JP2001251548A - Image input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image input device with which an accurate photographing area is easily recognized. SOLUTION: The image input device is provided with a camera and a light projecting means which emits two directional luminous fluxes to a subject whose image is to be picked up by the camera, and the device is further provided with a means which changes the directional angles of these projected luminous fluxes and a means which controls the parameters of the camera, on the basis of angles of light projection and the positional information of two luminous fluxes on the subject.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input device.

[0002]

2. Description of the Related Art When two-dimensional information such as characters and bar codes are captured and analyzed by a camera as image information, all information to be recognized in an image pickup area of the camera must be included. Therefore, there is a need for a means by which the photographer can easily confirm an accurate imaging region. When the subject can shoot the camera at eye level, a general method is to look through a finder built in the camera. However, it is often difficult to shoot while directly looking through the viewfinder, such as shooting from a high position or a low position, or shooting in a narrow place. In such a case, a method of viewing the finder through an accessory shoe, a method of viewing a liquid crystal monitor variably arranged with respect to the optical axis of the camera like a digital camera, and a method of displaying an image from a CCD camera on a display and so on.

On the other hand, Japanese Patent Application Laid-Open No. 7-64158 discloses a light projecting means which allows a photographer to confirm an image projected on a subject by projecting light from a light source toward a specific area in an imaging area. Has been proposed. This allows the camera's optical axis to be intuitively pointed at the subject, but captures the image by driving the zoom lens optical system to maintain the specified magnification according to the distance from the camera to the subject. Since the region is estimated, an accurate imaging region cannot be limited. Some medical X-ray apparatuses irradiate a rectangular frame-shaped guide light onto a subject so that an accurate imaging region can be easily confirmed while looking at the subject.

[0004]

The X-ray apparatus cannot support the zoom function because the size of the guide light for confirming the imaging area is fixed. However, when changing the imaging area without changing the distance from the camera to the subject, such as when shooting in a narrow place, zooming is indispensable.
The present invention provides an image input device that enables a photographer to intuitively confirm an accurate imaging area even in a situation where it is difficult to shoot while excluding a viewfinder, and that the imaging area can be easily adjusted by a zoom function. Aim.

[0005]

An image input apparatus having a camera body and light projecting means for projecting a visible light beam as a guide for imaging onto a subject, wherein the light projecting means emits at least a directional light beam. An image input device having two or more light sources and having a variable light projection angle is used.
Considering that the imaging range is rectangular, the imaging range can be limited by the two projection points. That is, by projecting two or more points around the imaging area, the photographer can easily confirm the imaging area while watching the projection point. Further, since the light projection angle is variable, it is possible to cope with a change in the imaging area by zooming.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention;

FIG. 1 is an external view of an embodiment of an image input apparatus according to the present invention. Around the CCD camera 1, there are light projecting means for emitting rod-shaped light that is directional and does not diffuse.
Are installed in four places.
3, 4, and 5 can adjust the projection angle by a projection angle adjustment motor. However, the light emitting means 2, 3, 4,
The projection angles of 5 are respectively connected by gears and are linked. FIG. 2 shows a state of the subject surface 10 when the light is projected with the optical axis 10 of the lens 9 perpendicular to the subject surface 11. The light projecting means 2, 3, 4, 5 are arranged such that their light projecting points 22, 23, 24, 25
1 is controlled so as to form a vertex of a rhombus 26 centered on the optical axis 10. Note that the shape of the light projecting point does not need to be circular, but a circular rod-shaped light is employed in this embodiment because the center of gravity is easily obtained.

When the zoom button 6 is pressed, the light emitting means 2,
The projection angles of 3, 4, and 5 change while interlocking, and the projection point 2
The size of the rhombus 26 formed by 2, 23, 24, 25 changes, but the shape itself does not change. Hereinafter, an area circumscribed by the diamond 26 and surrounded by a rectangle 27 constituted by sides parallel to the diagonal line of the diamond 26 is referred to as an imaging guide area.

