JP2017011443A - Image processing device, image forming device, image reading device and image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means of enhancing the accuracy of determination of color/monochrome.SOLUTION: There are provided an operation unit for accepting an input operation for designating a color or monochrome document type for plural documents to be read, a reading unit for reading images of the plural documents, a determination unit for calculating the number of color pixels for each image of the document read by the reading unit, determining that the image is color when the number of color pixels exceeds a threshold value, and determining that the image is monochrome when the number of color pixels does not exceed the threshold value, an adjustment unit for calculating an adjustment threshold value for each pixel of the document so that the result of the color/monochrome determination is coincident with the designated document type, performing the color/monochrome determination on the image of the document with each calculated adjustment threshold value set as the threshold value, calculating the concordance rate between the color/monochrome determination result and the designated document type and determining the threshold value based on the adjustment threshold value and the concordance rate, and a registration unit for registering the threshold value determined by the adjustment unit.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image processing apparatus, an image forming apparatus, an image reading apparatus, and an image processing method for determining whether a document is color or monochrome based on a read document image.

Conventional image processing apparatuses perform color / monochrome determination to determine whether a read original is color or monochrome because color printing and monochrome printing differ in printing time and ink consumption due to process differences. The printing is performed in an appropriate mode (see, for example, Patent Document 1).
In such an image processing apparatus, it is possible to adjust a threshold value for determining whether color or monochrome in color / monochrome determination, and a desired document can be obtained by reading an adjustment document with a scanner by a user operation. Color / monochrome determination can be performed with a threshold value.

JP-A-11-327376

However, in the conventional technology, when adjusting the threshold value for color / monochrome determination, an adjustment document is read by a scanner, and the threshold value is adjusted based on the read adjustment document. As a result, the accuracy of color / monochrome determination may be reduced.
An object of the present invention is to solve such a problem and to improve the accuracy of color / monochrome determination.

  Therefore, the present invention provides an operation unit that accepts an input operation for designating a color or monochrome document type for a plurality of documents to be read, a reading unit that reads images of the plurality of documents, and a document read by the reading unit. For each image, the number of color pixels is calculated, and when the number of color pixels exceeds a threshold, it is determined as color, and when it does not exceed the threshold, it is determined as monochrome. An adjustment threshold value is calculated for each image so that the result of the color / monochrome determination matches the designated document type, and color / monochrome determination is performed on the image of the document using each calculated adjustment threshold as the threshold value. An adjustment unit that calculates a matching rate between the color / monochrome determination result and the designated document type, and determines the threshold based on the adjustment threshold and the matching rate; and the adjustment There characterized by having a, a registration unit for registering the threshold determined.

  The present invention as described above is advantageous in that the accuracy of color / monochrome determination can be improved.

The block diagram which shows the control structure of the image processing apparatus in an Example External perspective view of the multifunction machine in the embodiment Explanatory drawing of the operation screen in the embodiment The flowchart which shows the flow of the ACS threshold value adjustment process in an Example The flowchart which shows the flow of the ACS threshold value determination process in an Example Explanatory drawing of the ACS threshold value determination method in an Example

  Hereinafter, embodiments of an image processing apparatus, an image forming apparatus, an image reading apparatus, and an image processing method according to the present invention will be described with reference to the drawings.

FIG. 2 is an external perspective view of the multifunction machine according to the embodiment.
In FIG. 2, the multifunction peripheral 100 as an image forming apparatus performs automatic color document determination (hereinafter referred to as “ACS determination”) for determining whether a document is color or monochrome based on a read document image. A scanner 101, a mounting table 102, an image sensor 103, a mounting table cover 104, an ADF (Auto Document Feeder) 105, an operation panel 106, a printer 108, and a cassette 109 are provided. In this embodiment, the scanner 101, the mounting table 102, the image sensor 103, the mounting table cover 104, the ADF 105, and the operation panel 106 constitute an image processing apparatus.

