JP2002271652A - Digital camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital camera that photographs an original at a correct position in the case of photographing for obtaining an image with high quality. SOLUTION: The digital camera includes a correct position discriminating means that discriminates whether the digital camera takes a correct positions to an object and a correct position display means that indicates the digital camera taking a correct position with the object, on the basis of the result of discrimination by the correct position discrimination means. This invention claims ten other claims.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital camera and, more particularly, to a technique suitable for capturing plane information such as a document.

[0002]

2. Description of the Related Art Conventionally, when electronically storing a document,
A scanner or a scanner unit of a copying machine or a facsimile is used exclusively as an image input device. Such a scanner device has a line sensor and can read a document at an accurate magnification.

On the other hand, recently, with the development of video cameras and digital still camera devices, there has been an increasing demand for inputting character originals, digitizing and storing them, and performing character recognition.

In particular, recent digital still cameras have begun to be used for various purposes as portable information collection tools due to the increase in the number of pixels and miniaturization. Documents, whiteboards,
For character information such as signboards and advertisements, sufficient information can be obtained with black and white images and binary images. In the case of binary images, the storage capacity required for storage is very small, so images with many pixels are taken. It is advantageous in some cases. Further, the binarized image can be transmitted by facsimile or can be reused by character recognition.

However, when a document is photographed by a digital camera, it is difficult to photograph the document from the front, that is, it is difficult to photograph the document with the document and the camera directly facing each other, and distortion often occurs in the image. The original with the distortion is photographed after being transformed into a trapezoidal shape or the like. Several so-called tilt correction techniques for correcting an image deformed in this way to a shape close to the original document, particularly a technique called digital tilt correction, have been disclosed.

In Japanese Unexamined Patent Application Publication No. 9-289611 or Japanese Unexamined Patent Application Publication No. 10-13733, an angle between a digital camera and a subject is input, and a picture is taken obliquely by using a distance measuring means from a distance between them. The image is corrected to a front shot image.

Japanese Patent Application Laid-Open No. Hei 10-145667 discloses a technique in which the angle and the focal length of a subject and a camera are automatically measured, and an obliquely shot image is automatically corrected.

[0008]

However, when an image is corrected as disclosed in Japanese Patent Laid-Open No. Hei 10-145667, there is a portion where the image is enlarged as shown in FIG. In such a portion, since the focus adjustment is performed near the center of the image, the focus is originally out of focus, and there is a high possibility that the image is out of focus. In other words, in order to enlarge the image in tilt correction in addition to being out of focus,
The image quality of characters is significantly degraded as compared with the vicinity of the center of the image, which makes it difficult to read as characters, and when binarizing an image, there is a problem that characters become blurred and become unreadable.

In the case where the original is not directly photographed as described above, the quality of the character cannot be improved even if the tilt correction is performed. That is, it is necessary to obtain a high-quality image by directly photographing the document when photographing for the first time.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a digital camera capable of easily realizing photographing directly on a document.

[0011]

According to a first aspect of the present invention, there is provided a digital camera, comprising: a digital camera; And a facing display means for indicating that the user is facing the subject based on the determination result.

According to a second aspect of the present invention, in the digital camera according to the first aspect, the facing display means is a light emitting means.

According to a third aspect of the present invention, in the digital camera according to the second aspect, the light emitting means is turned on when facing the subject.

According to a fourth aspect of the present invention, in the digital camera according to any one of the first to third aspects, there is provided an information display means for displaying information such as an image or a state of the camera. The facing display means displays characters on the information display means.

According to a fifth aspect of the present invention, in the digital camera according to any one of the first to third aspects, the digital camera has information display means for displaying information such as an image or a state of the camera. The facing display means displays a graphic on the information display means.

According to a sixth aspect of the present invention, in the digital camera according to any one of the first to fifth aspects, the facing display means is means for outputting a sound.

According to a seventh aspect of the present invention, in the digital camera according to any one of the first to sixth aspects, the facing-facing judging means determines a subject and a subject based on focus information at the time of performing automatic focus adjustment. It is characterized in that it is determined whether or not the camera faces directly.

According to an eighth aspect of the present invention, in the digital camera according to any one of the first to seventh aspects, the determination by the facing determination means is performed during a monitor operation of the digital camera. It is characterized by.

According to a ninth aspect of the present invention, in the digital camera according to any one of the first to eighth aspects, there is provided a facing determination setting means for setting whether or not to perform the facing determination. And

According to a tenth aspect of the present invention, in the digital camera according to the ninth aspect, when the facing determination is set by the facing determination setting means, the facing display means can also be used. And switching.