The photographer can freely adjust the size of the imaging guide area by pressing the zoom button 6 up or down. When the shutter button 7 is half-pressed, an image is captured and image analysis is performed.
8, the zoom adjustment of the lens 9 is repeated so that the imaging guide area in the imaging area is as large as possible, and the imaging area 28 is adjusted to the imaging guide area. That is, the imaging guide area is made to coincide with the imaging area 28. The shooting permission lamp 8 is turned on when the imaging area is determined, and an image can be obtained by fully pressing the shutter button 7. In this embodiment, the light emitting means is 4
The upper and lower left and right sides of the imaging area are used to project the imaging range so that the user can easily see the imaging range. However, even when two upper and lower left or upper right and left upper parts are used, the imaging guide area is used. Can be formed, and the same function as that of the present embodiment can be obtained under the condition of claim 1.

FIG. 3 is a block diagram showing the internal structure of the image input device. In the figure, thick arrows represent the flow of images, and thin arrows represent the flow of signals. A zoom drive motor 31, a focusing motor 32, and an aperture drive motor 3 are provided in the lens 9.
3 is built-in. The lens 9 projects the subject on the CCD 34, and the CCD 34 converts the image into an analog electric signal. The AD converter 35 converts an image, which is an analog electric signal, into digital data that can be easily analyzed, and is temporarily stored in the work memory 38. Arithmetic circuit for performing image processing The image processing circuit 37 performs necessary image processing by the data control circuit 36 for controlling the entire system. The data control circuit 37 analyzes the obtained image, and
Then, a necessary motor is moved to perform auto-focusing and the like, and processing such as saving in the memory card 39 is performed.

FIG. 4 is a flowchart showing the operation of the image input apparatus performed by the photographer in the present embodiment. Hereinafter, the operation procedure of the present embodiment will be described with reference to FIG.

First, in the initial state, the light emitting means 2,
The optical axes of 3, 4, 5 are set in parallel with the optical axis 10 of the lens 9, and the photographer turns the camera 1 to the subject while looking at the projection points of the projection means 2, 3, 4, and 5. Match. Then, the zoom button 6 is pressed to adjust the projection angle so that the subject is entirely included in the imaging guide area (Step S).
1). The process is repeated until all the subjects are included in the imaging guide area (step S2), and the shutter button 7 is half-pressed just at the stage where it is included (step S3). In step S4, processing inside the image input apparatus is performed, and zoom adjustment and focusing are performed. Details will be described later with reference to FIG. When the adjustment is completed, the photographing permission lamp 8 is turned on. However, if the image pickup guide area can be photographed, the green light is turned on (step S5). (Step S
6). When the red light is turned on, the shutter button 7 is released because the imaging guide area exceeds the zoom limit of the lens 9 because the imaging guide area is too large or too small (step S).
8) It is necessary to return to step S1 and readjust the projection angle. When the green light is turned on, the shutter button 7 is fully pressed (step S7), an image is captured, and image distortion that occurs when the object plane 11 is not perpendicular to the optical axis 10 is corrected. Output (Step S9). Step S9 is also processing inside the image input device, and details will be described later with reference to FIGS.

FIG. 5 is a detailed diagram of the processing in step S4 of FIG. 4, that is, a flowchart showing the operation of the image input apparatus from when the photographer half-presses the shutter button 7 until the photographing permission lamp 8 is turned on. is there. The purpose here is to match the imaging area with the imaging guide area. For this purpose, a method is adopted in which an image for analysis is taken in, the image is analyzed, and the zoom of the lens 9 is changed depending on the position of the light projecting point.

In step S11, the focus is automatically adjusted as a pre-process for capturing an image for analysis. Therefore, an image is input several times while changing the focal length, and the focal length with the sharpest image is adopted. Alternatively, a known method, for example, a method of irradiating an infrared light toward the subject, measuring the intensity of the returning light, measuring the distance, and calculating the focal length may be used.

