JP2003087647A - Digital still camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily record a document image while preventing movement of the hands. SOLUTION: A digital still camera is equipped with a CCD which receives a light image of a subject through an interchangeable lens and outputs an image signal corresponding to its light intensity, and further equipped with an operation part which can be operated from outside to select a document image mode as a photography mode, a document exposure control part 101 which makes the CCD divisional photography in a specific exposure time repeatedly when the document image mode is selected, a composition control part 103 which finds quantities of deviation between images obtained by the divisional photography and corrects the quantities of deviation to compose one image of the respective images, and a recording control part 94 which records the composite image on a card memory.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital still camera capable of suitably capturing a document image.

[0002]

2. Description of the Related Art Conventionally, various digital still cameras have been proposed in which not only natural images but also document images can be suitably photographed (recorded). For example, Japanese Patent Laid-Open No. 7-23
In Japanese Patent Publication No. 286, a digital image in which an image to be captured is divided into a binary image region such as a document image and a natural image region, and an area to be focused is selected according to the area ratio of each area. Still cameras have been proposed. Also,
In Japanese Patent Laid-Open No. 8-125870, the image data is compressed by the natural image compression means when the normal photographing mode is selected, and the image data is compressed by the document compression means when the document image mode is selected. A digital still camera has been proposed which is compressed and recorded on a recording medium. In addition, JP-A-10-16443
In Japanese Patent Laid-Open No. 0-202, there is proposed a digital still camera in which an image is divided into a plurality of blocks, and brightness correction is performed for each block to enable use as a scanner for capturing a document.

[0003]

Generally, when photographing with a camera, the image in the peripheral portion of the photographing range is condensed at a position deviated from the center of the photographing lens, so that the light collecting ability is lower than that in the central portion. For example, since the light intensity reaching the image pickup device composed of a CCD becomes small, a phenomenon called shading occurs in which the luminance of the peripheral portion is lower than that of the central portion.

This shading is not so noticeable in a natural image, but is more noticeable in a document image than in a natural image because the luminance distribution of the subject is uniform.

Therefore, when a document image is taken with a digital still camera, in order to reduce the influence of this shading, the aperture is usually narrowed down, but the amount of incident light is reduced, and the flash is emitted. It is possible. However, the general light distribution characteristic of the flash makes only the central portion of the shooting range bright. In addition, particularly in the case of a subject such as a whiteboard that has strong regular reflection light, it is necessary to consider the light emitting direction so that the reflected light of the flash does not return. As described above, since it is highly possible that a proper image cannot be obtained when the flash is used for shooting, it is common to shoot the document image without using the flash. There is.

Therefore, if the photographing environment is sufficiently bright, the document image can be photographed without any trouble, but such an environment is not always obtained. As a result, if the exposure time (shutter speed) exceeds the camera shake limit when the shooting environment is not sufficiently bright, the camera will be shaken during hand-held shooting.

Therefore, in order to prevent camera shake, it is conceivable to take a picture with the camera fixed to a dedicated stand, but if such a configuration is adopted, the device becomes extremely large. Moreover, since it is difficult to carry a dedicated stand, it is not possible to easily take a document image of a posted matter or the like.

However, such problems cannot be solved by the digital still cameras described in JP-A-7-23286 and JP-A-8-125870. Further, even the digital still camera described in Japanese Patent Laid-Open No. 10-164430, which corrects the brightness for each block in the shooting range, cannot prevent camera shake. As described above, the conventional digital still cameras described in the above publications are not suitable for easily recording a document image.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a digital still camera capable of easily recording a document image while preventing camera shake.

[0010]

The invention according to claim 1 is
In a digital still camera equipped with an image pickup unit that receives a light image of a subject through a shooting optical system and outputs an image signal according to the light intensity, it can be operated from the outside to select a document image mode as a shooting mode. When the document image mode is selected, the document photographing control means for causing the photographing means to successively perform the divided photographing with a predetermined exposure time a plurality of times, and The present invention is characterized by comprising a combination control means for obtaining a deviation amount between the images, correcting the deviation amount and combining each image into one image, and a recording control means for recording the combined image in a recording means. There is.

According to this structure, when the document image mode is selected as the photographing mode by an external operation, the photographing means continuously performs divided photographing with a predetermined exposure time a plurality of times. A shift amount between the obtained images is obtained, the shift amount is corrected, each image is combined into one image, and the combined image is recorded in the recording unit. This makes it possible to easily capture and record a document image without increasing the device configuration.

It is preferable that the predetermined exposure time is set to a time in which no camera shake occurs, and it may be set based on the information of the photographing optical system and the number of times of divided photographing, and stored in the storage means. Even in this case, it is possible to avoid insufficient exposure by performing the divided photographing a plurality of times.

According to a second aspect of the present invention, in the digital still camera according to the first aspect, the image signal output from the image pickup means when the document image pickup control means performs the divided photographing is subjected to a predetermined changing process. It is characterized in that it comprises change processing means, and the synthesis control means obtains the shift amount using the image signal subjected to the change processing.

According to this structure, when the photographing control means performs the divided photographing, the image signal output from the image pickup means is subjected to a predetermined changing process, and the image signal subjected to the changing process is used to shift the image signal. By calculating the amount, the amount of deviation can be calculated in a short time, depending on the purpose and application,
It becomes possible to perform with high accuracy.

In this case, if the image signal is binarized as the predetermined change processing (claim 3), the amount of data for calculation is reduced, so that the shift amount can be calculated at high speed. Assuming that the image signal is subjected to edge enhancement processing as the predetermined change processing (claim 4), the edges are emphasized so that the boundary between coincidence and disagreement between the images becomes clear. The amount of deviation can be calculated accurately.

Further, if the change processing means is to perform the change processing on a signal obtained by thinning out the image signal output from the image pickup means at a predetermined ratio (claim 5), the change processing can be performed at high speed. As a result, the shift amount can be calculated at high speed.

According to a sixth aspect of the present invention, in the digital still camera according to any one of the second to fifth aspects, the synthesizing control means uses the image signal before the change processing to generate each image. The feature is that they are combined into one image.

According to this structure, since each image is combined into one image by using the image signal before the change processing is performed, the image signal output from the image pickup means is used. The document image is preferably recorded without the image quality being deteriorated by the processing.

According to a seventh aspect of the present invention, in the digital still camera according to any one of the first to sixth aspects, the subject is photographed based on an image signal output from the image pickup means before the release switch is turned on. Exposure value calculating means for determining the brightness and calculating an exposure time for obtaining an image signal of an appropriate level based on the determined brightness of the subject, and the photographing optical system for determining whether the calculated exposure time causes camera shake. If the image capturing control unit determines that the image blur does not occur, the image capturing unit determines by the image capturing unit even if the document image mode is selected. It is characterized in that normal photographing is performed only once with the calculated exposure time.

According to this structure, the brightness of the subject is determined based on the image signal output from the image pickup means before the release switch is turned on, and an image signal of an appropriate level is obtained based on the determined brightness of the subject. The exposure time is calculated, and whether or not camera shake occurs at the calculated exposure time is determined based on the focal length information of the photographing optical system. If it is determined that the camera shake does not occur, the document image mode is selected. Even if the shooting is performed, the normal shooting is performed only once with the exposure time calculated by the imaging unit, so that the split shooting is not performed when the shooting environment is sufficiently bright, so that the shooting time can be shortened. .

According to an eighth aspect of the invention, in the digital still camera according to the seventh aspect, when the document image mode is selected, an external operation for always selecting whether or not to perform the divided photographing is performed. When the document photographing control means is selected by the second operating means to always perform the divided photographing,
Even when it is determined that hand-shake does not occur, the above-mentioned image pickup means is made to perform the above-mentioned divided photographing.

