JP2825344B2 - Image input device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input device that is a two-dimensional drawing reading device such as a facsimile, a copying machine, and an image scanner.

2. Description of the Related Art As a conventional technique relating to this field, there is an image input device used for an image scanner. FIG. 10 is a schematic side view showing one example. In the figure, 1001
Is the document to be read, 1002 is the glass plate that supports the document, 1003 is the fluorescent light that illuminates the document, 1004 is the lens that collects the reflected light at one point on the document, and 1005 is the light that is converted to an electrical signal A CCD 1006 is a CCD signal processing circuit.

In the conventional image input device configured as described above, the original 2 is illuminated by the fluorescent lamp 3, the lens 1004 captures the reflected light from the original 2, and forms an image on the CCD 1005. This optical system is scanned from left to right as viewed in FIG. The CCD 1005 converts luminance information corresponding to a scanning line perpendicular to the feed direction into an electric signal. By sequentially moving the optical system to the right in this manner, a plurality of pieces of luminance information corresponding to the scanning line segments are obtained, and are used as image input.

Problems to be Solved by the Invention However, in the above configuration, the original 1001 may be warped upward or downward due to physical restrictions such as binding. For this, the manuscript 1001 is a glass plate
There is a problem that the position information of the document is not correctly stored because the brightness information is obtained as an orthographic projection of each point on the space curved surface onto the glass surface approximately.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image input apparatus capable of correctly capturing a curved document or drawing as planar image information in order to solve the above-mentioned problems of the conventional image input apparatus.

Means for Solving the Problems The present invention relates to a method of reading a curved document surface to be read.
A position measuring means for measuring a three-dimensional position, a luminance measuring means for measuring luminance on the surface of the document, and a three-dimensional position on the document from the three-dimensional position and the luminance corresponding to the three-dimensional position from the luminance information. Three-dimensional luminance information generating means for generating discrete three-dimensional luminance information, three-dimensional luminance information storage means for storing the discrete three-dimensional luminance information, and the discrete three-dimensional luminance information storage means. Using the three-dimensional position of each element of the three-dimensional luminance information, the distance between the elements on the surface of the document is calculated, and the three-dimensional position of the element on two-dimensional orthogonal coordinates is stored so that the distance is preserved. It has two-dimensional expansion means for obtaining discrete two-dimensional luminance information by converting to a position, and luminance calculation means for calculating luminance on a grid point on two-dimensional orthogonal coordinates from the discrete two-dimensional luminance information. Features An image input device for.

In the present invention, a curved document is reproduced in a three-dimensional space based on the distance information obtained by the distance measuring means. And
After obtaining an image as luminance information on the curved surface, the image information can be obtained by expanding the image onto a plane while preserving the distance between each point on the curved surface by geometric calculation.

Further, in the present invention, by projecting the reference grating light on a curved surface, a lattice distorted by being projected on the curved surface is observed, and a deviation width from the reference grating assumed to be projected on a virtual plane is observed. Is corrected and calculated to calibrate the image position information and develop it into a planar image.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, FIG. 1, FIG. 2, FIG. 3, FIG.
This will be described with reference to FIGS.

FIG. 1 is a schematic configuration diagram of an image input device according to the present invention,
FIG. 2 is a side view for explaining the reading and position measurement state, FIG. 3 is an optical angle diagram for explaining the principle of the position measurement, FIG. 4 is an image reading coordinate system diagram, and FIG. It is a figure for explaining coordinate value conversion.

In FIG. 1, 101 is a position measurement circuit, 102 is a luminance measurement circuit, 103 and 104 are memories for storing the results of luminance measurement and position measurement, and 105 is a synthesis circuit of the obtained three-dimensional coordinate values and luminance values. , 106 is a triangular batch generation circuit for generating a triangular batch based on the luminance data obtained three-dimensionally in this way, 107 is a memory for storing the generated triangular batch, and 108 is a raster for developing the triangular batch into a plane 2 A dimension development circuit 109 is a luminance calculation circuit that calculates a luminance value on a grid point from the luminance on each point on the developed plane.

In the first embodiment of the present invention, the luminance and the position are measured using the mechanism shown in FIG. 2, reference numeral 201 denotes a document to be read; 202, a glass plate supporting the document; 203, a light source required to irradiate the document; 204, a condenser lens for condensing light from the light source 203; Is a slit for generating slit light from the light passing through the condenser lens 204, 206 is a light receiving lens for detecting and condensing the illuminated slit light, and 207 is a light receiving lens.
It is a CCD that converts slit light of a book into an electric signal. Second
By the mechanism shown in the figure, the brightness value and the values on the x, y, and z axes can be simultaneously obtained from the glass plate 202 shown in FIG. 4 in the coordinate system xyz. FIG. 3 shows parameters required at this time. That is, if the incident angle α of the slit light, the focal length f of the light receiving lens 206, the distance D between the slit light source and the center of the camera lens, and the observation position d on the CCD 207 are already known, the illumination of the surface of the original is performed by the principle of triangulation. I know the position.

