JPH09289610A - Digital camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the operability and to reduce a mistake in image pickup in the case that a tilt image is corrected into a pseudo front image for the image pickup. SOLUTION: In the tilt image pickup correction mode, when only a switch S1 of a shutter button 14 is closed, an object distance and a distribution of an image pickup magnification on an image pickup face are calculated based on a tilt angle between the object face and the image pickup face set by a mode setting switch 10 and on the object distance detected by a range finding section 33. A tilt image picked up by a CCd 18 is corrected into a pseudo front image based on the distribution of the object distance and the image pickup magnification at a tilt image pickup correction arithmetic section 26 and the image after the correction is displayed on a liquid crystal display finder 9. Furthermore, when a switch S2 of the shutter button 14 is closed, the image after the correction is stored in a card memory 27. The image after the correction is monitored before main image pickup to improve the operability of the image pickup and to reduce the mistake in the tilt image pickup correction mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital camera capable of correcting an image viewed from an oblique direction with respect to a subject to an image viewed from the front, and particularly, displaying the corrected image on a monitor. It is about.

[0002]

2. Description of the Related Art In a conference hall, for example, a participant's seat is usually arranged at a position oblique to the whiteboard, so that figures and characters drawn on the whiteboard without moving the seat are used. When the photograph is taken, the photographed image becomes an oblique image, and it becomes difficult to read figures, characters, and the like. In order to avoid such a problem of the oblique image, it is necessary to move the photographing position to the front position with respect to the whiteboard. However, since it is difficult to move the photographing position during the meeting, the camera simulates the oblique image. It is extremely convenient to provide a function of capturing an image by correcting it to a typical front image.

In the above oblique photographing scene,
Normally, in the vertical direction, the imaging surface and the subject surface are parallel, and the imaging surface and the subject surface are inclined in a horizontal plane. Therefore, if the inclination angle is θ, the subject image is S, and the shooting magnification is m, the camera captures the image. Since the oblique image projected on the surface is m · Scos (θ), if the inclination angle θ and the imaging magnification m are known, the oblique image is corrected to the front image based on the inclination angle θ and the imaging magnification m. It becomes possible.

Therefore, in the specification filed on the same day as the present application, the applicant has an angle setting means for setting an inclination angle formed by the image pickup surface of the image pickup means and a subject surface, and a distance measuring means for measuring a distance to the subject. And a digital camera that is capable of capturing an image by correcting a diagonal image into a front image based on a set tilt angle and a measured subject distance.

[0005]

By the way, in the digital camera having the function of correcting the oblique image, if the inclination angle is not accurately input, the correction of the oblique image becomes inadequate, and an unnatural photographed image is obtained. However, when the photographer sets the tilt angle between the imaging plane and the subject plane, the photographer senses and sets the approximate angle between the subject plane and the imaging plane of the camera. , It is difficult to set the inclination angle accurately.

Therefore, it is preferable that the corrected image can be monitored before photographing and the correction result can be confirmed.
Conventionally, such a monitor function has not been proposed.

The present invention has been made in view of the above problems, and makes it possible to monitor an image after correction before photographing, and to easily and easily correct an oblique image into a pseudo front image and photograph it. It provides a camera.

[0008]

According to the present invention, there is provided an image pickup means comprising a two-dimensional array of pixels comprising a plurality of photoelectric conversion elements,
An angle input means for inputting an inclination angle formed by the image pickup surface of the image pickup means and an object surface, a distance measuring means for measuring a distance to the object, and the above-mentioned based on the input inclination angle and the measured object distance. A digital camera including a correction unit that corrects an oblique image of the subject captured by the image capturing unit into a pseudo front image, the display unit displaying the image captured by the image capturing unit, and a monitor display instruction. The display device further includes an instruction unit and a display control unit for displaying the image corrected by the correction unit on the display unit when the monitor display is instructed by the instruction unit (claim 1).

According to the above construction, the oblique image photographed with the object surface tilted at the angle θ with respect to the image pickup surface of the image pickup means is measured by the tilt angle θ set by the angle setting means and the distance measuring means. Based on the detected subject distance D, the subject is corrected to a pseudo front image as seen from the front.

In this case, when the monitor display is instructed by the instructing means, the corrected pseudo front image is displayed, and the correction result of the obliquely photographed image can be confirmed.

According to the present invention, in the above digital camera, the display control means displays the image captured by the image capturing means on the display means when the monitor instruction by the instruction means is not instructed. There is (claim 2).

According to the above arrangement, when the monitor display is not instructed by the instructing means, the image captured by the image capturing means is displayed on the display means without being corrected, and when the monitor display is instructed. After the image picked up by the image pickup means is corrected, the corrected image is displayed on the display means.

