JPH10136194A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To selectively erase an image of a hand supporting an original by using information obtained through the pickup of the original from a side of a spread face in addition to information through the pickup of the spread face from an upper side so as to detect a position of the hand of the user thereby specifying an undesired image to be erased. SOLUTION: In this book scanner, an image of an upper end face of an original is caught by a glitter face having a slope of 45 deg. with respect to an upper side of an original platen and the image is picked up together with an image of a spread face of the original to obtain the read image GOb. The scanner has a 1st detection means that discriminates a hand placed on the spread face based on the difference from the luminance and the area of an upper image G1 of a bright original face, an image G20 of the original platen with a dark color tone, and a halftone image GH of the hand on the spread face. Furthermore, height distribution of the original is obtained from the end face image G181 of the original, The scanner has a 2nd detection means that specifies a position of the hand by obtaining a difference from the height because the rapid height increase of the original face results from the side image GH of the hand supporting the original, and also has an image correction means that erases a part of image corresponding to the images detected both by the 1st and 2nd detection means as an image of the hand.

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 apparatus called a book scanner has been commercialized. In this apparatus, an image pickup system is arranged above a 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 magazine (this is referred to as a “book original”), the user sets the book original upward on a platen with the book original opened. In response to turning on of the start key, scanning of a facing surface (document surface) which is a reading target surface (original surface) is started, and the read images are sequentially output to an external device. If the external device is a printer, a copied image is formed in real time. When a book scanner is used, pages can be turned on a document table, so that the efficiency of reading many pages can be improved. The book manuscript includes a filed document.

[0003] Unlike a sheet document, a book document sometimes needs to hold both ends of a spread surface in order to maintain a spread state. In such a case, the user's finger or back of the hand is photographed together with the document. To improve the appearance of the output image of the book scanner, it is necessary to delete unnecessary images such as finger images.

Conventionally, two methods are known for erasing unnecessary images. One is to attach a color imaging device to perform color photography, extract a skin color image from the photographed image, and remove it (Japanese Patent Laid-Open No. 6-1050).
No. 91). Another method is to determine a document portion in a photographed image based on, for example, a result of document size detection, to check a pixel density for the whole or a part of a peripheral area (margin area) of the document portion, and to determine a fixed density. In this method, an image composed of a certain number of pixels or more is extracted and deleted (Japanese Patent Laid-Open No. 6-7813).
No. 3).

[0005]

In the above-described method of extracting an unnecessary image by color discrimination, an unnecessary image is extracted in a case of a color photograph or a case where the paper is changed from white to yellowish color. However, there is a problem that errors easily occur. On the other hand, in the technique of extracting an unnecessary image existing in the peripheral area of the original part by simply determining the density, if there is a colored part that emphasizes a heading or a page number in the peripheral area of the original surface, the colored part is determined to be an unnecessary image. There is a problem that it is erased.

There is also known a scanner in which a transparent document cover covers the entire spread surface instead of the user pressing the spread surface manually. However, in this configuration, it is necessary to open and close the document cover every time a page is turned, which is troublesome. There is also a problem that the setting position of the book document is easily shifted when the document cover is closed.

The present invention enhances the reliability of an image correction function for selectively erasing an image of a pressed hand, which is an unnecessary image among read images, when a user holds a document by pressing it with his / her hand. It is an object of the present invention to provide a highly practical image reading apparatus which has a good image appearance and can easily fix a spread document.

[0008]

Focusing on the fact that the user's hand holding the document is three-dimensional, using information obtained by photographing the document from the side of the spread surface in addition to information obtained by photographing the spread surface from above, The position of the user's hand is detected, and an unnecessary image to be deleted is specified. Even if there is a part (such as a headline) in the peripheral area of the facing surface that has the same brightness as the skin color,
Because it is a plane, it can be reliably distinguished from a user's hand that is three-dimensional.

