JP2003179804A - Imaging device - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide an imaging apparatus for capturing a still image with high image quality and capable of real-time monitoring. A display image generation unit (5) and a recording image generation unit (9) that performs software processing by a microcomputer, and during monitoring, jump-scan the CCD (2) to generate a real-time display image. At the time of photographing, the CCD is sequentially scanned to generate a recorded image high-quality still image.

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, and more particularly to an image pickup apparatus suitable for still image pickup.

[0002]

2. Description of the Related Art In a conventional image pickup device that performs photoelectric conversion using an image pickup device such as a CCD (Charge Coupled Device) and digitally processes it to obtain a predetermined digital image signal, an analog output from the CCD is usually used. Image signal of A
After performing D / D conversion and converting into a digital signal, predetermined signal processing is performed to generate a digital image signal. Such an image pickup device is generally equipped with hardware for performing a predetermined calculation necessary for generating an image signal, and is characterized by high-speed processing. Such a device is described in, for example, Japanese Patent Application Laid-Open No. 2-280496. In addition, an LS that performs signal processing of such an imaging device
I and its image quality control are described in, for example, the 1991 Television Society Annual Conference Proceedings, pp. 361 to 362. Although this LSI is mainly used for capturing moving images, a device for capturing still images has also been developed, and is described in, for example, 1995, The Photographic Society of Japan, Fine Image Symposium Proceedings, pages 59 to 62. .

However, in the above-mentioned prior art, since the signal processing circuit of the image pickup device is constituted by dedicated hardware, the degree of freedom of signal processing is generally small. If the degree of freedom in signal processing is increased to support a plurality of types of CCDs or complicated signal processing is performed, the circuit scale becomes large. In addition, when adding a new function, it is often necessary to develop new hardware.

On the other hand, in order to increase the degree of freedom in signal processing, there is a method of performing signal processing by software using a microcomputer or DSP without using dedicated hardware. Regarding such an image pickup device, an example of performing image compression by JPEG with a microcomputer is described in 1995 by the Photographic Society of Japan.
Fine Image Symposium Proceedings, pp. 65-6
It is described on page 8.

[0005]

However, the signal processing by such software has a problem that the image cannot be displayed in real time because the processing time for generating one image is long. Specifically, when reproducing a moving image, the number of images per unit time is small and the image becomes intermittent, and there is a time lag between the actual movement of the subject and the displayed image, and a photo opportunity is missed. Or
It takes time for framing. This problem,
This becomes remarkable as the number of pixels of the image sensor increases and the processing time per image becomes longer.

It is an object of the present invention to provide an image pickup apparatus which solves the above problems and enables real-time monitoring.

[0007]

In order to solve the above problems, the present invention comprises an array of a plurality of pixels for converting an optical signal formed by an optical system such as a lens into an electric signal,
An image sensor which sequentially scans or interlaces electric signals stored in pixels to output an image signal, an image sensor driving unit which drives the image sensor in either sequential scanning or interlaced scanning, and an image signal A display image generating means for generating a display image signal from the recording image, a recording image generating means for generating an image signal for recording, a shutter button for specifying a photographing start timing, the image pickup element driving means, the display image generating means,
An imaging device is configured by a control unit that controls the recorded image generation unit. The control means detects the shutter button input,
The scanning method of the image pickup device is switched according to the input of the shutter button, the digital image signal interlaced and output from the image pickup device is processed and output by the display image generation unit, and the image pickup is performed by the recorded image generation unit. Control is performed so that the digital image signals obtained by sequentially scanning and outputting the elements are processed and output.