[0013]

FIG. 1 is a perspective view showing the appearance of a digital camera according to the present invention. Camera 1 shown in FIG.
Is equipped with a CCD area sensor as an image pickup device.
The image data picked up by the CD area sensor is P
The data is recorded on a CMCIA-compliant hard disk card. In the camera 1, an image of a subject (hereinafter, referred to as an oblique image) in which the imaging surface of the CCD area sensor is not parallel to the subject surface is referred to as an image of a subject in which the imaging surface and the subject surface are parallel (hereinafter, a front image). ) Is provided (hereinafter, this correction is referred to as oblique photographing correction).

That is, for example, as shown in FIG. 3, when a character or a figure drawn on the whiteboard 16 is photographed in a normal photographing mode from a position diagonally forward left (a), the photograph is taken. The image is a diagonal image K whose size on the right end side is smaller than that on the left end side as shown in FIG. 4A due to the different distribution of subject distances within the shooting screen, which will be described later. When the image is captured in the oblique image capture correction mode, the oblique image K is corrected to a front image K ′ almost as captured from the front position (b) of the whiteboard 16 as shown in FIG. 4B. is there.

Here, the principle of the oblique photographing correction will be briefly described. For convenience of description, a one-dimensional image will be described.

FIG. 5 is a schematic configuration diagram of the optical system of the camera 1. The optical system of the camera 1 includes a horizontally long rectangular CCD area sensor 18 (hereinafter, referred to as CCD 1) at an imaging position of the taking lens 2.
It is abbreviated as 8. ) Is arranged, and this imaging lens 2 and CC
A diaphragm 17 is arranged between the diaphragm 17 and D18. An optical image such as a drawing drawn on the whiteboard 16 is formed on the image pickup surface of the CCD 18 after passing through the taking lens 2 and the diaphragm 17.

FIG. 6 is a view of the image pickup system in oblique photographing as seen from directly above. The angle between the display surface of the whiteboard 16 (hereinafter, referred to as the object surface) and the image pickup surface of the CCD 18 is θ (hereinafter, the tilt angle θ). The image pickup system in the case of tilting only) is shown.

In FIG. 6, L is the optical axis of the taking lens 2. Further, N0, N1, and N2 are line segments parallel to the image pickup surface of the CCD 18 passing through the points P, F, and G on the whiteboard 16, respectively, and N3 is a subject plane (line that passes through the point A on the image pickup surface of the CCD 18). It is a line segment parallel to the segment FG). Point O is the intersection of the lens surface of the taking lens 2 and the optical axis L, point Q is the intersection of the line segment N1 and the optical axis L, point R is the intersection of the line segment N2 and the optical axis L, and D, E Are respectively the intersections of the line segment N0 and the extension line of the line segment BF and the line segment GC. The points B'C 'are the intersections of the line segment N3 and the extended lines of the line segment FB and the line segment GC, respectively.

The light image between FGs on the whiteboard 16 is C
An image is formed between BCs on the image pickup surface of the CD 18, but since the image pickup surface and the object surface are inclined at an inclination angle θ, the optical image BC formed on the image pickup surface of the CCD 18 is equivalent to an image between DEs. CC
It is projected on the image pickup surface of D18. CCD1
The imaging magnifications at points A, B, and C on the image pickup surface of No. 8 are m _A , m _B , and m _C , respectively, and the subject distance is D _A (= O).
_{P), D B (= OQ} ), when the _{D C (= OR), m} B =
_{m A · OP / OQ = m} A · D A / D B, m C = m A · OP / O
Since R = m _A · D _A / D _C , m _B > m _A > m _C ,
The optical image formed on the imaging surface becomes an oblique image K as shown in FIG. 4A. Of the optical images BC, point A (the optical axis L and the imaging surface Intersection).

In the oblique photographing correction, the imaged image of the projected image DE (corresponding to the image BC) is converted into the imaged image of the projected image FG (image B'C ').
(Corresponding to the above), and this correction is a photographing magnification mi (i = 3, i) at each point between ACs on the image pickup surface of the CCD 18.
4, ... n) and the photographing magnification mi '(i =
3, 4, ... N), and each point of the picked-up image of the optical image BC is enlarged or reduced based on the photographing magnifications mi, mi '.

The subject distance at an arbitrary point between BAs on the image pickup surface of the CCD 18 is Di, and the angle of view at that point (the angle between the line passing through the point and the point O and the optical axis L) is αi.
Then, D _A / Di = cos (αi−θ) / cos (αi) · cos
(θ), m _A = k × f / D _A (k; proportional coefficient, f; focal length), so the imaging magnification m at any point between ACs
i is calculated by the following formula from the tilt angle θ, the focal length f of the taking lens 2 and the taking field angle αi.

[0022]

[Equation 1]

The above D _A / Di = cos (αi−θ) / cos
(αi) · cos (θ) is calculated as shown in the following Expression 2, when the subject distance D _B with respect to the point B in FIG. 6 is described as an example.