According to a first aspect of the present invention, there is provided an apparatus having a document table, a photoelectric conversion device, and an optical system for projecting a document image onto the photoelectric conversion device, wherein a document is placed between the document table and the optical system. An image reading device having a structure in which an open space exists for the setting of a document, wherein the image capturing device captures an end surface of a double-page spread document placed in a state of being spread left and right on the platen in a direction perpendicular to the left-right direction. A first detection unit that detects an object on the spread surface based on a captured image of a spread surface that is a read target surface of the spread document; and a first detection unit that detects an object on the spread surface based on the captured image of the end surface. Second detecting means for detecting an object, image correcting means for partially erasing the read image obtained by reading the original image, and the first and the second of the read images of the double-page spread to the image correcting means. It has an image modification control means for erasing a portion corresponding to the object detected by both of the two detection means.

[0010]

FIG. 1 is a perspective view showing an appearance of a book scanner 1, FIG. 2 is a view showing a movable function of a document table 20, and FIG.

The book scanner 1 is an image reading apparatus suitable for reading a book original (spread original), and includes a main body housing 10 for accommodating a power supply circuit and the like, a dark original table 20 for supporting the original, and an electric image for the original. An image pickup unit 30 converts the image into a signal, and a lamp unit 40 illuminates the original. The document table 20 is arranged on the front side of the main body housing 10. The imaging unit 30 is arranged above the document table 20 and is supported in a cantilever manner by a support column 12 extending upward from the upper surface of the main body housing 10. The lamp unit 40 is fixed to a position on the lower surface side of the imaging unit 30 on the support 12. Platen 2
A space 80 between the camera unit 0 and the imaging unit 30 is open to a free space outside the apparatus, and has a sufficient size for setting a book document. The distance between the document table 20 and the lower surface of 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 projection plate 18 for detecting the height of the document surface is fixed to the lower end side. On the operation panel OP, together with the liquid crystal display, buttons for specifying a reading mode and reading conditions (reading size, magnification, number of output sheets, density, etc.) are arranged. The front surface of the projection plate 18 is a glossy surface and is a 45 ° inclined surface with respect to the upper surface of the document table 20. An image of the end surface S3 of the book document BD in a direction orthogonal to the left-right direction is reflected on the projection plate 18, and the projection plate 18 in that state is photographed together with the document image.

Operation panel O in main body housing 10
A main switch 51 is provided on a side surface on the right side toward P. A start key 5 for the user to instruct the start of reading is provided on both sides of the platen 20 in the left-right direction.
2 and 53 are provided one by one, and an armrest 25 is provided on the front side.

In FIG. 1, an image pickup unit 30 has a CC
A line sensor 31 composed 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 optical system OS including the mirror 33 and the imaging lens 32. The imaging lens 32
It is provided movably in the front-rear direction, and is positioned by an AF mechanism (lens driving unit) 132. The line sensor 31 is attached to a movable body of a sub-scanning mechanism (not shown), and moves in parallel along the left-right direction (sub-scanning direction) M2 while keeping the arrangement direction of the CCD elements in the vertical direction. By this parallel movement, a two-dimensional document image is captured. That is, in the book scanner 1, a two-dimensional imaging surface is formed by the movement of the line sensor 31. When an area sensor is used in place of the line sensor 31, its light receiving surface becomes an imaging surface. The main scanning direction of the document image is a front-back direction on the document table 20 and a vertical direction on the imaging surface. In the present embodiment, the image pickup unit 30 and the above-mentioned projection plate 18 constitute an image pickup means for the end face S3, and the image pickup unit 30 simultaneously picks up an image of the document surface S1 and the end face S3. By combining the book scanner 1 having the above configuration with a digital copying machine, a comprehensive copying system suitable for various types of documents can be constructed.

When using the book scanner 1, the user places the book document BD upward on the document table 20 with the book document BD opened. At this time, the boundary between the left and right pages is aligned with the center of the document table 20 in the left and right direction, and
The book document BD is pressed against the lower edge of the document to position in the front-back direction. The boundary between the projection plate 18 and the document table 20 is a reference line for setting the document. The center of the reference line is the reference position P0 (see FIG. 5). As shown in FIG. 2, the document table 20 is supported by a spring mechanism so that it can move up and down independently of the left and right in accordance with the weight of the document. Thus, regardless of the thickness of the book document BD, the height of the left and right pages becomes substantially the same regardless of which page is opened, and the shooting distance is a value within a certain range.

