JP2014072691A - Image reading apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a mounting direction of a book original in an image reading apparatus which reads the book original.SOLUTION: A multifunction machine with an image reading apparatus, includes a platen glass and a reading unit, which reads a book original mounted on the platen glass in a spread state by the reading unit (S6 and S18), obtains gradation value distribution in a main scanning direction or a sub-scanning direction by analyzing the obtained pre-scanned image (S8 and S20), detects whether a predetermined valley shape is present in the obtained gradation value distribution (S10 and S22), and identifies a mounting direction of the book original if there is the valley shape, on the basis of the direction of gradation value distribution in which the valley shape is detected.

Description

  The invention disclosed in this specification relates to an image reading apparatus that reads a book document.

  Conventionally, an image reading apparatus that reads a book document such as a book document is known (for example, Patent Document 1). In this image reading apparatus, a book document is read in the scanning direction, and the direction in which the character strings in the book document are arranged is detected from a luminance histogram of one line of image data read in the scanning direction. When the character strings in the book document are aligned in a direction parallel to the scan direction, it is determined that the book document is vertically written, and when the book document is aligned in a direction orthogonal to the scan direction, the book document is A technique for discriminating that the writing is horizontal writing is disclosed.

JP-A-9-200501

  When a book document is read by the image reading device, it is often unclear how the book document is placed with respect to the image reading device. Hereinafter, the placement direction in which the binding portion at the center of the book document is parallel to the main scanning direction that is the scanning direction is referred to as vertical placement, and the placement direction in which the binding portion is orthogonal to the main scanning direction is referred to as horizontal placement. . In this case, even if it is detected that the character strings in the book document are aligned in a direction parallel to the main scanning direction using the conventional technique, if the book document is placed vertically, the book document Is vertically written, and when the book document is placed horizontally, the book document is written horizontally. That is, in order to detect whether a book document is vertically written or horizontally written, it is first necessary to detect the orientation of the book document.

  The orientation of the book document is also required when rotating the read image obtained by reading the book document or when printing the read image. Thus, a technique for detecting the orientation of a book document is desired. However, the prior art does not disclose an effective technique for detecting the orientation of the book document.

  The present specification discloses a technique for detecting the orientation of a book document in an image reading apparatus that reads the book document.

  An image reading device disclosed in this specification includes a document placement table, a reading unit that reads in the main scanning direction of the document placement table, a drive unit that moves the reading unit in the sub-scanning direction of the document placement table, A control unit, wherein the control unit uses the reading unit to move the reading unit in the sub-scanning direction while moving the reading unit in the sub-scanning direction. Reading process for reading in the main scanning direction, and a main scanning strip area whose long side extends along the main scanning direction and extends over the entire area in the main scanning direction of the read image read by the reading process At least one of the density distribution in the main scanning direction, or the density distribution in the sub-scanning direction of the sub-scanning strip region of which the long side extends along the sub-scanning direction and extends over the entire area of the read image in the sub-scanning direction. The acquisition process for acquiring the degree distribution, the concentration distribution acquired by the acquisition process, the decrease distribution in which the concentration decrease continues over the reference distance and the increase distribution in which the concentration increase continues over the reference distance are continuous. In the case where there is a valley that occurs, the book document binding portion is placed along a direction orthogonal to the direction of the long side of the strip region where the density distribution in which the valley exists is acquired. A determination process for determining that the book document is placed on the document placement table;

  In this image reading apparatus, the density distribution in the main scanning direction or the sub-scanning direction is acquired from the read image obtained by reading the book document placed on the document table, and the booklet is obtained when a predetermined valley exists in the density distribution. The direction along which the binding portion of the document is along is specified. In the book manuscript, the direction along which the binding portion extends is specified, so that the orientation of the book manuscript is uniquely specified. Therefore, the orientation of the book document can be detected from the read image.

  In the image reading apparatus, the control unit acquires a density distribution in the main scanning direction of the main scanning strip region in the acquisition process, and the valley exists in the density distribution in the determination process. In this case, a configuration may be adopted in which it is determined that the binding portion of the book document is placed along the sub-scanning direction.

