JP2012095237A - Image reading device and image reading method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reading device that allows a user to change a condition for detecting an image area of a predetermined attribute (such as a character attribute) on his/her preference, with substantially no increase in cost of the device.SOLUTION: An image reading device includes: a reading control part 32 that carries out image reading, and creates a fist image data having basic resolution and a second image data having resolution for area detection that is different from the basic resolution; an area specifying part 33 that specifies an image area that satisfies a predetermined condition on the line number in the second image data; and an image processing part 34 that carries out predetermined image processing to the image area specified by the area specifying part in the first image data.

Description

  The present invention relates to an image reading apparatus and an image reading method.

  In order to improve the image quality of image data, a sharpening process is performed on an image area such as a character attribute or a line drawing, and a smoothing process is performed on an image area having a halftone such as a photograph. For this reason, for example, in the case of a document image in which characters and photographs are mixed, the character image area and the photograph image area are separated.

  On the other hand, in the case of printed matter of characters and photographs, the characters and photographs are represented by halftone dots. There is an apparatus that separates such a halftone dot portion and a non-halftone dot portion and extracts them from a document image (see, for example, Patent Document 1).

  When a printed material including a halftone image is read, the character image region and the photo image region in the halftone image obtained from the printed material are separated.

Japanese Patent Laid-Open No. 9-37073

  When separating a character image area and a photographic image area in a halftone dot image obtained from a printed matter, a halftone dot portion whose number of lines is equal to or less than a predetermined threshold is specified as an image region having a character attribute, and the other halftone dot portion Is specified as a halftone image area. A sharpening process is performed on the image area having the character attribute, and a smoothing process is performed on the image area having a halftone.

  In general, the number of lines serving as the threshold is determined in advance at the time of designing the apparatus, and parameters tuned to detect a halftone portion of the number of lines below the threshold (or above the threshold) are preliminarily set in the image reading apparatus. And a halftone dot portion is detected in a specific line number range based on the parameter.

  As described above, since the number of lines serving as a threshold is fixedly determined, the user cannot normally adjust the number of lines serving as the threshold according to preference.

  In order to allow the user to select the threshold value, parameters corresponding to each threshold value are stored in advance, and a large-capacity storage device that stores many parameters corresponding to many threshold values is provided. It becomes necessary. Such a large-capacity storage device is not preferable because it leads to an increase in the cost of the image reading apparatus.

  The present invention has been made in view of the above-described problem, and a condition for a user to detect an image area having a predetermined attribute (for example, a character attribute) according to his / her preference without substantially increasing the cost of the apparatus. An object of the present invention is to obtain an image reading apparatus and an image reading method capable of changing the above.

  In order to solve the above problems, the present invention is configured as follows.

  An image reading apparatus according to the present invention reads an image, generates a first image data having a basic resolution, and a second image data having a region detection resolution different from the basic resolution, and a second image data A region specifying unit that specifies an image region that satisfies a predetermined condition regarding the number of lines, and an image processing unit that performs predetermined image processing on the image region specified by the region specifying unit in the first image data. Prepare.

  Thereby, the condition of the number of lines for detecting an image area having a predetermined attribute (for example, a character attribute) is substantially changed by changing the area detection resolution while the condition of the number of lines in the area specifying unit is fixed. Will be changed.

  Accordingly, only one set of parameters is used to detect the image area, and the user can detect an image area having a predetermined attribute (for example, a character attribute) according to his / her preference without increasing the cost of the apparatus. The conditions for can be changed. That is, if the user changes the region detection resolution, the condition for detecting an image region having a predetermined attribute (for example, a character attribute) is changed (substantially).

  In addition to the above image reading apparatus, the image reading apparatus according to the present invention may be as follows. In this case, the area specifying unit specifies an image area that satisfies a predetermined condition based on a predetermined default number of lines as a threshold. Then, the reading control unit multiplies the basic resolution by the ratio of the default number of lines and the adjusted threshold number of lines to calculate the area detection resolution, the first image data of the basic resolution, and the second of the area detection resolution. Image data.