According to this structure, when the document image mode is selected, it is possible to always select whether or not to perform the divided shooting, and when it is selected to always perform the divided shooting, Even if it is determined that hand-shake does not occur, the image capturing means performs divided shooting, so that importance is attached to the ease of shooting and shortening of shooting time, the importance of improving image quality of images, and the like. It becomes possible to make a selection according to the use and the application, and the usability can be improved.

According to a ninth aspect of the present invention, in the digital still camera according to any one of the first to eighth aspects, a flash which emits light in synchronization with operation of a shutter button is provided.
When the document image mode is selected, the flash emission is prohibited.

According to this structure, when the document image mode is selected, the flash is prohibited from being emitted, so that when the document image is taken, the flash is erroneously emitted and the image quality is improved. It becomes possible to prevent the deterioration.

In this case, as a configuration for inhibiting the emission of the flash, an inhibition control means for inhibiting the emission control signal from being sent to the flash may be provided. Also,
In place of the prohibition control means, a switch means such as a semiconductor switch is provided between the power supply section for supplying electric power for light emission to the flash and the flash, and a switch control means for turning off the switch means is provided. You may do it.

According to a tenth aspect of the present invention, in the digital still camera according to any one of the first to ninth aspects, a third operation means that can be operated from the outside for setting the number of times of the divided photographing that is continuously performed. The document photographing control means is characterized in that the document photographing control means causes the image pickup means to continuously perform the divided photographing for the number of times set by the third operation means.

According to this structure, there is provided the third operating means which can be operated from the outside for setting the number of times of divided photographing to be carried out continuously, and the image pickup means is continuously operated for the number of times set by the third operating means. By performing divided shooting with, it becomes possible to set according to the purpose and application of the user, such as placing importance on ease of shooting and shortening of shooting time, and placing importance on high image quality of the image, The usability can be improved.

According to the eleventh aspect of the present invention, there is provided an image pickup means for receiving a light image of a subject through the photographing optical system and outputting an image signal corresponding to the light intensity, and for selecting the document image mode as the photographing mode. When a document image mode is selected, a digital still camera equipped with operating means that can be operated from the outside of the document photographing control for causing the photographing means to continuously perform divided photographing with a predetermined exposure time a plurality of times. Means, a combination control means for obtaining the amount of deviation between the images obtained by the divided photographing, correcting the deviation amount, and combining each image into one image, and recording the combined image in the recording means. A document photographing control program characterized by causing it to function as a recording control means.

According to this structure, when the document image mode is selected as the photographing mode by an operation from the outside, the photographing means continuously performs the divided photographing for a predetermined exposure time a plurality of times. A shift amount between the obtained images is obtained, the shift amount is corrected, each image is combined into one image, and the combined image is recorded in the recording unit. This makes it possible to easily capture and record a document image without increasing the device configuration.

It is preferable that the predetermined exposure time is set to a time at which hand shake does not occur. For example, the predetermined exposure time may be set based on the information of the photographing optical system and the number of times of divided photographing, and stored in the storage means. Even in this case, it is possible to avoid insufficient exposure by performing the divided photographing a plurality of times.

[0031]

1 is a front view of a camera body which constitutes an embodiment of a digital still camera according to the present invention.
2 is a top view showing the arrangement of the main members incorporated in the same embodiment, FIG. 3 is a right side view showing the arrangement of the main members incorporated in the same embodiment, and FIG. 4 is a rear view of the same embodiment. FIG. 5 is a diagram illustrating the configuration of the color image sensor.

As shown in FIG. 2, a digital still camera 1 according to this embodiment is a single-lens reflex camera equipped with a camera body 2 and an interchangeable lens 3 which is detachably attached to the camera body 2 substantially in the center of the front surface thereof. As shown in FIG. 3, the camera main body 2 includes an electronic view finder (EVF) 4 and a pop-up type flash 5 on the upper surface of the camera body 2.

In FIG. 1, the camera body 2 is provided with a mount portion 11 on which the interchangeable lens 3 is mounted at a substantially central portion of the front surface, and a grip portion 12 for a user to grip at a left end portion of the front surface. A plurality of contacts 13 for making an electrical connection with the mounted interchangeable lens 3 and a plurality of couplers 14 for making a mechanical connection are provided below the mount portion 11.

The electrical contact 13 receives the information peculiar to the lens (information such as the open F value and the focal length) from the lens ROM 15 (FIG. 6) built in the interchangeable lens 3 in the camera body 2 as a whole. (Fig. 6), or information about the position of the focus lens 6 (Fig. 6) and the zoom lens 7 (Fig. 6) in the interchangeable lens 3 to the overall control unit 90 (Fig. 6). Is.

As shown in FIG. 3, the coupler 14 has a driving force of a focus lens driving motor (FM) 16 provided in the camera body 2 and a zoom lens driving motor (Z).
M) the driving force of 17 and the respective lenses 6, 7 in the interchangeable lens 3.
It is intended to be transmitted to.

In FIG. 2, a battery storage chamber 18 and a card storage chamber 19 are provided inside the grip portion 12. Four AA batteries are used as the power source for the camera in the battery compartment 18.
A dry battery 20 is stored, and a memory card 2 for recording image data of captured images is stored in the card storage chamber 19.
1 is detachably stored.

Further, a color image pickup device 23 is arranged at an appropriate position in the camera body 2 on the optical axis 22 of the interchangeable lens 3 when it is mounted on the mount 11.

The color image pickup device (hereinafter referred to as "CCD") 23 is, as shown in FIG.
area sensor 2 in which pled devices) are two-dimensionally arranged
R (red), G (green), B (blue) on the surface of each CCD of 4.
Color filter 25 of is attached in a checkered pattern,
It is configured by a so-called Bayer type single plate type color area sensor, and in the present embodiment, for example, 1600.
(X direction) x 1200 (Y direction) = 1.92 million CCDs
(Hereinafter, also referred to as “pixel”).

As shown in FIG. 5, the area sensor 2
If the pixel position of the i-th row and the j-th column of 4 is (i, j), R,
For each of the G and B color filters, R is (2h + 1, 2k +
1) and G are (2h + 2,2k + 1), (2h + 1,2k
+2) and B are arranged at pixel positions of (2h + 2,2k + 2).

However, i = 1, 2, ..., N, j = 1, 2, ..., M, n = 1600, m = 1200, h = 0, 1, 2, ..., N / 2 (= 800), k = 0, 1, 2, ..., M / 2 (= 600) Is.

As shown in FIG. 1, a shutter button 26 is provided on the upper surface of the grip portion 12 of the camera body 2. The shutter button 26 is configured to be capable of being operated in a “half-pressed state” in which it is pressed halfway and operated in a “full-pressed state” in which it is further pressed. When a preparatory operation (a preparatory operation such as setting an exposure control value and a focus adjustment) for photographing a still image is executed and the shutter button 26 is fully pressed, the photographing operation (the CCD 23 is exposed, and the exposure is obtained by the exposure). A series of operations for performing predetermined image processing on the image signal and recording the image signal on the memory card 21 are executed.

3 and 4, the electronic viewfinder 4 has a finder display section 27, an eyepiece lens 28, and a finder window 29. The finder display section 27
In this embodiment, for example, the number of pixels is 200 (X direction) × 15.
It is composed of a color liquid crystal display device of 0 (Y direction) = 30000, and displays a monitor image of a subject photographed by the CCD 23, that is, an image of a subject photographed as a moving image by the CCD 23 in a photographing standby state where the shutter button 26 is not operated. It is a thing. The eyepiece lens 28 guides the monitor image displayed on the finder display section 27 to the outside of the finder window 29. With such a configuration, the photographer can visually recognize the subject by looking through the finder window 29 on the monitor image displayed on the finder display unit 27.