In the book document BD, unlike the sheet document, the document surface S1 is curved, so that it is necessary to perform processing such as focus adjustment of image pickup and correction of image distortion according to the curved state. In reading the book document BD, the user often presses the end of the book document BD in order to maintain the spread state or to flatten the document surface S1 as much as possible. In this case, since a part of the user's hand is imaged together with the document image, in order to improve the appearance of the output image, masking (correction of the read image) for deleting the unnecessary image of the user's hand is performed. Is desirable. From these facts, the book scanner 1 performs the preliminary scanning to measure the curved state of the original surface S1, and uses the method unique to the present invention using the photographing information of both the original surface S1 and the end surface S3. Detect the position of. Then, in accordance with the information obtained by the preliminary scanning, the main scanning operation conditions such as the focus adjustment amount (lens movement amount), the magnification for distortion correction, and the masking range are set. The image output to the external device is performed during the main scanning. The reading mode of the book scanner 1 includes a mode for reading both left and right pages at once (sheet document mode) and a mode for reading left and right pages separately (book division mode). In either mode, preliminary scanning and main scanning are performed on each page.

FIG. 4 is a diagram for explaining a method of measuring the curved state of the document surface. The broken line in FIG. 4B indicates the position of the line of interest. The read image G0 is composed of a photographed image (upper surface image) G1 of the upper surface of the book document BD, a photographed image G20 of the document table 20, and a photographed image G18 of the projection plate 18. An image G181 of the photographed image G18 indicates the shape of the end face (portion called “heaven” in the book) S3 in the set book document BD.
Image 1 of photographed image G18 other than image (end face image) G181
Reference numeral 80 denotes a background image reflected on the projection plate 18.

Since the document table 20 is colored dark as described above, the photographed image G20 is darker than other images. Further, the background image 180 is also darker than the end face image G181. Therefore, the upper surface image G1 and the end surface image G181 can be extracted by determining the magnitude of the luminance.
Specifically, the luminance (pixel value) is checked in order from the top pixel in the main scanning direction for each line, and the top pixel position (pixel number) n1 in the range where the luminance exceeds the first threshold th1 and the luminance is Then, pixel positions n3 and n4 on the leading and trailing ends of the range exceeding the threshold value th2 (th2> th1) of 2 are detected. The number of pixels between the pixel position n1 and the known pixel position n2 corresponding to the front edge of the projection plate 18 is the original surface S1 of the line.
And the number of pixels between the pixel position n3 and the pixel position n4 corresponds to the document size in the main scanning direction. The actual size is obtained by the calculation of dividing the number of pixels by the imaging resolution. The curved state of the document surface S1, that is, the height distribution is specified by a set of data indicating the height of the document surface S1 in each of all the lines. Further, the respective positions of the first line and the last line where the pixel positions n3 and n4 are detected correspond to both end positions of the document in the sub-scanning direction. Here, in the read image G0, the upper edge and the lower edge of the upper surface image G1 are curved because the height of the document surface S1 is not constant. That is, a subject near the imaging surface is imaged larger than a distant subject. At the time of the main scanning, image processing (image distortion correction) for correcting the curved upper surface image G1 into an image when the height of the original surface S1 is constant based on the height information of the original surface S1 obtained at the time of the preliminary scanning. ) Is performed. Specifically, with respect to the main scanning direction, a plane at a position at a fixed 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 S1 at each position in the sub-scanning direction is calculated. The upper surface image G1 is scaled accordingly. In the sub-scanning direction, the document surface S1
The upper surface image G1 is scaled according to the ratio of the creepage distance of the document surface S1 to the projection distance of the document surface S1 onto the document table 20.