The scanner 101 reads a document placed on the placement table 102 or a document placed on the ADF 105.
The mounting table 102 is a glass table or the like on which a document is mounted.
The image sensor 103 reads a document placed on the mounting table 102 or a document fed by the ADF 105.
The placement table cover 104 fixes the position of the document placed on the placement table 102 and prevents exposure of areas other than the document on the placement table 102 when the image sensor 103 emits light.

The ADF 105 is an automatic paper feeder that automatically feeds a placed document and causes the image sensor 103 to read a plurality of documents.
The operation panel 106 is input means and output means composed of operation keys such as a selection key for selecting a reading mode, a liquid crystal display and a touch panel. The operation panel 106 also has a start button 107 that accepts an operation to start reading a document image.

The printer 108 prints an image of a document read by the scanner 101 on printing paper, and prints printing data received from an external device such as a PC (Personal Computer) connected via a communication line on printing paper.
The cassette 109 stores printing paper therein. The printer 108 conveys printing paper stored in the cassette 109 and prints an image on the printing paper.

FIG. 1 is a block diagram illustrating a control configuration of the image processing apparatus according to the embodiment.
In FIG. 1, the image processing apparatus 200 includes a user interface unit 201, a document reading unit 202, a temporary data storage unit 203, an ACS determination unit 204, an ACS threshold adjustment unit 205, and a threshold registration unit 206. ing. Note that the image processing apparatus 200 is provided in the multifunction peripheral 100 shown in FIG.

The user interface unit 201 as a display unit and an operation unit displays an operation screen on the display unit of the operation panel 106 shown in FIG. 2 and accepts a user input operation using the displayed operation screen as an operation unit.
The user interface unit 201 displays, for example, an operation screen shown in FIG. 3 on the operation panel 106, inputs designation of adjustment modes (adjustment using a color document or adjustment using a monochrome document), and a plurality of adjustment documents. The determination result of the original document can be displayed and an ACS threshold value which is a threshold value used in the ACS determination can be input.

Here, the adjustment mode designates a color or monochrome document type for a plurality of adjustment documents to be read, and designates adjustment using a color document or adjustment using a monochrome document.
The user interface unit 201 also exchanges information with the document reading unit 202, the temporary data storage unit 203, the ACS determination unit 204, the ACS threshold adjustment unit 205, and the threshold registration unit 206 in order to adjust the ACS threshold. It can be done.

  A document reading unit 202 as a reading unit reads a document and generates image data. When the document reading unit 202 receives a reading start command from the user interface unit 201, the document reading unit 202 reads a plurality of documents set on the document table 102 or the ADF 105 of the scanner 101 shown in FIG. 2 and generates image data. The document reading unit 202 stores and stores the generated image data of a plurality of documents in the temporary data storage unit 203 and notifies the user interface unit 201 of the reading completion information.

  The temporary data storage unit 203 is a storage unit that temporarily stores the image data generated by the document reading unit 202 and the adjustment mode information received from the user interface unit 201.

The ACS determination unit 204 as a determination unit calculates the number of color pixels for each image data of the document read by the document reading unit 202, determines that the color pixel number exceeds the threshold value, determines that the color is a color, and exceeds the threshold value. If not, ACS determination (color / monochrome determination) is performed to determine monochrome.
More specifically, the ACS determination unit 204 calculates the number of color pixels for each image data of the document read by the document reading unit 202, and when the number of color pixels exceeds the registered ACS threshold value, It is determined that the image data of the document is a color document, and if not exceeded, ACS determination is performed to determine that the image data of the document is a monochrome document.

When the ACS determination unit 204 receives an ACS determination command from the user interface unit 201, the ACS determination unit 204 acquires a plurality of document image data and adjustment mode information from the temporary data storage unit 203 and performs ACS determination. The ACS determination unit 204 notifies the ACS threshold adjustment unit 205 of the ACS determination results of a plurality of document image data and the adjustment mode information thereof after the ACS determination is completed.
The ACS threshold value adjustment unit 205 as an adjustment unit adjusts the ACS threshold value. When the ACS threshold adjustment unit 205 receives the ACS determination results and the adjustment mode information of a plurality of document image data from the ACS determination unit 204, the ACS threshold adjustment unit 205 adjusts the ACS threshold so that the ACS determination result becomes the adjustment mode information.