Then, an image for analysis is fetched (step S12), and the image is binarized by the image processing circuit 37 to extract only the projection point (step S13). In order to facilitate the binarization, first, the image for analysis is smoothed to reduce the influence of noise, and the four corners of the imaging area which are not affected by the luminance by the light projecting means 2, 3, 4, and 5. Region 29
Find the maximum density value of The aperture is adjusted by the aperture drive motor 33 of the lens 9 so that the maximum density value is about 60 to 80% of the binarization threshold. By these pre-processing, it is possible to prevent a region other than the projection point from being extracted during binarization. In addition, labeling is performed when calculating the coordinates of the projection point, and if four points have been extracted in an area where the projection point can exist, the coordinates of the center of gravity of each label area are determined to obtain the coordinates of the extracted projection point. The coordinates are obtained.

Then, it is determined whether or not the four projection points are at the ends of the image pickup area (step S14). As a determination condition, as shown in FIG. 2, the imaging guide area occupies 80% or more of the imaging area in terms of area ratio, and the label area of the projection point does not protrude from the limit of the imaging area, and the coordinates can be calculated. Must. If the condition is satisfied, the coordinates of each projection point and the projection angle are stored (step S15),
The photographing permission lamp 8 is turned on in green (step S5).
The reason for storing the coordinates of the light projecting point is to use the coordinates at the time of image distortion correction in step S9. On the other hand, when the condition is not satisfied (step 16), the photographing permission lamp 8 is lit in red if the zoom mechanism is at its limit. If there is room in the zoom mechanism, the angle of view of the lens 9 is reduced by the zoom drive motor 31 if the light projecting point is located at the center, and the angle of view of the lens 9 is widened if there is no light projecting point (step 17). It returns to S11.

FIG. 6 is a detailed diagram of the processing in step S9 of FIG. 4, that is, a flowchart showing the operation of the image input apparatus from when the photographer fully presses the shutter button 7 until the image is stored. Before taking in an image, the light emitting point is turned off so that the light emitting point does not appear (Step S21). Thereafter, an image is captured (step 22).

Here, in some cases, the distortion image 5 shown in FIG.
As shown in FIG. 1, the captured image is distorted due to the angle between the object plane and the optical axis of the lens. In this state, barcodes and characters cannot be recognized.
Is corrected to an image in which the optical axis of the lens is perpendicular to the object plane (S23). In order to correct an image, depth information of the image is required. Therefore, depth information L of each projection point is obtained using the coordinates of the projection point and the projection angle stored in step S15. As shown in FIG. 8, the coordinates w of the projection point and the projection angle θ,
From the focal length f, the depth information L can be obtained by triangulation.

L = w (d + p × tan θ) / (fw × tan θ) (1) Correction is required if the depth information L of each projection point is different. Consider a polar coordinate system in which the optical axis 10 is the z axis and the center of the screen is the origin of the x and y axes. First, the equation of the plane of the space of the distortion image 51 is obtained. From the three-dimensional coordinates of the three projecting points, a normal vector (A, B, C) of the plane, and a point (a,
Since b and c) are obtained, the equation of the plane can be expressed as A (x-a) + B (y-b) + C (z-c) = 0 (2). Thus, any point (x,
From the equation (2), the depth information z of y) is as follows: z = − (A (x−a) + B (y−b)) / C + c (3) From this, 51 points (x, y) in the distorted image
Is projected on the corrected image by the following equation.

X ′ = z × x / LF (4) y ′ = z × y / LF (5) where (x ′, y ′) is a position on the correction screen to be projected, and LF is a distortion. This is the depth of a point located farthest from the camera on the screen 51, and the projection formulas of Expressions (4) and (5) are as shown in FIG. Means to map to the top. The reason why the projection plane is assumed based on the farthest point is to prevent loss of image information due to projection. The image correction can be performed by three of the light projecting means 2, 3, 4, and 5 used for confirming the imaging range, and the image processing circuit 37 built in the camera 1 main body. There is no need to prepare separate wear.