Next, the setting of the masking range will be described. In the book scanner 1, the image of the user's hand, which is an unnecessary image, is surely erased, and a part that should not be erased, such as a headline or a page number (herein referred to as a "heading part" for convenience) is prevented from being erased. That is, in order to enhance the reliability of masking, detection of the position of the unnecessary image (first position detection) based on the photographing information of the document surface S1 and detection of the end surface S
The detection of the position of the unnecessary image based on the photographing information of No. 3 (second position detection) is performed. The second position detection is performed on the original surface S1.
Is focused on the apparent local swelling of the document surface S1 due to the pressing of. That is, a heading portion that is not raised is not a target of the second position detection. Therefore, even if the heading portion corresponds to an unnecessary image in the first position detection, erasure of the heading portion can be avoided by integrating the results of the first and second position detections. Hereinafter, the first position detection method and the second position detection method will be described in order.

FIG. 5 is a plan view showing an example of reading a book document BD. FIG. 5A illustrates a state in which the user presses the book document BD on the document table 20 with the hand H.
(B) shows the main part of the read image G0 corresponding to FIG. 5 (A).

In the example of FIG. 5, the read image G0 is composed of an upper surface image G1 of the book document BD and a photographed image G2 of the document table 20.
0 and the photographed image GH of the user's hand H. Normally, the photographed image GH of the hand H is brighter than the photographed image G20 of the document table 20, and darker than the background portion of the upper surface image G1.
Therefore, the photographed image GH can be extracted by the luminance determination.

FIG. 6 is a schematic diagram showing an outline of extraction of an unnecessary image. FIG. 6B is an enlarged view of a portion surrounded by a broken line in FIG. As shown in FIG. 6 (A), for a portion corresponding to the document surface S1 in the top surface image G1, a concave shape discrimination in which the peripheral edge (the left and right side edges and the lower edge in the figure) is the outer edge E1. The target area AJ is set. The widths of the three sides of the determination target area AJ are selected such that the inner edge E2 of the determination target area AJ overlaps a required image such as a character image or an original image. That is, the determination target area AJ is made wider than the margin around the document surface S1. For example, the width of each of the right and left sides is about 30% of the size of the left and right documents, and the width of the lower side is also about 30% of the size of the upper and lower documents.

As shown in FIG. 6B, the determination target area AJ is subdivided into a large number of blocks b arranged in a matrix, and the presence or absence of an image is determined for each block b. In the example of FIG. 6B, a part of the character string Z1 and a character string Z2 indicating the page number
And a photographed image GH of the user's hand H. As a method of determining the presence or absence of an image, a method of determining the average value of the luminance of the pixels in the block b (imaging units of the line sensor 31) is used. There is a method to determine.

Then, a block group B3, which is a set of a plurality of blocks b each having an image and adjacent to each other and separated from the inner edge E2 of the determination target area AJ and in contact with the outer edge E2, is extracted. As shown in FIG. 6C, in the example of FIG. 6, a set of a plurality of blocks b each having an image and adjacent to each other is a block group B including a character string Z1.
1, block group B2 including character string Z2, and captured image GH
Are included in the block group B3. Of these block groups B1 to B3, only the block group B3 is apart from the inner edge E2 and in contact with the outer edge E2.

By erasing the image in the block group B3 extracted in this way, a read image consisting only of the necessary image is obtained. To erase the image in block group B3,
What is necessary is just to replace the data value of the pixel in the block group B3 with a value indicating the background color.

FIG. 7 is a diagram showing a procedure for determining a block group. At the stage of FIG. 7A, four block groups B4 to B7 have been extracted as primary candidates of unnecessary images to be deleted. With respect to these block groups B4 to B7, the attribute of the block b is checked. First, attention is paid to one block b1 as shown in FIG. 7 (F), and the reference position P is viewed from the block b1.
The presence / absence of an image in the three blocks b2 to b4 closer to 0 is checked. If there is no image in all three blocks b2 to b4, the attribute of block b1 is set to "1". If there is an image in at least one of the three blocks b2 to b4, the attribute of the block b1 is set to “2”. Block b1
Is in contact with the inner edge E2, the attribute of the block b1 is set to "0" (FIG. 7B). In this way, the attribute of each block is determined, and the block groups B5 and B7 including the block b having the attribute “1” are set as secondary candidates for unnecessary images [FIG.
(C)]. The process of extracting a secondary candidate from the primary candidates is referred to as an inside determination process.

