component by the luminance signal and color separation means 8 in the main signal processing circuit. The color carrier component is converted by the RGB separation circuit 9 into R
The R and B signals are converted into GB primary color signals, and the gains KR and KB are respectively converted by a white balance adjustment multiplier 10.
After that, the color difference signals KR • RG and KB • BG are created by the subtractor 11 for creating a color difference signal.

The generated color difference signals are used to calculate an average value of the entire screen by means 13 for calculating an average value of the entire screen, and these are taken into a microcomputer 14, which compares the average value with the reference value. The white balance adjustment gains KR and KB are controlled so that the average values of all the R and B color difference signals are zero.

[0008] By controlling the gains KR and KB in this way, white balance adjustment can be performed.
Finally, the chrominance signal is modulated by the modulator 12 using a chrominance carrier, added to the luminance signal, and output as a composite video signal.

[0009]

However, in the above-mentioned conventional image pickup apparatus, since there is only one white balance adjustment control system, when subjects having different color temperatures such as indoor and outdoor are combined, priority is given to indoors. If the white balance is adjusted, there is a problem that the white balance of the image outside the room does not match.

The present invention solves the above-mentioned conventional problem. When combining subjects having different color temperatures such as indoors and outdoors, two types of video signals having different exposure amounts can be independently adjusted in white balance. Thus, an object of the present invention is to provide an imaging apparatus capable of performing correct white balance correction both indoors and outdoors simultaneously.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an image pickup device which alternately outputs two kinds of video signals having a long exposure time and a short exposure time within one field period, A means for synthesizing a time-exposure image signal and a short-time exposure image signal at a predetermined luminance level, and a gain control of a short-time exposure video signal for each pixel for white balance adjustment of the short-time exposure image before synthesis Means for controlling the multiplier, means for controlling the multiplier for performing white balance adjustment of the long-time exposure image after image synthesis, means for creating a color difference signal, and means for detecting an average value of the color difference signal. The white balance of the long-time exposure image and the short-time exposure image is adjusted in a time-sharing manner based on the average value of the detected color difference signals.

In this manner, when subjects having different color temperatures such as indoors and outdoors are synthesized, white balance adjustment of two kinds of video signals having different exposure amounts can be performed independently. At the same time, correct white balance correction can be performed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to an image pickup device which alternately outputs two types of video signals having a long exposure time and a short exposure time within one field period, Means for synthesizing the exposure image signal and the short-time exposure image signal at a predetermined luminance level, and multiplication capable of controlling the gain of the short-time exposure video signal for each pixel in order to adjust the white balance of the short-time exposure image before synthesis Means for controlling the vessel;
Means for controlling a multiplier to perform white balance adjustment of a long-time exposure image after image synthesis, means for creating a color difference signal, and means for detecting an average value of the color difference signal,
An image pickup apparatus characterized in that the white balance adjustment of a long-time exposure image and a short-time exposure image is performed by time division from the average value of the detected color difference signals,
The white balance adjustment of the long exposure image and the white balance adjustment of the short exposure image can be performed independently.

According to a second aspect of the present invention, there is provided a means for generating a determination pulse for distinguishing between a dark area and a bright area by comparing a luminance signal of a long-time exposure image with a synthesis level, and the generated determination pulse. Means for selecting a color signal of each of the light and dark areas by means of a pulse so that an average value of the color difference signals of each of the light and dark areas can be detected after selecting the color signal of each of the light and dark areas. The image pickup apparatus according to claim 1 has an effect that the color difference average value information for white balance adjustment to be input to the microcomputer can be switched and controlled for each of the dark area and the bright area.

According to a third aspect of the present invention, there is provided a means for detecting activation of a white balance adjustment operation by creating an average value of color difference signals, and performing white balance adjustment of a long-time exposure image first, Next, means for detecting the completion of each other's white balance adjustment operation to perform white balance adjustment of the short-time exposure image is further provided, and the white balance adjustment of the long-time exposure image and the short-time exposure image is controlled by time division. 1. The image pickup apparatus according to item 1, wherein the white balance adjustment in the dark area and the white balance adjustment in the light area are recognized to be completed, and the white balance adjustment for each area is performed in a time-division manner. It has the effect of being able to.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

In FIG. 1, functional blocks for implementing white balance correction control in the image pickup apparatus according to the embodiment of the present invention include an image pickup device 101, a pre-processing unit 102 such as a CDS or AGC, and an A / D converter 103. And a time axis converter 104, a separation unit 105 for luminance signal and color signal, a synthesis unit 106 for luminance signal and color signal, a gradation correction unit 107, a multiplier 108 for white balance adjustment dedicated to a short exposure image signal. A dynamic range expansion signal processing circuit including a region detection pulse generating means 109 and a means for adding a luminance signal synthesized component and a color signal synthesized component whose gradation has been corrected; a luminance signal / color signal separating means 110; Means for separating into primary colors 11
1, a multiplier 112 for white balance adjustment, a subtractor 113 for creating a color difference signal, means 114 for modulating the color difference signal with a color carrier,
The microcomputer 117 includes a main signal processing circuit including an area designating means 115 for selecting the light and dark areas of the color difference signal by the area detection pulse, and a means 116 for creating an average value of the color difference signals.

