JPH09214735A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a read image in which the user applies image processing selectively to a designated area by correcting a read image in a curved state to be obtained into an image when the original face is assumed to be a plane and conducting specific image processing. SOLUTION: A read image G0 is made up of an image G1 of an original face of a book original BD, an image G20 on an original platen, and an image G18 displayed on a range finder board. Since the border between the images G18 and G20 is known with respect to a reference line, the height of input sheets is calculated based on a distance y71 between the order and a contour of the image G183. The contour is discriminated based on a difference of the luminance between the image G183 and a background image. In the case of main scanning, the curved image G1 is corrected into an image when the height of the original face based on the height information of the original obtained in a preliminary scanning as the image processing is constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus suitable for reading bound originals such as books and magazines.

[0002]

2. Description of the Related Art An image reading device called a book scanner has been commercialized. In this apparatus, an image pickup system is arranged above the document table, and an open space having a height of several tens cm exists between the document table and the image pickup system. When reading a book-shaped original such as a book or a magazine (referred to as a "book original"), the user sets the book original on the original table in an open state. In response to the start key being turned on, the lamp for illuminating the document is turned on, and scanning of the document surface (reading target surface) is started. Images read in parallel with scanning are sequentially output to an external device. If the external device is a printer, a copy image is formed in real time. Usually, unlike a single-cut sheet original, the original surface of a book original is curved. Therefore, the read image is distorted according to the curved state. A read image in which this distortion has been corrected, that is, a read image having the same image quality as when reading a sheet original is output to an external device.

When the book scanner is used, the pages can be turned on the document table, so that the efficiency of reading a large number of pages can be improved. Further, the damage to the book can be significantly reduced as compared with the case where the book is opened and the book is set on the face down (downward).

[0004]

The conventional book scanner does not have an editing function of extracting or partially erasing a part of a document image.

In the case of a sheet original, a pressure-sensitive tablet is suitable as an area designating means for editing. The user can specify a desired area while observing the original image by placing the sheet original on a flat input surface and pressing the input original with the stylus pen through the sheet original. If the area is rectangular, 2 on the diagonal
The area is specified by inputting the position of the point.

On the other hand, in the case of a book original, a plurality of sheets are usually overlapped even when the book original is opened, so that position input is not possible with the book original placed on the input surface. . Therefore, the user must place the book document face-up on a position other than the input surface and directly press the input surface while comparing the document image with the input surface to specify the desired area. However, since the document surface is curved, it is difficult to correctly specify the position on the document surface.

The present invention has an editing function of selectively performing image processing on a designated area, and allows a user to designate a desired area while viewing an image on the original regardless of the thickness of the original. The purpose is to realize an image reading device that can be used.

[0008]

According to a first aspect of the present invention, a document table that supports a document to be read, an image pickup unit that converts a document image into an electric signal, and the electric signal is quantized and output to an external device. An image reading apparatus having a signal processing system for inputting light, and having a structure in which an open space for setting an original exists between the original table and the image pickup means, and a flexible input for transmitting visible light. A tablet-type position input device provided with a sheet is attached to the document table as an area designating unit for image editing, and the signal processing system outputs document height data indicating a curved state of the document surface. Based on the document height distribution measuring means and the document height data, it is assumed that the document surface is a flat region in the document surface designated in a state where the input sheet is superposed on the document surface. Territory in case And a coordinate calculation means for converting the read image obtained by the image pickup means into an image when the document surface is assumed to be a flat surface, and the output of the coordinate calculation means in the corrected read image is Image editing means for performing specific image processing on the indicated region.

According to a second aspect of the present invention, the signal processing system measures a curved state of the input sheet in a state of being superposed on the document surface, and shifts the curved state between the input sheet and the document surface. It has a function of supplementing.

The area for image editing is designated by setting the original on the original table so that its original surface faces the image pickup means, and further by superposing the input sheet of the position input means on the original surface. Since the input sheet is translucent, the user can specify a desired position on the document surface while viewing the document image.

When reading a book document, the area designated on the curved document surface is converted into an area on the assumption that the document surface is flat, based on the document height data. The read image is also corrected to an image on the assumption that the document surface is a flat surface, and substantially the image is edited with respect to the corrected read image. The contents of image editing are roughly divided into a process of extracting only the designated region and a process of erasing the designated region.

In the area designation, it is desirable that the input sheet is in close contact with the original surface. However, the document surface and the input sheet are not always curved similarly. Therefore, if the curved state of the input sheet is measured, the position on the input sheet can be converted into the position on the document surface.