The monitor image is displayed in the finder display section 27.
Since it is for displaying on the
The CCD 23 is operated in an operation mode (hereinafter referred to as “draft mode”) different from normal still image shooting to shoot a monitor image of the same size as the display size of the finder display unit 27. That is, in this embodiment,
Since the finder display unit 27 is composed of 200 × 150 pixels, the CCD 23
Light is received by all the pixels of, but image data is read by X,
The pixel number is set to 200 in both Y directions by thinning-out with 8 pixel pitch, that is, 1/8.
A × 150 monitor image is obtained at high speed.

In FIG. 4, an external display section 30 is provided in the rear surface of the camera body 2 substantially in the center thereof. In the present embodiment, the external display unit 30 is composed of, for example, a color liquid crystal display element having a number of pixels of 200 (X direction) × 150 (Y direction) = 30000, and in the recording mode, a mode related to exposure control, a mode related to a shooting scene, and shooting conditions. It displays a menu screen for setting, etc., and reproduces and displays a captured image recorded in the memory card 21 in the reproduction mode.

On the left side of the external display unit 30, the power switch 3
1 is provided. The power switch 31 also serves as a mode setting switch that switches and sets a recording mode (a mode that performs a function of taking a photograph) and a reproduction mode (a mode that reproduces a recorded image on the external display unit 30). That is,
The power switch 31 is a three-point slide switch. When the contact is set to the central "OFF" position, the power is turned off. When the contact is set to the upper "REC" position, the power is turned on and the recording mode is changed. When the contact is set and the contact is set to the lower "PLAY" position, the power is turned on and the reproduction mode is set.

A quad switch 32 is provided on the upper right side of the external display section 30. The quadruple switch 32 has a circular operation button, and pressing operations in four directions of up, down, left, and right on the operation button are detected as operations of the upper switch 32U, the lower switch 32D, the left switch 32L, and the right switch 32R, respectively. It is like this.

The quad switch 32 has multiple functions,
For example, it functions as an operation switch for changing the item selected on the menu screen for setting the shooting scene displayed on the external display unit 30, and the reproduction target selected on the index screen on which a plurality of thumbnail images are arranged and displayed. The left switch 32L and the right switch 32R function as zoom switches for changing the focal length of the zoom lens of the interchangeable lens 3.

At the lower right position of the external display unit 30, a cancel switch 33 and a confirm switch 3 are provided as switches for operating the display and display contents of the external display unit 30.
4, a menu display switch 35 and a display changeover switch 36 are provided.

The cancel switch 33 is a switch for canceling the contents selected on the menu screen. The confirmation switch 34 is a switch for confirming the content selected on the menu screen. The menu display switch 35 is a switch for displaying a menu screen on the external display unit 30 and for switching the contents of the menu screen (for example, a shooting scene setting screen and a mode setting screen regarding exposure control).
Each time the menu display switch 35 is pressed, the menu screen switches.

The display change-over switch 36 is a switch for displaying or turning off the display on the external display section 30, and each time the display change-over switch 36 is pressed, the external display section 30 is pressed.
Are alternately displayed and hidden. In order to save the power of the battery 20, the external display unit 30 is not displayed when the camera is activated.

FIG. 6 is a block diagram showing the electrical configuration of the digital still camera 1, and FIG. 7 is a block diagram showing the functional blocks of the overall control unit of FIG. The same components as those in FIGS. 1 to 4 are designated by the same reference numerals. In addition, in FIG.
For convenience of explanation, the interchangeable lens 3 is shown separately in two places.

The digital still camera 1 includes an interchangeable lens 3, an image pickup section 40, a signal processing section 50, a light emission control section 58, a lens control section 60, a display section 70, an operation section 80, an overall control section 90 and the like.

The interchangeable lens 3 is provided with a focus lens 6, a zoom lens 7 and a diaphragm 8 for adjusting the amount of transmitted light, and stores peculiar information (information such as the open F value and focal length) relating to the lens. Lens ROM1
It is equipped with 5. The lens ROM 15 has an electrical contact 13
It is connected to the overall control unit 90 via.

The image pickup section 40 photoelectrically converts the subject light image incident through the interchangeable lens 3 and outputs it as an image signal (electrical image), and includes a CCD 23, a timing generator 41, and a timing control circuit 42.

The CCD 23 is the timing generator 4
Based on the drive control signal (accumulation start signal / accumulation end signal) input from 1, the subject light image is received for a predetermined exposure time and converted into an image signal (charge accumulation signal), and the image signal is output from the timing generator 41. The signal is sent to the signal processing unit 50 in accordance with the input read control signal (horizontal synchronizing signal, vertical synchronizing signal, transfer signal, etc.).

At this time, the image signal has the respective color components R, G, B.
And is sent to the signal processing unit 50. That is,
The image signal of the color component R is transmitted by sequentially reading the image signal received by each pixel at the pixel position (2h + 1, 2k + 1), and the pixel position (2h + 2, 2k + 1), (2h +
The image signal of the color component G is transmitted by sequentially reading the image signal received by each pixel of (1, 2k + 2), and the image signal received by each pixel of the pixel position (2h + 2, 2k + 2) is sequentially read to obtain the color. The image signal of the component B is transmitted.

In the following description, for convenience of explanation, in order to distinguish the light receiving signal of each pixel from the image signal which constitutes a photographed image by these groups, the light receiving signal of each pixel is changed to a pixel signal (analog value) as necessary. ) Or pixel data (digital value).

The timing generator 41 generates a drive control signal based on the control signal input from the timing control circuit 42 and a read control signal based on the reference clock signal, and sends them to the CCD 23.

The timing control circuit 42 controls the photographing operation of the CCD 23, and generates a photographing control signal based on the control signal input from the overall controller 90. This shooting control signal is a control signal for displaying a moving image of a subject (hereinafter referred to as “live view image”) on the finder display section 27 of the electronic viewfinder 4 while the image pickup is on standby in the recording mode. A control signal for operating a still image of a subject (hereinafter referred to as “recorded image”), a reference clock signal, and a timing signal for synchronizing the image signal sent from the CCD 23 with the signal processing unit 50 (synchronization). Clock signal) etc. This timing signal is input to the analog signal processing circuit 51 and the A / D conversion circuit 52 in the signal processing unit 50.

The signal processing unit 50 performs predetermined analog signal processing and digital signal processing on the image signal sent from the CCD 23, and the signal processing of the image signal is performed for each pixel signal constituting the image signal. . The signal processing unit 50 includes an analog signal processing circuit 51, an A / D conversion circuit 52, a black level correction circuit 53, a white balance (W
B) The circuit 54, the γ correction circuit 55, and the image memory 56 are provided, and the black level correction circuit 53, the WB circuit 54, and the γ correction circuit 55 constitute a circuit that performs digital signal processing.

The analog signal processing circuit 51 includes the CCD 23.
And a CDS (correlated double sampling) circuit for performing a predetermined analog signal processing on an image signal of an analog value output from the CDS (correlated double sampling) circuit,
An AGC (auto gain control) circuit for adjusting the level of the image signal is provided. The AGC circuit has a diaphragm 8
It also has a function of compensating for the lack of the level of the captured image when proper exposure cannot be obtained with the aperture value and the exposure time of the CCD 23 (for example, when capturing a very low brightness subject). The gain of the AGC circuit is set by the main body control unit 90.

The A / D conversion circuit 52 converts the image signal output from the analog signal processing circuit 51 into a digital value image signal (hereinafter referred to as "image data").
A pixel signal obtained by receiving light at each pixel is converted into, for example, 10-bit pixel data. The black level correction circuit 53 is
The black level of each pixel data that has been / D converted is corrected to a reference black level.

The WB circuit 54 adjusts the white balance of the photographed image, and converts the level of the pixel data of each color component R, G, B by using the level conversion table input from the overall control unit 90. Adjust the white balance of the shot image. The conversion coefficient of each color component in the level conversion table is set by the overall control unit 90 for each captured image.