According to the present invention, when a shutter button is pressed and a recording image is generated, the recording image generating means generates a high quality still image. Before inputting the shutter button, the image sensor is interlaced and scanned so that an image signal can be output at a rate necessary for displaying a moving image, and a display image is generated by the display image generation means, so real-time monitoring is possible. It will be possible.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an image pickup apparatus according to the present invention will be described. FIG. 1 is a block diagram showing the arrangement of an image pickup apparatus according to the present invention. In the figure, 1 is a lens,
Reference numeral 2 is a CCD, 3 is an amplifier circuit, and 4 is an A / D conversion circuit. Reference numeral 5 is a display image generation unit, 6 is a changeover switch, 7 is an encoder for generating a standard television signal such as NTSC or PAL, and 15 is a display unit such as a liquid crystal display. Further, 8 is a drive circuit for driving the CCD, 9 is a recorded image generation unit for generating a high-resolution still image, and 10 is a JPEG (Joint
This is a compression / decompression circuit that compresses and decompresses images using a method such as Photographic Expert Group). Reference numeral 12 is a recording medium for recording the recording image compressed by the compression / expansion circuit 10, and 17 is a memory for holding the image generated by the recording image generation unit 9. As the recording medium, a semiconductor memory such as a flash memory or a magnetic disk such as a hard disk is used. A removable medium such as a PC card may be used. 1
Reference numeral 1 is an interface circuit for outputting a recorded image to an external device such as a personal computer. Reference numeral 16 is a shutter button.

The operation of the image pickup apparatus in this embodiment will be described. The light incident on the lens 1 forms an image on the image pickup surface of the CCD 2. As shown in FIG. 2, the CCD 2 has a large number of pixels on its imaging surface. In FIG. 2, 20 is a pixel, 21 is a vertical transfer unit, 22 is a horizontal transfer unit, and 23 is an output unit. The pixel signal generated by photoelectric conversion in the pixel 20 is transferred to the vertical CCD 21. The transfer operation from the pixel to the vertical CCD is normally performed for all pixels simultaneously.
The pixel signal transferred to the vertical CCD is transferred upward in the vertical CCD, further transferred in the horizontal CCD, and then output from the output unit 23.

The CCD 2 has a structure capable of reading signals corresponding to two scanning modes of interlaced scanning and sequential scanning. The interlaced scanning mode is a mode in which horizontal rows in a CCD pixel array are thinned out and output, and the sequential scanning mode is a mode in which signals of all pixels are sequentially output without being thinned out. The interlaced scanning mode is a mode used when generating a display image for monitoring an image at the time of shooting, and the progressive scanning mode is a mode used when capturing a still image.

In the progressive scan mode, l1 and l in FIG.
The signals of all the pixels are output in order such as 2, l3, l4 ... In the interlaced scanning mode, for example, l1,
l2, l5, l6 ... l3, l4, l
Pixels in rows 7 and 18 are thinned out and output. The thinning method uses a method that is possible according to the rate required for displaying an image and the structure of the image sensor. Although the pixel rows after 16 are omitted in FIG. 2, the actual number of effective pixels in the CCD is, for example, 500 × 500, 1000 × 1000, and the total number of pixels is from several hundred thousand to several million.

A color filter having a fixed pattern is arranged on the image pickup surface of the CCD 2 to generate a color image signal, and each pixel photoelectrically converts only a specific color light corresponding to the type of the color filter. Is configured. As the color filter array, the three primary colors R shown in FIG.
A primary color system using (red), G (green), and B (blue), or a complementary color filter having a high light utilization rate such as Mg (magenta), Cy (cyan), and Ye (yellow) shown in FIG. 3B. There is a complementary color system using, and any array may be used. CCD
Since such a color filter is arranged at 2, the output signal is an image signal including a dot-sequential signal of pixels corresponding to the color filter.

The amplifier circuit 3 in FIG. 1 amplifies and outputs the above-mentioned image signal. In addition, here, CDS (Correlated Doubl
Known noise reduction processing such as e Sampling) may be performed. Next, the A / D conversion circuit 4 converts the analog pixel signal into a digital signal. The display image generation processing unit 5
An image signal for display is generated from the input digital image signal. The image for display is for a monitor at the time of shooting, and is usually a moving image.

The display image generation unit has the configuration shown in FIG. In FIG. 4, 50 and 51 are line memories, 52 is an addition circuit, 53 and 55 are matrix circuits, and 54 is a gamma correction circuit. The image signal generated by the display image generation circuit includes a luminance signal Y necessary for reproducing an image using a display device such as a liquid crystal display, and two kinds of color difference signals Cr and Cb. Therefore, the line memories 50 and 51
Generate signals for 3 lines including the input signal using
The product-sum operation of the equation (1) is performed on the signals of 3 × 3 pixels from the signals of these three lines. At this time, since the matrix coefficients for the pixels of the 1st line and the 3rd line may be made equal due to the symmetry of the pixel array, the signals of the 1st line and the 2nd line are added in advance in the adder circuit 52, and then equivalent to the equation (1). Performs various calculations.

