JP3063097B2 - Imaging device - Google Patents

Description

The present invention relates to an imaging device such as a television camera,
In particular, it relates to control of a luminance component level of an imaging output.

B. Summary of the Invention The present invention is directed to an imaging apparatus such as a television camera, in which the detection outputs of the respective color components separated from the imaging output are respectively weighted, and the weighted detection outputs are selectively used to selectively use the luminance components of the imaging output. By controlling the level, control of the luminance component level according to the color of the subject is realized.

C. Conventional Techniques In an imaging device such as a television camera, it is necessary to appropriately set a luminance component level of an imaging output in order to image the atmosphere of a subject without disturbing the atmosphere. Conventionally, various techniques for automating it have been proposed and put into practical use.

FIG. 3 shows a configuration example of a conventional imaging device. In this imaging device, a subject image given via a lens 31 is captured by an imaging element 32, and an imaging output of the imaging element 32 is taken out from a sample and hold circuit 33. The image sensor 32 is provided between the lens 31 and the image sensor 32.
An aperture plate 34 is provided to limit the amount of light reaching the aperture, and the size of the aperture opening formed by the aperture plate 34 is changed to a detection output obtained by detecting the output of the sample hold circuit 33 by the iris detection circuit 35. It is controlled accordingly. It is also known that a so-called electronic shutter that controls the light receiving time of the image sensor 32 instead of the aperture plate 34 in order to limit the amount of light received by the image sensor 32 is known. The video output taken out from the sample hold circuit 33 is guided to an AGC circuit 36, the amplitude of which is adjusted, and then applied to a color separation circuit 37 and a low-pass filter (LPF) 38 to be divided into a color signal and a luminance signal. . AGC circuit 3 above
The gain of 6 is configured to perform negative feedback control according to the detection output of the output of the AGC circuit 36 detected by the AGC detection circuit 39.

In this imaging device, the size of the aperture opening of the aperture plate 34 and the gain of the AGC circuit 36 are controlled so that the luminance component level of the imaging output becomes appropriate. And
Conventionally, these controls are performed by the iris detection circuit 35 or the AG, as disclosed in, for example, JP-A-57-4666.
The average value and the peak value of the luminance component level of the video output have been set to predetermined values by the C detection circuit 39.

D. Problems to be Solved by the Invention However, in such a conventional imaging apparatus, since the luminance component level of the video output is controlled by the luminance regardless of the color of the subject, the luminance level may be inappropriate depending on the color of the subject. In some cases, the image became unnatural.

That is, for example, when a snow scene or the like is imaged at a ski resort, setting a higher luminance component level of the imaging output makes the white lighter and the atmosphere is better transmitted. However, if the same setting is used to image, for example, a person against the background of a lawn, the green color is too bright to produce an unnatural image. For this reason, the luminance component level of the imaging output is generally set so that the latter can be imaged well. However, in such a case, the white color of the snow becomes gray at a ski resort, and an unnatural image is obtained. turn into.

The present invention has been made in view of such circumstances, and enables a luminance component level of an imaging output to be set in accordance with the color of a subject so that the subject can be captured in a natural atmosphere in various scenes. It is an object of the present invention to provide an imaging device that can perform the imaging.

E. Means for Solving the Problems In order to achieve the above object, an image pickup apparatus according to the present invention is a color image pickup apparatus that separates an image pickup output obtained by imaging an object through an image pickup optical system into respective color components. Separation means, detection means for detecting the output of each color component from the color separation means, weighting means for weighting the detection output of each color component from the detection means, and output of each color component from the color separation means Color discriminating means for discriminating the color of the subject by comparing the signal levels of the object and a weighting value corresponding to the color of the subject based on the color discriminating output of the color discriminating means. Weight control means for controlling the degree of weighting of the object, and the maximum level of the detection output of each color component weighted by the detection means with a weight value corresponding to the color of the subject. Comprising a control means for performing level control of the aperture control with the imaging output of said imaging optical system selectively using one of Le.

F. Action In the imaging apparatus according to the present invention, based on the color discrimination output by the color discrimination means for discriminating the color of the subject by comparing the signal level of the output of each color component from the color separation means, by the weight control means, A weighting value corresponding to the color of the subject is given to the weighting means, the degree of weighting of the weighting means is automatically controlled, and each color component weighted by the weighting means with the weighting value corresponding to the color of the subject The aperture control of the image pickup optical system and the level control of the image pickup output are performed by selectively using the maximum level of the detection outputs.

G. Examples Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram illustrating a configuration of the imaging apparatus 1 according to the first embodiment.

The image pickup apparatus 1 picks up an image of a subject given through a lens 2 with an image pickup device 3 such as a CCD.
Is output from the sample and hold circuit 4 to the low pass filter (LPF) 6 via the AGC circuit 5 to generate a luminance signal, and the output of the AGC circuit 5 is output to the color separation circuit 7.
To generate three primary color (R, G, B) color signals having a balanced white balance, and to supply these luminance signals and color signals to subsequent circuits.

Between the lens 2 and the image sensor 3, an aperture plate 8 driven by a drive motor (not shown) to change the size of the aperture is provided to limit the amount of light reaching the image sensor 3. ing.