The image pickup device 101 can alternately output two kinds of video signals in which the transfer speed of the horizontal CCD is twice as fast as the normal CCD and the exposure amount is long and short, within one field period. The video signal output from this is CDS,
After performing pre-processing 102 such as AGC, it is converted into a digital signal by an A / D converter 103, and a long-time exposure image signal and a short-time exposure image signal at standard speed and at the same timing by a time axis converter 104. Is separated into

When the image sensor 101 is an image sensor for a single-chip color camera using a mosaic color filter, the exposure amount output from the time axis converter 104 is different.
The video signal of the system contains a color modulation component, and when these are combined at a predetermined luminance level, after being separated into a luminance signal and a color carrier component by a filter 105 that separates the luminance signal and the color modulation component. Synthesis of luminance signal and color component 10
Perform step 6.

The composite component of the luminance signal is supplied to a gradation correcting means 107.
After the correction is performed so that the contrast is enhanced as the gray level of the image becomes higher, the color modulation component is added and sent to the main signal processing circuit.

In this embodiment, since the dynamic range expansion signal processing circuit and the main signal processing circuit have independent LSI structures, the luminance signal and the color modulation signal are treated as multiplexed signals.

A short-time exposure image signal before separation into a luminance signal and a color modulation component is multiplied by a gain controllable pixel by pixel.
After the white balance adjustment of the short-time exposure image is performed via 108, the image is separated. Since the color filter of the image sensor has an array of four colors, it is sufficient to set four kinds of gains, adjust the timing for each pixel, and set the gain in the multiplier 108.
At this time, if the gain is calculated so that the sum of the two types of gains, which are the basic signals for generating the RY signal, is kept constant, the white balance in the R direction can be controlled. BY
The same applies to signals.

The white balance adjustment of the long-time exposure image is performed in the main signal processing circuit. In the main signal processing circuit, the luminance signal and chrominance signal separating means 110 separates the luminance signal and the chrominance carrier component again. The color carrier components are converted into RGB primary color signals by an RGB separation circuit 111, and the R and B signals are multiplied by gains KR and KB by a white balance adjustment multiplier 112, respectively, and then subtracted by a subtracter 113 for generating a color difference signal. The color difference signal K
R, R-G, and KB-BG are created.

The generated color difference signal is used to calculate an average value of the entire screen by means for calculating an average value of the entire screen, and the calculated average value of the entire screen is taken into the microcomputer 117. , The white balance adjustment gains KR and KB are controlled so that the average value of the entire screen of both the R and B color difference signals becomes zero.

By controlling the gains KR and KB in this manner, white balance adjustment can be performed.
Finally, the chrominance signal is modulated by a modulator 114 using a chrominance carrier, added to a luminance signal, and output as a composite video signal.

Here, it should be noted that the means 109 for generating a determination pulse for distinguishing a dark area from a bright area by comparing the luminance signal of a long-time exposure image with the synthesis level is provided on the dynamic range expansion signal processing circuit side. Along with the main signal processing circuit, an area designating means 115 is provided on the side of the main signal processing circuit for selecting each of the bright and dark areas of the color difference signal inputted to the circuit for detecting the average value of the color difference signal by the determination pulse. Therefore, the color difference signal in either the bright or dark region can be selected by controlling the determination pulse. The selected color difference signal is a means for creating an average value of the color difference signals.
The data is input to the microcomputer 117 via the microcomputer 116.

FIG. 2A shows light / dark areas (short / lon).
An example is shown in which a determination pulse is output by detecting a (g region). For a luminance signal, the brightness level (short
If the following is a dark region (long region), the region discrimination pulse is as shown in FIG. 2A. If this is treated as region designation control information, the Low period of the region discrimination pulse is lo.
The color difference signal of the ng region and the High period can be extracted as the color difference signal of the short region.

The microcomputer 117 has white balance gain control software, and performs feedback control of the white balance control multiplier 112 so that the average value of the color difference signal becomes equal to the reference value.

FIG. 2B shows the concept of operation timing for explaining white balance correction control in the present embodiment. This shows the processing contents of the software for executing the white balance control, with the horizontal axis representing time.

First, white balance adjustment in the dark area (long area) is performed by the white balance adjustment multiplier 112 in the main signal processing circuit. The color difference signal average value data at this time is created from the color difference signals in the dark region by the light / dark region discrimination pulse. The completion of the adjustment of the white balance in the dark area is recognized by detecting that the color difference average value signal has become zero.