  Thereby, the condition of the number of lines for detecting an image area of a predetermined attribute (for example, a character attribute) is substantially changed by changing the area detection resolution while the threshold of the number of lines in the area specifying unit is fixed. Will be changed.

  For example, when the threshold value of the area specifying unit is 100 LPI (Line Per Inch) and the adjusted threshold line number is 150 LPI, the area detection resolution is set to 1.5 times the basic resolution. For this reason, 100 LPI at the region detection resolution corresponds to 150 LPI at the basic resolution, and the image region is practically specified in the first image data with 150 LPI as a threshold value.

  The image reading apparatus according to the present invention may be as follows in addition to any of the image reading apparatuses described above. In this case, the image reading apparatus further includes an operation unit that receives a user operation. Then, the adjusted threshold line number is calculated from the default line number and the adjustment value input to the operation unit.

  Thereby, the adjusted threshold line number is set according to the user's preference.

  The image reading apparatus according to the present invention may be as follows in addition to any of the image reading apparatuses described above. In this case, the area specifying unit specifies the first image area having the number of lines equal to or less than the threshold and specifies the second image area having the number of lines larger than the threshold. The image processing unit performs a sharpening process on the first image area and performs a smoothing process on the second image area.

  Thereby, the sharpening process is appropriately performed on the image area having the character attribute, and the smoothing process is appropriately performed on the halftone image area such as a photograph.

  The image reading apparatus according to the present invention may be as follows in addition to any of the image reading apparatuses described above. In this case, the area specifying unit specifies an image area having a character attribute. Then, the image processing unit performs a sharpening process on the identified image region.

  Thereby, the sharpening process is appropriately performed on the image area having the character attribute.

  The image reading apparatus according to the present invention may be as follows in addition to any of the image reading apparatuses described above. In this case, the image processing unit performs a smoothing process on an image area other than the specified image area.

  Thereby, the sharpening process is appropriately performed on the image area having the character attribute, and the smoothing process is appropriately performed on the halftone image area such as a photograph.

  The image reading apparatus according to the present invention may be as follows in addition to any of the image reading apparatuses described above. In this case, the image reading apparatus further includes a storage device that stores a parameter setting value for detecting an image region that satisfies the above-described predetermined condition. Then, the area specifying unit reads the parameter setting value from the storage device, and specifies the image area in the second image data using the read parameter setting value.

  An image reading method according to the present invention performs image reading to generate first image data having a basic resolution and second image data having a region detection resolution different from the basic resolution, and the second image data includes: A step of specifying an image region that satisfies a predetermined condition regarding the number of lines; and a step of performing predetermined image processing on the specified image region in the first image data.

  Thereby, the condition of the number of lines for detecting an image area of a predetermined attribute (for example, a character attribute) is substantially changed by changing the area detection resolution while the threshold of the number of lines in the area specifying unit is fixed. Will be changed.

  According to the present invention, a condition for detecting an image region having a predetermined attribute (for example, a character attribute) can be changed according to a user's preference without substantially increasing the cost of the apparatus.

FIG. 1 is a block diagram showing a configuration of an image reading apparatus according to an embodiment of the present invention. FIG. 2 is a flowchart showing a procedure until the user obtains a desired image quality by operating the image reading apparatus shown in FIG. FIG. 3 is a diagram showing an example of an adjustment value setting screen displayed on the operation panel in FIG. FIG. 4 is a flowchart for explaining the operation of the image reading apparatus shown in FIG. FIG. 5 is a diagram for explaining the principle of substantially changing the threshold of the number of lines by using image data with different resolutions in the image reading apparatus shown in FIG.

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

  FIG. 1 is a block diagram showing a configuration of an image reading apparatus according to an embodiment of the present invention. The image reading apparatus shown in FIG. 1 is a copier. However, the image reading apparatus may be a scanner machine that does not have a printing function, a multifunction machine that has various functions in addition to the copying function, and the like.

  The image reading apparatus includes a printer 11, a scanner 12, an operation panel 13, a storage device 14, and a control device 15.