[0024]

[Equation 2]

If the object distance at any point between ACs on the image pickup surface of the CCD 18 is Di 'and the shooting angle of view at that point is βi, D _A / Di' = cos (βi + θ) / cos
Since (βi) · cos (θ), the imaging magnification mi ′ at an arbitrary point between BA is calculated from the tilt angle θ, the focal length f of the taking lens 2 and the taking field angle βi by the following formula.

[0026]

(Equation 3)

The above D _A / Di '= cos (βi + θ) / co
The equation of s (βi) · cos (θ) is calculated as shown in the following Equation 4 when the subject distance D _C with respect to the point C in FIG. 6 is taken as an example.

[0028]

(Equation 4)

By the way, according to the principle of the above-mentioned oblique photographing correction, it is necessary to perform the reduction correction for the BA portion and the enlargement correction for the AC portion of the optical image BC. Therefore, the correction is performed for the actual two-dimensional image. If you do, the process becomes complicated. Since the subject to be corrected for oblique photographing is often included in a range with a relatively narrow depth of field such as the figures and characters drawn on the whiteboard 16 as described above, the aperture 17 should be narrowed down. If shooting is performed so that the entire subject to be corrected is in focus as much as possible, good diagonal shooting is possible even if the image on the other side is magnified with respect to the position of the closest one end (point B in FIG. 6). Corrections can be made.

That is, in FIG. 6, even if the oblique image BC is corrected to the image BC ″ instead of being corrected to the image B′C ′, it is considered that the pseudo front image does not give a feeling of strangeness. , The intersection of a line segment N4 parallel to the line segment N3 passing through the point B and an extension line of the line segment GC. Also, A '
The point is the intersection of the line segment N4 and the optical axis L.

Therefore, in this embodiment, as shown in FIG. 7, the diagonal image K (whiteboard 1) shown in FIG.
6) is obliquely photographed from the left side), the diagonal photographing correction is performed by enlarging the image on the right edge side as shown in FIG. I am trying.

In this case, in the pseudo front image K'shown in FIG. 7 (b), the pixel data lacking in the area X1 (pixel data of the hatched portion in FIG. 7 (b)) is line-by-line. As shown in FIG. 8A, for example, the pixel data g1, g1 ', g2, g2' at both ends are interpolated to add pixel data g3, g3 '(image data shaded in the drawing) As for the pixel data of X2, as shown in FIG. 8B, the diagonal photographing correction is performed by interpolating the pixel data g5 of the next line with the entire pixel data g4 of the known line. The details of the diagonal image capturing correction will be described later.

Returning to FIG. 1, the camera 1 has a taking lens 2 arranged substantially in the center of the front surface, and a projecting window 4 and a light receiving window 5 for measuring a subject distance by an active distance measuring method are provided above the taking lens 2. A photometric window 3 for measuring the brightness of a subject is provided between the windows. The light projecting window 4 is a window for irradiating the subject with infrared light, and the light receiving window 5 is a window for receiving the reflected light of the infrared light from the subject. In the present embodiment, the active distance measuring method is adopted as the distance measuring method, but a passive distance measuring method may be used.

A card insertion opening 6 for inserting and removing a hard disk card is provided on the side surface of the camera 1, and a card eject button 7 for ejecting the hard disk card installed is provided above the card insertion opening 6. There is. When printing out the shooting result, the hard disk card can be removed from the camera 1 by pressing the card eject button 7, and can be mounted in a printer to which the hard disk card can be mounted and printed out.

The camera 1 is provided with an interface of a SCSI cable, and the camera 1 and the printer are connected to the SCSI cable.
Alternatively, the camera 1 may be directly connected to the printer to transfer the image data to the printer so that the captured image is printed out.

In this embodiment, a hard disk card conforming to PCMCIA is used as a recording medium for image data. However, if a photographing result can be stored as image data, a memory card or a mini disk (MD)
And other recording media.

On the back surface of the camera 1, as shown in FIG.
The main switch 8 is provided above the left end and the mode setting switch 10 is provided below the left end.

The mode setting switch 10 has a function of switching and setting a normal photographing mode and a diagonal photographing correction mode for performing diagonal photographing correction on a diagonal image, and setting a tilt angle θ (see FIG. 6). .

The mode setting switch 10 is composed of a horizontally long guide groove 11 having an angle scale 13 on the upper portion thereof and an operation button 12 movable along the guide groove 11, and the operation button 12 is provided on the angle scale 13. The inclination angle θ can be set by setting it at a predetermined angular position.

The angle scale 13 is provided with angles of 15 °, 30 °, and 45 ° on the left and right sides of the central angle of 0 °, and three types of inclination angles θ can be set on the left and right sides. ing. Here, the angle on the left side is an inclination angle when photographing from the left side toward the subject (hereinafter, this oblique photography is referred to as oblique photographing on the left side), and the angle on the right side is when photographing from the right side toward the subject (hereinafter, oblique photographing). This oblique photography is referred to as right oblique photography.). When the operation button 12 is set to the front position, since the inclination angle is 0 °, the oblique photographing correction is not performed on the photographed image, and the normal photographing mode is set.

