JP2000299870A - Digital camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital camera which records a subject by an optical sensor using either of a complementary color filter or a primary color filter in response to a photographing situation, thereby outputting a picture of a different picture tone. SOLUTION: This digital camera is provided with a complementary color system CCD 14 and a primary color system CCD 15 and allows either of the complementary color system CCD 14 and the primary color system CCD 15 to receive a light from an object by using a moving mirror 13 to switch an optical path. An A/D converter 16 executes different image correction processing between an output signal from the complementary color system CCD 14 and an output signal from the primary color system CCD 15. Thus, a CCD used for photographing is selected depending on the photographing situation and a picture of a different picture tone is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital camera that converts light from a subject into image data and records the image data.

[0002]

2. Description of the Related Art Conventionally, CCD (Charge Coupled Device)
2. Description of the Related Art There is known a digital camera that converts light into an electric signal using an optical sensor such as an optical sensor, converts the electric signal into image data, and records the image data on a recording medium such as a flash memory. Initially, most digital cameras used CCDs for video cameras, and most of them adopted CCDs of the complementary color filter interlaced scan type. After that, CCD for exclusive use with digital camera adopting the progressive scan method of primary color filter with excellent color reproducibility and excellent S / N ratio
Was developed and widely used for digital cameras.

A CCD using a complementary color filter (hereinafter, a CCD using a complementary color filter is referred to as a "complementary color CCD").
Is subtracted using two colors of R (Red), G (Green), and B (Blue) included in each color of C (Cyan), M (Magenta), and Y (Yellow) to perform RGB CCD using a primary color filter because the calculation to derive
(Hereinafter, a CCD using a primary color filter is referred to as a “primary color CC
D ". ) Is characterized by poor color reproducibility. Further, since the complementary color filter has twice the transmittance of the primary color filter, the complementary color CCD has a characteristic that the sensitivity is twice as high as that of the primary color CCD.

For this reason, a digital camera is provided with a complementary color CCD.
Is used, a calm tone image can be obtained.
When a CD is used, an image with a vivid tone can be obtained. On the other hand, complementary color CCDs are superior in edge processing, and each has advantages and disadvantages in image quality.

[0005]

However, with the adoption of megapixel CCDs in digital cameras, the light receiving area of each photodiode constituting the CCD has been reduced, and high resolution has been realized. Digital cameras have to employ complementary color CCDs with excellent sensitivity in order to compensate for the absolute lack of light quantity of the photodiodes. Therefore, in order to obtain high resolution, a complementary color CCD
The digital camera adopting the method has a problem that it has a drawback of a complementary color CCD which has a lot of noise and poor color reproducibility.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object is recorded by an optical sensor using either a complementary color filter or a primary color filter in accordance with a photographing situation, so that a different image quality is obtained. It is an object of the present invention to provide a digital camera that outputs an image.

Another object of the present invention is to provide a digital camera having a function capable of switching between photographing giving priority to resolution and photographing giving priority to color reproducibility according to the situation.

[0008]

According to a first aspect of the present invention, an image pickup unit includes a primary color filter that transmits primary color light, a complementary color filter that transmits complementary color light, and a photoelectric conversion unit. Light transmitted through the filter or the complementary color filter is received by a photoelectric conversion unit and converted into an electric signal. The switching means transmits light from the subject to one of the primary color filter and the complementary color filter and causes the photoelectric conversion means to receive the light. The conversion unit converts an output signal of the imaging unit into image data. The storage unit records the image data. The control unit controls the imaging unit, the switching unit, the conversion unit, and the storage unit. For this reason, the filter used for photographing is switched by the switching means, and the output signal of the imaging unit is converted into image data in accordance with the switching, whereby an image having a different tone can be output.

According to the digital camera of the second aspect of the present invention, the imaging section has a primary color optical sensor having a primary color filter and photoelectric conversion means and a complementary color optical sensor having a complementary color filter and photoelectric conversion means. , Calibration is easy. When the number of pixels of the complementary color light sensor is larger than the number of pixels of the complementary color light sensor, it is possible to switch between photographing giving priority to resolution and photographing giving priority to color reproducibility according to the situation.

According to the digital camera of the third aspect of the present invention, the switching means changes the optical path of the light from the subject using the optical system, so that it can be switched to either the primary color optical sensor or the complementary color optical sensor. Since the light from the subject is incident, the structure can be simple.