  The printer 11 is an internal device that prints an image on printing paper. The scanner 12 is an internal device that optically reads a document image from a document and generates image data of the document image.

  In addition, the operation panel 13 is disposed on the surface of the casing of the image reading apparatus, and includes a display device that displays various types of information to the user, and an input device as an operation unit that receives a user operation. For example, a liquid crystal display is used as the display device. A key switch, a touch panel, or the like is used as the input device.

  The storage device 14 is a non-volatile storage device that stores various data. As the storage device 14, a hard disk drive, a flash memory, or the like is used. The storage device 14 stores parameter setting value data 21 in advance.

  The parameter set value data 21 is parameter set value data for detecting an image region that satisfies a predetermined condition regarding the number of lines.

  The predetermined condition for the number of lines is that the number of lines is equal to or less than a predetermined threshold (or higher), and when the threshold is predetermined as 100 LPI or the like at the time of designing the apparatus, the threshold is equal to or lower than the threshold (or the threshold). The parameter values tuned to detect the halftone dot portion of the above number of lines are stored as parameter setting value data 21. The parameter includes a threshold value for the number of consecutive dots in a halftone dot. That is, if the number of points equal to or greater than the threshold is not continuous, the halftone dot portion that satisfies the condition is not detected.

  The control device 15 controls internal devices such as the printer 11, the scanner 12, and the operation panel 13 and performs various data processing.

  For example, a computer such as a microprocessor having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), or the like is used as the control device 15. In the control device 15, programs stored in the ROM, the storage device 14, and the like are loaded into the RAM and executed by the CPU, thereby realizing various processing units. In the control device 15, an adjustment value setting unit 31, a reading control unit 32, an area specifying unit 33, an image processing unit 34, and a print control unit 35 are realized.

  The adjustment value setting unit 31 displays an adjustment value setting screen on the operation panel 13 and specifies an adjustment value input to the operation panel 13 by a user operation.

  The reading control unit 32 controls the scanner 12 to read an image, and generates first image data having a basic resolution and second image data having a region detection resolution different from the basic resolution.

  The basic resolution is the resolution of image data generated by image reading and used for output such as subsequent printing.

  The area detection resolution is the resolution of the second image data used when detecting a halftone dot area under a detection condition different from the default detection condition.

  In this embodiment, the reading control unit 32 calculates the region detection resolution by multiplying the basic resolution by the ratio of the predetermined default number of lines and the adjusted threshold number of lines, the first image data of the basic resolution, Second image data having a region detection resolution is generated. The adjusted threshold line number is calculated from the default line number and the adjustment value input by the adjustment value setting unit 31. For example, when the default number of lines is 100 LPI and the adjustment value is +50, the adjusted threshold number of lines is 150 LPI.

  The area specifying unit 33 specifies an image area that satisfies a predetermined condition regarding the number of lines in the second image data described above.

  In this embodiment, the area specifying unit 33 specifies an image area that satisfies a predetermined condition based on the default number of lines as a threshold. In this embodiment, the area specifying unit 33 specifies the first image area having the number of lines equal to or less than the threshold as the image area having the character attribute, and selects the second image area having the number of lines larger than the threshold. Identify. In this embodiment, the area specifying unit 33 reads the parameter setting value data 21 from the storage device 14 and specifies the image area in the second image data using the read parameter setting value data 21.

  The image processing unit 34 performs predetermined image processing on the image region specified by the region specifying unit 33 in the first image data.

  In this embodiment, the image processing unit 34 performs a sharpening process on the first image area and performs a smoothing process on the second image area. That is, the image processing unit 34 performs a smoothing process on an image area other than the first image area.

  In the case of copying, after performing such image processing, the image processing unit 34 performs processing such as halftoning to generate print data from the image data.

  The print control unit 35 controls the printer 11 to print an image based on the print data.

  Next, the operation of the image reading apparatus will be described.

  FIG. 2 is a flowchart showing a procedure until the user obtains a desired image quality by operating the image reading apparatus shown in FIG.