 Hereinafter, the processing procedure of the first embodiment of the present invention will be described.

(Step 1); The projected slit light is observed as a curve as shown in FIG. The slit projection systems 203 and 20 shown in FIG.
4, 205 and the light receiving systems 206, 207 move on the glass plate 202 in the sub-scanning direction. Discrete position j in the sub-scanning direction (0≤j≤M-1)
In, slit light is searched for in the main scanning direction, and a set of three terms (x _ij , y _ij , z _ij ) of three-dimensional coordinates is calculated at a discrete position i (0 ≦ i ≦ N−1). At the same time, the brightness I _ij
Is obtained.

(Step 2): Coordinate data and luminance data are fused to form a four-term set (I _ij , x _ij , y _ij , z _ij ) ｛0 ≦ j ≦ M−1,0 as three-dimensional luminance information.
≦ j ≦ N−1}. Hereinafter, this is called a nod.

(Step 3): Neighbor nodes on the grid ij are connected to form triangular patch data as shown in FIG. 5 (a).

(Step 4): After selecting one reference node, two adjacent nodes are selected, and two suitable nodes orthogonal to each other on a plane passing through the three nodes are selected.
A dimensional expansion coordinate system uv is determined. At this time, 2 of 3 nodes
The position of the dimensional expansion coordinate system is uniquely determined.

(Step 5); It is assumed that the distance between each point on the manuscript 201 is stored in the observation coordinate system in a minute section, and starts from the vicinity of the three nodes obtained in the previous step and recursively calculates the spatial distance between the nodes. A position on the two-dimensional coordinate system UV is determined. In FIG. 5 (a)
Create the first triangular patch from P ₀ , P ₁ , and P ₂ , from which planar coordinates are created. P0 is the origin. In FIG. 5 (b), so that the distance _{P 1 ~P 3, P 2 ~P} 3 is stored, the P ₃ u
A coordinate position in the -v space is determined. Thereby, two-dimensional luminance information is obtained.

(Step 6) As a result of the previous Step 5, the position of each node in the developed coordinate system does not generally exist on the square lattice as shown in FIG. 5 (c). Therefore, each luminance value on the grid point is calculated from the luminance values on the neighboring nodes. This method includes convolution interpolation (Cubic Convolutio
Use n)). For example the point P of the 5 diagram (c) is P _0,
It is calculated by convolution interpolation from P ₁ , P ₂ , P ₃ , P ₄ , P ₅ , and P ₆ .

As described above, in this embodiment, by projecting the slit light, the luminance value on the surface of the document 201 is read at the same time as the depth information is read, and the document 201 is reconstructed three-dimensionally as a triangular patch. Then, by expanding this on a two-dimensional plane, the curved document 201 can be corrected and input.

 Next, a second embodiment of the present invention will be described.

In the second embodiment, the position measurement method is different from that of the first embodiment, but the other devices and methods are the same. Therefore, only the difference will be described below.

In the first embodiment, the three-dimensional coordinate position is obtained based on the principle of triangulation, but in the second embodiment, the three-dimensional coordinate position is obtained by using a focus adjustment mechanism system. This will be described with reference to FIGS. 6 and 7. FIG. 6 is a mechanical diagram of a reading optical system according to the second embodiment, and FIG. 7 is a mechanical diagram for explaining a scanning system for inputting an image. In FIG. 6, reference numeral 601 denotes a light source that emits laser light, 602 denotes a condenser lens for condensing the laser light, 603 denotes a lens barrel, and 604 denotes a half mirror that guides reflected light reflected from a document 609 to the outside of the lens barrel. Reference numeral 605 denotes a focus detection optical system that detects a focal point based on the width of the laser light detected through the reflection of the document 609, 606 denotes a detector for obtaining a luminance value of the laser light irradiation position on the document surface, and 607 denotes a detector 606 for the reflected light. 608 is an objective lens for irradiating laser light to the document surface, 610 is an actuator coil that moves up and down the lens barrel 603, and 611 is an actuator coil that changes the vertical position of the lens barrel 603 into an electric signal. It is a potentiometer.