  According to this image reading apparatus, it can be determined that the binding portion of the book document is placed along the sub-scanning direction.

  In the image reading apparatus, the control unit acquires the density distribution in the sub-scanning direction of the sub-scanning strip region in the acquisition process, and the valley exists in the density distribution in the determination process. In this case, it may be configured that it is determined that the binding portion of the book document is placed along the main scanning direction.

  According to this image reading apparatus, it can be determined that the binding portion of the book document is placed along the main scanning direction.

  In the image reading apparatus, when the control unit determines that the binding portion of the book document is placed along the main scanning direction in the determination process, the control unit further reads the read image by 90. It is also possible to perform a rotation process in which the read image is maintained without being rotated when it is determined that the binding portion of the book document is placed along the sub-scanning direction.

  According to this image reading apparatus, since the placement direction of the book document is determined from the read image, it is possible to execute an appropriate rotation process on the read image using the placement direction.

  In the image reading apparatus, the control unit divides the strip area into a plurality of blocks in at least the long side direction of the strip area and calculates a density value for each block in the acquisition process. A density distribution is acquired, and in the determination process, a decrease distribution in which the density decrease continues over the adjacent blocks of the reference number corresponding to the reference distance, and an increase in density over the adjacent blocks of the reference number. It is good also as a structure which judges that the said trough exists when the continuous ascent distribution generate | occur | produces continuously.

  According to this image reading apparatus, by dividing the strip region into a plurality of blocks, it is easy to determine whether or not a valley exists in the density distribution, and it is easy to specify the direction along which the binding portion of the book document is along.

  In the image reading apparatus, the control unit may further include, in the determination process, the decrease distribution and the increase from one end point in the long side direction of the strip region where the density distribution in which the valley exists is acquired. A configuration may be adopted in which an estimation process for estimating twice the distance to the boundary point with the distribution as the document width of the book document is executed.

  According to this image reading apparatus, it is possible to estimate the document width of the book document using the valley of the density distribution acquired from the read image.

  In the image reading apparatus, the document placing table has a rectangular shape as viewed from the placement surface on which the book document is placed, and one vertex is set as an origin, and the book document is May be placed with the origin as a reference, and the strip area may be set on the edge side of the read image including a reference point corresponding to the origin in the read image.

  According to this image reading apparatus, it is easy to obtain a density distribution using a preset main scanning strip region or sub-scanning strip region.

  According to the present specification, in the image reading apparatus that reads a book document, the orientation of the book document can be detected.

Schematic cross-sectional view of the MFP in the main scanning direction Block diagram schematically showing the electrical configuration of the MFP Flow chart showing image reading process Schematic top view of platen glass when a book document is placed horizontally Gradation value distribution in the main scanning direction of the first pre-scan image PG1 Book document binding direction and document width in main scanning direction Schematic top view of platen glass when a book document is placed vertically Tone value distribution in the sub-scanning direction of the analysis image KG Book document binding direction and document width in the sub-scanning direction

<Embodiment>
One embodiment will be described with reference to FIGS.

1. FIG. 1 is a cross-sectional view of a multifunction machine 10 according to the present embodiment in the main scanning direction. The multifunction machine 10 is a multifunction peripheral device having a printer function, a scanner function, a copy function, a facsimile function, and the like, and is an example of an image reading apparatus.

  As shown in FIG. 1, the multifunction machine 10 includes a platen glass 12 for placing a document G on the upper surface of the main body 11, a reading unit 30, and a drive shaft 42. A document cover 15 that covers the platen glass 12 is provided. The platen glass 12 is an example of a document placement table.

  The platen glass 12 is a transparent rectangular glass plate disposed horizontally on the upper surface of the main body 11 (see FIGS. 4 and 7), and is supported by a frame body 13 disposed on the outer periphery. 4 and 7, the platen glass 12 is arranged with its short side along the front-rear direction of the main body 11, and the long side of the platen glass 12. Arranged along the left-right direction of the main body 11. Further, one vertex of the placement surface 12A of the platen glass 12 is set to the origin P, and the original G is placed on the basis of the origin P when placed on the placement surface 12A of the platen glass 12. Placed.