Y = ΣKijxSij --- (1) In the equation (1), Kij is a matrix coefficient and Sij is a pixel signal. Equation (1) is an equation for the luminance signal Y,
Also for RGB, the values of the coefficients Kij are different, but they are expressed by the same formula. The spectral characteristic and the frequency characteristic of the YRGB signal can be set by the value of the coefficient Kij. Also, white balance adjustment is performed by controlling RGB gains. The coefficient Kij can be set by the control circuit 13 shown in FIG. The gamma correction circuit 54 performs gamma correction, which is a known process for correcting the input / output characteristics of the display, on the RGB signals generated by the matrix circuit 53. Further, the matrix circuit 55 generates the color difference signals Cr and Cb from the gamma-corrected RGB signal by matrix calculation. In this example, the matrix processing is performed in the range of 3 × 3 pixels, but the processing may be performed in a larger size. In this case, a line memory corresponding to the size is required.

The image signal generated by the display image generating section by the above-described operation is encoded by the encoder 7 via the changeover switch 6 into a predetermined signal format such as NTSC and is supplied to the display section 15. The changeover switch 6 is for changing over an image generated by the recording image generation unit 9 described later and a display image displayed during monitoring. In addition, other than NTSC input as the display unit 15,
For example, RGB input may be used. In this case, the RGB signal generated after performing RGB generation instead of the encoder 7 may be input to the display unit.

On the other hand, the recorded image generating section 9 generates a high definition image. Usually, the generated image is a still image. Image processing DSP (D
(igitalSignalProcessor) constitutes the recorded image generation unit 9. The signal processing contents in the recorded image generation circuit 9 are as follows.
Basically, the processing is the same as the processing in the display image generation unit 5, but the thinning-out like the display image is not performed, and the CCD is set to the sequential scanning mode to generate a full-size image. In addition to matrix coefficients, parameters such as gamma correction curve, white, black level, and coring are supplied from the control circuit so that the image quality can be controlled freely.

The recorded image generating section 9 outputs the luminance signal Y and the color difference signals Cr and Cb as in the display image generating circuit 5. These output signals are recorded in the recording medium 12 after being compressed by JPEG or the like in the compression / decompression circuit. When reproducing the image recorded on the recording medium, the image is transferred to the memory 17 after being expanded by the compression / expansion circuit. When the memory side is selected by the changeover switch, the encoder 7 is de-encoded and displayed on the display device 15. When outputting an image recorded on a recording medium to a personal computer or the like, the interface circuit outputs compressed or uncompressed image data.

The actual shooting operation is as follows. When the photographing mode and the recording mode changeover switch (not shown) are set to the photographing mode, the control circuit 13 controls the CCD drive circuit 8 to drive the CCD 2 in the interlaced operation mode. The display image generation circuit generates a moving image for display and displays it on the display device. The photographer turns on the shutter button when taking a still image while monitoring the image on the display device. When the control circuit 13 detects that the shutter is on, it sequentially switches the operation mode of the CCD 2 to the operation.
The recorded image generating unit 9 generates full-size still images sequentially operated and output, compresses them in the compression / expansion circuit 12, and then records them in the recording medium 12.

In the present embodiment, a display image generation unit that generates a display image for a monitor using an image that is interlaced and scanned by a CCD, and a recording image generation unit that generates a high-quality still image using images that are sequentially scanned. Since it is provided, real-time monitoring is possible. Since the recorded image generation unit is configured by the DSP, the degree of freedom in image processing is high and a high-quality still image can be generated.

Another embodiment of the present invention will be described with reference to FIG. FIG. 5 is a block diagram showing the configuration of this embodiment, in which 20 is a microcomputer, 22 is a buffer, and 21 is a DR.
A memory such as AM, 23 is a bus, and includes a data bus and an address bus of the microcomputer 20. The portion 14 surrounded by the broken line is the same as the portion 14 surrounded by the broken line in FIG.
This is the part that performs the same function as. Other parts are shown in Figure 1.
It has the same configuration as the block diagram of FIG. The microcomputer 20 processes all operations of the recorded image generation unit 9, the compression / expansion circuit 10, and the control circuit 13 in FIG. 1 by software.