The γ correction circuit 55 performs gradation correction by correcting the γ characteristic of pixel data, and has, for example, five types of γ correction tables having different γ characteristics as a look-up table (LUT) and set. The γ correction of the pixel data is performed by a predetermined γ correction table according to the captured scene. In this γ correction process, 10-bit pixel data is converted into 8-bit (256 gradations) pixel data. The pixel data before the γ correction processing is set to 10-bit data in order to prevent the image quality from being deteriorated when the γ correction is performed with the γ characteristic having strong nonlinearity. Further, the pixel data of each color component R, G, B has undergone a predetermined level conversion in the WB circuit 54, and these pixel data are respectively γ-corrected by the γ-correction table.

The image memory 56 is a memory for temporarily storing the image data for which signal processing has been completed, and has a capacity capable of storing, for example, image data for 8 frames in this embodiment. This is because, as will be described later, in the present embodiment, since it is possible to perform the divided photographing in which the exposure is continuously performed eight times in the document image mode, it is possible to store the image data of eight frames, respectively. .

In the present embodiment, the storage capacity for storing one frame of image data is 19 since the number of pixels of the CCD 23 is 1600 × 1200 = 1920,000.
The capacity is capable of storing 20,000 color pixel data.

The light emission control unit 58 controls the light emission of the flash 5 based on the light emission control signal input from the overall control unit 90. The light emission control signal includes a light emission preparation instruction, a light emission timing, and a light emission amount. Be done.

The light emission control unit 58 charges the main capacitor to be in a light emission enable state when a light emission preparation instruction signal is sent from the general control unit 90, and synchronizes with the timing signal when a light emission timing signal is further sent. To discharge the stored charge of the main capacitor, which causes the flash 5
Light up. Then, when the light emission stop signal is sent from the overall control unit 90, the discharge of the main capacitor is stopped,
As a result, the flash 5 emits a required amount of light.

The lens controller 60 includes a focus lens drive motor (FM) 16 and a zoom lens drive motor (ZM) 17, and an aperture control circuit 61, a focus control circuit 62, and a zoom control circuit 63. .

The aperture control circuit 61 controls the aperture value of the aperture 8. The aperture control circuit 61 drives the aperture 8 based on the aperture value input from the overall controller 90 and sets the aperture amount to the aperture value. .

The focus control circuit 62 controls the drive of the FM 16, and the A input from the overall control unit 90.
The FM 16 is driven based on the F control signal (for example, a control value such as the number of drive pulses) to move the focus lens 6 to the focus position. The driving force of the FM 16 is transmitted to the focus lens 6 via the coupler 14.

The zoom control circuit 63 controls the driving of the ZM 17, and based on the zoom control signal (operation information of the quad switch 32) input from the overall control section 90, the ZM 17 is controlled.
17 is driven to move the zoom lens 7. ZM
The driving force of 17 is transmitted to the zoom lens 7 via the coupler 14.

The zoom control circuit 63 includes the overall control unit 9
When the operation information of the right switch 32R of the 4-switch 32 is input from 0, the ZM 17 is driven in the positive direction to move the zoom lens 7 to the wide side, and the operation information of the left switch 32L of the 4-switch 32 is input. Then, the ZM 17 is driven in the reverse direction to move the zoom lens 7 to the tele side.

In the zoom operation of the interchangeable lens 3, the interchangeable lens 3 continuously moves to the wide-angle side while the right switch 32R of the quad switch 32 is pressed, and the left switch 32L of the quad switch 32 is moved. The interchangeable lens 3 continuously moves to the telephoto side only while pressing.

The display section 70 is the finder display section (E
A VF) 27 and an external display unit (LCD) 30 are provided, and VRAMs 71 and 72 are provided.

The VRAM 71 is a buffer memory for storing the display image on the external display unit 30, and the external display unit 3
The VRAM 72 has a memory capacity capable of storing 30,000 color pixel data corresponding to the number of pixels of 0, and the VRAM 72 is a buffer memory for storing a display image on the finder display unit 27. It has a memory capacity capable of storing 30,000 color pixel data corresponding to the number of pixels.

The operation section 80 has a lock switch 81 which is turned on when the shutter button 26 (FIG. 4) is half pressed.
And a release switch 82 that is turned on when the shutter button 26 (FIG. 4) is fully pressed, and the switch groups 31 to 36 shown in FIG. 4 are included. Is entered.

The EEPROM 86 is a C of the overall control unit 90.
It stores a control program for controlling the operation of the PU. The RAM 87 temporarily stores various data in arithmetic processing and control processing.

The overall control unit 90 is composed of a CPU, etc.
It controls the operation of each part of the digital still camera 1 according to the control program stored in the EEPROM 86. When the shutter button 26 is half-pressed and the ON signal of the lock switch 81 is detected, a still image of the subject is taken. When the shutter button 26 is fully pressed and an ON signal of the release switch 82 is detected, a preparatory operation for setting (exposure control value setting, preparatory operation such as focus adjustment) is performed,
Photographing operation (exposing the CCD 23, subjecting the image signal obtained by the exposure to predetermined image processing, and then performing the memory card 2
1 has a function of executing a series of operations recorded in 1.).

The overall control unit 90 uses the card I / F 11
I / F for communication connected to the memory card 21 via
External personal computer (PC) via 112
It is connected to 113. The card I / F 111 is an interface for writing image data to the memory card 21 and reading image data. I for communication
The / F 112 is, for example, an interface compliant with the RS-232C standard, and is for enabling communication with the PC 113.

As shown in FIG. 7, the overall control section 90 includes a photographing mode control section 91, an exposure value calculation section 92, a display control section 93, a recording control section 94, and a reproduction control section 95 as functional blocks. The recording control unit 94 includes a document exposure control unit 101, a change processing unit 102, a combination control unit 103, and a camera shake determination unit 104 as functional blocks for capturing a document image.

The photographing mode control unit 91 controls the setting of the photographing mode, and is set based on the operation of the operation unit 80 performed while the menu screen for mode setting is displayed. The shooting mode includes a shooting scene mode and an exposure control mode.

Here, the setting of the mode relating to the shooting scene will be described with reference to FIGS. On the menu screen, for example, a plurality of items are displayed in an array, and a display indicating the selected state of the currently selected item (for example, cursor or reverse display) is performed. For example, when selecting a mode relating to a shooting scene, a menu screen as shown in FIG. 8 is displayed on the external display unit 30. FIG. 8 is a diagram showing an example of a menu screen displayed on the external display unit 30 when a mode relating to a shooting scene is selected.

In the menu screen of FIG. 8, when the upper switch 32U of the quad switch 32 is pressed, the display position of the black triangle cursor 73 (that is, the item indicated by the cursor 73) cyclically moves upward. When the lower switch 32D of the quad switch 32 is pressed, the display position indicated by the cursor 73 cyclically moves downward. Then, when the confirmation switch 34 is pressed, the cursor 7
The item (document image in FIG. 8) designated by No. 3 is set as a shooting scene.

Therefore, the photographer operates the quadruple switch 32 in the vertical direction on the menu screen for selecting the photographing mode to select the desired photographing mode, and operates the confirm switch 34 to set the photographing mode. be able to.

When the document image mode is selected on the menu screen of FIG. 8, the menu screens shown in FIGS. 9 to 11 are displayed. 9 to 11 are diagrams showing an example of a menu screen displayed on the external display unit 30 when the document image mode is selected.

When the right switch 32R is pressed while the cursor 73 is set on the document image as shown in FIG. 8, the menu screen is switched to "Document image mode setting 1" shown in FIG.

When the up / down switches 32U and 32D of the quad switch 32 are pressed on the menu screen of FIG. 9, the cursor 73 cyclically moves in the up / down direction. With this, it is possible to select "divided exposure only when the camera shake limit is exceeded", "always divided exposure", or "divided exposure not performed". When the left switch 32L of the quad switch 32 is pressed in the display state of FIG. 9, the menu screen shown in FIG. 8 is displayed, and when the right switch 32R is pressed, the “Document image mode setting 2” shown in FIG. 10 is displayed. Switch to the menu screen.