  As shown in FIG. 2, when a user (including a service person) turns on the power, the image reading apparatus is activated (step S1). When the user presses the copy button, the image reading apparatus executes copying as described later (step S2). The user confirms the printed matter generated by copying and determines whether or not the image quality is a preference (step S3). If the desired image quality is obtained, the user ends the image quality adjustment. If the desired image quality is not obtained, the user changes the adjustment value (step S5) and performs the copying operation again. In this way, the adjustment value is changed until a desired image quality is obtained.

  When changing the adjustment value, the user first performs an operation for displaying an adjustment value setting screen. FIG. 3 is a diagram showing an example of an adjustment value setting screen displayed on the operation panel 11 in FIG. In the image reading apparatus, the adjustment value setting unit 31 displays an adjustment value setting screen as shown in FIG. Adjustment buttons 101 and 102 are displayed on the adjustment value setting screen. When the adjustment button 101 is pressed, the operation is detected by the touch panel of the operation panel 13 or the like, and the adjustment value setting unit 31 decreases the adjustment value. On the other hand, when the adjustment button 102 is pressed, the operation is detected by the touch panel of the operation panel 13 or the like, and the adjustment value setting unit 31 increases the adjustment value.

  Here, the operation of the image reading apparatus during document copy (step S2) will be described.

  FIG. 4 is a flowchart for explaining the operation of the image reading apparatus shown in FIG.

  When the copy button on the operation panel 13 is pressed, the reading control unit 32 specifies the adjustment value set at the present time (step S11), specifies the basic resolution, and detects the area from the basic resolution and the adjustment value. The resolution is calculated (step S12).

  Then, the reading control unit 32 causes the scanner 12 to perform image reading (step S13), and based on the image data supplied from the scanner 12, image data with basic resolution (first image data) and image data with region detection resolution. (Second image data) is generated (step S14).

  Next, the area specifying unit 33 reads the parameter setting value data 21 from the storage device 14 and uses the parameter setting value data 21 to set the default number of lines in the image data (second image data) for area detection resolution. A halftone dot region that satisfies the conditions is specified (step S15). For example, the default line number condition is 100 LPI or less, and parameter setting value data 21 for the default line number condition is stored in the storage device 14 in advance.

  FIG. 5 is a diagram for explaining the principle of substantially changing the threshold of the number of lines by using image data with different resolutions in the image reading apparatus shown in FIG.

  When the default threshold value of the line number condition is 100 LPI and the adjustment value is 0, one dot in the 100 LPI document image shown in FIG. 5A is read by three pixels as shown in FIG. It is done.

  On the other hand, when the default threshold value for the line number condition is 100 LPI, the adjustment value is +50, and the adjusted threshold value is (substantially) 150 LPI, 1 in the 150 LPI document image shown in FIG. In the basic resolution, the dot is 2 pixels as shown in FIG. 5D, but in the area detection resolution, it is 3 pixels as shown in FIG. 5E.

  Since the region detection resolution is adjusted according to the adjustment value, one dot in the document image becomes three pixels in the second image data regardless of the adjustment value. Therefore, the region specifying unit 33 can detect the network to be detected under a certain precondition that one dot in the document image becomes three pixels in the second image data even if the threshold of the line number condition changes. Identify the point area.

  For this reason, only the parameter setting value data 21 tuned when one halftone dot in the document image corresponds to three pixels in the image data is stored in the storage device 14, and the area specifying unit 33 does not depend on the adjustment value. The halftone dot region is specified based on the parameter setting value data 21.

  When the target halftone area is specified in the second image data in this way, the image processing unit 34 specifies the area in the first image data corresponding to the halftone area specified in the second image data. . That is, a region having the same shape and the same position as the shape and position of the halftone dot region in the image based on the second image data is specified in the image based on the first image data.

  Then, the image processing unit 34 performs predetermined image processing on the halftone dot region that satisfies the line number condition specified in the first image data, that is, the basic resolution image data (step S16). For example, the sharpening process is executed for the halftone dot area where the number of lines is equal to or less than the threshold value, and the smoothing process is executed for the halftone dot area where the number of lines is greater than the threshold value.

  Further, the image processing unit 34 generates print data from the processed first image data.

