JPH02278983A - Still picture pickup device - Google Patents

Abstract

PURPOSE:To attain accurate white balance control by storing a video signal from an image pickup element into a storage means, and using a video signal from the image pickup element to generate a control signal for white balance. CONSTITUTION:The device is provided with a memory 3 storing a still picture video signal of one field or one frame subject to signal processing tentatively, a detection circuit 4 detecting color temperature information of a light source giving radiation to an object or a light source being an object with a video signal from a process signal processing circuit 2 and an arithmetic circuit 5 taking white balance of a video signal from the memory 3. Then the video signal from an image pickup element 1 is stored in the memory 3, while the signal for white balance control is generated from the video signal from the image pickup element 1 to apply white balance control for the video signal read from the memory 3. Thus, white balance control is implemented accurately and image pickup is applied with a small release time lag.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a still image imaging device that performs white balance control using a video signal from an image sensor.

(Prior art) Conventionally, as a white balance control method for a still image imaging device, a colorimetric sensor for detecting color temperature information of a light source is provided in addition to the image sensor, and based on the output of this sensor, an appropriate white balance is determined. The video signal from the image sensor was controlled to achieve balance.

(Problem to be solved by the invention) However, in the conventional example described above, a colorimetric sensor is required in addition to the image sensor, and the color temperature of the light source entering the colorimetric sensor and the subject actually being imaged are If the color temperature of the illuminating light source differs, accurate white balance cannot be achieved.

In addition, in the conventional case, the so-called release time lag occurs because it is necessary to detect color temperature information from a colorimetric sensor and complete preparations for white balance control between pressing the shutter button and the actual exposure. There was a problem with getting bigger.

The present invention has been made to solve these problems, and an object of the present invention is to provide a still image imaging device that can perform accurate white balance and has a small release time lag.

[Means to solve the problem]

In order to achieve the above object, the present invention configures a still image imaging device as follows.

an image sensor, a storage means for writing one field or one frame of a video signal from the image sensor, a detection means for detecting color temperature information of a light source related to a subject from the video signal from the image sensor, and an output of the detection means. and control means for performing white balance control on a video signal read out from the storage means in response to the received image.

[Effect]

1 With the above configuration, the video signal from the image sensor is stored in the storage means, and on the other hand, the signal for white balance control is generated from the video signal from the image sensor.
White balance control can be performed accurately, and photography can be performed with a small release time lag.

〔Example〕

The present invention will be explained below with reference to Examples.

FIG. 1 is a schematic block diagram showing a still image capturing apparatus according to a first embodiment of the present invention. In the figure, 1 is an image sensor, 2 is a circuit block that performs process signal processing of the video signal from the image sensor, and 3 is a memory that temporarily stores the signal-processed still image video signal of one field or i-frame. (storage means), 4 is a detection circuit (detection means) that detects color temperature information of a light source that illuminates the subject or a light source that is the subject (hereinafter referred to as a light source related to the subject) from the video signal from the process signal processing circuit 2; This is an arithmetic circuit (control means) for white balancing the video signal from the memory 3.

White balance control will be explained using FIG. 2, which shows a detailed block diagram of the above-mentioned configuration. In the figure, the image sensor 1 and process signal processing 2 have the same functions as the same code blocks in FIG. is subjected to signal processing in step 2. 11
12.13 is an A/D converter, 14, 15.16 are field or frame memories, and 17.18 is an arithmetic circuit that controls the gains of the R and B video signals from the memory 14.16. 19°20 is a matrix calculation circuit with 5
The color difference signals R-Y and B-Y are generated, respectively. 21.2
2 is an integrator that integrates the RY and BY signals. 23.
24 is an A/D converter which converts the outputs of the integrators 21 and 22 into digital data. 25 is a microcomputer, 26 is a gain control data ROM, and the microcomputer 25 is an A/D converter 23.24
Based on the data, a control amount is selected from the table in the gain control data ROM 26 so as to obtain an appropriate white balance, and is supplied to the gain control calculation circuits 17 and 18.

Circuit for white balance control having the above-mentioned configuration (19
~26: The ability to obtain an appropriate white balance using the color temperature information detection circuit 4) was disclosed in the earlier application published in Japanese Patent Application Laid-open No. 63.
This is explained in detail in Japanese Patent No. 300688, etc., and the explanation here will be omitted.

In this way, since the signal for white balance control is generated from the video signal from the image sensor, the color temperature information of the light source related to the subject can be accurately grasped, and accurate white balance control can be performed.

In addition, since the video signal to be subjected to white balance processing is captured in the field (frame) memories 14 to 16, it is possible to carefully examine the image signal to select appropriate white balance control data, allowing accurate white balance control. It can be performed.

It should be noted that blocks 19 to 26 in FIG. 2 correspond to detection means for detecting color temperature information of a light source regarding a subject as referred to in the claims, and blocks 17 to 18 correspond to control means for performing white balance control as referred to in the claims. corresponds to

FIG. 3 shows a second embodiment of the present invention, which includes an image sensor 1, a process signal processor 2, and an A/D converter ti.

12.13, Field (Frame) Memory 14.1.
5, 16, and gain 11J control calculation circuits 17 and 18 have the same functions as the parts with the same symbols in FIG.

In this embodiment, R, G, and B digital video signals output from the field memories 14, 15, and 16 are used to obtain a white balance control signal. 31.32 is a digital matrix calculation circuit for obtaining color difference signals R-Y, BY, and 33.34 is an integrator for integrating these color difference signals. 35 is a microcomputer, and 36 is a gain control data ROM, which selects a control amount from a table in the gain control data ROM 36 to obtain an appropriate white balance based on the color difference signal integral data of the integrators 33 and 34, and controls the gain. It is supplied to the control calculation circuit 17°1B.

In this embodiment, field (frame) memories 14 and 1 are used as detection signals for white balance.
Since the output signal of 5.16 is used, it is possible to carefully examine the appropriate white balance control data, and the white balance control data can be read out from the memory 14.16 many times to correct the white balance control data. is possible.

Further, a third embodiment will be explained. Instead of the feed-forward control regarding the white balance in the second embodiment described above, the output signals of the gain control calculation circuits 17 and 18 and the field (frame) memory 15 are used as feedback signals to perform feedback control regarding the white balance. This allows for more accurate white balance control.

The operation of each of the above embodiments is schematically shown in a flowchart as shown in FIG.

(Effects of the Invention) As described above, according to the present invention, a video signal from an image sensor is stored in a storage means, and a control signal for white balance is generated using the video signal from the image sensor. This allows accurate white balance control and reduces release time lag.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a first embodiment of the present invention;
3 is a block diagram of the second embodiment of the present invention, and FIG. 4 is a flowchart schematically showing the operation of each embodiment. 1.-Image sensor 3...Field (frame) memory (storage means) 4
-Color temperature +1IIfIi detection circuit (detection means) 5...
・Arithmetic circuit (control means)

Claims (1)

[Claims] an image sensor, a storage means for writing one field or one frame of a video signal from the image sensor, a detection means for detecting color temperature information of a light source related to a subject from the video signal from the image sensor, and an output of the detection means. and control means for performing white balance control on a video signal read out from the storage means in response to the received image.