When the up / down switches 32U and 32D of the quad switch 32 are pressed on the menu screen of FIG. 10,
The cursor 73 moves cyclically in the vertical direction. As a result, the number of divisions when performing the divided exposure is “2”,
It is possible to select from "4" and "8". When the left switch 32L of the quad switch 32 is pressed in the display state of FIG. 10, the menu screen shown in FIG. 9 is displayed, and when the right switch 32R is pressed, the “Document image mode setting 3” shown in FIG. 11 is displayed. Switch to the menu screen.

When the up / down switches 32U and 32D of the quad switch 32 are pressed on the menu screen of FIG. 11,
The cursor 73 moves cyclically in the vertical direction. As a result, the recording mode at the time of recording an image by photographing a document can be selected from “monochrome simple binarization”, “monochrome dither matrix”, “253 colors (so-called Web color)”, and “full color”. You can do it. When the left switch 32L of the quad switch 32 is pressed in the display state of FIG. 11, the menu screen shown in FIG. 10 is displayed.

When the confirmation switch 34 is pressed in the display state shown in FIGS. 9 to 11, the setting of the document image mode is completed. The set contents are stored in the RAM 87.

Returning to FIGS. 6 and 7, the mode relating to the exposure control is a mode relating to how to determine the exposure control value at the time of photographing (image recording), that is, the aperture value of the diaphragm 8 and the exposure time. In the present embodiment, the mode relating to the exposure control includes, for example, a program mode, a shutter priority mode, and an aperture priority mode. The exposure control value is set by using one of a plurality of preset program charts. In the program mode, the exposure control value is set by using a standard program chart, and the shutter is set. In the priority mode, the exposure control value is set using a program diagram that gives priority to the shutter speed (exposure time) over the aperture value.
In the aperture priority mode, the exposure control value is set using a program diagram that gives priority to the aperture value over the shutter speed. As for the mode related to the exposure control, a desired mode can be similarly set by using the quad switch 32. The set contents are stored in the RAM 87.

The exposure value calculation unit 92 calculates an exposure control value when a live view image is captured or a subject is photographed, that is, an exposure time TV (EV value) of the CCD 23 and an aperture value AV (EV value) of the diaphragm 8. Therefore, the brightness of the subject is determined using the image data of the color component G of the live view image, and the exposure control value is calculated based on the determination result and the setting contents of the mode relating to the exposure control.

The display control section 93 displays C in the recording mode.
The live view image captured from the CD 23 to the image memory 56 is displayed on the finder display unit 27, and the recorded image read from the memory card 21 to the image memory 56 in the reproduction mode is displayed on the external display unit 30.
The image data temporarily stored in the image memory 56 is read out, the image size is adjusted to the display size of the display units 27 and 30 if necessary, and then transferred to the VRAMs 71 and 72.

In the photographing standby state, the CCD 23 is driven in the draft mode, and the image data of the number of pixels 200 × 150 decimated to ⅛ of the image picked up by the CCD 23 is output every 1/30 seconds and the signal is output. Processing circuit 5
After being subjected to predetermined signal processing by the 1 to γ correction circuit 55, it is stored in the image memory 56 and is sequentially read by the overall control unit 90 and transferred to the VRAM 72, whereby a live view image of the subject is obtained. It is displayed on the finder display unit 27. Further, when the display of the external display unit 30 is instructed by the operation of the display changeover switch 36, the image data is transferred to the VRAM 71 as well, whereby the monitor image of the subject is displayed on the external display unit 30. This allows the photographer to select one of the display units 27, 30.
The subject image can be visually recognized from the image displayed on.

Further, when the menu display is instructed by operating the menu switch 37, the image data of the menu screen stored in the EEPROM 86 is read into the VRAM 71 and the display content of the external display section 30 is switched to the menu screen.

In the reproduction mode, the memory card 21
Image data for index display is created from each frame image file recorded in the
The external display unit 30 displays an index screen, which is a list of photographed images read by the memory 71 and recorded in the memory card 21.
Is displayed in. On the index screen, memory card 2
Thumbnail images for a plurality of frames (for example, 9 frames in this embodiment) are arranged and displayed according to a predetermined format (for example, 3 × 3 in this embodiment) from all the images recorded in No. 1 and the currently selected frame is displayed. The display selected for (for example, blinking display or frame display) is performed.

When any one of the upper, lower, left and right switches of the quad switch 32 is pressed, the display showing the selected state of the index screen moves to the item or frame in that direction.
For example, when the upper switch 32U is pressed, the display showing the selection state of the index screen moves to the upper item or frame. When a frame to be reproduced is specified by operating the quad switch 32, image data of a captured image recorded in a predetermined format is read from the image file corresponding to the frame recorded in the memory card 21, After the predetermined signal processing is performed by the overall control unit 90, it is adjusted to the display size of the external display unit 30 and transferred to the VRAM 71. As a result, the captured image is reproduced and displayed on the external display unit 30.

The recording control unit 94 uses the C
The recorded image taken from the CD 23 into the image memory 56 is recorded in the card memory 21, and when the photographing is instructed by pressing the shutter button 26 fully in the normal photographing mode, it is temporarily stored in the image memory 56 after the photographing instruction. Image data (image data of a still image) is read into the RAM 87, and JPEG (Joint Photographic coding Experts) such as two-dimensional discrete cosine transform or Huffman coding is read.
The image data for recording is created by performing a predetermined compression process according to the Group method.

Further, the recording control section 94 reads out the frame image, which is photographed in the draft mode immediately before the shutter button 26 is fully pressed and is stored in the image memory 56, to the RAM 87, and thereby the thumbnail image of 200 × 150 pixels is displayed. create.

Further, the recording control section 94 creates tag information relating to the photographed image recorded together with these recording image data. This tag information includes the lens name, frame number, focal length at the time of shooting, F number at the time of shooting, focus position, subject brightness, white balance adjustment value, shooting mode, compression rate, shooting date, whether flash light is emitted, etc. included.

Then, the recording control unit 94 attaches tag information to the image data of the compressed photographed image and thumbnail image to create an image file of EXIF (EXchangeable Image file Format) format, and this image file is stored in a memory card. Record at 21.

Further, the recording control unit 94, when photographing a document image, sets "black and white simple binarization", "black and white dither matrix" in "document image mode setting 3" (see FIG. 11). The document image is recorded according to the recording mode set among "253 colors" and "full color".

The reproduction control section 95 reads the photographed image to be reproduced, which is recorded in the memory card 21 in the reproduction mode, into the image memory 56 and performs reproduction processing on the external display section 30. When the mode is set, thumbnail images are read from each image file recorded in the memory card 21 and sequentially read in a predetermined format (for example, two-dimensional 3 × 3 per page).
= VRAM according to (arrange 9 thumbnail images)
71. As a result, the nine 2
The three-dimensionally arranged thumbnail images are displayed as an index.

When the thumbnail image of the frame to be reproduced with respect to the thumbnail image displayed in the index is designated by the quad switch 32, the cancel switch 33, the confirm switch 34, etc., the reproduction controller 95 corresponds to the frame. Read the captured image data from the image file,
After performing a predetermined decompression process, the image data is stored in the image memory 56. The data read out to the image memory 56 is adjusted in data size by the display control unit 93 and transferred to the VRAM 71 as described above, whereby the external display unit 3 is operated.
Playback is displayed at 0.

Next, each functional block of the recording control unit 94 of FIG. 7 will be described with reference to FIGS. FIG. 12 is a diagram showing an example of an edge enhancement filter,
FIG. 13A is a diagram showing an example of a histogram when a document is photographed with an appropriate exposure time (charge accumulation time), and FIG.
It is a figure which shows the histogram when a document was image | photographed by the exposure time of 1/4 of (a). Further, FIG. 14 is a diagram for explaining calculation of a shift amount of two images, and FIG. 15 is a diagram for explaining image composition.