  The reading unit 30 is disposed below the platen glass 12 in the main body unit 11 and includes an image sensor such as a CIS (Contact Image Sensor) or a CCD (Charge Coupled Device). The reading unit 30 is formed so as to extend in the short side direction of the platen glass 12, and a plurality of reading elements are arranged in the direction on the upper surface facing the platen glass 12. The reading unit 30 reads the document G placed on the platen glass 12 in the short side direction of the platen glass 12. Specifically, the reading unit 30 irradiates the original G placed on the platen glass 12 with light, reads the reflected light using each reading element, and generates read data of the original G. The short side direction of the platen glass 12 is an example of the main scanning direction, and the long side direction of the platen glass 12 is an example of the sub-scanning direction.

  The drive shaft 42 is an axis that moves the reading unit 30 in the long side direction of the platen glass 12, and the driving unit 40 (see FIG. 2) moves the reading unit 30 along the drive shaft 42, that is, in the sub-scanning direction. Move.

  The document cover 15 is attached so as to be openable and closable via a rotating shaft 16 provided at the rear of the upper surface of the main body 11. In a state where the document cover 15 is opened (see the solid line in FIG. 1), the placement surface 12A of the platen glass 12 is opened, and the user can place the document G on the placement surface 12A. When the document cover 15 is closed (see the two-dot chain line in FIG. 1), the document cover 15 covers the placement surface 12A and the document G placed on the placement surface 12A from above, and the document G is covered with the platen glass 12. Press against.

  The multifunction device 10 further includes various buttons, a touch panel, and the like, an operation unit 17 that receives an operation input from a user, a display, a lamp, and the like, and a display unit 18 that displays the state of the multifunction device 10. Yes.

2. Next, the electrical structure of the multifunction machine 10 will be described. As shown in FIG. 2, the multifunction machine 10 includes a central processing unit (hereinafter referred to as CPU) 20, ROM 26, RAM 27, reading unit 30, analog front end (hereinafter referred to as AFE) 22, image processing unit 24, and driving unit 40. The operation unit 17, the display unit 18, and the like are connected to these via a bus 29. As shown by a dotted line 21 in FIG. 2, the one including the CPU 20, the ROM 26, and the RAM 27 is an example of the control unit.

  The ROM 26 stores a program for executing various operations of the multifunction machine 10 such as an image reading process to be described later. The CPU 20 controls each unit according to the program read from the ROM 26.

  The reading unit 30 reads a document G placed on the platen glass 12 in the main scanning direction based on a command from the CPU 20 and moves it in the sub-scanning direction by the driving unit 40 while moving the document G on a predetermined reading range YH ( Reading is repeated over a range of times (see FIGS. 4 and 7). Accordingly, when the reading unit 30 acquires a read image configured by arranging a plurality of read data in the main scanning direction and the sub-scanning direction, the reading unit 30 outputs the read image to the AFE 22.

  The AFE 22 is connected to the reading unit 30, and converts read data that is an analog signal output from the reading unit 30 into gradation data that is a digital signal based on a command from the CPU 20. The AFE 22 stores the converted gradation data in the RAM 27 via the bus 29. As a result, a read image configured by arranging a plurality of gradation data in the main scanning direction and the sub-scanning direction is stored in the RAM 27.

  The image processing unit 24 performs edge extraction processing such as binarization processing on the gradation data stored in the RAM 27 based on a command from the CPU 20. Further, the image processing unit 24 obtains a density distribution in the main scanning direction or the sub-scanning direction from the gradation data stored in the RAM 27 based on a command from the CPU 20, and a predetermined decrease distribution or increase in the density distribution. Processing for determining whether or not a distribution exists, processing for rotating a read image stored in the RAM 27, and the like are executed.