According to an eleventh aspect of the present invention, in the digital camera according to any one of the first to tenth aspects, the facing display means can be switched in accordance with a use.

[0022]

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

FIG. 9 is an illustration of a digital camera viewed from directly above. The camera can be switched between a natural image mode for photographing a normal natural image and a character binarization mode (hereinafter simply referred to as a character mode) for photographing an original or a whiteboard with the mode switching button 101. The liquid crystal display 10 on the top of the main unit
2 displays either the natural image mode or the character mode, whichever is selected.

First, the digital camera is set to the character mode. In conjunction with the setting to the character mode, the output to the facing display circuit 10 of the CPU 9 in the digital camera shown in FIG. 1 is enabled.
And the camera is ready to display that the subject is facing the camera.

During the monitoring, as shown in FIG.
The output of digitized image data from D converter 4
Input to AF control circuit 8.

The AF control circuit 8 applies a high-pass filter or a band-pass filter to the input image data,
The lens position at which the average output of this filter becomes maximum is calculated, and the calculated lens position value is output to the CPU 9. Hereinafter, an example using a band-pass filter will be described.

The CPU 9 controls the lens driving mechanism 2 in accordance with the calculated value of the lens position near the center of the image to adjust the focus.
Further, as will be described in detail later, the AF control circuit 8 outputs a signal indicating whether or not the subject and the camera face each other to the facing display circuit 10. The facing display circuit 10 indicates that the subject and the camera are facing each other when they face each other.

The lens 1 of the digital camera is moved back and forth by the driving mechanism 2 to adjust the focus, and images with different lens positions are obtained.

These images captured in the monitor are subjected to white balance adjustment by a white balance adjuster 5 and then input to a color liquid crystal display control circuit 6.
Converted to an image signal suitable for color liquid crystal 7
Appears in 7. FIG. 3 shows the relationship between the average output of the bandpass filter (see FIG. 2) obtained by the AF control circuit 8 and the lens position.

The lens position at which the average output of the band-pass filter is maximum means the best focus position for the subject. In a normal digital camera, only the lens position near the center of the image is calculated. In the present embodiment, the lens position at which the average output of the bandpass filter is maximized not only in the center of the image but also in four surrounding areas as shown in FIG. 4 is calculated.
In this case, the calculated values of the lens positions in the areas A, B, C, D, and E are DA, DB, DC, DD, and DE, respectively.

FIG. 5 shows the configuration of the AF control circuit 8. The output of the band-pass filter 91 is selected by the selector 92 in accordance with the position of the input image, and the output is selected by the integration circuits (93, 9).
6, 99, 912, 915). When processing for one frame of the image is completed, the integration circuit (93, 96, 99, 912)
, 915) are output from comparison circuits (94, 97, 910, 9), respectively.
13, 916). Comparison circuit (94, 97, 910, 913
, 916), the maximum average output of the band-pass filter 91 corresponding to the position in the image temporarily stored in the register (95, 98, 911, 914, 917) is compared with the integral output selected by the selector 92. Is done. By the comparison, the maximum average value of the band-pass filter 91 and the calculated lens position value (input from the CPU 9) that gives the maximum average value are updated. When the process of calculating the average value of the bandpass filter at all lens positions is completed, the register stores the maximum average value of the bandpass filter and the lens position that gives it,
The calculated values of the lens positions are output to the facing determination circuit 918 as DA, DB, DC, and DD, respectively. Since DE is a calculated value of the lens position at the center of the image, it is used for adjusting the focal length of the camera, and is not used for the facing determination. The DE is output to the CPU 9 and used as information for controlling the drive mechanism 2.

Next, the four calculated lens position values are input to a facing determination circuit 918 to determine whether the subject and the digital camera are facing each other.

Whether the subject and the digital camera face each other is determined if the camera and the subject face each other when the following equation is satisfied.

Max (DA, DB, DC, DD)-Min (DA, DB, DC, DD) <TD (1) where Max () is a function for selecting the maximum value, and Min () is the function for selecting the minimum value. The function to select. TD is a predetermined constant.

When the expression (1) is satisfied, the facing judgment circuit 91
From "8", "1" is output to the facing display circuit 10 to perform facing display.

As shown in FIGS. 6A to 6D, the facing display circuit 10 includes various facing display control circuits (6, 11, 13, 15) and facing display devices (7, 12) corresponding thereto. , 14, 16), and an instruction is issued to the color liquid crystal display control circuit 6, the black and white liquid crystal display circuit 11, the audio output control circuit 13, and the LED control circuit 15 so as to perform the direct display.