  More specifically, the ACS threshold adjustment unit 205 matches the specified document type (adjustment mode information) with the ACS determination (color / monochrome determination) result in the ACS determination unit 204 for each document image. An adjustment threshold value (color document threshold value to be described later) is calculated, and the ACS determination unit 204 performs ACS determination for all image images using the calculated adjustment threshold values as ACS threshold values. The ACS determination result and the specified document type A coincidence rate with (adjustment mode information) is calculated, and an ACS threshold is determined based on the adjustment threshold and the coincidence rate.

The ACS threshold adjustment unit 205 notifies the user interface unit 201 of ACS determination results for a plurality of document image data with the adjusted ACS threshold.
The threshold value registration unit 206 stores and registers information on the ACS threshold value determined by the ACS threshold value adjustment unit 205. The threshold value registration unit 206 receives the ACS threshold value notified from the user interface unit 201 and registers it in the image processing apparatus 200.

FIG. 3 is an explanatory diagram of an operation screen in the embodiment. This operation screen is an operation screen displayed on the operation panel 106 shown in FIG. 2 by the user interface unit 201 shown in FIG.
FIG. 3A shows a menu screen in which the basic setting 11 and the image quality adjustment 12 can be selected, and the image quality adjustment screen 10 with the image quality adjustment 12 selected is displayed. On the image quality adjustment screen 10, function selection buttons for “background removal”, “saturation adjustment”, “RGB adjustment”, and “ACS adjustment” are arranged, and an operation button 13 for selecting a function of “ACS adjustment” is selected. Then, the ACS threshold value adjustment setting screen 20 shown in FIG. 3B is displayed.

  The ACS threshold value adjustment setting screen 20 shown in FIG. 3B includes an operation area 21 for selecting “basic level base” for determining the ACS threshold, an operation area 22 for selecting “registration mode base”, and “ACS Three operation means of the “threshold adjustment” selection button 23 are displayed. When a level is selected in the operation area 21 for selecting “basic level base” and the “apply” button 24 is pressed, the ACS threshold is determined as the ACS threshold corresponding to the selected level.

When a registration mode is selected in the operation area 22 for selecting “registration mode base” and the “apply” button 24 is pressed, a default corresponding to the registration mode (for example, toner save mode) in which the ACS threshold is selected is selected. ACS threshold information is determined.
When the “ACS threshold adjustment” selection button 23 is pressed, a plurality of ACS threshold adjustment documents prepared by the user are read according to the displayed operation screen, and the ACS threshold is adjusted.
If the return button on the ACS threshold adjustment setting screen 20 is pressed, an image quality adjustment screen 10 shown in FIG. 3A is displayed.

The operation screen when the “ACS threshold adjustment” selection button 23 is pressed will be described below.
When the “ACS threshold adjustment” selection button 23 is pressed on the ACS threshold adjustment setting screen 20 shown in FIG. 3B, an ACS threshold adjustment original input screen 30 shown in FIG. 3C is displayed. On the ACS threshold adjustment original input screen 30, an operation guide message 31 such as “Set the ACS threshold adjustment input original and select a mode” and a “color mode” for selecting the mode as a color mode. ”Selection button 32, a“ monochrome mode ”selection button 33 for selecting the mode as a monochrome mode, and a“ start ”button 34 for starting ACS threshold adjustment are displayed.