[0013]

1 is a perspective view showing the external appearance of a book scanner 1, and FIG. 2 is a view showing the configuration of an optical system of an image pickup unit 30.

The book scanner 1 includes a main body housing 10 for accommodating an electric circuit, a dark-colored manuscript table 20 for supporting a manuscript, and an image pickup unit 3 for converting a manuscript image into an electric signal.
0 and a lamp unit 40 for illuminating the original. The document table 20 is arranged on the front side of the main body housing 10. The image pickup unit 30 is arranged above the document table 20 and is supported in a cantilevered manner by a column 12 extending upward from the upper surface of the main body housing 10. The lamp unit 40 is arranged on the lower surface side of the image pickup unit 30 and is fixed to the column 12. A space 80 between the document table 20 and the imaging unit 30 is open to a free space outside the apparatus, and has a sufficient space for setting a book document. The distance between the document table 20 and the imaging unit 30 is 30 cm or more.

An operation panel OP is provided on the upper end side of the front surface of the main body housing 10, and a distance measuring plate 16 for detecting the height of the document surface is fixed on the lower end side. Rangefinder 1
The front surface of 6 is a glossy flat surface, which is an inclined surface of 45 ° with respect to the upper surface of the document table 20. The upper end surface of the distance measuring plate 16 is a white plate 1 for shading correction.
Function as 8. On the right side surface of the main body housing 10 facing the operation panel OP, the main switch 5
1 is provided.

A start key 52 is provided on each of the left and right sides of the document table 20 for the user to instruct the start of reading, and the armrest 25 is provided on the front side.
Is provided. Further, the document table 20 is provided with two position input devices 70 for designating an area in image editing. One of these position input devices 70 is used to specify the area of the right page of the book document BD, and the other is used to specify the area of the left page.

In FIG. 1, the image pickup unit 30 is a CC
A line sensor 31 formed of a D array, an imaging lens 32,
And a mirror 33. The original image is projected on the light receiving surface of the line sensor 31 by the mirror 33 and the imaging lens 32. The imaging lens 32 is provided so as to be movable in the front-rear direction, and is positioned by an AF mechanism (not shown). The line sensor 31 is attached to a movable body of a scanning mechanism (not shown), and moves in parallel along the horizontal direction (sub-scanning direction) M2 while keeping the arrangement direction of the CCD elements in the vertical direction. This parallel movement captures a two-dimensional original image. That is, in the book scanner 1, the movement of the line sensor 31 forms a two-dimensional image pickup surface. When an area sensor is used instead of the line sensor 31, its light receiving surface becomes the image pickup surface. The main scanning direction of the original image is the front-back direction on the original table 20 and the vertical direction on the imaging surface.

As shown in FIG. 2, a movable mirror 34 is arranged between the imaging lens 32 and the line sensor 31. During the main scanning in which the line sensor 31 scans the original image, the movable mirror 34 is held at the retracted position indicated by the chain line in the figure. The movable mirror 34 is used at the time of preliminary scanning performed prior to the main scanning. The light transmitted through the imaging lens 32 is reflected by the movable mirror, passes through the relay lens 35, and enters the area sensor 36. The area sensor 36 is provided to measure the curved state of the document surface of the book document BD and the input surface of the position input device 70. By using the area sensor 36, the speed of preliminary scanning can be increased. However, the resolution of imaging is lower than that of scanning by the line sensor 31. The relay lens 35 is the area sensor 3
It is provided in order to match the magnification of the image pickup by 6 with the magnification of the image pickup by line sensor 31.

The book scanner 1 having the above structure is an image input means suitable for reading a book document BD. By combining the book scanner 1 and the digital copying machine, a comprehensive copying system suitable for various originals can be constructed.

When the book scanner 1 is used, the user places the book document BD on the document table 20 with the book document BD open, as shown in FIG. At that time, the boundary between the left and right pages is aligned with the center of the document table 20 in the left-right direction, and the book document BD is pressed against the lower end of the distance measuring plate 16 to perform the front-back direction positioning. The boundary between the distance measuring plate 16 and the document table 20 serves as a reference line for setting the document. The document table 20 is configured to be vertically movable independently of left and right. As a result, the heights of the left and right pages when opened can be made substantially the same.

The book scanner 1 performs preliminary scanning and main scanning on the same document. Since the document surface of the book document BD is curved unlike the sheet document, it is necessary to adjust the focus of imaging according to the curved state. It is also necessary to perform processing for compensating for the difference in brightness and correction for image distortion. Therefore, the curved state is detected by the preliminary scanning, and the processing required for the main scanning is performed based on the detection result. Image output to an external device is performed during main scanning. Read mode
There are a mode in which both the left and right pages are read collectively (sheet original mode), and a mode in which the left and right pages are read separately (book original mode). In both modes, preliminary scanning and main scanning are performed on each page. In addition, this scanning is
The operation is performed with the position input device 70 retracted from above the document surface.