  The drive unit 40 is connected to the motor M and transmits a pulse signal to the motor M based on a command from the CPU 20. The motor M is driven to rotate by one rotation angle with one pulse of the pulse signal. When the motor M is driven by one step, the reading unit 30 moves along the drive shaft 42 by a predetermined distance. When reading the document G, the CPU 20 transmits a prescribed number of pulse signals per second using the driving unit 40 and causes the reading unit 30 to read the document G at a reading speed corresponding to the prescribed number, thereby driving the driving unit 40. The document G is read in the main scanning direction by using the reading unit 30 while moving the reading unit 30 in the sub-scanning direction by using.

3. Image Reading Process Next, an image reading process for the original G in the multifunction machine 10 will be described with reference to FIGS. 3 to 9. In the present embodiment, a book document G such as a book is placed on the placement surface 12A of the platen glass 12 in a spread state (hereinafter, on the platen glass 12), and an image of a pair of spread pages of the book document G is read. Will be described.

  Since the book document G is generally constituted by binding a plurality of sheets, when the book document G is placed on the platen glass 12 in a spread state as shown in FIG. A central portion Z of the page floats from the platen glass 12. Hereinafter, the central portion Z of the book document G is referred to as a binding portion Z.

  Therefore, when the book original G is placed on the platen glass 12 and read, the binding portion Z of the book original G floating from the platen glass 12 is not easily irradiated with light from the reading unit 30 and corresponds to the binding portion Z. The intensity of the reflected light read by the reading element is weakened (see FIGS. 5A and 8A). Hereinafter, the low gradation range appearing in the read image corresponding to the binding portion Z is referred to as a valley T. The detailed definition of the valley T will be specifically described later.

  In the image reading process of the present embodiment, the book original G is read and the valley T is detected from the acquired read image, whereby the book original G is placed vertically with the binding portion Z arranged in the main scanning direction ( 7) or whether the binding portion Z is placed horizontally (see FIG. 4) arranged along the sub-scanning direction. In the present embodiment, when the book document G is placed on the platen glass 12, the book document G is placed so that the top of the book document G is on the origin P side of the platen glass 12.

  FIG. 3 shows a flowchart of an image reading process executed by the CPU 20 according to a predetermined program. The CPU 20 starts processing when the user places a book document G on the platen glass 12 and inputs an instruction to read the book document G from the user via the operation unit 17.

  When starting the image reading process, the CPU 20 confirms whether or not a book scan is selected according to the input reading instruction (S2). When the book scan is not selected by the reading instruction (S2: NO), the CPU 20 executes the sheet scan process (S4) on the book original G.

  In the sheet scanning process, the CPU 20 pre-scans the book document G in the same manner as when the sheet document G is placed on the platen glass 12. That is, the CPU 20 sets the entire range corresponding to the platen glass 12 as a pre-scan range, and performs reading over the pre-scan range. The CPU 20 specifies an area where the book document G is placed on the platen glass 12 using a known edge extraction process from the result of reading the prescan range.

  Further, when the book scan is selected in the reading instruction (S2: YES), the CPU 20 executes the book scan process on the book original G (S6 to S30). In the book scan process, the CPU 20 first pre-scans the front end of the document (S6). The CPU 20 sets a range of the reference width KW from the end of the tip where the origin P exists in the sub-scanning direction in the range corresponding to the platen glass 12 to the first pre-scan range PH1 (see the dotted line in FIG. 4). Reading is performed over one prescan range PH1.

  The CPU 20 identifies an area (corresponding to the one-dot chain line in FIG. 4) on which the book document G is placed using a known edge extraction process from the result of reading the first pre-scan range PH1. A first pre-scan image PG1 that is a read image is acquired. The first pre-scan image PG1 is an example of a read image, and is an example of a read image in a main scanning strip area.

  As shown in FIGS. 5A and 5C, the first pre-scan image PG1 has a strip shape, and its long side extends along the main scanning direction. Further, the first pre-scan image PG1 has a long side extending over the entire region in the main scanning direction of the region where the book document G is placed on the platen glass 12 (see FIG. 4). The CPU 20 analyzes the acquired first prescan image PG1 and acquires the gradation value distribution in the main scanning direction (S8). The gradation value distribution is an example of a density distribution.

  Specifically, the CPU 20 divides the first prescan image PG1 into a plurality of blocks in the main scanning direction, and sums the gradation values of the read data included in each block. Thereby, the CPU 20 acquires a gradation value distribution in the main scanning direction in which the total gradation values for each block are arranged in correspondence with each block (see FIGS. 5B and 5D).

  Next, the CPU 20 detects whether a valley T exists in the gradation value distribution in the main scanning direction (S10). In the gradation value distribution, the CPU 20 has a decreasing distribution GB in which the total gradation value decreases over a specified number of adjacent blocks, and a rising distribution ZB in which the total gradation value increases over a specified number of adjacent blocks. When it occurs continuously, it is detected that a valley T exists in the gradation value distribution. The reference number is an example of a reference distance.

  As shown in FIG. 5B, when the valley T is present in the gradation value distribution in the main scanning direction (S10: YES), the CPU 20 performs sub-scanning in which the binding portion Z of the book document G is orthogonal to the main scanning direction. It is determined that they are arranged along the direction (see FIG. 6), that is, it is determined that the book document G is placed horizontally (S12). In this case, the CPU 20 detects the center position of the valley T, that is, the boundary point V1 between the decreasing distribution GB and the rising distribution ZB, and calculates the distance W1 from one end point in the main scanning direction. Specifically, in the first prescan image PG1, a distance W1 in the main scanning direction between the reference point Q obtained by reading the origin P of the platen glass 12 and the boundary point V1 is calculated.

  Then, as shown in FIG. 6, the CPU 20 obtains a distance obtained by doubling the calculated distance W1, and estimates the distance as the document width GW in the main scanning direction of the horizontally placed book document G (S14). Further, the CPU 20 assumes that the book document G is a standard size document such as A6 size or B5 size, and estimates the document length GL in the sub-scanning direction corresponding to the estimated document width GW (S16).

  On the other hand, as shown in FIG. 5D, when the valley T does not exist in the gradation value distribution in the main scanning direction (S10: NO), the CPU 20 pre-scans the entire document (S18). The CPU 20 sets the entire range corresponding to the platen glass 12 to the second prescan range PH2 (see the dotted line in FIG. 7), and performs reading over the second prescan range PH2.

  The CPU 20 identifies a region where the book document G is placed using a known edge extraction process from the result of reading the second pre-scan range PH2, and the second pre-scan that is a read image of the identified region. An image PG2 is acquired. The second pre-scan image PG2 is another example of the read image.

  Next, the CPU 20 analyzes the acquired second pre-scan image PG2 (S20). The CPU 20 sets an analysis image KG used for analysis from the second pre-scan image PG2. The CPU 20 sets, as the analysis image KG, an image of the region of the reference width KW from the end of the reference end where the reference point Q exists in the main scanning direction (corresponding to the one-dot chain line in FIG. 7) in the second pre-scan image PG2. . The analysis image KG is an example of a read image in the sub-scanning strip area.

  As shown in FIGS. 8A and 8C, the analysis image KG has a strip shape, and its long side extends in the sub-scanning direction. In addition, the long side of the analysis image KG extends over the entire area in the sub-scanning direction of the area where the book document G is placed on the platen glass 12 (see FIG. 7). The CPU 20 analyzes the selected analysis image KG and acquires the gradation value distribution in the sub-scanning direction.

  Specifically, the CPU 20 divides the analysis image KG into a plurality of blocks in the sub-scanning direction, and sums the gradation values of the read data included in each block. Thereby, the CPU 20 acquires a gradation value distribution in the sub-scanning direction in which the total gradation values for each block are arranged in correspondence with each block (see FIGS. 8B and 8D).

  Next, the CPU 20 detects whether or not a valley T exists in the gradation value distribution in the sub-scanning direction (S22). As shown in FIG. 8B, when the valley T is present in the gradation value distribution in the sub-scanning direction (S22: YES), the CPU 20 performs main scanning in which the binding portion Z of the book document G is orthogonal to the sub-scanning direction. It is determined that they are arranged along the direction (see FIG. 9), that is, the book document G is placed vertically (S24). In this case, the CPU 20 detects the boundary point V2 of the valley T, and calculates the distance W2 in the sub-scanning direction between the reference point Q and the boundary point V2 in the analysis image KG.

  Then, as shown in FIG. 9, the CPU 20 obtains a distance obtained by doubling the calculated distance W2, and estimates the distance as the document width GW in the sub-scanning direction of the vertically placed book document G (S26). Further, the CPU 20 assumes that the book document G is a standard-size document, and estimates the document length GL in the main scanning direction corresponding to the estimated document width GW (S28).

  On the other hand, as shown in FIG. 8D, when the valley T does not exist in the gradation value distribution in the sub-scanning direction (S22: NO), the CPU 20 does not detect the valley T in the pre-scan image PG, and the book document It is determined that the detection of the mounting direction of G has failed (S30).

  Next, the CPU 20 performs a full scan on the entire document (S32). When the document width GW and the document length GL of the book document G are estimated in the above processing, the CPU 20 sets the range determined by the document width GW and the document length GL from the origin P of the platen glass 12 as the reading range YH. Then, the book original G is read. Further, when the document width GW and the document length GL of the book document G are not estimated in the above processing, the CPU 20 reads the entire range corresponding to the platen glass 12, and the book specified from the read result. The area where the original G is placed is set to the reading range YH, and the book original G is read.

  When the main scan of the entire document is completed, the CPU 20 confirms whether the book document G is placed vertically (S34). When the CPU 20 determines that the book original G is placed vertically in the above process (S34: YES), the CPU 20 rotates the read image acquired in the main scan 90 degrees to the left (S36), and ends the image reading process. To do. On the other hand, if the CPU 20 does not determine that the book original G is placed vertically in the above process (S34: NO), the CPU 20 maintains the read image without rotating it (S38), and ends the image reading process. In the case where “the book document G is not determined to be placed vertically”, the placement direction of the book document G is not detected together with the case where it is determined that the book document G is placed horizontally. Including cases.

4). Advantages of the present embodiment (1) In the multifunction machine 10 of the present embodiment, the gradation value distribution in the main scanning direction or the sub-scanning direction from the pre-scan image PG obtained by pre-scanning the book document G placed on the platen glass 12. When the valley T exists in the gradation value distribution, the direction along the binding portion Z of the book document G is specified, and the placement direction of the book document G is specified.

  Specifically, when the valley T exists in the gradation value distribution in the main scanning direction, it is specified that the binding portion Z of the book document G is arranged along the sub-scanning direction, and the book document G is placed horizontally. To be identified. When the valley T exists in the gradation value distribution in the sub-scanning direction, it is specified that the binding portion Z of the book document G is arranged along the main scanning direction, and the book document G is placed vertically. Identify that. According to the multifunction machine 10, the orientation of the book original G can be specified using a read image such as the pre-scan image PG.

(2) In the multifunction machine 10 of this embodiment, the orientation of the book document G is specified using the read image, and when the book document G is placed vertically, the book orientation G is placed in the same orientation as the pre-scan. The scanned image of the scanned book document G is rotated.

  When the book original G is placed vertically, the orientation of the image described in the book original G, that is, the direction along the binding portion Z of the book original G is parallel to the main scanning direction. In general, when a read image is displayed on the display unit 18 of the multifunction machine 10 or a display unit of a personal computer (hereinafter referred to as a PC) outside the multifunction machine 10, the main scanning direction of the read image is the main scanning direction ( That is, it is displayed so as to be in the horizontal direction. For this reason, if the read image of the book document G placed vertically is displayed on these display units without being rotated, it is difficult for the user to view. According to the multifunction machine 10, the read image of the book original G is appropriately rotated based on the placement direction specified from the read image, so that the user can read the read image on the display unit 18 of the multifunction machine 10 or the PC. Easy to check when checking on the display.

(3) In the MFP 10 of the present embodiment, when acquiring the gradation value distribution in the main scanning direction or the sub-scanning direction from the pre-scan image PG, the strip-shaped first pre-scan image PG1 is displayed in the long side direction. A gradation value distribution in the main scanning direction is obtained by being divided into a plurality of blocks. In addition, the strip-shaped analysis image KG set from the second pre-scan range PH2 is divided into a plurality of blocks in the long side direction to obtain a gradation value distribution in the sub-scan direction. According to the multi function device 10, by dividing a strip-shaped image into a plurality of blocks in the long side direction, it is easy to determine whether or not the valley T exists in the gradation value distribution, and the book original G is bound. It is easy to specify the direction along which the part Z is aligned.

(4) In the MFP 10 of the present embodiment, when the valley T exists in the gradation value distribution in the main scanning direction or the sub-scanning direction, the long side direction of the strip-shaped image from which the gradation value distribution is acquired. Since the document width GW is estimated from the distance W from the end point to the center position of the valley T, that is, the boundary point V, the document width GW can be easily estimated.

(5) In the multifunction machine 10 of the present embodiment, the gradation value distribution in the main scanning direction or the sub-scanning direction is acquired from the first pre-scan image PG1 and the analysis image KG. The first pre-scan image PG1 and the analysis image KG are the end side on the origin P side of the platen glass 12, that is, the end side of the front end in the sub-scanning direction, and the main scan in the area where the book original G is placed. Since this is a read image obtained by reading the range on the edge side of the reference end in the direction, it is easy to specify the read image using the front end or the reference end, and to acquire the gradation value distribution.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and the drawings, and for example, the following various aspects are also included in the technical scope of the present invention.
(1) In the above embodiment, the description has been made using the multifunction machine 10, but the present invention is not limited to this, and other functions such as a printer function, a copy function, and a facsimile function are provided as long as at least a scanner function is provided. May not be provided.

(2) In the above embodiment, the MFP 10 has one CPU 20, and an example in which the control of each unit such as the reading unit 30 and the image processing unit 24 is executed by the one CPU 20 has been described. Is not limited to this. For example, if each unit may be configured by a plurality of CPUs, each unit may be configured only by a hardware circuit such as an ASIC (Application Specific Integrated Circuit). Furthermore, each part may be comprised by one or several CPU and ASIC.

(3) The program executed by the CPU 20 is not necessarily stored in the ROM 26, and may be stored in the CPU 20 itself or in another storage device.

(4) In the above embodiment, the book document G is pre-scanned before the book document G is actually scanned, and the placement direction of the book document G is specified using the pre-scan image PG acquired by the pre-scan. However, the present invention is not limited to this. For example, the placement direction of the book document G may be specified using the read image acquired by the main scan.

(5) In the above-described embodiment, the first pre-scan image PG1 and the analysis image KG from which the gradation value distribution in the main scanning direction or the sub-scanning direction is acquired are the regions on the edge side on the origin P side of the platen glass 12. Although the description has been made using an example of a read image that has been read, the present invention is not limited to this. If it is a read image for acquiring the gradation value distribution in the main scanning direction, it has a strip shape, its long side is along the main scanning direction, and its long side is on the platen glass 12. Any region may be used as long as it extends over the entire region in the main scanning direction of the region where G is placed. Similarly, a read image for obtaining a gradation value distribution in the sub-scanning direction has a strip shape, the long side thereof is along the sub-scanning direction, and the long side is on the platen glass 12. Any area may be used as long as it extends over the entire area in the sub-scanning direction of the area where the book original G is placed.

(6) Furthermore, it is not necessary to have a strip shape. However, since it has a strip shape and the width in the direction in which the gradation value distribution of the read image is not acquired, the processing load for acquiring the gradation value distribution is reduced.

(7) In the above embodiment, when the valley T does not exist in both the main scanning direction and the sub-scanning tone value distribution acquired from the first pre-scan image PG1 and the analysis image KG, the book original G is loaded. Although the description has been made using an example in which it is determined that the detection of the orientation has failed, the present invention is not limited to this. For example, when there is no valley T in both the main scanning direction or the sub-scanning direction gradation value distribution acquired from the first pre-scan image PG1 and the analysis image KG, another image is used to perform the main scanning direction or the sub-scanning direction. You may acquire the gradation value distribution of a scanning direction. The other image referred to here may be an image that has been newly pre-scanned and acquired using the same or different region, or may be set from a pre-scanned image that has already been acquired.

10: MFP, 12: Platen glass, 30: Reading unit, 40: Drive unit, G: Document (book document), PG: Pre-scan image, KG: Analysis image, YG: Scanned image, ZB: Ascent distribution, GB : Decrease distribution, GL: Document length, GW: Document width, T: Valley, V: Boundary point, PH: Pre-scan range, YH: Reading range, Z: Binding portion

Claims (7)

A document table,
A reading unit for reading in the main scanning direction of the document table;
A drive unit for moving the reading unit in the sub-scanning direction of the document table;
A control unit;
With
The controller is
A reading process for reading a book document placed on the document table in the main scanning direction using the reading unit while moving the reading unit in the sub-scanning direction using the driving unit;
Of the read image read by the reading process, the density distribution in the main scanning direction of the main scanning strip region where the long side extends along the main scanning direction and extends over the entire region of the main scanning direction, or An acquisition process for acquiring at least one density distribution in the sub-scanning direction of the sub-scanning strip region of which the long side extends along the sub-scanning direction and extends over the entire area of the read image in the sub-scanning direction;
When the concentration distribution acquired by the acquisition process includes a valley in which a decreasing distribution in which the concentration decrease continues over a reference distance and a rising distribution in which the concentration increase continues over the reference distance continuously occur In addition, the book document is placed on the document placement table so that the binding portion of the book document is placed along a direction orthogonal to the direction of the long side of the strip region where the density distribution in which the valleys exist is acquired. A determination process for determining that
An image reading apparatus that executes The image reading apparatus according to claim 1,
The controller is
In the acquisition process, a density distribution in the main scanning direction of the main scanning strip region is acquired;
In the determination process, the image reading apparatus determines that the binding portion of the book document is placed along the sub-scanning direction when the valley exists in the density distribution. The image reading apparatus according to claim 1,
The controller is
In the acquisition process, a density distribution in the sub-scanning direction of the sub-scanning strip region is acquired;
In the determination process, the image reading apparatus determines that the binding portion of the book document is placed along the main scanning direction when the valley exists in the density distribution. The image reading apparatus according to claim 2, wherein:
The controller is
Furthermore,
In the determination process, when it is determined that the binding portion of the book document is placed along the main scanning direction, the read image is rotated by 90 degrees, and the binding portion of the book document is moved in the sub-scanning direction. An image reading apparatus that executes a rotation process to maintain the read image without rotating when it is determined that the image is placed along the image. An image reading apparatus according to any one of claims 1 to 4,
The controller is
In the acquisition process, the strip region is divided into a plurality of blocks at least in the direction of the long side of the strip region, a density value is calculated for each block, and a density distribution is acquired.
In the determination process, a decreasing distribution in which the density decrease continues over the adjacent blocks of the reference number corresponding to the reference distance and a rising distribution in which the density increase continues over the adjacent blocks of the reference number are continuous. An image reading device that determines that the valley exists. An image reading apparatus according to any one of claims 1 to 5,
The controller is
Furthermore,
In the determination process, the book original is set to twice the distance from one end point in the direction of the long side of the strip area where the density distribution in which the valley exists is obtained to the boundary point between the decreasing distribution and the rising distribution. An image reading process for executing an estimation process for estimating the document width of the document. An image reading apparatus according to any one of claims 1 to 6,
The document placing table has a rectangular shape as viewed from the placement surface on which the book document is placed, and one vertex thereof is set as the origin,
The book document is placed with the origin as a reference,
The image reading apparatus, wherein the strip region is set on an end side of the read image including a reference point corresponding to the origin in the read image.

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