The operation at the time of photographing is as follows. In the shooting mode, the CCD is interlaced and scanned until the shutter button is pressed, and a moving image for monitor is generated by the display image generation unit as in the previous embodiment. When the shutter button is pressed, the microcomputer 20 detects it and switches the CCD to the sequential scanning mode. The microcomputer writes the digital image data output from the CCD 2 and output from the A / D conversion circuit 4 into the memory 21 via the buffer 22. The microcomputer 21 uses the data in the memory to perform the processing contents of the recording image generation unit 9 and the compression / expansion circuit 10 in FIG. 1 by software processing. Further, the microcomputer 20 also serves as the control circuit 13 in FIG. 1, and writes image data to the recording medium 12, communicates with a personal computer via the interface circuit 11, outputs captured image data, and the like.

In the present embodiment, the microcomputer 20 also performs a plurality of processes such as generation and compression of a still image, control of peripheral circuits such as the CCD drive circuit 8, and the like, which simplifies the configuration and provides a highly flexible software. Since processing can be performed, high-quality still images can be captured.

Another embodiment of the present invention will be described. FIG. 6 is a block diagram showing the configuration of the present embodiment. Reference numeral 60 is an AF (autofocus) lens, 61 is an aperture, 62 is an aperture drive circuit, and 63 is an AF motor.

This embodiment operates similarly to the embodiment shown in FIG. 5, but has an autofocus function and an exposure control function using the diaphragm 61. In order to perform the autofocus control, it suffices to detect a high frequency component from the image signal and perform feedback control of the lens position so that the detected value becomes maximum. Also for exposure control, the signal level may be detected from the image signal, and the aperture value and shutter speed may be feedback-controlled so that the detected value matches the reference value. For this purpose, it is necessary to perform AF detection and exposure detection. Usually, hardware for performing these detections is provided, but in the present embodiment, during the monitoring operation, the AF detection and the exposure detection by the software processing are performed using the microcomputer 20. Similarly, AWB (white balance) detection is also performed. The AWB detection is performed by, for example, obtaining an integrated value of RGB signals. The AWB control is to make the signal level of the RGB signal when the white object is imaged almost constant, and the gain of the RGB matrix may be controlled so that the detected integrated value of RGB becomes substantially constant.

During the interlaced scanning of the CCD 2 and the processing of the display image in the display image generating section 5, the microcomputer 20 uses the image signals written in the memory 21 to perform the AF and A mentioned above.
E, AWB detection is performed. As a result, these control amounts are obtained, the AF motor 63 is controlled for AF control, the diaphragm drive circuit 62 is controlled for aperture control, and the RGB matrix coefficients are transmitted to the display image generation unit for AWB to perform these controls. ing.

In this embodiment, the microcomputer 20
Since the detection and control of F, AE, and AWB are performed, it is not necessary to provide these detection circuits in the display image generation unit, and the circuit scale can be reduced.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a configuration of a CCD

FIG. 3 is a diagram showing a CCD color filter array.

FIG. 4 is a block diagram showing a configuration of a display image generation unit according to an embodiment.

FIG. 5 is a block diagram showing a configuration of an embodiment of an image pickup apparatus according to the present invention.

FIG. 6 is a block diagram showing a configuration of an embodiment of an image pickup apparatus according to the present invention.

[Explanation of symbols]

1 ... Lens 2 ... CCD 3 ... Amplifying circuit 4 ... A / D conversion circuit 5 ... Display image generation unit 8 ... CCD drive circuit 9: Recorded image generator 10 ... Compression / decompression circuit 16 ... Shutter button 20 ... Microcomputer 21 ... Memory

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 9/04 H04N 101: 00 // H04N 101: 00 5/91 L (72) Inventor Toshiro Kinugasa Kanagawa F-Term (Reference) 5C022 AA13 AB12 AB17 AB29 AC03 AC32 AC42 AC69 5C053 FA08 FA27 GA19 GB36 KA04 KA24 LA02 5C065 AA03 CC01 CC08 DD02 DD17 EE05 GG15 GG26 GG32

Claims (7)