In the present embodiment, the photographer can discretely set the tilt angle θ measured by the eye amount, but the tilt angle θ is continuously set according to the slide amount of the operation button 12. You may do it.

Further, the LCD (Li
A liquid crystal finder 9 composed of a quid crystal display is provided. The liquid crystal finder 9 is a display unit for visually recognizing a captured image.

A shutter button 14 and a subject width setting switch 15 are provided on the right end of the upper surface of the camera 1. The shutter button 14 is linked with the S1 switch which is turned on by half-press and the S2 switch which is turned on by full-press.
When the S1 switch is turned on, preparation for photographing such as focal length adjustment and exposure control value setting is performed. When the oblique photographing correction mode is set by the mode setting switch 10, the image after the oblique photographing correction (pseudo front image) is displayed on the liquid crystal finder 9 on the monitor. Thus, the photographer can confirm how the image obliquely photographed before photographing is corrected to the pseudo front image by holding the shutter button 14 half-pressed in the diagonal photographing correction mode. it can.

On the other hand, when the S2 switch is turned on, the main photographing is performed, and the image displayed on the liquid crystal finder 9 immediately before the photographing is recorded in the card memory. In the oblique photographing correction mode, the corrected pseudo front image displayed on the liquid crystal finder 9 immediately before photographing is recorded on the hard disk card.

The object width setting switch 15 is for inputting the lateral size d (size corresponding to the distance between BCs in FIG. 6) in the CCD 18 of the object to be subjected to oblique photographing correction. The subject width setting switch 15 is a slide switch having a stationary position in the center and movable in the left and right directions.

The information on the horizontal size d is input to set the depth of field in focus for the entire subject (whiteboard 16 in the example of FIG. 3) to be the subject of oblique photographing correction in the image pickup screen. It is what is done. In a shooting scene that requires oblique shooting correction, it is possible to stop the aperture 17 so that the entire shooting screen is in focus. However, if the brightness of the subject is low, the shutter speed will slow down and Since the degree of freedom is limited, in the present embodiment, the aperture value of the aperture 17 should be increased to a value that is equal to or greater than the depth of field that can cover the subject to be corrected for oblique photographing in the photographing screen. Instead, the above problems are reduced as much as possible.

As shown in FIG. 9, the liquid crystal finder 9 displays a photographing screen frame 19 and, when the oblique photographing correction mode is set by the mode setting switch 10, as shown in FIGS. 10 and 11. , Vertical display lines 21 and 22 at both ends in the frame of the photographing screen frame 19, and two pairs of triangular markers 23 and 23 'and the marker 2 outside the upper and lower frames, respectively.
4, 24 'are displayed.

The markers 23 and 23 'are indications for visually recognizing the operation amount of the subject width setting switch 15 at the time of oblique photographing to the right, and the markers 24 and 24' are the indicators of the object width setting switch 15 at the time of oblique photographing to the left. This is a display for visually recognizing the operation amount.

The display line 21 indicates the reference position of the lateral width d'of the image 20 (hereinafter referred to as the correction target image 20) which is the target of the diagonal image pickup correction inputted by the markers 24 and 24 'during the left oblique photographing. It is a reference line, and the display line 22 is
It is a reference line indicating a reference position of the lateral width d ′ of the correction target image 20 input by the marker 23 at the time of obliquely right photographing. The display lines 21 and 22 are reference lines for aligning the vertical direction of the correction target image 20 with the vertical direction of the shooting screen.

The horizontal size d of the correction target image 20 on the image pickup surface of the CCD 18 is input by the photographing screen frame 19 and the CCD 1.
Since the positional relationship with 8 is known in advance, the shooting screen frame 1
This is performed by converting the lateral width d'set between the markers 23, 23 'and the markers 24, 24' in 9 into the lateral size d.

In the present embodiment, for example, when the image pickup surface of the CCD 18 and the object surface are in the vertical plane and the image pickup surface and the object surface are tilted at the tilt angle θ only in the horizontal plane, the oblique image is obtained. Since the lens is rotated in the horizontal plane to perform the diagonal image pickup correction, in order to properly perform the diagonal image pickup correction, the photographer must ensure that the image pickup surface of the CCD 18 and the object surface are not twisted in a vertical plane. Need to set the camera to. That is, it is necessary to set the shooting screen of the camera 1 so that the vertical line of the image pickup surface of the CCD 18 and the vertical line of the subject surface are parallel to each other.

Therefore, in the oblique photographing correction mode,
By displaying the display lines 21 and 22 on the liquid crystal finder 9 and adjusting the vertical direction of the subject plane to the display line 21 (or 22), the photographing screen and the subject plane in the vertical direction of the photographing screen in the screen setting of the photographer are displayed. The deviation is reduced.