Next, the attribute of the block b is examined for the secondary candidate. As shown in FIG. 7 (G), attention is paid to one block b5, and the presence or absence of an image in three blocks b6 to b8 farther from the reference position P0 as viewed from the block b5 is examined. If there is no image in all three blocks b6 to b8, the attribute of block b5 is set to "0". If there is an image in at least one of the three blocks b6 to B8, the attribute of the block b5 is set to “2”. Block b1 is outer edge E1
, The attribute of the block b5 is set to "1" (FIG. 7D). In this way, the attribute of each block is determined, and the block group B5 including the block b having the attribute “1”
Is a tertiary candidate for an unnecessary image [FIG. 7 (E)]. The process of extracting a tertiary candidate from the secondary candidates is referred to as outer determination processing.

Finally, the dimensional condition is determined for the tertiary candidate. For example, the third candidate has a size corresponding to a finger,
If there is no extreme difference in the length and width, the tertiary candidate is regarded as an unnecessary image. As a result, it is possible to avoid errors in erasing necessary images such as indexes and ruled lines.

The original side (spread side) is obtained by each of the above processes.
Unnecessary image (finger image) detected based on the captured image in S1
Is set as the “first candidate” of the position for specifying the masking range in the correction of the read image.

FIG. 8 is a view showing a read image G0b corresponding to another example of reading. 5, the same reference numerals are given to the components corresponding to those in FIG. 5 irrespective of the difference in shape.

The read image G0b is composed of an upper surface image G1, a photographed image GH of the user's hand, a photographed image G20 of the document table 20, and a photographed image G18 of the projection plate 18. The photographed image G18 includes an end face image G181 and a hand image Gh. In the example of FIG. 8, the left page of the double-page spread is a document page in which black characters and graphics are printed on a white background, and a margin exists around this page. However, the index is color-printed on the left edge. On the other hand, the right page is a photograph page in which color printing is performed in the entire area. The user is holding the edge of the right page, and the lack of white space on the page inevitably hides some of the photo. Further, in the illustrated example, an image Gg of a color similar to the photographed image GH of the hand is provided at the right end of a portion corresponding to the right page in the upper surface image G1, and there is a bright image Gw surrounding the image Gg. When the above-described first position detection is performed on such a read image G0b, the respective positions of the right page image Gg and the left page index image Gi may be “first candidates”. When the image Gs of the peripheral portion of the photographed image GH in the upper surface image G1 is relatively bright, the position of the photographed image GH is a “first candidate”. However, when the image Gs is relatively bright,
There is a possibility that the position of the captured image GH does not become the “first candidate”. That is, in the first position detection, it is difficult to reliably extract only the photographed image GH that is an unnecessary image. For this reason,
The second position detection is performed using the photographed image G18, which is photographing information of the book document BD substantially from directly in front of the end surface S3.

FIG. 9 is a diagram showing a procedure of the second position detection. When the user presses the book document BD, the height distribution of the book document BD is obtained in the manner shown in FIG.
As shown in (A), the distribution is raised near the end in the sub-scanning direction. The raised portion corresponds to the hand (object) H on the document surface S1. The position yf of the boundary (inflection point) between the gentle curved portion corresponding to the document surface S1 and the raised portion in the distribution curve is defined as a “second candidate” for specifying the masking range. In order to find the position yf of the inflection point, as shown in FIGS. 9B and 9C, the difference between the heights of the lines adjacent from the center in the sub-scanning direction toward the right and left sides is obtained. What is necessary is just to check the reversal. Difference is negative (-)
Is a position yf of the inflection point.
As shown in FIG. 9C, if there is no object on the document surface S1, there is no position where the height difference changes from negative to positive.

At the time of masking, the “second candidate” detected in this way is compared with the “first candidate” described above.
When the values match, the unnecessary image corresponding to the “first candidate” may be deleted. However, in the present embodiment, since the optical image of the document is projected on the line sensor 31 using the imaging lens 32, an error described later occurs in the “second candidate”. Therefore, it is necessary to compare the “second candidate” with the “first candidate” in consideration of the error.