In FIG. 7, the document exposure control unit 101 of the recording control unit 94 is used when the document image is set in the mode setting relating to the shooting scene, as shown in FIGS.
According to the setting contents of the document image mode explained using
It controls a plurality of continuous divided exposures (divided shooting).

That is, "Document image mode setting 1"
In FIG. 9, when the “divided exposure only when the camera shake limit is exceeded” is set, the camera shake determination unit 10
The divided exposure is performed only when it is determined by 4 that the camera shake limit is exceeded. When the "always divided exposure" is set, the divided exposure is always performed, and "the divided exposure is not performed" is set. In this case, the divided exposure is not performed. Also,
Divided exposure is performed the number of times set among "2", "4", and "8" in "Document image mode setting 2" (see FIG. 10).

The document exposure control unit 101 sets the exposure time when performing the divided exposure operation to a value that does not cause camera shake based on the focal length of the interchangeable lens 3. For example, the power switch 31 is turned on. When the lens ROM1
Set the exposure time for divided exposure based on the information from 5,
It is stored in the EPROM 86 or the RAM 87.

Further, the document exposure control section 101 controls to inhibit the flash 5 from emitting light in the document image mode. This control is performed by, for example, setting an off flag in the control signal sent to the light emission control unit 58.

The change processing unit 102 performs a predetermined change process on the image data obtained by the divided exposure. In the present embodiment, for example, the edge enhancement process is performed and then the binarization process is performed. ing.

The edge emphasis processing is performed by a known method using a digital filter. For example, by applying the edge emphasis filter shown in FIG. 12 to each pixel data, the image data with the edges emphasized can be obtained. Becomes As a result, the change in the correlation value between the images obtained by the divided exposure with respect to the peak becomes steep as the edge is emphasized, so that the shift amount between the images can be accurately obtained.

The binarization process is performed with a predetermined threshold value T. For example, as shown in FIG. 13B, when the exposure time in divided exposure set in consideration of the camera shake limit is ¼ of the appropriate exposure time, the threshold T for binarization is T = It becomes 256/4/2 = 32. However, in this embodiment, the digital value of the image data is represented by 8 bits.

The synthesizing control unit 103 calculates a shift amount of a plurality of images obtained by continuous divided exposure, corrects the shift amount, and synthesizes the image data into one image data.

For example, as shown in FIG. 14, for one reference image data (for example, image data obtained by the first exposure) 111, other image data 112 are respectively expressed by X-L≤X'≤X + LY. Within the range of −D ≦ Y ′ ≦ Y + D, pixel by pixel in X (horizontal) direction and Y (vertical)
Then, the correlation value with respect to the reference image data 111 at each position is obtained, and the shift amount (dX, dY) of the position where the maximum correlation value is obtained from the original position is obtained.

At this time, the synthesizing control unit 103 uses the image data that has been changed by the change processing unit 102. In this embodiment, for example, L = 40 pixels and D =
It has 30 pixels. Further, in the present embodiment, the change processing unit 1
The change process by 02 and the shift amount calculation by the synthesis control unit 103 are performed by using, for example, only the color component G in the color image data, thereby shortening the calculation time.

Then, as shown in FIG. 15, the other image data 112 is superposed on the reference image data 111 while being moved by the shift amount (dX, dY), and the non-overlapping image data (in FIG. (The indicated portion) is deleted and the image data is combined into one image data. At this time, the synthesis control unit 103
Is performed using the original image data, that is, the data that has not been changed by the change processing unit 102. Note that in FIG. 15, the other image data 112 is 1 for convenience of description.
Only one is shown.

The camera shake determination unit 104 includes an exposure value calculation unit 92.
It is determined whether or not the exposure time (shutter speed) calculated by exceeds the camera shake limit. When 1 / f <S, it is determined that the camera shake limit is exceeded. Where S
Is the exposure time. Further, f is the focal length of the interchangeable lens 3, and a value converted into a 35 mm film based on the pixel pitch of the CCD 23 is used.

Next, a procedure for photographing a document image will be described with reference to FIGS. 16 and 17 are flowcharts showing a document image mode subroutine (document photographing control program), and FIG. 18 is a flowchart showing a deviation amount calculation subroutine of # 165 in FIG.

When the document image mode is set on the menu screen of FIG. 8, the control main routine (not shown) of the digital still camera 1 executed by the overall control unit 90 calls the subroutines of FIGS. 16 and 17. .

In FIG. 16, first, the flash 5 is turned off (# 100), then it is determined whether or not the lock switch 81 is on (# 105), and if it remains off (NO in # 105). , Return to the main routine. on the other hand,
The shutter button 26 is pressed halfway and the lock switch 8
When 1 is turned on (YES in # 105), immediately before the CCD
The brightness of the subject is determined based on the image signal output from H. 23, and based on the determination result, an appropriate exposure time in the state where the aperture 8 is narrowed down to the maximum is calculated (# 1
10).

Then, the setting contents of the document image mode stored in the RAM 87 are fetched (# 115), the setting contents are discriminated (# 120), and when the setting "do not perform division exposure" is set ( # 120), # 125
If it is set to "divide the exposure only when the camera shake limit is exceeded"(# 120), go to # 130 and set to "Always perform the divided exposure"(# 120).
(At 120), proceed to # 135.

In # 125, it is determined whether or not the shutter release button 82 is turned on by fully pressing the shutter button 26, and if it is not turned on (NO in # 125).
O), returns to # 105 and is turned on (Y in # 125.
ES), normal shooting is performed (# 140), and the process proceeds to # 175.

In # 130, it is determined whether or not the camera shake limit is exceeded. If the camera shake limit is not exceeded (NO in # 130), the process proceeds to # 125, and if the camera shake limit is exceeded (YES in # 130). ), Proceed to # 135.

At # 135, it is determined whether or not the shutter release button 82 is turned on by fully pressing the shutter button 26, and if it is not turned on (N at # 135).
O), returns to # 105 and is turned on (Y in # 135
ES), divided exposure is performed the set number of times (# 14).
5).

Next, a binarization threshold value corresponding to the number of divided exposures is set (# 150), and edge enhancement processing is performed (# 150).
155), and then the image data is binarized by the set binarization threshold (# 160).

Using this binarized data, the shift amount between the images is calculated (# 165), and then the original image data of 8-bit data is corrected by the obtained shift amount. Are combined into one image data (# 17
0). Next, the combined image is recorded in the memory card 21 (# 175), and this subroutine is finished.

Next, the subroutine of FIG. 18 will be described. First, each binarized image data is fetched (# 200).

Next, for one reference image data,
For other image data, one pixel at a time in the X (horizontal) direction and Y (vertical) within the range of X-L≤X'≤X + L Y-D≤Y'≤Y + D.
And the correlation value with respect to the reference image data 111 at each position is obtained (# 205).

Then, the deviation amount (dX, dY) of the position having the maximum correlation value from the original position is obtained (# 210).

Then, until all image data other than the reference image data is completed (NO in # 215),
When # 205 and # 210 are repeated and shift amounts are obtained for all other image data (YES in # 215),
finish.

As described above, according to the present embodiment, the menu screen for setting the shooting mode by the shooting mode control unit 91 is displayed on the external display unit 30, and the switches 32 to 32 of the operation unit 80 are displayed on the menu screen. When the document image mode is set by the operation of 36, the CCD 23 performs the divided exposure operation continuously a plurality of times with the exposure time in which the camera shake does not occur, and the shift amount between the images obtained by the divided exposure operation is corrected. Since the images are combined into one image and recorded in the memory card 21, the document image can be easily recorded in the memory card 21 without increasing the device configuration.