Therefore, particularly when the subject to be corrected for oblique photographing is a rectangle such as the whiteboard 16, the display lines 21 and 22 of the liquid crystal finder 9 and the marker 2 are displayed.
By displaying 3, 23 ', 24, 24', it is possible to easily set the position of the correction target image with respect to the image pickup screen and input the lateral size thereof.

The setting of the position of the image to be corrected and the input of its lateral size with respect to the image pickup screen are performed as follows. That is, when the tilt angle θ in the left oblique photographing is set by the mode setting switch 10, the liquid crystal finder 9 displays the operation amount visual confirmation of the subject width setting switch 15 shown in FIG. The markers 23 and 23 'are the display lines 21.
The display positions of the markers 24 and 24 ′ fixed to the upper position move to the left and right according to the left and right operation amount of the subject width setting switch 15. The fixed markers 23, 23 'are displayed in a vertically longer triangle than the movable markers 24, 24' so that both markers 23, 23 ', 24, 24' can be identified.

When the photographer aligns the left side of the correction target image 20 with the display line 21 and operates the subject width setting switch 15 to match the display positions of the markers 24 and 24 'with the right side of the correction target image 20, the image pickup screen is displayed. The shooting position of the correction target image 20 for the marker 23 and the marker 2 are set.
4 (or the marker 23 'and the marker 24'), the lateral size d of the correction target image 20 on the imaging surface is input.

When the tilt angle in the right oblique photographing is set by the mode setting switch 10, the liquid crystal finder 9 displays the operation amount visually of the object width setting switch 15 shown in FIG. 11, and the markers 24, 24 are displayed. ′ Is display line 2
The display positions of the markers 23 and 23 'are fixed on the position 2, and the display positions of the markers 23 and 23' are moved to the left or right according to the operation amount of the left and right of the subject width setting switch 15. The photographer aligns the right side of the correction target image 20 with the display line 22 as opposed to the diagonal left photography, and operates the subject width setting switch 15 to match the display positions of the markers 23 and 23 'with the left side of the correction target image 20. By letting
The shooting position of the correction target image 20 with respect to the imaging screen can be set, and the lateral size d of the correction target image 20 on the imaging surface of the CCD 18 can be input.

FIG. 12 is a block diagram of the camera 1 according to the present invention. In the figure, the same members as those described above are denoted by the same reference numerals. In addition, the CCD drive unit 2
Reference numeral 5 controls the imaging operation of the CCD 18 based on the shutter speed Tv of the exposure control value input from the CPU 34. The CCD 18 performs an image pickup operation (charge accumulation operation) based on a control signal input from the CCD drive unit 25.
Then, each pixel data is converted into time series data and output to the oblique photographing correction calculation unit 26. That is, the CCD 18
As shown in FIG. 13, the respective pixel data of are sequentially read in the direction of the arrow for each vertical line, and the oblique photographing correction calculation unit 26
Is input to

The oblique photographing correction calculation section 26 performs correction processing of the image to be corrected in the oblique photographing correction mode. The oblique photographing correction calculation unit 26 includes a line buffer 26.
1, 263, the latch circuit 262, the image memory 264, the read clock control unit 265, and the read address control unit 266.
It is composed of

The line buffer 261 temporarily stores each pixel data output from the CCD 18 in line units (vertical line units in FIG. 13). The read clock control unit 265 generates a read clock for reading each pixel data of the control unit line buffer 261 based on the control signal from the CPU 34, and the line buffer 26
It is input to 1.

Each pixel data of the line buffer 261 is
The data is read by the latch circuit 262 in synchronization with the read clock. At this time, line-direction enlargement processing (line-direction enlargement processing shown in FIG. 8A) is performed as necessary,
Diagonal shooting correction is performed line by line. That is, Y
When increasing the pixel data in the axial direction, the read clock control unit 265 stops the read clock by one to several clocks at the timing corresponding to the position to be increased, and requires the same data as the pixel data immediately before the clock stop. The number of pixels is read to the latch circuit 262.

The latch circuit 262 latches the pixel data for one line which has been subjected to the oblique photographing correction and sequentially outputs this pixel data to the line buffer 263. Further, the line buffer 263 includes a latch circuit 262.
Each pixel data after the oblique photographing correction output from is temporarily stored in line units.

The image memory 264 is a memory for storing an image which has been subjected to oblique photographing correction in the Y-axis direction. The image memory 264 includes a RAM (Random Access Memory),
Each pixel data forming each line after the oblique photographing correction, which is sequentially output from the line buffer 263, is stored in a predetermined storage position. When all pixel data output from the CCD 18 is stored in the image memory 264 via the line buffer 261, the latch circuit 262, and the line buffer 261, an oblique image is enlarged in the image memory 264 only in the Y-axis direction. The stored image is stored.

The read address control unit 266 generates an address of each pixel data read from the image memory 264 to the card memory 27 and inputs it to the image memory 264 when reading each pixel data. The read address control unit 266 generates a read address of the image memory 264 based on the control signal from the CPU 34.

