JPH08181922A - Imaging device - Google Patents

Abstract

PURPOSE: To pick up a video image with high quality and less noise by compositing plural video signals whose signal level is controlled by a control means. CONSTITUTION: Plural video signals obtained by changing an image forming position on a light receiving face of a CCD 3 by a VAP image forming position change means 1 are stored in memories 9-1 to 9-4. A mean luminance level of the plural video signals is calculated by a mean value calculation circuit 10 and a gain set by a gain setting circuit 11 accordingly is multiplied with the video signals stored in the memories 9-1 to 9-4 by multipliers 12-1 to 12-4. Then the products are composited in a signal processing circuit 13 and is outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device for picking up an image of a subject.

[0002]

2. Description of the Related Art At present, an image pickup device for printing or a computer using a solid-state image pickup device such as a CCD arranged two-dimensionally has a shortage of total pixels as compared with a one-dimensional pixel arrangement such as a scanner. However, there is a problem that the resolution of the obtained image is low and a high quality output image cannot be obtained. To solve such a problem, by synthesizing images of four frames, which are obtained by shifting the image forming position of the optical image formed on the light receiving surface of the solid-state image pickup device in units of 1/2 pixel vertically and horizontally, for example, Attempts have been made to reconstruct a high definition image with four times the number of pixels.

For example, a method of displacing a CCD horizontally and vertically by using a piezoelectric element described in JP-A-64-69160, and between an image pickup lens system and a CCD described in JP-A-63-284979. A method of improving apparent resolution by a method using the provided optical optical path displacing means is disclosed. In addition, JP-A-4-3114
In 48, Vari-Angle-Prism (VA
P) is used.

[0004]

However, in the above-mentioned conventional example, when the amount of light hitting the subject being photographed changes while capturing still images for four frames, for example, a level difference occurs for each pixel when the images are combined. Therefore, there is a problem that this becomes a carrier component and leads to image quality deterioration.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and in an image pickup device, a photoelectric conversion means for photoelectrically converting an optical image into a video signal and the photoelectric conversion means are provided. An image forming optical system for forming an optical image, an image forming position changing means for changing an image forming position of the optical image on the photoelectric converting means by the image forming optical system, and the photoelectric conversion by the image forming position changing means. Storage means for storing a plurality of video signals having different image-forming positions obtained by being photoelectrically converted by the photoelectric conversion means when the image-forming position of the optical image on the means is changed to a predetermined position; Calculating means for calculating the average signal level of the video signal, and control means for controlling the signal levels of the plurality of video signals stored in the storage means according to the signal level calculated by the calculating means,
And a synthesizing unit for synthesizing a plurality of video signals whose signal levels are controlled by the control unit.

[0006]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of the configuration of an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes Vari, which is an image forming position changing means.
-Angle-Prism (VAP), 2 is an imaging lens system which is an imaging optical system, and 3 is a CCD (Charge-couple) which is photoelectric conversion means.
d device), 4 is a double correlation sampling (CDS) circuit, 5 is an automatic gain control (AGC) circuit, 6
Is an A / D converter.

Reference numeral 7 is a first switch, 8 is a second switch, 9-1 is a first frame memory, 9-2 is a second frame memory, 9-3 is a third frame memory, and 9-4.
Is a fourth frame memory. This frame memory 9
A storage unit is composed of -1 to 9-4.

Reference numeral 10 is an average value calculation circuit which is a calculation means.
1 is a gain setting circuit, 12-1 is a first multiplier, 12-
2 is a second multiplier, 12-3 is a third multiplier, 12-4
Is a fourth multiplier. The gain setting circuit 11 and the multipliers 12-1 to 12-4 constitute a control means. Thirteen
Is a signal processing circuit which is a synthesizing means, 14 is an output terminal, and 15
Is a control circuit, 16 is a horizontal VAP actuator, 1
Reference numeral 7 is a vertical VAP actuator.

Next, the operation of the embodiment of the present invention will be described with reference to FIG. The optical image formed on the light receiving surface of the CCD 3 through the VAP 1 and the imaging lens system 2 is photoelectrically converted, noise is removed by the double correlation sampling circuit 4, and the AGC circuit 5 is used.
After the gain is controlled by, the digital signal is converted by the A / D converter 6. Then, it is input to the first switch 7. The output of the first switch 7 is divided into four, 0 to 3, which are respectively connected to the memories 9-1 to 9-4. Also, the outputs 0 to 3 of the first switch 7
Are also connected to the inputs 0 to 3 of the second switch 8, respectively, and the output of the second switch 8 is the average value detection circuit 1
Input to 0.