FIG. 10 is a view for explaining the error of the second candidate, and is a schematic view of reading assuming that the optical path when the hand H holding the original is photographed using the projection plate 18 is a straight optical path without turning back. It is.

An optical path L extending from the vicinity of both ends of the document surface S1 in the sub-scanning direction to the line sensor 31 is inclined with respect to the optical axis Lc of the imaging lens 32. Accordingly, light traveling from the tip A of the hand H holding the end of the document surface S1 toward the line sensor 31 passes through the projection plate 18 at a point B inside (closer to the center) than the tip A. The distance between the tip A and the point B in the sub-scanning direction increases as the tip A is farther from the projection plate 18.
The position of the point B in the sub-scanning direction can be obtained based on the coordinates of the leading end A obtained from the photographing information of the document surface S1 and the distance between the optical system OS and the document table 20.

FIG. 11 shows the signal processing system 1 of the book scanner 1.
It is a block diagram of 00. The signal processing system 100 includes a CPU
101, AD converter 102, image processing circuit 103, line memory 104, RAM 105, and height measuring unit 110
have. The CPU 101 includes three functional elements of a luminance detecting unit 201, a counting unit 203, and a position detecting unit 203.

In the preliminary scanning, the photoelectric conversion signal output from the line sensor 31
The image data is converted into, for example, 8-bit photographing data D1 by 2 and input to the height measuring unit 110 and the line memory 104 in the order of pixel arrangement. The height measuring unit 110 includes a comparator 111
And a counter 112. The comparator 111 compares the input photographing data D1 with thresholds th1 and th2,
The result is notified to the CPU 101 and the counter 112. The counter 112 counts the number of pixels whose luminance exceeds the threshold th1. That is, the height of the document surface S1 is measured. C
The PU 101 takes in the count value of the counter 112 as height data DH, and takes in the pixel positions n3 and n4 detected by the comparator 111 to generate size data DS. Height data DH and size data D
S is stored in the RAM 105. On the other hand, shooting data D
1 is transferred from the line memory 104 to the luminance detecting unit 201 of the CPU 101. The luminance detecting unit 201 creates a luminance histogram by summing the luminance of each pixel for each predetermined line in the sub-scanning direction, and calculates a threshold value for determining the background luminance and the presence or absence of an image. The counting unit 202 counts the number of pixels whose luminance is equal to or less than a threshold based on the luminance histogram. The position detection unit 203 indicates a scanning position on the imaging surface. The CPU 101 extracts an unnecessary image based on three pieces of information of the background luminance, the frequency of the pixel corresponding to the image, and the scanning position, and obtains a first candidate, as shown in FIG.

After the completion of the preliminary scanning, the CPU 10
1 is height data DH in preparation for main scanning.
, A masking range is set based on the second candidate, and details of focus adjustment and image distortion correction are set.

In this scanning, the AD converter 1
02, the photographing data D is sent to the image processing circuit 103. The CPU 101 instructs the image processing circuit 103 to change the pixel value in the masking range. The photographed image GH of the hand H, which is an unnecessary image, is deleted by the masking unit 305 of the image processing circuit 103, and the read image after the deletion is output to the external device. The image processing circuit 103 includes, in addition to the masking, a process of correcting illuminance unevenness on the document surface S1, an MTF correction for improving image quality, a scaling process including a correction of image distortion caused by the curvature of the document surface S1, and a density. Make corrections.

It should be noted that the CPU 101 is provided with the imaging control circuit 13.
0, and also controls a drive system including the sub-scanning mechanism 131, the AF mechanism 132, and the lamp control unit 140, and gives a predetermined instruction (operation instruction) to each control target. CPU 101
Is connected to an operation panel OP and various switches.

FIG. 12 is a flowchart showing the general operation of the book scanner 1. Start key 52 (or 5
Preliminary scanning is executed in response to turning on of (3) (# 1, # 2). In the preliminary scanning, the document surface S1
And the imaging of the end face S3 are performed simultaneously. After the completion of the preliminary scanning, the second position detection is performed based on the photographing information of the end face S3 (# 3). The function of the CPU 101 executing the step # 3 corresponds to the second detecting means of the present invention. If there is no second candidate in the second position detection, it means that the user has not pressed the document, and in this case, masking within the effective reading range corresponding to the document size is unnecessary (no finger image). A determination is made (# 4, # 5).