Then, the read address is controlled to enlarge and correct the image to be corrected in the X-axis direction, that is,
Interpolation processing (addition of pixel data in units of lines shown in FIG. 8B) of pixel data of the insufficient line is performed, whereby the correction target image K is corrected in the card memory 27 in both X-axis and Y-axis directions. The pseudo front image is stored. The interpolation processing of the pixel data of the insufficient line is performed by repeatedly outputting the addresses of the pixel data of the known line for the required number of lines to the image memory 264 and repeatedly reading the pixel data of the line to the line to be added.

In the present embodiment, since the same data as the known pixel data is interpolated into the data of the increasing pixel position, the density change of the corrected image may be unnatural. However, for example, JP-A-5-16100
By applying the density interpolation method disclosed in Japanese Patent Laid-Open No. 0-161100 and Japanese Patent Laid-Open No. 5-161001, the density change of the corrected image can be made more natural.

The card memory 27 corresponds to a hard disk card inserted and mounted in the card insertion slot 6. Further, the card drive unit 28 controls the drive of the card memory 27 so as to record the image data.

The liquid crystal finder driving section 29 controls the driving of the liquid crystal finder 9. The liquid crystal finder drive unit 29 configures a display screen based on the pixel data (image data before correction) output from the CCD 18 or the pixel data (image data after correction) output from the oblique photographing correction calculation unit 26. The drive of each pixel is controlled to display the captured image or the corrected image. Further, based on a control signal from the CPU 34, switching of a display image (image before correction or image after correction) and control of display timing are performed.

The memory 35 stores the data (subject distance Di and photographing magnification mi at each pixel position of the CCD 18) necessary for performing the oblique photographing correction calculated by the CPU 34.

The diaphragm drive unit 30 controls the aperture amount of the diaphragm 17 based on the aperture value Av of the exposure control value input from the CPU 34. In addition, the lens driving unit 31 is C
The focusing operation of the taking lens 2 is controlled based on the AF control value input from the PU 34.

The photometry section 32 is composed of a light receiving element such as an SPC provided at the rear position of the photometry window 3 and measures the brightness of the subject. The distance measuring unit 33 detects a subject distance, is provided at a position behind the light projecting window 4, and is provided at a position behind the light projecting unit 331 that emits infrared light and the light receiving window 5.
The light receiving unit 332 receives the infrared light reflected by the subject.

The CPU 34 inputs the object distance D _A at the distance measuring point detected by the distance measuring unit 33 (the center position of the image pickup surface of the CCD 18), the photographing magnification m _{A at} the distance measuring point, and the object width setting switch 15. The information about the both end positions (the positions of the markers 23 and 24 or the markers 23 'and 24' in FIG. 10) of the subject to be corrected for the oblique photographing and the required depth of field from the tilt angle θ input by the mode setting switch. W (corresponding to the distance RQ in FIG. 6) is calculated.

The depth of field W will be described with reference to FIG. 6. If both end points B and C of the object on the image pickup surface are known, the distance OA between the taking lens 2 and the image pickup surface of the CCD 18 will be described.
Is known, the shooting angle of view β, α with respect to the end points F and G of the subject from the distances OA and AB, AC.
Are calculated respectively, and the shooting angle of view β, α and the tilt angle θ,
From the subject distance D _A , D _B = D _A · cos (α−θ) / cos (α)
_{· Cos (θ), D C} = D A · cos (β + θ) / cos (β) · cos (θ)
It is calculated using both equations (see above equation).

The CPU 34 calculates the exposure control value (aperture value Av, shutter speed Tv) by giving priority to the depth of field W based on the brightness information of the subject detected by the photometric unit 32 and the depth of field W. Then, the calculation results are output to the diaphragm drive unit 30 and the CCD drive unit 25, respectively.

Further, the CPU 34 calculates a lens driving amount for setting the photographing lens 2 to the in-focus position based on the subject distance D _A detected by the distance measuring unit 33, and the calculation result is used as an AF control value for the lens control. Output to the drive unit 31.

The CPU 34 is a control unit for centrally controlling the photographing operation of the camera 1 and is composed of a microcomputer. C
The PU 34 controls normal photography and also CC
The subject distance Di and the photographing magnification mi at each pixel position of D18 are calculated, and the read clock generated by the read clock control unit 265 and the read address generated by the read address control unit 266 are controlled based on the calculation results. Controls photography in the oblique photography correction mode.

Next, shooting control in the oblique shooting correction mode will be described with reference to the flowchart of FIG.