FIG. 3 is a diagram showing the configuration of the position input device 70. The position input device 70 includes a rectangular input sheet 71 made of a transparent soft material in a plan view, a support 72 that reinforces one end edge of the input sheet 71, and an input sheet position sensor 78 for detecting an arrangement state of the input sheet 71. It is a tablet-type coordinate input means having.

The input sheet 71 is flexible enough to be curved along the document surface of the book document BD. The support 72 has a protrusion (not shown) that engages with the long groove 201 provided in the document table 20. The input sheet 71 is attached to the document table 20 via the support 72 so as to be movable in the left-right direction. The input sheet position sensor 78 outputs a signal according to the distance between the metal portion 79 provided on the upper surface of the input sheet 71 as shown in FIG. When the input sheet 71 covers the book document BD as shown in FIG. 3C (this is called a closed state), the metal portion 79 is separated from the input sheet position sensor 78.
When the input sheet 71 is folded back toward the outside of the document table 20 (this is called an open state), the metal portion 79
And the input sheet position sensor 78 are close to each other.

After setting the book document BD, the user stacks the input sheet 71 on the document surface so that the edge of the input sheet 71 is aligned with the center line of the spread. At that time, the position of the input sheet 71 is adjusted according to the size and thickness of the book document BD. The input sheet 71 is bent by its own weight and is curved along the original surface. In this state, the user uses the stylus pen 80 to specify a desired editing area.

FIG. 4 is a principle diagram of position input by the position input device 70. In FIG. 4, the position input device 70 is 2
The sheet-shaped transparent resistors (for example, transparent resin mixed with conductive fine particles) 711 and 712 are provided. These resistors 711 and 712 are overlapped with each other via a spacer 713.

The left-right direction of the document table 20 is the X direction of the two-dimensional coordinates, and the front-back direction is the Y direction. One resistor 711
Then, when a voltage is applied between both ends in the X direction, a voltage Vx corresponding to the distance x from one end in the X direction is generated at an arbitrary position in the plane regardless of the position in the Y direction. In the other resistor 712, when a voltage is applied between both ends in the Y direction, a voltage Vy corresponding to a distance y from one end in the Y direction is generated at an arbitrary position in the plane regardless of the position in the X direction. Occur.

As shown in FIG. 4B, for example, a resistor 711.
When a voltage is applied only to the resistor 711 and the resistor 711 is pressed by the styrus pane 80 to bring the resistor 711 and the resistor 712 into local contact, the voltage Vx appears in the resistor 712. On the contrary, when the voltage is applied only to the resistor 712, the voltage Vy appears in the resistor 711. Position input device 7
0 detects the position input by the user separately in the X direction and the Y direction.

The structure of the position input device 70 is not limited to the air gap type in which the spacer 713 is interposed between the resistors 711 and 712, but is a close contact type in which a pressure sensitive elastic body whose conductivity changes with pressure is interposed. May be. Instead of the pressure-sensitive method, it is possible to adopt a method of detecting a change in capacitance. However, according to the pressure-sensitive method, it is not necessary to use a special stylus pen 80, and high-resolution position input is possible.

FIG. 5 is a diagram showing an example of image editing. In the book scanner 1, it is possible to perform image editing in which the image in the editing area aa that is a part of the original image Ga is left and the output image Gb in which the image of the other part is erased is generated.

In the example of FIG. 5, the editing area aa is a quadrangle, and is specified by designating two points p1 and p2 on the diagonal. That is, the user may use the position input device 70 to specify the points p1 and p2.

FIG. 6 is a diagram for explaining the method of measuring the curved state of the document surface, and shows the image pickup information in the setting state of FIG. However, in FIG. 6, a plan view image of the position input device 70 is omitted.

The read image G0 is composed of an image G1 of the document surface of the book document BD, an image G20 of the document table 20, and an image G18 reflected on the distance measuring plate 18. Images G181 and 182 in the image G18 show the shape of the end face (a part called "heaven" in the book) of the book document BD in the open state. The image G183 is displayed on the input sheet 7
1 shows the shape of the end surface of No. 1. Image G18 in image G18
Parts other than 1, 182 and 183 are background images reflected on the distance measuring plate 18. If the input sheet 71 is in the open state, the image G183 is naturally absent.