Next, the area designation by the light / dark area discrimination pulse is set to a light area (short area), a color difference signal of the light area is detected, and a short time is set so that the average value of the color difference signal becomes equal to the reference value. The gain of the multiplier 108 capable of gain control is calculated for each pixel of the time-exposure image signal, and the white balance of the short-time exposure image is adjusted. At this time, the gain of the white balance adjustment multiplier 112 in the main signal processing circuit is fixed.

As described above, the white balance adjustment in the dark area is performed by controlling the white balance adjustment multiplier in the main signal processing circuit based on the average value of the color difference signals in the dark area. The control is performed by controlling the multiplier 108 in the dynamic range expansion signal processing circuit capable of controlling the gain for each pixel of the short-time exposure image signal based on the average value of the color difference signals in the bright region, and the two types of control loops are alternately performed. By performing the adjustment, the white balance is adjusted.

According to the above configuration and operation, correct white balance can be simultaneously performed both indoors and outdoors.

[0034]

As described above, according to the present invention, there are provided an image pickup device which alternately outputs two kinds of video signals having a long exposure time and a short exposure time within one field period, a long exposure image signal and a short exposure image signal. Means for synthesizing the exposure image signal at a predetermined luminance level, and means for controlling a multiplier capable of controlling the gain of the short-time exposure video signal for each pixel in order to perform white balance adjustment of the short-time exposure image before synthesis. Means for controlling a multiplier for performing white balance adjustment of a long-exposure image after image synthesis, means for generating a color difference signal, and means for detecting an average value of the color difference signal. By adjusting the white balance of the long-exposure image and the short-exposure image in a time-sharing manner from the average value, the exposure amount when combining subjects with different color temperatures such as indoors and outdoors As it is the white balance adjusted independently two different video signals, the room, the excellent effect of being able to provide an image pickup apparatus may perform the correct white balance correction simultaneously to the outdoor both obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing functional blocks for realizing white balance correction control in an imaging apparatus according to an embodiment of the present invention;

FIG. 2A is an explanatory diagram for detecting a long / short region and outputting a determination pulse according to the embodiment, and FIG.
FIG. 9 is a diagram showing a concept of operation timing for explaining white balance correction control in the present embodiment,

FIG. 3 is a diagram showing functional blocks for realizing white balance correction control in a conventional imaging apparatus.

[Description of Signs] 1, 101 Image sensor 2, 102 Pre-processing such as CDS, AGC, etc. 3, 103 A / D converter 4, 104 Time axis converter 5, 105 Means for separating a luminance signal and a color modulation component ( Filters 6, 106 Combining means for luminance signal and color signal 7, 107 Gradation correcting means 8, 110 Separating means for luminance signal and color signal in main signal processing circuit 9, 111 Separates color signals into RGB primary colors Means 10, 112 Multiplier for white balance adjustment in main video signal processing circuit 11, 113 Subtractor for color difference signal creation 12, 114 Means for modulating color difference signal with color carrier 13, 116 Creates average value of color difference signal Means 14, 117 Microcomputer 108 White balance adjustment multiplier dedicated to short-time exposure image signal 109 Area detection pulse creation means 115 Area designation means

Claims (3)

[Claims] An image pickup device for alternately outputting two kinds of video signals having a long exposure time and a short exposure amount within one field period, and a long-time exposure image signal and a short-time exposure image signal at a predetermined luminance level. Means for controlling the multiplier which can control the gain of the short-time exposure video signal for each pixel in order to adjust the white balance of the short-time exposure image before the synthesis, and a long-time exposure image after the image synthesis. Means for controlling a multiplier to perform white balance adjustment, means for creating a color difference signal, and means for detecting an average value of the color difference signals. An imaging apparatus, wherein white balance adjustment between an exposure image and a short-time exposure image is performed. 2. A means for generating a discrimination pulse for distinguishing between a dark area and a light area by comparing a luminance signal of a long-time exposure image with a synthesis level, and generating a discrimination pulse for each of the light and dark areas by the generated discrimination pulse. 2. The imaging apparatus according to claim 1, further comprising means for selecting a color signal, wherein an average value of the color difference signals of the light and dark areas is detected after selecting the color signal of each of the light and dark areas. 3. A means for detecting activation of a white balance adjustment operation by creating an average value of color difference signals, first performing white balance adjustment of a long exposure image, and then performing white balance adjustment of a short exposure image. 2. The apparatus according to claim 1, further comprising means for detecting completion of each other's white balance adjustment operation for performing the adjustment, and controlling the white balance adjustment of the long-time exposure image and the short-time exposure image in a time division manner.
An imaging device according to any one of the preceding claims.