According to the digital camera of the fourth aspect of the present invention, the switching means moves one of the primary color light sensor and the complementary color light sensor on the optical path of the light from the subject, thereby changing the primary color light. Light from a subject is made incident on one of the sensor and the complementary color light sensor. Therefore, the physical size of the digital camera can be reduced.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; (First Embodiment) As shown in FIG. 1, a digital camera 1 according to a first embodiment of the present invention
2. Movable mirror 13 as switching means, complementary color CCD 1
4 and an primary color CCD 15; an A / D converter 16; and a RAM 17 (Rando) for temporarily storing image data.
m Access Memory), a flash memory 18 for recording image data, a liquid crystal display (LCD) 21 for displaying images,
It comprises a VRAM 20 for storing data for an image to be displayed on the liquid crystal display device, an interface 19 for outputting data from the flash memory 18 to an external device, and the like.

The control unit 11 includes a CPU (not shown), a ROM (not shown) in which programs for performing various controls of the digital camera 1 are recorded, and input / output means. The input means includes a shutter button for instructing execution of photographing and an input button for operating various functions of the digital camera. The condenser lens 12 is provided with a stop and a shutter (not shown) for adjusting the amount of light incident on the condenser lens 12. The movable mirror 13 as a switching means includes a mirror rotatably supported by a casing (not shown) and a driving means (not shown) for rotating the mirror.

The complementary color CCD 14 is C, M, Y, or G
A one-shot type in which photodiodes as a plurality of photoelectric conversion means for arranging any of the complementary color filters transmitting light of the wavelength on the light receiving surface in a matrix. The complementary color filter may transmit CMY monochromatic light. The primary color system CCD 15 is a one-shot type in which a plurality of photodiodes as photoelectric conversion means for arranging, on a light receiving surface, one of primary color filters transmitting light of R, G, or B wavelength is arranged in a matrix. .

A DRAM (Dynamic RAM) having a self-refresh function is used as the RAM 17 as a storage means. The flash memory 18 is a rewritable recording medium capable of holding recorded contents without power supply, and is built in the digital camera 1 or is detachably attached to the digital camera 1. By using a memory card conforming to the PCMCIA standard or a memory card attachable to a PCMCIA card adapter as the flash memory 18, the contents of the flash memory 18 can be directly read and written by a personal computer having a PCMCIA card slot.

Hereinafter, the operation of the digital camera 1 will be described. As shown in FIGS. 1 and 2, when the movable mirror 13 is rotated by the driving means, the optical path is changed so that light from the subject passes through the condenser lens and enters one of the complementary color CCD 14 and the primary color CCD 15. Is done. The driving unit is controlled by the control unit 11, and by operating an input button, it is possible to switch which CCD is used to shoot a subject.

When the user presses the shutter button,
All the electric charges accumulated in the imaging unit are once discharged, and then the light condensed by the condenser lens and incident on the imaging unit is converted into electric charges according to the light amount.

When light from a subject is received by the imaging unit,
After the charge is accumulated in the photodiode for a predetermined period, the accumulated charge is discharged, and an output signal is transmitted from the complementary color CCD 14 or the primary color CCD 15. Complementary color CCD1
The electric signal output from the CCD 4 or the primary color system CCD 15 is converted into digital data by an A / D converter 16 as conversion means, and the digital data output from the A / D converter 16 is DMA ( Direct Memory Acces
According to s), the address is directly specified and stored in the RAM 17 without going through the control unit. The image data stored in the RAM 17 is subjected to image correction such as white balance adjustment, interpolation processing, and color correction by a program stored in the ROM. This image correction process is performed using different algorithms when the subject is photographed by the complementary color CCD 14 and when the subject is photographed by the primary color CCD 15.

The corrected image data is stored in a JPEG (Joint P
The image data is compressed by the irreversible compression method according to the standard of the Hotographic Experts Group, and small-sized image data is generated. JPEG is a commonly used image compression method that can handle an image of about 16.7 million colors, and the storage image quality can be adjusted by changing the compression ratio. JP
The EG compression is performed by software by the control unit 11, and a dedicated circuit can be used for speeding up. The JPEG-compressed image data is recorded in the flash memory 18.

It may take several seconds to several tens of seconds from the start of the recording of the image data to the flash memory 18 to the completion thereof, during which time the LCD 21 keeps displaying the image based on the image data.