Since the boundary between the image G18 and the image G20 corresponds to the above-mentioned reference line and is known, the boundary and the image G18 are known.
Input sheet 71 from the distance (pixel count) y ₇₁ from the contour line of 3
The height (distance from the document table 20) can be calculated. The contour line can be identified by the difference in luminance between the image G183 and the background image. To facilitate this determination, the end surface of the input sheet 71 is colored white. Similarly, image G1
The height of the document surface can be calculated by discriminating the contour lines 81 and 182. In that case, the image G
A read image without 183, that is, photographing information in the open state is preferable. The book scanner 1 performs preliminary scanning twice, and separately measures the height of the input sheet 71 and the height of the document surface. However, the end surface of the input sheet 71 is colored so as to have an intermediate brightness between the brightness of the background image and the brightness of the end surface of the book document BD, and the image 18 is discriminated using the brightness difference.
The height of the input sheet 71 and the height of the document surface may be measured by one preliminary scanning.

The boundary between the image G1 and the image G20 can be easily identified by utilizing the difference between the background color of the document surface and the color of the document table 20. If the boundary between the images G1 and G20 is known,
The edge of the book document BD on the imaging surface is found.

In the read image G0, the upper and lower edges of the image G1 are curved because the height of the document surface is not constant. That is, a subject closer to the imaging surface is captured larger than a subject far away. During the main scanning, image processing (image distortion correction) is performed to correct the curved image G1 into an image when the height of the document surface is constant, based on the height information of the document surface obtained during the preliminary scanning. Be seen. Specifically, with respect to the main scanning direction, the plane at a certain distance (for example, 5 cm) above the document table 20 is used as a reference surface, and the height difference between the reference surface and the document surface at each position in the sub scanning direction is used. The image G1 is scaled. In the sub-scanning direction, the image G1 is magnified according to the ratio of the creepage distance of the document surface to the projection distance of the document surface on the document table 20 for each minute section.

FIG. 7 shows the signal processing system 10 of the book scanner 1.
It is a block diagram of the principal part of 0. During the pre-scanning, the output of the area sensor 36 is the AD conversion unit 122.
Is converted into, for example, 8-bit image data. The image data is fetched by the CPU 101. CPU1
In 01, the height of the input sheet 71 and the height of the document surface at each position where the sub-scanning range is subdivided into equal intervals are calculated based on the image data, and image distortion correction and density correction are performed in preparation for main scanning. To generate data for.
When performing image editing, data Daa indicating the editing area
Also generate.

At the time of main scanning, the output of the line sensor 31 is converted into, for example, 8-bit image data by the AD conversion unit 102 and input to the image processing unit 103. The image processing unit 103 corrects unevenness of illuminance on the document surface, MTF correction for improving image quality, scaling processing including correction of image distortion caused by curvature of the document surface, density correction,
Also, it is responsible for processing such as image editing in which the outside of the designated area is blank. The data Daa is given to the image processing unit 103 as control data for image editing. The image data subjected to the predetermined image processing is output to an external device such as a copying machine or a printer.

The CPU 101 controls a drive system including a sensor drive unit, a lens drive unit, and a lamp drive unit lamp. A memory 105, which is a work area for control, an operation panel OP, a position input device 70, and the like are connected to the CPU 101. The document height data DH indicating the curved state of the document surface is stored in the memory 105 for each preliminary scanning.
S2, input sheet height data DH71 indicating the curved state of the input sheet 71, and data Daa are temporarily stored.

FIG. 8 is a diagram showing a procedure for calculating the editing area. As shown in FIG. 8A, the input sheet 71 is not always in close contact with the document surface S2. Position input device 7
The output of 0 is the input position p from the edge of the input sheet 71.
8C, that is, the linear distance from the edge to the input position p when the input sheet 71 is a flat surface as shown in FIG. 8B. Therefore, the input sheet 71 and the document surface S2
If there is a large difference in the curved state between and, an error will occur in the position input.

Therefore, first, the input sheet height data DH7
1 is used to find the coordinate X ₁ in the X direction on the original table 20 at the input position p. As described above, the height H of the input sheet 71 is measured at every sampling point at equal intervals in the X direction. As shown in FIG. 8C, the input sheet 71 is approximated by a straight line, and a sampling point at which the length from the end of the polygonal line is the value closest to the value indicated by the position input device 70 is found. Let the coordinates of the found sampling point be coordinates X ₁ . If the sampling period is made small enough, the approximation error does not matter.

Once the coordinate X ₁ is obtained, the coordinate X _{2 in} the X direction of the input position p'when the document surface S1 is assumed to be a flat surface.
Can be asked. That is, the document height data DH
The document surface S2 may be approximated by a straight line using S2, and the creepage distance of the document surface S2 may be calculated in the range from the origin in the X direction to the coordinate X ₁ . The calculated value corresponds to the coordinate X ₂ .