When the second candidate is detected in the second position detection, the first position is detected based on the photographing information of the document surface S1 (# 7). CPU 10 executing step # 7
The first function corresponds to the second detecting means of the present invention. If the first candidate is detected in the first position detection (# 8), it is checked whether there is a first candidate that matches the second candidate (#
9). If they match, the first candidate is determined as a position to be erased, and a masking range is set (# 10). When there is no first candidate despite the presence of the second candidate (No in # 8), and when there is no first candidate that matches the second candidate (#
In the case of (No at 9), there is a possibility that the document image is partially hidden by the hand H as in the example of FIG. 8, so an error process is performed to notify the user of this fact by display or the like (# 11). At this time, measures such as changing the position of the user or the hand H and instructing to start again may be taken.

If it does not correspond to the error processing, the main scanning is performed (# 6). In the main scanning, masking is performed in a range set in the preparation stage. When it is determined in step # 5 that "there is no finger image", the masking unit 305 of the image processing circuit 103 is set to the through state.

According to the above-described embodiment, the projection plate 18 is provided so that the imaging unit 30 is also used for photographing the original surface S1 and the end surface S3. Therefore, the configuration is simplified and the height measurement is made more accurate. Can be achieved. However, the present invention is not limited to such a configuration. In addition to the imaging unit 30, an optical system and an imaging device for imaging the end face S3 may be incorporated.

[0045]

According to the first aspect of the present invention, when the user holds down the document by hand, the image correction function for selectively erasing the pressed hand image, which is an unnecessary image among the read images, is provided. The image reading apparatus can improve the reliability of the image reading apparatus, can provide a good appearance of the read image, and can easily fix the spread original.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a movable function of a document table.

FIG. 3 is a schematic diagram of reading by a book scanner.

FIG. 4 is a diagram for explaining a method of measuring a curved state of a document surface.

FIG. 5 is a plan view illustrating an example of reading a book document.

FIG. 6 is a schematic diagram illustrating an outline of extraction of an unnecessary image.

FIG. 7 is a diagram showing a procedure for determining a block group.

FIG. 8 is a diagram showing a read image corresponding to another example of reading.

FIG. 9 is a diagram illustrating a procedure of a second position detection.

FIG. 10 is a diagram illustrating an error of a second candidate.

FIG. 11 is a block diagram of a signal processing system of the book scanner.

FIG. 12 is a flowchart illustrating a schematic operation of the book scanner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Book scanner (image reading apparatus) 18 Projection board (component of the imaging means of an end face) 20 Original table 30 Imaging unit (component of the imaging means of an end face) 31 Photoelectric conversion device 80 Space (open space) 101 CPU (image correction) Control means) 305 Masking unit (image correction means) BD Book original (spread original) G0, G0b Read image G1 Top surface image (photographed image of spread surface) G18 Photographed image (photographed image of end face) H Hand (object) M2 Sub-scan Direction (left-right direction) OS Optical system S1 Original surface (read target surface) S3 End surface

Claims (1)

[Claims] An open space for setting a document between the platen and the optical system, comprising: a platen; a photoelectric conversion device; and an optical system for projecting a document image onto the photoelectric conversion device. An image reading apparatus having a structure including: a photographing means for photographing an end face in a direction orthogonal to the left-right direction of a spread document placed in a state of being spread right and left on the document table; and reading the spread document. A first detection unit that detects an object on the spread surface based on a captured image of the spread surface that is the target surface; and a second detection unit that detects an object on the spread surface based on the captured image of the end surface. Detecting means; image correcting means for partially erasing a read image obtained by reading a document image; and both of the first and second detecting means of the read image of the spread document with respect to the image correcting means. Thus the image reading apparatus characterized by having an image modification control means for erasing a portion corresponding to the detected object, the.