  Thereafter, the print control unit 35 causes the printer 11 to execute printing based on the print data (step S17).

  As described above, according to the above-described embodiment, the reading control unit 32 performs image reading and generates first image data having a basic resolution and second image data having a region detection resolution different from the basic resolution. The area specifying unit 33 specifies an image area that satisfies a predetermined condition regarding the number of lines in the second image data, and the image processing unit 34 specifies the image area specified by the area specifying unit in the first image data. Predetermined image processing is performed on the image.

  Thereby, the condition of the number of lines for detecting an image area of a predetermined attribute (for example, a character attribute) can be obtained by changing the resolution for area detection while the condition of the number of lines in the area specifying unit 33 is fixed. Substantially changed.

  Therefore, only one set of parameters is used to detect the image area, and the user can detect an image area having a predetermined attribute (for example, a character attribute) according to his / her preference without increasing the cost of the apparatus. The conditions for can be changed. That is, if the user changes the region detection resolution, the condition for detecting an image region having a predetermined attribute (for example, a character attribute) is changed (substantially). Moreover, since only one set of parameters is required, it is not necessary to tune multiple sets, and the burden on the developer can be reduced.

  The above-described embodiments are preferred examples of the present invention, but the present invention is not limited to these, and various modifications and changes can be made without departing from the scope of the present invention. is there.

  For example, in the above-described embodiment, the adjustment value input by the user is stored in a non-volatile storage device such as the storage device 14, and the adjustment value is not input by the user from the next time and stored. You may make it read from an apparatus.

  In the above embodiment, an example in which the adjustment value is +50 has been described. However, the adjustment value may be a negative value. For example, when the default threshold value for the line number condition is 150 LPI and the adjustment value is −50, the adjusted threshold value is 100 LPI, and the region detection resolution is 2/3 of the basic resolution (= 100/150). Is done.

  The present invention is applicable to, for example, a copy machine, a multifunction machine, and the like.

13 Operation panel (example of operation unit)
14 Storage Device 32 Reading Control Unit 33 Area Specifying Unit 34 Image Processing Unit

Claims (8)

A reading control unit that performs image reading and generates first image data having a basic resolution and second image data having a region detection resolution different from the basic resolution;
In the second image data, an area specifying unit that specifies an image area that satisfies a predetermined condition for the number of lines;
An image processing unit that performs predetermined image processing on the image region specified by the region specifying unit in the first image data;
An image reading apparatus comprising: The area specifying unit specifies an image area that satisfies the predetermined condition based on a threshold value of a predetermined default number of lines,
The reading control unit calculates the area detection resolution by multiplying the basic resolution by a ratio of the default number of lines and the adjusted threshold number of lines, the first image data of the basic resolution, and the area detection Generating second image data of resolution;
The image reading apparatus according to claim 1. It further includes an operation unit that accepts user operations,
The adjusted threshold line number is calculated from the default line number and an adjustment value input to the operation unit;
The image reading apparatus according to claim 2. The area specifying unit specifies a first image area having a number of lines equal to or less than the threshold, and specifies a second image area having a number of lines larger than the threshold,
The image processing unit performs a sharpening process on the first image area and performs a smoothing process on the second image area;
The image reading apparatus according to claim 2. The area specifying unit specifies an image area having a character attribute,
The image processing unit performs a sharpening process on the identified image region;
The image reading apparatus according to claim 1.   The image reading apparatus according to claim 5, wherein the image processing unit performs a smoothing process on an image area other than the specified image area. A storage device for storing a parameter setting value for detecting an image region that satisfies the predetermined condition;
The region specifying unit reads the parameter setting value from the storage device, and specifies the image region in the second image data using the read parameter setting value;
The image reading apparatus according to claim 1, wherein the image reading apparatus is an image reading apparatus. Performing image reading to generate first image data having a basic resolution and second image data having a region detection resolution different from the basic resolution;
In the second image data, identifying an image region that satisfies a predetermined condition for the number of lines;
Performing predetermined image processing on the identified image area in the first image data;
An image reading method comprising:

Images