The control circuit 15 sets the image forming position of the optical image on the light receiving surface of the CCD 3 to the first position which is the first position,
A second position horizontally displaced from the first position by 1/2 pixel, a third position horizontally displaced from the first position by 1/2 pixel in the vertical direction, and a first position displaced from the first position. Sequential control is performed so that the fourth position is shifted by 1/2 pixel in the vertical direction. At the same time, the first switch 7 and the second switch 8
Are 0, 1, respectively when they are in the respective image forming positions.
It is controlled so as to switch to 2 and 3.

By the above operation, the image signal of the CCD 3 is
After noise reduction, gain control, and digital conversion, the image at the first position is stored in the first frame memory 9-
The images at the first and second positions are the second frame memory 9-2,
The image at the third position is the third frame memory 9-3, the fourth
The images at the positions are sequentially stored in the fourth frame memory 9-4.

On the other hand, the average value calculation circuit 10 calculates the average level of the digital video signal input through the second switch 8. Here, for example, even if the signal from the CCD 3 is a signal including the color carrier component of the complementary color mosaic, the average value thereof represents the brightness level. Therefore, the output of the average value calculation circuit 10 indicates the brightness level of each imaged frame, and the gain setting circuit 11 determines the gain according to the calculated brightness level, and each multiplier 12-1.
12-4, the gains of the digital video signals stored in the memories 9-1 to 9-4 are multiplied.
Then, the video signals are combined in the signal processing circuit 13 and output from the output terminal 14.

As a result, the digital video signals for four frames input to the signal processing circuit 13 become signals with uniform brightness levels, and are combined in the signal processing circuit 13 even if the illuminance of the subject changes during the image pickup process. The image quality is not impaired.

Since the AGC circuit 5 performs a rough gain control to operate when it is necessary to apply a large gain, mainly when picking up an image of a low illuminance object, the video signal is used here. It is not possible to exactly align the brightness levels of. In addition, the change in the imaging position is
Needless to say, it does not have to be.

With the above-mentioned structure, it is possible to capture and combine high-quality still images even when the light amount changes during photography.

[0017]

As described above, according to the present invention, in the image pickup device, photoelectric conversion means for photoelectrically converting an optical image into a video signal,
An image forming optical system for forming an optical image on the photoelectric converting means, an image forming position changing means for changing an image forming position of the optical image on the photoelectric converting means by the image forming optical system, and the image forming position. A plurality of video signals having different image forming positions obtained by being photoelectrically converted by the photoelectric converting unit when the image forming position of the optical image on the photoelectric converting unit is changed to a predetermined position by the changing unit are stored. Storage means, calculation means for calculating an average signal level of the plurality of video signals, and control for controlling signal levels of the plurality of video signals stored in the storage means according to the signal levels calculated by the calculation means And a synthesizing means for synthesizing a plurality of video signals whose signal levels are controlled by the control means.

With the above-mentioned structure, it is possible to capture and combine high-quality still images even when the light amount changes during photography.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of an image pickup apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 1 VAP 10 Average value calculation circuit 11 Gain setting circuit

Claims (5)

[Claims] 1. A photoelectric conversion means for photoelectrically converting an optical image into a video signal, an imaging optical system for forming an optical image on the photoelectric conversion means, and an optical system on the photoelectric conversion means by the imaging optical system. Image forming position changing means for changing the image forming position of the image, and photoelectric conversion means for converting the image forming position of the optical image on the photoelectric converting means to a predetermined position by the photoelectric converting means. A storage unit for storing a plurality of video signals having different image-forming positions obtained by conversion, a calculation unit for calculating an average signal level of the plurality of video signals, and Control means for controlling the signal levels of the plurality of video signals stored in the storage means, and synthesizing means for synthesizing the plurality of video signals whose signal levels are controlled by the control means. Imaging device. 2. The image pickup device according to claim 1, wherein the storage unit is composed of a plurality of storage units. 3. The image pickup device according to claim 1, wherein the signal level is a brightness level. 4. The image pickup device according to claim 1, wherein the photoelectric conversion means is a CCD (Charge-coupled device). 5. The image pickup device according to claim 1, wherein the image forming position changing means is a VAP (Vari-Angle Prism).