[Claims] 1. An array of a plurality of pixels for converting an optical signal formed by an optical system into an electric signal is provided, and the electric signal accumulated in the pixel is sequentially scanned or interlaced to output an image signal. An image sensor, and the image sensor, the two types of scanning methods, that is, sequential scanning,
Image sensor driving means for selecting and driving one of the interlaced scanning methods, display image generating means for generating a display image signal from an image signal output by the image sensor, and an image output by the image sensor A recording image generation unit that generates an image signal for recording from a signal, a shutter button that specifies a shooting start timing, a shutter button input is detected, and the scanning method of the image sensor is switched according to the input of the shutter button. The display image generating means processes and outputs the image signal which is interlaced and scanned and output from the image pickup device, and the recording image generating means processes and outputs the image signal which is sequentially scanned and output from the image pickup device. An image pickup apparatus comprising: a control unit. 2. The image pickup device according to claim 1, wherein the display image generating means generates a moving image and the recorded image generating means generates a still image. 3. An image pickup device according to claim 1, wherein the recording image generating means and the control means are constituted by a microcomputer. 4. The image pickup device according to claim 1, wherein the recorded image generating means generates an image signal by software processing. 5. An array of a plurality of pixels for converting an optical signal formed by an optical system into an electric signal is provided, and the electric signal accumulated in the pixel is sequentially scanned or interlaced to output an image signal. An image sensor, and the image sensor, the two types of scanning methods, that is, sequential scanning,
Image sensor driving means for selecting and driving one of the interlaced scanning methods, display image generating means for generating a display image signal from an image signal output by the image sensor, and an image output by the image sensor A recording image generation unit that generates an image signal for recording from a signal, a shutter button that specifies a shooting start timing, a shutter button input is detected, and the scanning method of the image sensor is switched according to the input of the shutter button. The display image generating means processes and outputs the image signal which is interlaced and scanned and output from the image pickup device, and the recording image generating means processes and outputs the image signal which is sequentially scanned and output from the image pickup device. And a control means, wherein the recorded image generation means includes color signal level detection means,
An image pickup apparatus which controls a color signal level in a display image generating means based on a value detected by the color signal level detecting means. 6. An array of a plurality of pixels for converting an optical signal formed by an optical system into an electric signal is provided, and the electric signal accumulated in the pixel is sequentially or interlacedly scanned to output an image signal. An image sensor, and the image sensor, the two types of scanning methods, that is, sequential scanning,
Image sensor driving means for selecting and driving one of the interlaced scanning methods, diaphragm means for changing the exposure amount, and display image generating means for generating a display image signal from an image signal output by the image sensor. A recording image generation means for generating an image signal for recording from an image signal output by the image pickup device, a shutter button for designating a photographing start timing, and a shutter button input is detected, and in response to the input of the shutter button While switching the scanning method of the image pickup device, the display image generating means processes and outputs the image signal skipped and output from the image pickup element, and the recorded image generating means outputs the image signal obtained by sequentially scanning and outputting the image pickup element. Control means for controlling so as to process and output the recorded image generation means, and the recorded image generation means includes signal level detection means. Diaphragm means based on the detected value
And an image pickup apparatus characterized in that the exposure time is controlled. 7. An optical system having a focus adjustment function, and an array of a plurality of pixels for converting an optical signal formed by the optical system into an electric signal, the electric signal accumulated in the pixel is sequentially scanned, Alternatively, an image sensor for performing interlaced scanning and outputting an image signal, and the image sensor for the two types of scanning methods, that is, sequential scanning,
Image sensor driving means for selecting and driving one of the interlaced scanning methods, display image generating means for generating a display image signal from an image signal output by the image sensor, and an image output by the image sensor A recording image generation unit that generates an image signal for recording from a signal, a shutter button that specifies a shooting start timing, a shutter button input is detected, and the scanning method of the image sensor is switched according to the input of the shutter button. The display image generating means processes and outputs the image signal which is interlaced and scanned and output from the image pickup device, and the recording image generating means processes and outputs the image signal which is sequentially scanned and output from the image pickup device. The recording image generating means includes a focus detecting means for detecting the amount of high frequency components from the image signal, and the detected value by the focus detecting means. Imaging device, characterized in that had focus control based.