Regarding the front-back direction of the document table 20,
Since the document surface S2 can be regarded as a plane, the Y direction output (y) of the position input device 70 is used as it is as the Y coordinate on the document table 20. When the input sheet 71 is highly flexible and the adhesion between the input sheet 71 and the document surface S2 is good, the height of the input sheet 71 does not necessarily have to be measured, and the height of the document surface S2 is not necessarily measured. The coordinate X ₂ can be obtained only by measuring

By the above procedure, the position on the coordinate of the input sheet 71 is converted to the position on the document table 20 (the position on the document surface S2 when it is assumed to be a flat surface), and the editing area on the document table 20 is changed. The data Daa shown is generated.

FIG. 9 is a flow chart of reading by the book scanner 1. When the input sheet 71 is overlaid on the set original, the CPU 101 turns on the lamp and waits for the designation operation of the editing area (# 1 to 4). When the area is designated, the first preliminary scanning by the area sensor 36 is performed, and the read image obtained is analyzed to obtain the height of the input sheet 71 (# 6). At this time,
The CPU 101 functions as the document height distribution measuring means of the present invention. Based on the height of the input sheet 71, coordinate conversion is performed to obtain the designated area on the document table 20 by the above-described linear approximation calculation (# 7). When the open state of the input sheet 71 is detected, the lamp is once turned off and the start key 52 is turned on (# 8-10).

In response to the start key 52 being turned on, the lamp is turned on again, the second preliminary scanning is performed by the area sensor 36, and the obtained read image is analyzed to measure the height of the document surface S2. (# 11, 12). Based on the document height data DHS2, coordinate conversion is performed to obtain a designated area on the document surface S2 assuming that the document surface is flat (# 13). At this time, the data Daa indicating the editing area
Is generated. That is, the CPU 101 functions as the coordinate calculation means of the present invention.

After the movable mirror 34 is retracted, the main scanning is started (# 14, 15). During the main scanning, masking for replacing the data in the area other than the editing area aa with blank data is executed in parallel with the imaging by the line sensor 31 (# 16). When the main scanning is completed, the movable mirror 34 is returned to the position for the preliminary scanning, and the lamp is turned off (# 17 to 19).

[0047]

According to the invention of claim 1, the user:
A read image in which image processing is selectively applied to the designated area can be obtained, and a desired area can be designated while viewing the image on the original regardless of the thickness of the original.

According to the second aspect of the present invention, the accuracy of area designation for image editing is improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an appearance of a book scanner.

FIG. 2 is a diagram showing a configuration of an optical system of an imaging unit.

FIG. 3 is a diagram showing a configuration of a position input device.

FIG. 4 is a principle diagram of position input by a position input device.

FIG. 5 is a diagram showing an example of image editing.

FIG. 6 is a diagram illustrating a method of measuring a curved state of a document surface.

FIG. 7 is a block diagram of a main part of a signal processing system of the book scanner.

FIG. 8 is a diagram showing a procedure of calculating an editing area.

FIG. 9 is a flowchart of reading with a book scanner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 book scanner (image reading device) 20 document table 30 imaging unit (imaging means) 70 position input device 71 input sheet 80 space (open space) 100 signal processing system 101 CPU 103 image processing unit (image editing means) aa editing area ( Area) BD Book original (Original) DHS2 Original height data S2 Original surface

Claims (2)

[Claims] 1. A document table which supports a document to be read, an image pickup means for converting a document image into an electric signal, and a signal processing system which quantizes the electric signal and outputs it to an external device.
An image reading device having a structure in which an open space for setting a document exists between the document table and the image pickup means, and a tablet-type position input including a flexible input sheet that transmits visible light. An apparatus is attached to the document table as an area designating unit for image editing, and the signal processing system includes a document height distribution measuring unit that outputs document height data indicating a curved state of a document surface, Coordinate calculation means for converting an area in the original surface specified with the input sheet overlaid on the original surface into an area on the assumption that the original surface is a flat surface based on the original height data. And correcting the read image obtained by the image pickup means to an image when the document surface is assumed to be a flat surface, and showing the output of the coordinate calculation means in the corrected read image. Image reading apparatus characterized by having an image editing means for performing specific image processing on the region. 2. The signal processing system has a function of measuring a curved state of the input sheet in a state of being superposed on the document surface and compensating for a deviation of the curved state between the input sheet and the document surface. The image reading apparatus according to claim 1.