The user sets a plurality of ACS threshold adjustment originals on the ADF 105 shown in FIG. 2, and selects a mode of the ACS threshold adjustment original input screen 30 (for example, when determining a plurality of ACS threshold adjustment originals as colors). , “Color mode” is selected), a plurality of documents for ACS threshold adjustment are read, and the image data of the document is stored together with information indicating the selected mode. Further, when the “start” button 34 on the ACS threshold adjustment original input screen 30 is pressed, ACS threshold adjustment is started based on a plurality of ACS threshold adjustment originals read by the multi-function peripheral. When the ACS threshold adjustment is completed, an automatic adjustment result display screen 40 shown in FIG. 3D is displayed that displays the discrimination results of a plurality of documents for ACS threshold adjustment using the adjusted ACS threshold.
When the return button on the ACS threshold adjustment original input screen 30 is pressed, an ACS threshold adjustment setting screen 20 shown in FIG. 3B is displayed.

  When the “start” button 34 of the ACS threshold value adjustment document input screen 30 shown in FIG. 3C is pressed, an ACS threshold value adjustment result display screen 40 shown in FIG. 3D is displayed. The ACS threshold adjustment result display screen 40 includes an ACS determination result area 41 in which the number of a document determined to be color using the adjusted ACS threshold and the number of a document determined to be monochrome are displayed, and an ACS threshold. The ACS threshold adjustment slide 42 and the ACS threshold adjustment slide 42 are displayed in a picture (hereinafter referred to as “slider”) and displayed so that the user can manually slide the slider to adjust the ACS threshold. An “apply” button 43 for saving the determined ACS threshold is displayed.

For example, when the color originals 1 to 4 and the monochrome originals 1 to 3 shown in FIG. 6 are read as ACS adjustment originals and the adjusted ACS threshold is “609”, the ACS determination result area 41 is determined to be color. The numbers of the color documents 1 to 4 and the monochrome document 1 are displayed, and the numbers of the monochrome documents 2 and 3 determined to be monochrome are displayed.
Further, when the ACS threshold adjustment slide 42 is operated and the ACS threshold is changed to “640” (ACS threshold adjustment slide 42a) in a state where the ACS threshold is “609”, as shown in FIG. In the result area 41a, the numbers of the color originals 1 to 3 determined to be in color are displayed, and the numbers of the color original 4 determined to be monochrome and the numbers of the monochrome originals 1 to 3 are displayed.

In this way, the ACS threshold adjustment slide 42 is a means that can change the threshold determined by the ACS threshold adjustment unit 205 shown in FIG.
Of the originals displayed in the ACS determination result areas 41 and 41a, those that are shaded represent monochrome documents, and those that are not shaded represent color documents.
When the user adjusts the ACS threshold with the ACS threshold adjustment slide 42 and presses the “Apply” button 43, the adjusted ACS threshold is saved, and the ACS threshold registration screen 50 shown in FIG. 3F is displayed.
When the “delete” button on the ACS threshold adjustment result display screen 40 is pressed, the adjusted ACS threshold is canceled and the ACS threshold adjustment original input screen 30 shown in FIG. 3C is displayed.

  When the “apply” button 43 on the ACS threshold value adjustment result display screen 40 shown in FIG. 3D is pressed, an ACS threshold value registration screen 50 shown in FIG. 3F is displayed. The ACS threshold value registration screen 50 includes a mode name 51 for displaying the registration mode selected on the ACS threshold value adjustment setting screen 20 shown in FIG. 3B, a registrant 52 for displaying the user name and ID, and FIG. A color document determination threshold value 53 for displaying the ACS threshold value determined on the ACS threshold value adjustment result display screen 40 shown in (d), and a preview image for displaying a preview image of a color document and a monochrome document determined by the determined ACS threshold value. 54 and an “apply” button 55 for registering the ACS threshold displayed in the color document determination threshold 53 is displayed.

Next, an outline of the ACS threshold value adjustment process performed by the image processing apparatus in response to a user operation on the operation screen illustrated in FIG. 3 will be described with reference to FIGS. 1 and 2.
When the user interface unit 201 of the image processing apparatus 200 detects that the “ACS threshold adjustment” selection button 23 is pressed on the ACS threshold adjustment setting screen 20 shown in FIG. 3B, the user interface unit 201 uses the ACS threshold adjustment shown in FIG. A document input screen 30 is displayed on the operation panel 106.