Further, the three primary colors (R, G,
The color signal B) is supplied to the control unit 9. The color signals from the color separation circuit 7 are detected by the detection circuits 10R, 10G, and 10B, respectively, in the control section 9, and become detection outputs according to the color component levels of the three primary colors of the video signal. And
This detection output is appropriately weighted by each of the weighting circuits 11R, 11G, and 11B. These weighting circuits 11R, 11G, 11
The degree of weighting of B is variable, and is set by the user so as to obtain a good image as described later. Further, these weighted detection outputs are supplied to a control circuit 12, and the control circuit 12 selectively extracts the maximum level of the detection outputs. The output of the control circuit 12 is supplied to a drive motor for driving the AGC circuit 5 and the aperture plate 8, and the output controls the gain of the AGC circuit 5 and the size of the aperture of the aperture plate 8 Controlled.

Here, the degree of weighting by the weighting circuits 11R, 11G, 11B is set as follows according to the color of the subject. That is, when a subject that is mostly white is photographed, such as a ski resort or a desert on a sunny day, the white level is set to 70 to 80% so that the part is photographed brightly in white. Also, when photographing a subject that is mostly red, the white level is set to about 40% so that the part is photographed in natural red. In this way, the degree of weighting is set so that an optimum white level is obtained according to the color of the subject.

The supply of the weighted detection output allows the control circuit 12 to control the aperture of the aperture plate 8 and the gain of the AGC circuit 5 according to the color of the subject, thereby obtaining the luminance component of the video signal. The level is optimized according to the color of the subject.

Therefore, the image pickup apparatus 1 can optimize the luminance component level of the image pickup output according to the color of the subject. The subject can be imaged in a natural atmosphere.

As a mechanism for controlling the amount of light received by the imaging device 3, the shutter speed of the electronic shutter of the imaging device 3 can be varied according to the control output of the control circuit 12 in addition to the mechanism using the aperture plate 8. It can also be used.

FIG. 2 is a block diagram showing the configuration of the imaging device 20 of the second embodiment.

The imaging device 20 adds a comparison circuit 21 and a memory table 22 to the control unit 9 of the imaging device 1 of the first embodiment, and automatically determines the degree of weighting of the weighting circuits 11R, 11G, and 11B. This is to be set. That is,
The output of the color separation circuit 7 is output from each of the detection circuits 10R, 10G, 10
B and to the comparison circuit 21. The comparison circuit 21 determines the color of the subject by comparing the levels of the respective color signals, and supplies an output indicating the determination result to the memory table 22. This memory table
In the area 22, an optimal weighting value according to the color of the subject is stored in advance. When the output indicating the color of the subject is supplied from the comparison circuit 21, the memory table 22
Reads out the optimal weighting value according to the color of the subject and gives it to each of the weighting circuits 11R, 11G, and 11B. As a result, the weighting circuits 11R, 11G, and 11B set optimal weighting degrees in accordance with the color of the subject.

With such a configuration, the imaging device 20
Automatically sets the optimal luminance component level of the imaging output according to the color of the subject, so that the subject can be imaged in a natural atmosphere in various scenes without forcing the user to perform cumbersome setting operations. Become.

In each of the above embodiments, the three primary colors (R, G, B)
Although the aperture control and the AGC control are performed using the color signals described above, the control can be similarly performed using a complementary color signal or a color difference signal. If the processing of the control unit 9 is digital information processing using a microcomputer, complicated control according to the color of the subject, such as changing the degree of weighting according to the saturation of the color of the subject, can be easily performed. It is also possible to realize.

H. Effects of the Invention In the imaging apparatus according to the present invention, the weight control unit is based on the color determination output by the color determination unit that determines the color of the subject by comparing the signal levels of the outputs of the respective color components from the color separation unit. Thus, the weighting value according to the color of the subject is given to the weighting means, the degree of weighting of the weighting means is automatically controlled, and the weighting is performed by the weighting means with the weighting value according to the color of the subject. The aperture control of the imaging optical system and the level control of the imaging output are performed by selectively using the maximum level of the detection output of each color component, so that the optimal luminance component level of the imaging output according to the color of the subject. It can be set, and the subject can be imaged in various situations in a natural atmosphere.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention, and FIG. 2 is a block diagram showing a configuration of a second embodiment of the present invention. FIG. 3 is a block diagram showing a configuration of a conventional imaging device. DESCRIPTION OF SYMBOLS 1 ... Image pick-up device 3 ... Image pick-up element 5 ... AGC circuit 7 ... Color separation circuit 8 ... Aperture plate 9 ... Control part 10R, 10G, 10B ... Detection circuit 11R, 11G, 11B ... Weighting circuit 12 ...... Control circuit

Continuation of front page (56) References JP-A-1-109983 (JP, A) JP-A-1-103074 (JP, A) JP-A-1-101091 (JP, A) JP-A-62-25598 (JP) JP-A-1-120191 (JP, A) JP-A-63-104591 (JP, A) JP-A-63-104033 (JP, A) JP-A-60-150392 (JP, A) 2-276380 (JP, A) Fully open 1979-40720 (JP, U) Fully open 1979-63815 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 9/07 H04N 9/77 H04N 9/64

Claims (1)

(57) [Claims] 1. A color separation means for separating an imaging output obtained by imaging an object through an imaging optical system into respective color components, and a detection means for detecting the output of each color component from the color separation means. A weighting means for weighting the detection output of each color component from the detection means, a color discrimination means for discriminating the color of the subject by comparing the signal level of the output of each color component from the color separation means, Weighting means for giving a weighting value according to the color of the subject based on the color discrimination output by the discriminating means to the weighting means, and controlling the degree of weighting of the weighting means; The aperture control of the imaging optical system and the imaging output are selectively performed by selectively using the maximum level of the detection output of each color component weighted by the detection means. Imaging apparatus characterized by comprising a control means for performing level control.