With the above configuration, the reading optical system can
The focus is adjusted at any time simultaneously with the luminance value of one point on the surface, and the depth information is simultaneously obtained by the output of the potentiometer 611.

In the first embodiment of the present invention, the slit light is projected in the main scanning direction, and one scanning line is simultaneously obtained by the CCD 207.
In the second embodiment of the present invention, the reading unit is mechanically operated in the main operation direction. This will be described with reference to FIG. In FIG. 7, reference numeral 705 denotes the reading optical system shown in FIG. 701 and 703 are belts for moving the belt 702 in the sub scanning direction, 704 is a motor for driving the pulley 703, 70
6 is the original to be read, 707 is the actuator coil
A drive circuit 610, a reading circuit 708 for reading the output voltage of the potentiometer 611, a pulley 709 for pulling a belt in the main scanning direction, a belt 710, and a motor 711 for driving the belt 710.

With the scanning system configured as described above, the reading optical system 705 repeats the reciprocating operation in the main scanning direction and scans once in the sub-scanning direction to capture an image. Thereafter, the same processing as in the first embodiment is performed.

As described above, in the present embodiment, it is possible to take in an image and correct the curvature of a document while performing focus adjustment by the above-described configuration.

Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a schematic configuration diagram of the image input device,
FIG. 9 is an operation explanatory diagram for explaining the operation of the image input device. In FIG. 8, reference numeral 801 denotes a circuit for measuring the position of the orthogonal projection of the projected reference grating light onto the glass plate; 802, a circuit for measuring the luminance; 803, 804, memories for storing the position and luminance; Is a correction value calculation storage circuit that calculates a correction value based on the position of the observed reference lattice light, 806 is a correction circuit that gives corrected coordinate positions to the data in the distortion correction circuit 805 and the luminance value read from the memory 804, and 807 Is a luminance calculation circuit for calculating a luminance value on the reference grid from the corrected coordinate position. In the first and second embodiments of the present invention, the depth of the image obtained from the curved surface is corrected by obtaining the depth to the surface of the original. In the present embodiment, however, the two-dimensional shape is obtained from the distortion of the projected reference pattern. And perform correction.

This operation will be described with reference to FIG. Before or at the same time as reading the document, a spot light is projected as a reference grating light onto the document at a position indicated by x on the glass surface in FIG. 9A. In this case, T and S spot lights are projected vertically and horizontally. When the original is floated from the glass surface, when the original is observed, the original is obtained with a shift as indicated by a circle in FIG. 9A. Therefore, the observation position is changed by using this deviation as a correction value. Now, the observed coordinate values on the reference grid point are represented by x ′ _pq , y ′ _pq , (0 ≦ p ≦ S−1,0 ≦
q ≦ T−1), and let x _pq and y _pq be coordinates to be observed (coordinates when light is projected on the glass surface), and each correction value cx
_pq and cy _{pq become} cx _pq = x _pq -x ' _pq cy _pq = y _pq -y' _pq . In this embodiment, the number of grid points is
Since the accuracy of 1 cannot be obtained higher than the luminance measurement, it is smaller than the sample point of the image. Therefore, correction values cx _ij , cy for the values of the coordinates x ′ _ij , y ′ _ij obtained by scanning
_ij cannot be obtained directly (FIG. 9 (b)). Therefore, the ninth
In the situation shown in FIG. 2B, the correction value is obtained by the following equation.

cx _ij = cx _pq + (x ′ _ij −x ′ _pq ) (cx _{p + 1q} −cx _pq ) / cx _pq + (y ′ _ij −y ′ _pq ) (cx _{pq + 1} −cx _pq ) / cx _pq cy _{ij = cy pq + (y '} ij -y' pq) (cy p + 1q -cy pq) / cy pq + (x 'ij -x' pq) (cy pq + 1 -cy pq) / cy pq more The equation is a linear interpolation on the two-dimensional coordinates of the correction value. By the above operation, corrected for resultant luminance values I _ij coordinate values x _ij, calculating a y _ij. As a result of this correction, the coordinates of the obtained luminance value do not fall on the grid,
The luminance value on the lattice point is calculated and output by the convolution interpolation shown in the embodiment.

As described above, in the present embodiment, by projecting the reference grid, the distortion multiplied by the curvature of the document can be corrected by the correspondence of each point on the two-dimensional coordinates.

In the above embodiment, when each luminance value on a grid point is calculated from a luminance value on a neighboring node, the convolution interpolation method is used, but it may be obtained by another method.

As the light, spot light may be used instead of slit light.