Further, according to this embodiment, the change processing unit 1
By 02, the image data of each image obtained by the divided exposure operation is binarized to obtain the shift amount. Therefore, since the amount of data to be calculated is reduced, the calculation time of the shift amount between the images is reduced. It can be shortened.

Further, according to this embodiment, the change processing unit 1
02, the edge enhancement processing is performed on the image data of each image obtained by the divided exposure operation, and the other image is moved pixel by pixel with respect to the reference image, and the image is shifted by the movement amount that maximizes the correlation value between the images. I try to find the quantity,
Since the edge is emphasized and the change curve with respect to the peak of the correlation value becomes steep, and the boundary of coincidence / non-coincidence between the images becomes clear, the shift amount can be accurately calculated.

Further, according to this embodiment, the synthesis control unit 1
C before binarization or edge enhancement processing by 03.
1 for each image using the image data output from CD23
Since the images are combined into one image, it is possible to preferably record the document image without degrading the image quality.

Further, according to the present embodiment, when the document image mode is selected, on the menu screen of “Document image mode setting 1” displayed on the external display section 30, “only when the camera shake limit is exceeded is divided. "Exposure", "always divided exposure",
The setting is made by operating each of the switches 32 to 36 of the operation unit 80 from among "do not perform divisional exposure", and the divisional exposure is performed according to the setting contents. It is possible to improve the usability of the digital still camera 1.

In this case, if "divided exposure only when the camera shake limit is exceeded" is set, divided exposure is performed only when the camera shake determination unit 104 determines that the camera shake limit is exceeded, so the camera shake limit is exceeded. It is possible to obtain a high-quality image, and it is possible to shorten the shooting time when the camera shake limit is not exceeded.

If "divided exposure always" is set, the judgment by the camera shake judgment unit 104 becomes unnecessary, and an image without camera shake can be surely obtained. Further, if "do not perform divisional exposure" is set, it is possible to reliably reduce the photographing time.

Further, according to the present embodiment, when the document image mode is selected, “2” is displayed on the menu screen of “Document image mode setting 2” displayed on the external display unit 30.
Each switch 32 of the operation unit 80 from among “4” and “8”
It is possible to perform the photographing operation according to the use and purpose of the user because the setting is performed by the operations of to 36 and the divided exposure is performed by the set number of times, and the usability of the digital still camera 1 is improved. be able to. For example, if you set it to “2”, you can shorten the shooting time.
When set to "8", a high quality document image can be obtained although the shooting time becomes long, and when set to "4", the document image can be shot at a medium shooting time and image quality.

Further, according to the present embodiment, when the document image mode is selected, the document exposure control unit 101 prohibits the flash 5 from emitting light, so that the document image is erroneously photographed. It is possible to prevent the flash 5 from emitting light in advance, so that a document image can be appropriately captured.

Further, the digital still camera of the above embodiment includes a state in which a still image is photographed by a digital video camera having a still image photographing function.

The present invention is not limited to the above embodiment,
The following modifications can be adopted.

(1) For example, as shown in FIG. 13B, when divided exposure is performed with an exposure time of 1/4 of an appropriate exposure time, a histogram as shown in FIG. May be generated, and the image data may be binarized with the binarization threshold value T = 128.

(2) In the above embodiment, as shown in FIG. 17, edge enhancement processing is performed (# 155) and binarization (# 160) is performed, but the present invention is not limited to this.
Only the edge enhancement processing may be performed and the binarization may not be performed. According to this modification, it takes more time to calculate the shift amount than in the above-described embodiment, but the shift amount can be obtained with higher accuracy.

Alternatively, only binarization may be performed and the edge emphasis processing may not be performed. According to this variant,
It is possible to shorten the calculation time of the shift amount as compared with the above embodiment.

Further, in the above embodiment, the edge enhancement processing may be performed between the processing # 145 and the processing # 150.

(3) In the above embodiment, for example, FIG.
As shown in (a), when shooting is performed with an appropriate exposure time, the binarization threshold value T = 128 is set in the case of 8 bits, but the threshold value is not limited to this, and the threshold value is a so-called “background removal”. When T is a low value, for example, 8 bits, T = 8
It may be set to 10. According to this modification, since the dirt on the background is removed and the correlation value is obtained only in the line image portion, the shift amount can be calculated with higher accuracy.

(4) In the above embodiment, on the menu screen of "Document image mode setting 1", "divided exposure only when the camera shake limit is exceeded", "always divided exposure", and "divided exposure not performed". Although the divided exposure is performed according to the contents set from the inside, the present invention is not limited to this. For example, when the camera shake determination unit 104 determines that the camera shake does not occur, the exposure time calculated by the exposure value calculation unit 92 automatically performs the normal shooting on the CCD 23 only once at the calculated exposure time. You may allow it.
According to this modification, the setting by the user is unnecessary, and the menu screen can be simplified.

(5) In the above embodiment, the number of divided exposures is selected from 2, 4, and 8, but the number is not limited to this. For example, the number of divided exposures is automatically set based on the quotient obtained by dividing the calculation result of the exposure time calculated by the exposure value calculation unit 92 by the exposure time that is equal to or less than the shake limit determined by the shake determination unit 104. You may According to this modification, it is possible to surely prevent the occurrence of camera shake and underexposure.

(6) In the above embodiment, the flash 5 is prohibited from emitting light by setting the OFF flag in the control signal sent from the document exposure controller 101 to the light emission controller 58. Not limited. For example, a semiconductor switch is provided between the flash 5 and the main capacitor that supplies power to the flash 5 in the light emission control unit 58, and this semiconductor switch is connected to the document exposure control unit 101.
May be turned off by.

(7) In the above embodiment, the overall controller 90
The control program is stored in the EEPROM 86, but the control program is not limited to this. For example, a control program including the document photographing control program shown in FIGS. 16 to 18 may be stored in the memory card 21 and downloaded to the EEPROM 86 or the RAM 87.

[0152]

As described above, according to the inventions of claims 1 and 11, when the document image mode is selected as the photographing mode by an external operation, the divided photographing with a predetermined exposure time is continuously performed. Multiple times to obtain the shift amount between the images obtained by the divided photographing, correct the shift amount, combine each image into one image, and record the combined image in the recording means. Therefore, the document image can be easily photographed and recorded without increasing the size of the apparatus.

According to the second aspect of the invention, the image signal output from the image pickup means when the divided image pickup is performed is subjected to a predetermined change process, and the image signal subjected to the change process is used to shift the image signal. Since the amount is calculated, the amount of deviation can be calculated in a short time or with high accuracy, depending on the purpose and application.

Further, according to the third aspect of the invention, since the image signal is binarized as the predetermined changing process, the amount of data for calculation is reduced, and therefore the shift amount is calculated at high speed. be able to.

Further, according to the invention of claim 4, since the image signal is subjected to the edge enhancement processing as the predetermined change processing, the edge enhancement is performed so that the coincidence and non-coincidence between the respective images are detected. Since the boundary becomes clear, the amount of deviation can be calculated accurately.

Further, according to the invention of claim 5, since the change processing is performed on the signal obtained by thinning out the image signal output from the image pickup means at a predetermined ratio, the change processing can be performed at high speed. As a result, the shift amount can be calculated at high speed.

Further, according to the invention of claim 6, since the respective images are combined into one image by using the image signal before the change processing is performed, the image signal output from the image pickup means. Is used, it is possible to preferably record the document image without deteriorating the image quality due to the changing process.

According to the invention of claim 7, the brightness of the subject is judged based on the image signal output from the image pickup means before the release switch is turned on, and the proper level is determined based on the judged brightness of the subject. The exposure time for obtaining the image signal is calculated, and whether or not camera shake occurs at the calculated exposure time is determined based on the focal length information of the photographing optical system, and when it is determined that camera shake does not occur, Even if the document image mode is selected, since the normal shooting is performed only once with the exposure time calculated by the image pickup means, the split shooting is not performed when the shooting environment is sufficiently bright. , The shooting time can be shortened.