When the main switch 8 is turned on and the camera 1 is activated, the camera is ready for shooting, and the distance measuring unit 33 first measures the subject distance (# 1). Subsequently, the drive amount to the in-focus position of the photographing lens is calculated from the measured subject distance D _A (corresponding to the distance OP in FIG. 6), and the photographing lens 2 is driven based on the calculation result to adjust the focus. Is performed (# 2). Subsequently, the brightness of the subject is measured by the photometric unit 32 (# 3), and the gain of the CCD 18 (adjustment of the dynamic range) is performed based on the measurement result so as to obtain proper exposure (# 4). Subsequently, charge accumulation (integration) of the CCD 18 and readout of the accumulated charge (output of pixel data) are performed, and the liquid crystal finder driving unit 29 drives the liquid crystal finder 9 based on the pixel data output from the CCD 18 to capture an image. The image is displayed (# 5). That is, as shown in FIG.
The image 20 of the subject actually viewed through D18 is reproduced on the liquid crystal finder 9.

Subsequently, it is determined whether or not the S1 switch has been turned on (whether or not the shirt button 14 has been half-depressed) (# 6), and if the S1 switch has been turned off (NO in # 6). ), Returning to # 1, the finder operation by the liquid crystal finder 9 is continued.

When the S1 switch is turned on (Y in # 6
S), the tilt angle θ is fetched from the setting position of the operation button 12 of the mode setting switch 10 (# 7), and subsequently, the markers 23, 24 (or the markers 23 ', 23) in the photographing screen frame 20 are acquired.
The lateral size d of the subject to be corrected for oblique photographing is fetched from the position information of 24 ') (# 8).

Subsequently, the photographing field angles αi, βi for each pixel position of the CCD 18 are calculated, and the photographing field angles αi, βi,
From the subject distance D _A and the tilt angle θ, the subject distance Di at each pixel position (that is, the subject distance distribution in the imaging screen) is calculated, and the focal length f and the subject distance D are calculated.
Photographing magnification m _A in the distance measuring point from the _A is computed, the photographing magnification m _A, the object distance D _A, photographing magnification mi at each pixel location imaging angle .alpha.i, from βi and the inclination angle θ by the above or arithmetic expression (That is, the imaging magnification distribution within the imaging screen) is calculated (# 9). Then, the data of the subject distance distribution and the photographing magnification distribution are stored in the memory 35.

Subsequently, the aperture value of the aperture 17 at which the entire subject to be corrected has the subject depth is calculated from the subject distance D _A , the photographing magnification m _A , the lateral size d of the image to be corrected and the tilt angle θ (# 10). The gain of the CCD 18 is adjusted so that the proper exposure can be obtained from this aperture value and the subject brightness measured immediately before (# 11).

Subsequently, after the aperture 17 is set to the aperture value (# 12), the oblique photographing correction calculation is started for the image captured by the CCD 18 (# 13). That is, CC
Each pixel data sequentially read from D18 is subjected to vertical enlargement correction for each vertical line in the oblique photographing correction calculation unit 26, and then enlarged in the horizontal direction when output from the oblique photographing correction calculation unit 26. The correction is performed, and the oblique photographing correction is performed, and the correction result is output to the liquid crystal finder driver 29 and the card memory 27 (# 13).

In this oblique photographing correction process, data of the subject distance Di and the photographing magnification mi corresponding to each pixel position is read from the memory 35 to the CPU 34, and the CPU 34 determines the pixel position to be added in the vertical enlargement process. The calculated result is output to the read clock control unit 265, the pixel position to be added in the horizontal enlargement process is calculated, and the calculated result is output to the read address control unit 266.

Then, the read clock control unit 265 controls the read clock of the pixel data read from the line buffer 261 to the latch circuit 262 to perform vertical enlargement correction, and the read address control unit 266 controls the image memory 264. The horizontal enlargement correction is performed by controlling the read address of the pixel data output from the card memory 27 to the liquid crystal finder drive unit 29 from.

A display switching signal is output from the CPU 34 to the liquid crystal finder drive unit 29, and the liquid crystal finder 9 is driven based on the pixel data output from the oblique photographing correction calculation unit 26, as shown in FIG. Although the corrected image 20 is displayed on the liquid crystal finder 9 on the monitor (# 14), no recording signal is output from the CPU 34 to the card driving unit 28, and the corrected image data is stored in the card memory 27. Is not recorded.

Subsequently, it is judged whether or not the S2 switch is turned on (whether or not the shirt button 14 is fully pressed) (# 15), and if the S2 switch is in the off state (NO in # 15). ), It is further determined whether or not the S1 switch is held in the ON state (# 16), and if the S1 switch is in the ON state (YES in # 15), the process returns to # 15 until the S2 switch is turned ON. , The corrected image is continuously displayed on the monitor. On the other hand, if the S1 switch is OFF (NO in # 16), the process returns to # 1.

When the S2 switch is turned on while the corrected image is displayed on the monitor (YES in # 15), a recording control signal is output from the CPU 34 to the card drive unit 28, and the corrected image data is stored in the card memory 27. Recording is started (# 17). That is, from the CPU 34 to the card drive unit 2
A recording control signal is output to 8, and the oblique photographing correction calculation unit 2 is output.
The pixel data output from 6 is sequentially written into the card memory 27.