As described above, in this embodiment, four light projecting means are used, but only three light projecting points are used for image correction, and it can be seen that the invention described in claim 2 can be realized. .

Finally, the corrected image is stored in the memory card 3
9 and used for barcode recognition and character recognition.

[0023]

According to the present invention, the photographer can accurately recognize the imaging range of the subject without looking through the finder. Further, according to the present invention, it is possible to change the imaging range without changing the depth of field. Further, according to the present invention, it is possible to perform imaging in an imaging range intended by an imaging person.

According to the present invention, it is possible to input an image without distortion even in a situation where an image can be picked up only from an oblique direction. In addition, since the photographer does not need to worry about the angle between the optical axis of the lens and the object plane, the photographing operation is facilitated.
Further, it is possible to always project light by extending the interval between the light projecting points to fill the entire screen. That is, even if the angle of view changes due to zooming, the error in the inclination of the object plane due to triangulation can be minimized, and the accuracy of image distortion correction is improved.

[Brief description of the drawings]

FIG. 1 is an external view of an embodiment of an image input device according to the present invention.

FIG. 2 illustrates a state of the subject surface when the light is projected onto the subject surface with the optical axis of the lens vertical.

FIG. 3 is a block diagram showing an internal structure of the image input device.

FIG. 4 is a flowchart illustrating an operation of the image input apparatus performed by a photographer in the present embodiment.

FIG. 5 is a detailed flowchart of the zoom / focus adjustment processing of FIG. 4;

FIG. 6 is a detailed flowchart of the image capturing / skew correction process of FIG. 4;

FIG. 7 is a comparison diagram before a tilt correction process and after a tilt correction process;

FIG. 8 is a diagram for obtaining a depth of field by triangulation.

FIG. 9 is a diagram illustrating a state of a subject plane for explaining a tilt correction process.

FIG. 10 is a diagram specifically illustrating a tilt correction process.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Camera, 2 ... Left light emitting means, 3 ... Upper light emitting means, 4
... Right light emitting means, 5 ... Lower light emitting means, 6 ... Zoom button, 7 ... Shutter button, 8 ... Shooting permission lamp, 9 ...
Lens, 22 ... Lighting point (by left light emitting means), 23 ...
Projecting point (by upper projecting means), 24: Projecting point (by right projecting means), 25 ... Projecting point (by lower projecting means).

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H04N 5/228 H04N 1/04 C (72) Inventor Hiroshi Masashima 7-1-1, Omikacho, Hitachi City, Ibaraki Pref. Hitachi, Ltd., Hitachi Research Laboratory (72) Inventor Yoshiki Kobayashi 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor, Eiji Shimizu 5-2-2, Omika-cho, Hitachi City, Ibaraki Prefecture No. 1 Hitachi Process Computer Engineering Co., Ltd. F term (reference) 5B047 AA01 AB01 BA02 BB04 BC05 BC16 CA12 CB10 CB23 5C022 AA13 AB23 AB51 AB62 AB66 AC01 AC32 AC42 AC52 AC54 AC74 5C072 AA01 BA02 BA17 MA01 MB01 RA12 XA10

Claims (2)

[Claims] 1. An image input apparatus having a camera and a light projecting means for projecting a visible light beam as a guide of an imaging range to a subject, wherein the light projecting means for emitting a directional light beam has a light projecting angle. Providing at least two or more light projection angle driving means for changing, and controlling the zoom of the camera from the light projection angle of the light projection means and the positional information of at least two lights projected on the subject. An image input device characterized by the following. 2. An image input apparatus comprising: a camera; and a light projecting means for projecting a visible light beam serving as a guide of an imaging range to a subject, wherein a light projecting angle of the light projecting means for emitting a directional light beam is determined. An arithmetic circuit that includes at least three or more light projection angle driving means for changing, and corrects an image distortion due to a tilt of a plane of the object from position information of at least three lights projected on the object by the light emitting means. An image input device comprising: