Image reading device and image reading method

Abstract

To suitably correct a ground color.SOLUTION: A compound machine (1) comprises a reading unit (33), a RAM (23), and a CPU (21). When a margin being the length from the tip of a reading glass (32) to a reading start position is less than a specific value, the CPU does not correct the ground color of read image data and stores it in the RAM. When the margin is the specific value or more, the CPU corrects the ground color of the read image data and stores the image data subjected to the ground color correction, in the RAM.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an image reading device and an image reading method. [Background technology]

[0002] There is known an image reading device that reads an original document, such as characters, pictures, and photographs, and converts it into digital image data. In this type of image reading device, when the original document is not white paper but colored paper with a background color, a background color correction process is performed on the image data to remove the influence of the background color.

[0003] For example, the image reading device of Patent Document 1 first reads pixel values ​​for one line from the leading edge of a document while taking into account the margins set by the user, and calculates a background color correction value using the pixel values. After that, the image reading device of Patent Document 1 reads the remaining area on the other end side of the document from the area of ​​the one line, and corrects the pixel values ​​of the read area using the previously calculated background color correction value. This allows the image reading device of Patent Document 1 to reduce the time required to read a document. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-148050 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the image reading device of Patent Document 1, when the very leading edge of a document is read with no margins set, there is a risk of reading an area outside the document, an edge, a shadow, etc. When an area outside the document is read, if pixel values ​​of a one-line area from the leading edge of the document are used, the pixel values ​​are from an area outside the document, etc., so there is a problem that the background color of the document cannot be correctly recognized.

[0006] An object of one aspect of the present invention is to appropriately perform background color correction. [Means for solving the problem]

[0007] In order to achieve the above object, the image reading device of the present invention includes an image reading unit that reads image data from a document, a storage unit that stores the read image data, and a control unit. When a margin, which is a length from the end of a readable area to a reading start position, is less than a predetermined value, the control unit stores the read image data in the storage unit without performing background color correction on the read image data, and when the margin is equal to or greater than the predetermined value, the control unit performs background color correction on the read image data and stores the background color corrected image data in the storage unit.

[0008] If the margin is less than a predetermined value, there is a possibility that the background color will be erroneously recognized due to errors in the mechanical system, the way the document is placed, during transport, etc. According to the above, since background color correction is not performed when the margin is less than a predetermined value, it is possible to prevent background color correction from being performed on image data that has been read using a background color that may have been erroneously recognized. Therefore, according to the above, background color correction can be performed appropriately.

[0009] In addition, the image reading device may be configured so that the control unit corrects the tilt of the read image data, and when the margin is less than the specified value and the result of correcting the tilt of the read image data is normal, the control unit corrects the background color of the tilt-corrected image data and stores the background-color-corrected image data in the memory unit.

[0010] Even if the margin is less than a predetermined value, the inclination correction is normally performed, so that the leading edge of the read image data is in the original document state, and therefore the background color can be correctly corrected.

[0011] In addition, the image reading device may be configured such that, when an inclination angle of the read image data with respect to a reference direction is equal to or smaller than a predetermined angle, the control unit corrects the inclination of the read image data.

[0012] By limiting the tilt of image data to be subjected to tilt correction, excessively tilted image data is excluded from the target of tilt correction, which has the effect of enabling accurate tilt correction.

[0013] The image reading device may be configured so that, when a density value of the background color at the reading start position in the read image data is equal to or greater than a reference value, the control unit performs background color correction on the read image data.

[0014] By limiting the density value of the background color of the image data to be subjected to background color correction, background colors with high density are excluded from the target of background color correction, so that the background color can be corrected correctly.

[0015] In the image reading device, the control unit may store, in the storage unit, an average value of values ​​of image data read at the reading start position as a density value of the background color.

[0016] Since the density value of the background color is determined by the average value of the image data values ​​at the reading start position, the density value of the background color can be obtained at an early stage of image reading, and background color correction can be performed for each line of read image data.

[0017] In addition, in the image reading device, the control unit may be configured not to perform background color correction on the read image data when the mode of the image reading unit is not suitable for background color correction.

[0018] Since it is determined whether or not to perform background color correction depending on the mode of the image reading unit, it is possible to prevent image data that is not suitable for background color correction from being subjected to background color correction.

[0019] Furthermore, the image reading method of the present invention is an image reading method that reads image data from a document and stores the read image data in a memory unit, and includes a step of determining whether a margin, which is the length from the tip of a readable area to a reading start position, is less than a predetermined value, a step of storing the read image data in the memory unit without performing background color correction on the read image data if it is determined that the margin is less than the predetermined value, and a step of performing background color correction on the read image data and storing the background color corrected image data in the memory unit if it is determined that the margin is equal to or greater than the predetermined value.

[0020] According to the above, when the margin is less than a predetermined value, background color correction is not performed, and as a result, it is possible to prevent background color correction of the read image data using a background color that may be erroneously recognized due to an error in the mechanical system, the way the document is placed, or during transport, etc.

[0021] A control method for implementing the above-mentioned image reading device, a computer program, and a computer-readable recording medium storing the computer program are also novel and useful. Effect of the Invention

[0022] According to one aspect of the present invention, background color correction can be performed appropriately. [Brief description of the drawings]

[0023] [Figure 1] 1 is a block diagram showing a hardware configuration of a multifunction peripheral according to a first embodiment of the present invention. [Diagram 2] 4 is a table showing modes of the scanner 3 according to the first embodiment of the present invention. [Diagram 3] 5A and 5B are diagrams illustrating a relationship between margins and reading of an original according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing a background color correction process according to the first embodiment of the present invention. [Diagram 5] 5 is a flowchart showing an image reading process according to the first embodiment of the present invention. [Figure 6] 5 is a flowchart showing a background color correction flag setting process according to the first embodiment of the present invention. [Figure 7] 5 is a flowchart showing a calculation process of a correction coefficient according to the first embodiment of the present invention. [Figure 8] FIG. 11 is a schematic diagram showing an overview of tilt correction processing according to the second embodiment of the present invention. [Figure 9] 10 is a flowchart showing an outline of determination of background color correction according to the second embodiment of the present invention. [Figure 10] 10 is a flowchart showing an image reading process according to a second embodiment of the present invention. [Figure 11] 10 is a flowchart showing an image reading process according to a second embodiment of the present invention. [Figure 12] 10 is a flowchart showing a background color correction flag setting process according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] [Embodiment 1] Hereinafter, the first embodiment of the present invention will be described in detail with reference to FIGS.

[0025] (Configuration of Multifunction Device 1) Fig. 1 is a block diagram showing the hardware configuration of a multifunction device 1 according to this embodiment. The multifunction device 1 is an example of an image reading device. As shown in Fig. 1, the multifunction device 1 includes a printer 2, a scanner 3, a CPU 21, a ROM 22, a RAM 23, an EEPROM (registered trademark) 24, and an ASIC 26, which are connected to each other via a bus line 25.

[0026] The printer 2 records an image on a recording sheet based on image data read by the scanner 3, image data input from the outside, etc. The scanner 3 reads image data from an original. In detail, the scanner 3 includes a reading unit 33 (see FIG. 3) as an example of an image reading unit. The reading unit 33 is a CIS (Contact Image Sensor) and includes a light source and a light receiving unit. The light source of the reading unit 33 irradiates light onto the original 5 placed on the reading glass 32. The light receiving unit of the reading unit 33 receives light reflected by the original 5 to read the original. The operation panel 4 is for operating the printer 2, the scanner 3, etc. Note that the embodiment of the present invention is applicable to both an FBS (Flat Bed Scanner) and an ADF (Auto Document Feeder).

[0027] The CPU 21, which is an example of a control unit, controls each unit connected via the bus line 25 in accordance with fixed values, programs, and control of each function of the multifunction device 1, which are stored in the ROM 22, RAM 23, etc. The ROM 22 is a non-rewritable memory that stores various control programs executed by the multifunction device 1.

[0028] The RAM 23, which is an example of a storage unit, is a rewritable memory for storing various data. The RAM 23 includes a background color correction value memory 231 and an image memory 232. The background color correction value memory 231 is a memory for storing background color correction values ​​used when performing background color correction on pixel values ​​read by the scanner 3. The image memory 232 is a memory for storing image data read by the scanner 3 from a document.

[0029] When the margin, which is the length from the tip of the reading glass 32 as an example of a readable area to the reading start position, is less than a predetermined value, the CPU 21 does not perform background color correction on the read image data and stores the read image data in the image memory 232 of the RAM 23. When the margin is equal to or greater than the predetermined value, the CPU 21 performs background color correction on the read image data and stores the background color corrected image data in the image memory 232 of the RAM 23. Details will be described later.

[0030] (Scanner 3 mode) 2 is a table showing the modes of the scanner 3 according to this embodiment. The multifunction device 1 determines whether to perform background color correction or not according to the mode of the reading unit 33 of the scanner 3 set by a user operation on the operation panel 4.

[0031] As shown in FIG. 2, in a mode where the "operation" is "scan" and the "reading mode" is "monochrome" or "gray," the multifunction device 1 performs background color correction. In a mode where the "operation" is "copy," the "reading mode" is "monochrome," and the "document type" is "text," the multifunction device 1 performs background color correction. On the other hand, in a mode where the "operation" is "copy," the "reading mode" is "monochrome," and the "document type" is "photo," the multifunction device 1 does not perform background color correction. Furthermore, in a mode where the "operation" is "fax" and the "reading mode" is "monochrome," the multifunction device 1 performs background color correction.

[0032] (Margin M and reading manuscript 5) 3 is a diagram showing the relationship between the margin M according to this embodiment and the reading of the original 5. The scanner 3 includes a black-and-white tape 31, a reading glass 32, and a reading unit 33. The black-and-white tape 31 is made up of a white portion and a black portion. The black-and-white tape 31 has a black-and-white boundary position P1, which is a portion where the color changes from white to black in the scanning direction of the reading unit 33, that is, from the top to the bottom of the figure. The reading glass 32 is a transparent glass on whose top surface the original 5 is placed and with which the reading surface of the original 5 comes into contact.

[0033] The reading unit 33 reads image data from the original 5. The reading unit 33 reads the reading surface of the original 5 that is in contact with the upper surface of the reading glass 32 while moving along the lower surface of the reading glass 32. The CPU 21 determines the distance from the black-and-white boundary position P1 of the black-and-white tape 31 to the reading start position according to the margin M set by the user. The margin M is the length from the tip of the reading glass 32 to the reading start position, and is also called the margin. Then, the reading unit 33 starts reading the image data from the original 5 from a position moved by the said distance from the black-and-white boundary position P1 as the reading start position.

[0034] 3, for example, when the margin M is 0 mm, the reading start position is P2, that is, the leading edge of the reading glass 32. In that case, the reading end position is the rear end of the document 5, and as a result, the length of the reading range RR2 in the sub-scanning direction coincides with the length L of the document 5 in the sub-scanning direction. On the other hand, when the margin M is 3 mm, the reading start position is P3, that is, 3 mm behind the leading edge of the reading glass 32. In that case, the reading end position is 3 mm short of the rear end of the document 5, and as a result, the length of the reading range RR3 in the sub-scanning direction is the length L of the document 5 minus 6 mm.

[0035] (Background color correction) 4 is a diagram showing the processing of background color correction according to the present embodiment. The CPU 21 determines whether or not to perform background color correction on the read image data RD according to the density value of the background color of one line in the main scanning direction at the reading start position of the reading unit 33 in the image data RD read from the document 5 by the reading unit 33 of the scanner 3.

[0036] 4, the horizontal axis indicates the position of pixels PX for one line in the main scanning direction, and the vertical axis indicates image data RD for the pixels PX. The image data RD is 8-bit (0 to 255) data, and is obtained by AD-converting the values ​​read by the reading unit 33 on the original 5. The image data RD indicates that the smaller the value, the higher the density, and that the larger the value, the lower the density.

[0037] 4, V1 is the background color density value when the image data RD is (1). The background color density value V1 is the average value of the values ​​of the image data RD.

[0038] When the background color density value V1 for one line in the main scanning direction is smaller than the threshold value TH, which is a reference value, the CPU 21 does not perform background color correction on the read image data RD.

[0039] On the other hand, V2 in Fig. 4 is the background color density value when the image data RD is (2). The background color density value V2 is an average value of the values ​​of the image data RD. When the background color density value V2 of one line in the main scanning direction is equal to or greater than the threshold value TH, the CPU 21 performs background color correction on the read image data RD. At that time, the CPU 21 calculates a correction coefficient from the background color density value V2, and then uses the correction coefficient to perform background color correction on the remaining area of ​​the image data RD.

[0040] (Image reading processing) 5 to 7 are flow charts showing the processing of the multifunction device 1 according to this embodiment. Fig. 5 shows image reading processing by the CPU 21. The following will explain the process in the order of step numbers.

[0041] (Step S501) First, the CPU 21 sets the background color correction flag F to true or false. Specifically, the CPU 21 sets the background color correction flag F to a value of 1 as true, or to a value of 0 as false. Then, the CPU 21 stores the value of 1 or 0 of the background color correction flag F in the RAM 23. The background color correction flag F set to true indicates that background color correction is performed, and set to false indicates that background color correction is not performed. The background color correction flag F is referred to by the CPU 21 in steps S506 and S508. Details of the setting will be described separately with reference to FIG. 6.

[0042] (Step S502) Next, the CPU 21 sets the reading start position. In detail, as shown in Fig. 3, the CPU 21 sets the reading start position to a value obtained by adding a margin M set by a user operation on the operation panel 4 to the length from the black / white boundary position P1 to the tip of the reading glass 32.

[0043] (Step S503) Next, CPU 21 causes scanner 3 to move reading unit 33 or transport original 5. That is, when the image reading mechanism is FBS, CPU 21 instructs scanner 3 to start moving reading unit 33. On the other hand, when the image reading mechanism is ADF, CPU 21 instructs scanner 3 to start transporting original 5. As a result, scanner 3 starts moving reading unit 33 or transporting original 5.

[0044] (Step S504) The CPU 21 determines whether or not a notification has been received from the scanner 3 that the reading unit 33 or the document 5 has reached the reading start position. If the notification has been received (YES in step S504), the CPU 21 executes the process of step S505. On the other hand, if the notification has not been received (NO in step S504), the CPU 21 repeats the determination in step S504.

[0045] (Step S505) The CPU 21 instructs the scanner 3 to start reading the image data. As a result, the scanner 3 starts reading the image data. Note that the processes of steps S506 to S510 are performed for each line of the image data read by the scanner 3.

[0046] (Step S506) CPU 21 determines whether the image data read by scanner 3 is the first line and the background color correction flag F is true. If the image data is the first line and the background color correction flag F is true (YES in step S506), CPU 21 executes the process of step S507. On the other hand, if the above does not apply, that is, if the read image data is not the first line or the background color correction flag F is false (NO in step S506), CPU 21 executes the determination of step S508. Note that the read image data is not the first line means that it is the second line or later.

[0047] (Step S507) The CPU 21 calculates the correction coefficient AC, and stores the correction coefficient AC in the RAM 23. Details of the calculation will be described separately with reference to FIG.

[0048] (Step S508) The CPU 21 determines whether the background color correction flag F is true. If the background color correction flag F is true (YES in step S508), the CPU 21 executes the process of step S509. If the background color correction flag F is not true, that is, false (NO in step S508), the CPU 21 executes the process of step S510.

[0049] (Step S509) The CPU 21 performs background color correction on the read image data using the correction coefficient AC, and stores the background color corrected image data in the image memory 232 of the RAM 23.

[0050] (Step S510) The CPU 21 stores the read image data as it is in the image memory 232 of the RAM 23 without performing background color correction.

[0051] (Step S511) The CPU 21 determines whether or not the reading of the image data is completed. If the reading is completed (YES in step S511), the CPU 21 ends the image reading process. If the reading is not completed (NO in step S511), the CPU 21 executes the determination in step S506.

[0052] (Setting process of background color correction flag F) 6 shows the setting process of the background color correction flag F by the CPU 21. The process will be described below in the order of step numbers.

[0053] (Step S601) First, the CPU 21 judges whether the mode of the scanner 3 is suitable for background color correction. If the mode is suitable for background color correction (YES in step S601), the CPU 21 executes the process of step S602. If the mode is not suitable for background color correction (NO in step S601), the CPU 21 executes the process of step S607.

[0054] (Step S602) The CPU 21 initializes a threshold value TH for the density value of the pixel PX, and stores the threshold value TH in the RAM 23. The threshold value TH is a value for determining whether or not to perform background color correction, as shown in FIG.

[0055] (Step S603) The CPU 21 determines whether the margin M is equal to or greater than a predetermined value. The predetermined value is, for example, 1.0 mm. If the margin M is equal to or greater than the predetermined value (YES in step S603), the CPU 21 executes the process of step S604. If the margin M is less than the predetermined value (NO in step S603), the CPU 21 executes the process of step S605.

[0056] (Step S604) The CPU 21 sets the background color correction flag F to true, and stores the background color correction flag F in the RAM 23. Then, the CPU 21 ends the background color correction flag F setting process.

[0057] (Step S605) The CPU 21 sets the background color correction flag F to true, and stores the background color correction flag F in the RAM 23.

[0058] (Step S606) The CPU 21 sets the threshold value TH to the maximum density value, and stores the threshold value TH in the RAM 23. By setting the threshold value TH, the background color correction flag F is set to false in the calculation process of the correction coefficient shown in Fig. 7. Then, the CPU 21 ends the setting process of the background color correction flag F.

[0059] (Step S607) The CPU 21 sets the background color correction flag F to false, and stores the background color correction flag F in the RAM 23. That is, the CPU 21 does not perform background color correction on the read image data. Then, the CPU 21 ends the setting process of the background color correction flag F.

[0060] (Calculation process of correction coefficient AC) 7 shows the calculation process of the correction coefficient AC by the CPU 21. Hereinafter, the process will be described in the order of the step numbers.

[0061] (Step S701) First, the CPU 21 obtains the background color density value V of the first line of the image data from the scanner 3. The first line of the image data includes pixel data at the reading start position in the read image data. The background color density value V is an average value of the image data of the first line. The CPU 21 may store the average value of the image data located at the center of the first line of the image data as the background color density value V in the RAM 23.

[0062] (Step S702) Next, the CPU 21 judges whether the background color density value V is equal to or greater than the threshold value TH. If the background color density value V is equal to or greater than the threshold value TH (YES in step S702), the CPU 21 executes the process of step S703 to perform background color correction on the read image data. If the background color density value V is less than the threshold value TH (NO in step S702), the CPU 21 executes the process of step S704.

[0063] The image data RD is an 8-bit (0 to 255) AD converted value, with a smaller value indicating a higher density and a larger value indicating a lower density.

[0064] When the value of the image data RD is equal to or greater than the threshold value, that is, when the density value of the image data RD is smaller than the threshold value, the CPU 21 performs background color correction on the read image data RD.

[0065] When the value of the image data RD is less than the threshold value, that is, when the density value of the image data RD is equal to or greater than the threshold value, the CPU 21 does not perform background color correction on the read image data RD.

[0066] (Step S703) The CPU 21 calculates the correction coefficient AC used for the background color correction, and then the CPU 21 ends the calculation process of the correction coefficient AC.

[0067] (Step S704) The CPU 21 sets the background color correction flag F to false, and stores the background color correction flag F in the RAM 23. Then, the CPU 21 ends the calculation process of the correction coefficient AC.

[0068] [Embodiment 2] A second embodiment of the present invention will be described below. For the sake of convenience, the same reference numerals are used for members having the same functions as those described in the first embodiment, and the description thereof will not be repeated. Furthermore, only a brief description will be given of the matters described in detail in the first embodiment.

[0069] Fig. 8 is a schematic diagram showing an overview of the tilt correction process according to this embodiment. As shown in the right diagram of Fig. 8, if the original 5 is tilted with respect to the reading glass 32, the first line LN1 of the read image data is not the original 5, so that the background color cannot be corrected correctly even if the first line LN1 is used.

[0070] Therefore, as shown in the left diagram of Fig. 8, by correcting the skew of the read image data, in the first line LN1 of the skew-corrected image data, data that is not of the original 5 is replaced with the original data of the original 5. As a result, by using the first line LN1 of the skew-corrected image data, the background color can be corrected correctly.

[0071] FIG. 9 is a flowchart showing an outline of background color correction determination according to this embodiment.

[0072] (Step S901) First, the CPU 21 judges whether the currently set mode is a background color correction mode. If the currently set mode is a background color correction mode (YES in step S901), the CPU 21 performs tilt correction on the read image data and executes the judgment of step S902. If the currently set mode is not a background color correction mode (NO in step S901), the CPU 21 executes the process of step S905.

[0073] (Step S902) The CPU 21 determines whether the margin M is equal to or greater than a predetermined value. The predetermined value is, for example, 1.0 mm. If the margin M is equal to or greater than the predetermined value (YES in step S902), the CPU 21 executes the process of step S904. If the margin M is less than the predetermined value (NO in step S902), the CPU 21 executes the determination of step S903.

[0074] (Step S903) The CPU 21 judges whether the result of the tilt correction of the read image data is normal or not. If the result of the tilt correction is normal (YES in step S903), the CPU 21 executes the process of step S904. If the result of the tilt correction is not normal (NO in step S903), the CPU 21 executes the process of step S905.

[0075] (Step S904) The CPU 21 performs background color correction on the read image data, and stores the background color corrected image data in the image memory 232 of the RAM 23.

[0076] (Step S905) The CPU 21 does not perform background color correction on the read image data.

[0077] 10 to 12 are flowcharts showing the processing of the multifunction device 1 according to this embodiment. Figs. 10 and 11 show image reading processing by the CPU 21. The following description will be given in the order of the step numbers. Note that the flowchart in Fig. 10 includes steps S1001 to S1010. The flowchart in Fig. 11 includes steps S1011 to S1019.

[0078] (Step S1001) First, the CPU 21 sets true or false to the background color correction flag F. Then, the CPU 21 stores the background color correction flag F in the RAM 23. Details of the setting will be described separately with reference to FIG.

[0079] (Step S1002) Next, the CPU 21 causes the scanner 3 to move the reading unit 33 or transport the document 5 .

[0080] (Step S1003) The CPU 21 determines whether or not a notification has been received from the scanner 3 that the reading unit 33 or the document 5 has reached the reading start position. If the notification has been received (YES in step S1003), the CPU 21 instructs the scanner 3 to start reading the image data, and then executes the determination in step S1004. On the other hand, if the notification has not been received (NO in step S504), the CPU 21 repeats the determination in step S1003.

[0081] (Step S1004) CPU 21 determines whether or not to perform tilt correction on the read image data. For example, if the tilt angle of the read image data with respect to the reference direction is equal to or smaller than a predetermined angle, CPU 21 determines to perform tilt correction on the read image data. The predetermined angle is, for example, 6 degrees. If it is determined to perform tilt correction (YES in step S1004), CPU 21 executes the process of step S1005. On the other hand, if it is determined not to perform tilt correction (NO in step S1004), CPU 21 executes the process of step S1009.

[0082] (Step S1005) The CPU 21 detects the leading edge of the document 5 in the read image data. In more detail, the CPU 21 detects the width and inclination of the document 5.

[0083] (Step S1006) The CPU 21 stores the detection result of the leading edge of the document 5 in the RAM 23. When the CPU 21 detects the skew angle, the CPU 21 sets the skew angle as a skew correction value and stores the skew correction value in the RAM 23.

[0084] (Step S1007) The CPU 21 determines whether or not the detection result of the leading edge of the document 5 is successful. If the detection result is successful (YES in step S1007), the CPU 21 executes the process of step S1008. If the detection result is unsuccessful (NO in step S1007), the CPU 21 executes the process of step S1009.

[0085] (Step S1008) The CPU 21 sets true or false to the background color correction flag F. Then, the CPU 21 stores the background color correction flag F again in the RAM 23. This corresponds to updating the background color correction flag F. Details of the setting will be described separately with reference to FIG. 12.

[0086] (Step S1009) The CPU 21 sets the inclination correction value to 0 degrees, and stores the inclination correction value in the RAM 23.

[0087] (Step S1010) After correcting the tilt of the read image data, the CPU 21 stores the tilt-corrected image data in the image memory 232 of the RAM 23. However, when the tilt correction value is 0 degrees, the CPU 21 stores the read image data in the image memory 232 of the RAM 23 without correcting the tilt.

[0088] (Step S1011) The CPU 21 determines whether the image data read by the scanner 3 is the first line and the background color correction flag F is true. If the image data is the first line and the background color correction flag F is true (YES in step S1011), the CPU 21 executes the process of step S1012. On the other hand, if the above does not apply, that is, if the read image data is not the first line or the background color correction flag F is false (NO in step S1011), the CPU 21 executes the determination of step S1016.

[0089] (Step S1012) The CPU 21 obtains the background color density value of the first line of the image data from the scanner 3, and calculates a correction coefficient AC to be used for background color correction.

[0090] (Step S1013) The CPU 21 determines whether the background color density value V is equal to or greater than the threshold value TH. If the background color density value V is equal to or greater than the threshold value TH (YES in step S1013), the CPU 21 executes the process of step S1014. If the background color density value V is less than the threshold value TH (NO in step S1013), the CPU 21 executes the process of step S1015.

[0091] (Step S1014) The CPU 21 performs background color correction on the image data using the correction coefficient AC, and stores the background color corrected image data in the image memory 232 of the RAM 23.

[0092] (Step S1015) The CPU 21 sets the background color correction flag F to false, and stores the background color correction flag F in the RAM 23.

[0093] (Step S1016) The CPU 21 determines whether the background color correction flag F is true. If the background color correction flag F is true (YES in step S1016), the CPU 21 executes the process of step S1014. If the background color correction flag F is not true, that is, false (NO in step S1016), the CPU 21 executes the process of step S1017.

[0094] (Step S1017) The CPU 21 stores the image data in the image memory 232 of the RAM 23 .

[0095] (Step S1018) The CPU 21 determines whether or not the reading of the image data is completed. If the reading is completed (YES in step S1018), the CPU 21 executes the determination in step S1019. If the reading is not completed (NO in step S1018), the CPU 21 executes the process of step S1010.

[0096] (Step S1019) The CPU 21 determines whether or not there is a next document. If there is a next document (YES in step S1019), the CPU 21 executes the determination in step S1002. If there is no next document (NO in step S1019), the CPU 21 ends the image reading process.

[0097] 12 shows the setting process of the background color correction flag F by the CPU 21. The process will be described below in the order of step numbers.

[0098] (Step S1201) First, the CPU 21 judges whether the mode of the scanner 3 is suitable for background color correction. If the mode is suitable for background color correction (YES in step S1201), the CPU 21 executes the process of step S1202. If the mode is not suitable for background color correction (NO in step S1201), the CPU 21 executes the process of step S1207.

[0099] (Step S1202) The CPU 21 initializes a threshold value TH for the density value of the pixel PX, and stores the threshold value TH in the RAM 23. The threshold value TH is a value for determining whether or not to perform background color correction, as shown in FIG.

[0100] (Step S1203) The CPU 21 determines whether the margin M is equal to or greater than a predetermined value. If the margin M is equal to or greater than the predetermined value (YES in step S1203), the CPU 21 executes the process of step S1205. If the margin M is less than the predetermined value (NO in step S1203), the CPU 21 executes the determination of step S1204.

[0101] (Step S1204) CPU21 determines whether the tilt correction result is a success, a failure, or not yet performed. If the tilt correction result is a success ("Success" in step S1204), CPU21 executes the process of step S1205. If the tilt correction result is a failure ("Failure" in step S1204), CPU21 executes the process of step S1206. If the tilt correction result is not yet performed ("Not yet performed" in step S1204), CPU21 executes the process of step S1207.

[0102] (Step S1205) The CPU 21 sets the background color correction flag F to true, and stores the background color correction flag F in the RAM 23. Then, the CPU 21 ends the background color correction flag F setting process.

[0103] (Step S1206) The CPU 21 sets the background color correction flag F to true, and stores the background color correction flag F in the RAM 23. Next, the CPU 21 sets the threshold value TH to the maximum background color density, and stores the threshold value TH in the RAM 23. By setting the threshold value TH, the background color correction flag F is set to false in the process of step S1015 shown in Fig. 11. Then, the CPU 21 ends the process of setting the background color correction flag F.

[0104] (Step S1207) The CPU 21 sets the background color correction flag F to false, and stores the background color correction flag F in the RAM 23. Then, the CPU 21 ends the background color correction flag F setting process.

[0105] Other embodiments In the first and second embodiments, the CPU 21 obtains the background color from the first line of the image data read from the document, and then performs background color correction using the obtained background color, but the entire image data may be used. For example, after reading the image data from the document, the CPU 21 may obtain the pixel density distribution, i.e., the histogram, of the entire image data, and set the density value with the largest number of pixels as the background color density value.

[0106] [Software implementation example] The CPU 21, which is the control block of the multifunction device 1, may be realized by hardware, which is a logic circuit formed on an IC chip or the like, which is an integrated circuit, or may be realized by software.

[0107] In the latter case, the multifunction machine 1 includes a computer that executes instructions of a program, which is software that realizes each function. The computer includes, for example, one or more processors, and a computer-readable recording medium that stores the program. The object of the present invention is achieved by the processor reading the program from the recording medium and executing it in the computer. The processor may be, for example, a CPU (Central Processing Unit). The recording medium may be a "non-transient tangible medium," such as a ROM (Read Only Memory), as well as a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like. The multifunction machine 1 may further include a RAM (Random Access Memory) that expands the program. The program may be supplied to the computer via any transmission medium capable of transmitting the program, that is, a communication network, a broadcast wave, or the like. Note that one aspect of the present invention may also be realized in the form of a data signal embedded in a carrier wave, in which the program is embodied by electronic transmission.

[0108] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0109] 1. Multifunction printer (image reader) 3. Scanner 5 Manuscript 21 CPU (control unit) 23 RAM (memory section) 32 Reading glass (readable area) 33 Reading unit (image reading unit) M Margin

Claims

1. an image reading unit that reads image data from a document; A storage unit that stores the read image data; Control unit and Equipped with The control unit is When a length in a sub-scanning direction of a margin existing between a leading end of a readable area and a reading start position is less than a predetermined value, the read image data is stored in the storage unit without performing background color correction on the read image data; When the length of the margin in the sub-scanning direction is equal to or greater than the predetermined value, the read image data is subjected to background color correction, and the background color corrected image data is stored in the storage unit.

1. An image reading apparatus comprising:

2. The control unit is The read image data is skew-corrected; When the length of the margin in the sub-scanning direction is less than the predetermined value, if the result of correcting the inclination of the read image data is normal, the inclination-corrected image data is subjected to background color correction, and the background-color-corrected image data is stored in the storage unit.

2. The image reading apparatus according to claim 1, wherein the image reading apparatus comprises:

3. The control unit corrects the skew of the read image data when the skew angle of the read image data with respect to a reference direction is equal to or smaller than a predetermined angle.

3. The image reading apparatus according to claim 2, wherein the image reading apparatus comprises:

4. The control unit is The image data is a value read by the image reading unit, and the smaller the value, the higher the density, and the larger the value, the lower the density. When the density value of the image data at the reading start position in the read image data is smaller than a reference value, the read image data is subjected to background color correction.

4. The image reading device according to claim 1, wherein the image reading device is a digital camera.

5. The control unit stores an average value of values ​​of the image data read at the reading start position in the storage unit as a density value of the background color.

5. The image reading apparatus according to claim 4,

6. The control unit does not perform background color correction on the read image data when the mode of the image reading unit is not suitable for background color correction.

6. The image reading device according to claim 1, wherein the image reading device is a digital camera.

7. 1. An image reading method for reading image data from an original and storing the read image data in a storage unit, comprising: A step of determining whether or not a length in a sub-scanning direction of a margin existing between a leading end of a readable area and a reading start position is less than a predetermined value; storing the read image data in the storage unit without performing background color correction on the read image data when it is determined that the length of the margin in the sub-scanning direction is less than a predetermined value; a step of correcting a background color of the read image data and storing the background-color-corrected image data in the storage unit when it is determined that the length of the margin in the sub-scanning direction is equal to or greater than the predetermined value; 2. An image reading method comprising:

Images