In recent years, megapixel CCDs have been used in popular digital cameras, and photodiodes have been highly integrated. Comparing a 350,000 pixel CCD and a 1.3 million pixel CCD of the same size, 13
The area of one photodiode used for a CCD of 100,000 pixels is about ４ of that of a photodiode used for a CCD of 350,000 pixels. The area of the photodiode is 1 /
When the number is 4, the variation in image information and the S / N ratio are deteriorated, and the amount of light that can be absolutely received by the photodiode decreases. To avoid this, open the aperture and increase the amount of light received by the CCD within a certain period of time, or reduce the shutter speed to
It is necessary to lengthen the period during which D receives light. However, there is a limit to the amount of opening the aperture, and if the shutter speed is slowed down for a certain period of time, the so-called "shake" during shooting
Occurs. For this reason, a complementary color CCD having a light transmittance twice as high as that of the primary color CCD is used for the CCD having a high integration ratio.

On the other hand, the complementary color CCD derives RGB by performing a subtraction process on the basis of G at the stage of conversion into RGB, and this operation causes dropout of the number of significant digits. Noise occurs more frequently than primary color CCDs, such as poor color quality, lack of resolution, uneven hue in the monochromatic gradation area, and incompatibility of colors in the highlights of metallic objects. Get up.

Taking into account the respective disadvantages and advantages of the complementary color CCD and the primary color CCD, photographing using a high-resolution complementary color CCD does not always achieve a preferable image expression for a user. When a complementary color CCD and a primary color CCD having the same number of pixels are compared,
As the shutter speed increases, the amount of light that can be received by the CCD decreases, and it may be difficult to express a wide gradation with a primary color CCD.

Since the digital camera 1 according to the first embodiment of the present invention includes both the complementary color CCD 14 and the primary color CCD 15, it is possible to obtain a high-resolution image by utilizing the characteristics of the complementary color CCD, A fast subject can be expressed with rich gradations, and an image with excellent color reproducibility can be obtained by utilizing the characteristics of the primary color CCD. For this reason, a digital camera capable of expressing a wide range of images can be realized by allowing the user to use each CCD properly.

(Second Embodiment) FIG. 3 shows a digital camera 2 according to a second embodiment of the present invention. Parts substantially the same as those in the first embodiment are denoted by the same reference numerals.

The switching means comprises a rotating part 22 in which the complementary color CCD 14 and the primary color CCD 15 are arranged to face in opposite directions, and a driving means 23 for inverting the rotating part 22 by 180 °. When the rotating unit 22 is rotated by the driving unit 23, the complementary color CC is placed on the optical path of the light from the subject.
Either D14 or the primary color CCD 15 is localized. The driving unit 23 is controlled by the control unit 11 and can switch which CCD is used to photograph the subject by operating an input button.

Although the present embodiment has been described assuming that the primary color light or the complementary color light is photoelectrically converted by using the complementary color CCD and the primary color CCD, the same effect can be obtained by switching only the filter covering the photodiode. It is possible to obtain

[Brief description of the drawings]

FIG. 1 is a block diagram showing a digital camera according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a digital camera according to a first embodiment of the present invention.

FIG. 3 is a block diagram illustrating a digital camera according to a second embodiment of the present invention.

[Explanation of symbols]

 1, 2 Digital camera 11 Control unit 12 Condenser lens 13 Movable mirror (switching means) 14 Complementary color CCD 15 Primary color CCD 16 A / D converter (converting means) 17 RAM (storage means) 22 Rotating body (switching means) 23 Driving device (switching means)

Claims (4)

[Claims] 1. A primary color filter that transmits primary color light, a complementary color filter that transmits complementary color light, and a photoelectric conversion unit, wherein light transmitted through the primary color filter or the complementary color filter is received by the photoelectric conversion unit and converted into an electric signal. An imaging unit that performs light transmission from an object to one of the primary color filter and the complementary color filter, and a switching unit that causes the photoelectric conversion unit to receive the transmitted light; and converts an output signal of the imaging unit into image data. A digital camera comprising: a conversion unit; a storage unit that stores the image data; and a control unit that controls the imaging unit, the switching unit, the conversion unit, and the storage unit. 2. The imaging device according to claim 1, wherein the image pickup unit includes a primary color light sensor having the primary color filter and photoelectric conversion means, and a complementary color light sensor having the complementary color filter and photoelectric conversion means. Digital camera. 3. The switching unit changes an optical path of light from a subject using an optical system, thereby causing light from the subject to be incident on one of the primary-color light sensor and the complementary-color light sensor. The digital camera according to claim 2, wherein: 4. The switching means according to claim 1, wherein one of said primary color light sensor and said complementary color light sensor is moved on an optical path of light from a subject. 3. The digital camera according to claim 2, wherein light from a subject is incident on one of the sides.