Then, the card memory 27 for all pixel data
When the writing to the memory is completed (YES in # 18), the control signal for ending the reading of the pixel data is output to the CCD driving unit 25 and the control signal for ending the writing of the pixel data is output to the card driving unit 28. (# 19, # 20) One image capturing operation ends, and the process returns to # 1 to perform the next image capturing operation.

[0089]

As described above, according to the present invention,
It is a digital camera capable of correcting a diagonal image to a pseudo front image for shooting, and since the corrected pseudo front image can be displayed on the monitor, the corrected image can be confirmed before the actual shooting, It is possible to reduce shooting mistakes in oblique images.

Further, normally, the photographed image is displayed on the display means, and when the monitor display is instructed, the corrected pseudo front image is displayed on the monitor. Therefore, the display means for the finder is used for the monitor. The structure of the display means can be simplified by also using the display means.

[Brief description of drawings]

FIG. 1 is a perspective view showing the appearance of a digital camera according to the present invention.

FIG. 2 is a rear view of the digital camera according to the present invention.

FIG. 3 is a diagram illustrating oblique photographing of a subject.

4A and 4B are diagrams for explaining oblique imaging correction, in which FIG. 4A is a diagram illustrating an oblique captured image, and FIG. 4B is a diagram illustrating an image after oblique imaging correction.

FIG. 5 is a schematic configuration diagram of an optical system of the digital camera according to the present invention.

FIG. 6 is a diagram of an imaging system in oblique imaging as viewed from directly above.

FIG. 7 is a diagram for explaining a method for correcting oblique shooting,
(A) is a diagram showing an oblique image, and (b) is a diagram showing an image after oblique photographing correction.

FIG. 8 is a diagram for explaining pixel data interpolation processing in oblique image pickup correction; FIG. 8A is a diagram showing vertical direction interpolation processing;
(B) is a figure which shows the interpolation process of a horizontal direction.

FIG. 9 is a diagram showing display contents of a liquid crystal display unit in a finder in a normal shooting mode.

FIG. 10 is a diagram showing a display content of a liquid crystal display unit in the finder at the time of diagonal left photographing in the diagonal photographing correction mode.

FIG. 11 is a diagram showing a display content of a liquid crystal display unit in the finder at the time of diagonally right photographing in the diagonal photographing correction mode.

FIG. 12 is a block diagram of a digital camera according to the present invention.

FIG. 13 is a diagram showing a readout direction of pixel data of a CCD.

FIG. 14 is a flowchart showing shooting control in a diagonal shooting correction mode.

FIG. 15 is a diagram showing a display example of a liquid crystal finder in a finder display.

FIG. 16 is a diagram showing a display example of a liquid crystal finder in a monitor display of a corrected image.

[Explanation of symbols]

 1 Camera 2 Photographic Lens 3 Metering Window 4 Distance Measuring Light Emitting Window 5 Distance Measuring Receiving Window 6 Card Insertion Slot 7 Card Ejection Button 8 Main Switch 9 Liquid Crystal Viewfinder (Display Means) 10 Mode Setting Switch (Angle Input Means) 11 Guide Groove 12 Operation button 13 Angle scale 14 Shutter button (instruction means) 15 Subject width setting switch 16 Whiteboard 17 Aperture 18 CCD area sensor (imaging means) 19 Shooting screen frame 20 Correction target image 21, 22 Display line 23, 24 Marker 25 CCD drive unit 26 Oblique image capturing correction calculation unit (correction means) 261 and 263 Line buffer 262 Latch circuit 264 Image memory 265 Read clock control unit 266 Read address control unit 27 Card memory 28 Card drive unit 29 Liquid crystal finder drive unit 30 Aperture drive unit 31 lens Drive unit 32 Photometric unit 33 Distance measuring unit (distance measuring unit) 331 Light emitting unit 332 Light receiving unit 34 CPU (display control unit) 35 Memory

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G06T 3/00 G06F 15/62 380 H04N 5/225 15/66 360

Claims (2)

[Claims] 1. An image pickup means in which pixels composed of a plurality of photoelectric conversion elements are two-dimensionally arranged, and an angle input means for inputting an inclination angle formed by an image pickup surface of the image pickup means and a subject surface.
A distance measuring means for measuring the distance to the subject and a correcting means for correcting the oblique image of the subject captured by the image capturing means into a pseudo front image based on the input inclination angle and the measured subject distance. And a display unit for displaying an image captured by the image capturing unit, an instruction unit for instructing a monitor display, and a monitor display for instructing the monitor display, the image is corrected by the correcting unit. A digital camera comprising display control means for displaying an image on the display means. 2. The digital camera according to claim 1, wherein the display control means displays the image captured by the imaging means on the display means when the monitor instruction by the instruction means is not instructed. A digital camera characterized by being present.