Further, in the above embodiment, the original 201 is supported by the glass plate 202, the slit light is projected from below, the position measurement and the brightness measurement are performed, but at this time, the influence of the refraction of the light by the glass plate 202 causes a measurement error. May occur. In this case, the original may be read from above without passing through the glass plate 202.

 In addition, infrared light can be used as light.

In that case, the grating measurement unit 801 receives the infrared light and can simultaneously perform the grating measurement and the luminance measurement.

Effects of the Invention As described above, according to the image input apparatus of the present invention, even a curved document can be input as a flat image, and can be applied to recording, transmission, character recognition, and the like of document data. Its practical effect is great.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an image input apparatus according to the present invention, FIG. 2 is a side view showing a mechanism for reading and measuring the position of the embodiment, and FIG. FIG. 4 is a ray diagram for explaining the principle of position measurement, FIG. 4 is an image reading coordinate system diagram of the embodiment, FIG. 5 is a coordinate system diagram for explaining coordinate value conversion of the embodiment, and FIG. FIG. 7 is a sectional view showing a mechanism of a reading optical system according to a second embodiment of the image input device according to the present invention, FIG. 7 is a scanning system mechanism diagram for image input according to the second embodiment, and FIG. FIG. 9 is a schematic configuration diagram of an image input device according to a third embodiment of the device, FIG. 9 is a configuration diagram illustrating the operation of the image input device, and FIG. 10 is a side view of a conventional image input device. 101: position measurement circuit, 102: luminance measurement circuit, 103, 104, 10
7 ... memory, 105 ... combining circuit of 3D coordinate value and luminance value, 10
6: a generation circuit for generating a triangular patch, 108: a two-dimensional expansion circuit, 109: a luminance calculation circuit, 201: an original, 202: a glass plate, 2
03: light source, 207: CCD, 601: laser light source, 705: reading optical system, 706: manuscript.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G06T 3/00 G06T 7/00 H04N 1/04

Claims (7)

(57) [Claims] 1. A curved document surface 3 to be read.
Position measuring means for measuring a three-dimensional position; luminance measuring means for measuring luminance on the surface of the document; and three-dimensional position on the document from the three-dimensional position and the luminance corresponding to the three-dimensional position from the three-dimensional position and the luminance information. Discrete 3
Three-dimensional luminance information generating means for generating three-dimensional luminance information; three-dimensional luminance information storage means for storing the discrete three-dimensional luminance information; and the discrete three-dimensional luminance information stored by the three-dimensional luminance information storage means Using the three-dimensional position of each element, the distance between the elements on the surface of the document is calculated, and the three-dimensional position of the element is converted to a position on two-dimensional orthogonal coordinates so that the distance is preserved. Thereby, two-dimensional developing means for obtaining discrete two-dimensional luminance information, and luminance calculating means for calculating luminance on a grid point on two-dimensional orthogonal coordinates from the discrete two-dimensional luminance information are provided. Image input device. 2. The position measuring means scans a document to be read with a spot light and measures a distance in a depth direction from an apparent position of a point illuminated by the spot light by using a principle of triangulation. The image input device according to claim 1, wherein: 3. The position measuring means scans a document to be read with slit light, and measures a distance in a depth direction from an apparent position of a point illuminated by the slit light by using a principle of triangulation. The image input device according to claim 1, wherein: 4. An image input apparatus according to claim 1, wherein said position measuring means operates using a focus detection optical system. 5. The position measuring means uses projection light whose projection width changes according to the distance, adjusts the optical system so that the projection width of the projection light is minimized, and obtains the distance based on the adjustment value. 2. An image input apparatus according to claim 1, wherein said luminance measuring means simultaneously obtains luminance information from said adjusted optical system. 6. A luminance measuring means for measuring a luminance of a curved original surface to be read, a projecting means for irradiating a reference lattice light consisting of two-dimensional coordinates orthogonal to the original, and A grid position measuring means for measuring an apparent position; and calculating as a correction value a deviation width from an apparent position obtained by the grid position measuring means and a grid position assumed to be projected by the projecting means on a virtual plane by the projecting means. Correction value calculation storage means for storing and storing; correction means for converting an apparent position into coordinates on the projected reference grid based on the correction value stored in the correction value calculation storage means; Brightness calculation means for calculating the brightness of each point of the equally-spaced grid on the virtual plane from the obtained coordinate position and the brightness information obtained by the brightness measurement means, That image input device. 7. A projection means for projecting infrared light,
7. The image input device according to claim 6, wherein the grid measuring unit receives the infrared light and performs grid measurement and luminance measurement simultaneously.