Further, according to the invention of claim 8, when the document image mode is selected, there is provided a second operation means which can be operated from the outside for always selecting whether or not to perform the divided photographing, When the second operation means is selected to always perform the split shooting, the split shooting is performed by the image pickup means even when it is determined that the camera shake does not occur. It is possible to make a selection according to the purpose and application of the user, such as placing importance on shortening the image quality or placing emphasis on improving the image quality of the image, thus improving usability.

Further, according to the invention of claim 9, when the document image mode is selected, the flash is prohibited from being emitted. Therefore, when the document image is taken, the flash is erroneously taken. It is possible to prevent light emission and image quality deterioration.

According to the tenth aspect of the invention, there is provided third operating means that can be operated from the outside for setting the number of times of divided photographing to be performed consecutively, and only the number of times set by the third operating means is provided. Since it is designed to continuously perform divided shooting with the image pickup means, it is set according to the purpose and use of the user, such as emphasis on ease of shooting and shortening of shooting time, and emphasis on improving image quality. It becomes possible to improve the usability.

[Brief description of drawings]

FIG. 1 is a front view of a camera body that constitutes an embodiment of a digital still camera according to the present invention.

FIG. 2 is a top view showing an arrangement of main members incorporated in the same embodiment.

FIG. 3 is a right side view showing the arrangement of main members incorporated in the same embodiment.

FIG. 4 is a rear view of the same embodiment.

FIG. 5 is a diagram illustrating a configuration of a color image sensor.

FIG. 6 is a block diagram showing an electrical configuration of a digital still camera.

7 is a block diagram showing functional blocks of the overall control unit of FIG.

FIG. 8 is a diagram showing an example of a menu screen displayed on an external display unit when a mode relating to a shooting scene is selected.

FIG. 9 is a diagram showing an example of a menu screen displayed on the external display unit when the document image mode is selected.

FIG. 10 is a diagram showing an example of a menu screen displayed on the external display unit when the document image mode is selected.

FIG. 11 is a diagram showing an example of a menu screen displayed on the external display unit when the document image mode is selected.

FIG. 12 is a diagram showing an example of an edge enhancement filter.

13A is a diagram showing an example of a histogram when a document is photographed with an appropriate exposure time, and FIG. 13B is a quarter of FIG.
It is a figure which shows the histogram when a document is image | photographed by the exposure time of.

FIG. 14 is a diagram illustrating calculation of a shift amount between two images.

FIG. 15 is a diagram illustrating image composition.

FIG. 16 is a flowchart showing a document image mode subroutine.

FIG. 17 is a flowchart showing a document image mode subroutine.

FIG. 18 is a flowchart showing a deviation amount calculation subroutine of # 165 of FIG.

FIG. 19 is a diagram showing a histogram obtained by multiplying the gradation value of FIG. 13B by four.

[Explanation of symbols]

5 flash 21 Memory card (recording means) 23 CCD (imaging means) 26 Shutter button 80 operation section (first, second and third operation means) 81 Lock switch 82 Release switch 86 EEPROM 90 Overall control unit 91 shooting mode control unit (document shooting control means) 92 Exposure value calculator (exposure value calculator) 93 Display control unit 94 recording control unit (recording control means) 95 Playback control section 101 document exposure control unit (document photographing control means) 102 change processing unit (change processing means) 103 synthesis control unit (synthesis control means) 104 Shake Detection Unit (Shake Detection Unit)

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G06T 3/00 400 G06T 3/00 400J 5C052 H04N 1/387 H04N 1/387 5C053 5/335 5/335 Z 5C076 5 / 907 5/907 B 5/91 101: 00 // H04N 101: 00 5/91 JF Term (reference) 2H053 CA41 DA03 2H054 AA01 5B057 AA11 BA02 BA19 CA02 CA08 CA12 CA16 CB02 CB12 CB16 CC03 CE10 CE12 DA07 DB02 DB05 DB08 DC34 DC36 5C022 AA13 AB17 AB55 AC12 AC42 AC69 CA07 5C024 AX01 BX01 CX39 DX01 GY01 5C052 AA17 DD02 GA02 GE08 5C053 FA08 JA16 LA01 5C076 AA12 AA22 AA31 AA36 BA01 BA06 BB06

Claims (11)

[Claims] 1. A digital still camera having an image pickup means for receiving a light image of a subject through a photographing optical system and outputting an image signal corresponding to the light intensity, for selecting a document image mode as a photographing mode. Operation means operable from the outside of the camera, and a document photographing control means for causing the photographing means to continuously perform divided photographing at a predetermined exposure time a plurality of times when the document image mode is selected, and the divided photographing. A combination control unit that obtains a deviation amount between the obtained images, corrects the deviation amount and combines the images into one image, and a recording control unit that records the combined image in a recording unit A digital still camera characterized by that. 2. The digital still camera according to claim 1, further comprising change processing means for performing a predetermined change processing on an image signal output from the image pickup means when the document image pickup control means performs divided image pickup. The digital still camera, wherein the synthesizing control means obtains the shift amount by using the image signal subjected to the change processing. 3. The digital still camera according to claim 2, wherein the change processing means binarizes the image signal as the predetermined change processing. 4. The digital still camera according to claim 2, wherein the change processing means performs an edge enhancement process on the image signal as the predetermined change process. 5. The digital still camera according to claim 2, wherein the change processing unit performs the change process on a signal obtained by thinning out an image signal output from the image pickup unit at a predetermined ratio. A digital still camera characterized by being applied. 6. The digital still camera according to any one of claims 2 to 5, wherein the synthesizing control unit synthesizes each image into one image by using the image signal before the change processing is performed. A digital still camera characterized by being a thing. 7. The digital still camera according to claim 1, wherein the brightness of the subject is determined based on an image signal output from the image pickup means before the release switch is turned on. Exposure value calculation means for calculating an exposure time for obtaining an image signal of an appropriate level based on the brightness of the subject, and whether or not camera shake is caused by the calculated exposure time, in the focal length information of the photographing optical system. The image capturing control unit includes a camera shake determination unit that makes a determination based on the above, and when the document image capturing control unit determines that no camera shake occurs, the document image mode is selected.
A digital still camera, wherein normal photographing is performed only once with the calculated exposure time by the image pickup means. 8. The digital still camera according to claim 7, wherein when the document image mode is selected,
A second operation unit that can be operated from the outside for always selecting whether or not to perform the divided photographing is provided, and the document photographing control unit is selected by the second operation unit to always perform the divided photographing. The digital still camera is characterized in that, even when it is determined that hand-shake does not occur, the image pickup means performs the divided shooting. 9. The digital still camera according to claim 1, further comprising a flash that emits light in synchronization with operation of a shutter button, and when the document image mode is selected, the flash of the flash is displayed. A digital still camera characterized in that it is configured to prohibit light emission. 10. The digital still camera according to claim 1, further comprising a third operation unit that can be operated from the outside to set the number of times of the divided photographing that is continuously performed. The digital still camera, wherein the control means causes the image pickup means to continuously perform the divided photographing for the number of times set by the third operation means. 11. An image pickup means for receiving a light image of a subject through a photographing optical system and outputting an image signal corresponding to the light intensity, and an externally operable device for selecting a document image mode as a photographing mode. When the document image mode is selected, a digital still camera equipped with an operating means is provided with a document photographing control means for causing the photographing means to successively perform a plurality of divided photographing with a predetermined exposure time, and the divided photographing. Functioning as a combination control unit that obtains the amount of deviation between the images obtained by the above, corrects the amount of deviation, and combines each image into one image, and a recording control unit that records the combined image in the recording unit. A computer-readable recording medium in which a document photographing control program is recorded.