Based on these signals, the color liquid crystal 7
The black-and-white liquid crystal 12, the speaker 14, and the LED 16 indicate that the subject and the camera are facing each other, output sound, and light up. When notifying the photographer that the user is facing directly, the display may not be performed entirely but may be performed only on the one requested by the photographer. For example, in the initial setting of the camera, the display facing directly is set to only lighting.

As shown in FIG. 7, in the case of an LED located beside the finder mounted on the back of the digital camera as shown in FIG.
16 comes on.

As shown in FIG. 8, the character "facing" may be displayed in the liquid crystal 7 for image display.

Further, as shown in FIG. 9, a positive sign may be displayed on the liquid crystal display unit 102 at the top of the digital camera, or a sound of "facing" may be output from a speaker. That is, it is important to provide a display that is easy for the camera user to understand.

The following effects can be achieved by configuring the digital camera as in this embodiment. -Since it is notified by voice, characters, figures and light that it is facing, it is easy to understand whether the camera and the subject are facing. The device for determining the confrontation can be realized at low cost because only the focus determination is added to the automatic focus adjustment mechanism.・ Because it is determined whether or not the user is facing directly before the photographing operation, the photographing can be performed quickly when deciding the composition. -By having the character binarization mode, setting more suitable for photographing a document can be performed. -When notifying that a person is facing the right, a notification method that is sometimes suitable can be used. -By designating the character binarization mode, the face-to-face display is automatically activated, so that the photographer does not have to set both the character binarization mode and the face-to-face display each time.

[0042]

As described above, according to the present invention,
Since the camera judges that the camera is directly facing the subject, it is possible to easily capture high-quality images of planar information such as documents.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of an embodiment.

FIG. 2 is an example of a bandpass filter.

FIG. 3 is a diagram illustrating a relationship between an average output of a bandpass filter and a lens position.

FIG. 4 is a diagram showing an area for calculating a lens position.

FIG. 5 is an example of an AF control circuit.

FIG. 6 is a functional block diagram of a facing display circuit shown for each type of facing display.

FIG. 7 shows LE as an example of the facing display, next to the viewfinder.
It is a figure showing the case where D is used.

FIG. 8 is a diagram showing another example of the facing display device in which characters are displayed on a liquid crystal display unit.

FIG. 9 is a diagram of the digital camera as viewed from above.

FIG. 10 is a diagram illustrating a tilt correction function.

[Explanation of symbols]

 Reference Signs List 1 lens 2 drive mechanism 3 CCD 4 A / D converter 5 white balance adjuster 6 color liquid crystal display control circuit 7 color liquid crystal 8 AF control circuit 9 CPU 10 facing display circuit 11 black and white liquid crystal display control circuit 12 black and white liquid crystal 13 audio output Control circuit 14 Speaker 15 LED control circuit 16 LED 91 Band pass filter 918 Facing judgment circuit

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // H04N 101: 00 H04N 101: 00

Claims (11)

[Claims] 1. An apparatus according to claim 1, further comprising: facing means for determining whether the subject is directly facing the subject, and facing display means for indicating that the subject is facing the subject based on the determination result of the facing determining means. Digital camera that features. 2. The digital camera according to claim 1, wherein said facing display means is a light emitting means. 3. The digital camera according to claim 2, wherein the light emitting unit is turned on when facing the subject. 4. The digital camera according to claim 1, further comprising an information display unit for displaying information such as an image or a state of the camera.
A digital camera, wherein the facing display means displays characters on the information display means. 5. The digital camera according to claim 1, further comprising an information display unit for displaying information such as an image or a state of the camera.
A digital camera, wherein the facing display means displays a graphic on the information display means. 6. The digital camera according to claim 1, wherein the facing display means comprises:
A digital camera, which is means for outputting sound. 7. The digital camera according to claim 1, wherein said facing-facing determining means comprises:
A digital camera which determines whether or not a subject and a camera are directly facing each other based on focus information at the time of performing automatic focus adjustment. 8. The digital camera according to claim 1, wherein the determination by the facing determination unit is performed during a monitor operation of the digital camera. . 9. The digital camera according to claim 1, further comprising a facing determination setting unit configured to determine whether to perform facing determination. 10. The digital camera according to claim 9, wherein when the facing determination is set by the facing determination setting means, the facing display means is switched so as to be usable. A digital camera characterized in that: 11. The method according to claim 1, wherein
3. The digital camera according to claim 1, wherein the facing display means can be switched in accordance with the intended use.