When the user sets a plurality of documents for ACS threshold adjustment on the ADF 105 of the image processing apparatus 200 and selects the mode of the ACS threshold adjustment document input screen 30 shown in FIG. 3C, the user interface unit 201 is selected. Information representing the selected mode is received as adjustment mode information, and a reading command is notified to the document reading unit 202.
Upon receiving the reading command, the document reading unit 202 reads a plurality of documents placed on the ADF 105 and sends image data of the read documents to the temporary data storage unit 203. Further, the document reading unit 202 notifies the user interface unit 201 that the reading is completed.

When the user interface unit 201 receives a notification that reading has been completed, the user interface unit 201 notifies the temporary data storage unit 203 of the adjustment mode information of the image data of the document.
The temporary data storage unit 203 receives and stores image data of a plurality of documents sent from the document reading unit 202. The temporary data storage unit 203 receives and stores the adjustment mode information notified from the user interface unit 201.

When the user presses a “start” button 34 on the ACS threshold adjustment original input screen 30 shown in FIG. 3C, the user interface unit 201 notifies the ACS determination unit 204 of an instruction to perform ACS determination.
When the ACS determination unit 204 receives an instruction to perform ACS determination, the ACS determination unit 204 acquires image data and adjustment mode information of a plurality of documents from the temporary data storage unit 203, and is a color document for the image data of the plurality of adjustment documents. ACS determination is performed to determine whether the document is a monochrome document. It is assumed that the ACS determination unit 204 performs ACS determination using a color document threshold described later.

When the ACS determination is completed, the ACS determination unit 204 notifies the ACS threshold adjustment unit 205 of the determination results of the image data of a plurality of documents and the adjustment mode information.
When the ACS threshold value adjustment unit 205 receives the determination result of the image data of a plurality of documents and the information of the adjustment mode, the ACS threshold value adjustment unit 205 performs ACS threshold value determination processing. When the ACS threshold value determination process is completed, the ACS threshold value adjustment unit 205 performs ACS determination by the ACS determination unit 204 using the determined ACS threshold value. The ACS threshold value adjustment unit 205 notifies the user interface unit 201 of the result of ACS determination of the image data of a plurality of documents performed using the determined ACS threshold value.

When the user interface unit 201 receives the determination results of the image data of a plurality of documents, the user interface unit 201 displays an ACS threshold value adjustment result display screen 40 shown in FIG.
The user interface unit 201 classifies the document number as information for identifying a plurality of documents based on the ACS determination result received from the ACS threshold adjustment unit 205 into color or monochrome and displays it in the ACS determination result area 41.

When the ACS threshold is changed by the ACS threshold adjustment slide 42 on the ACS threshold adjustment result display screen 40, the user interface unit 201 performs the ACS determination by the ACS determination unit 204 using the changed ACS threshold, and the ACS threshold adjustment unit. Based on the ACS determination result received from 205, the document number as information for identifying a plurality of documents is classified into color or monochrome and redisplayed in the ACS determination result area 41.
When the user interface unit 201 detects that the “apply” button 43 on the ACS threshold value adjustment result display screen 40 is pressed by the user, the user interface unit 201 displays the ACS threshold value registration screen 50 shown in FIG.

When the user interface unit 201 detects that the “apply” button 55 on the ACS threshold value registration screen 50 is pressed by the user, the user interface unit 201 notifies the ACS threshold value adjustment unit 205 and the threshold value registration unit 206 of a threshold value registration command. When the ACS threshold adjustment unit 205 receives the threshold registration command, the ACS threshold adjustment unit 205 notifies the threshold registration unit 206 of the adjusted threshold information. Upon receiving the adjusted threshold information, the threshold registration unit 206 registers the threshold information in the image processing apparatus 200.
In this way, the image processing apparatus 200 performs the ACS threshold adjustment process.

The operation of the above configuration will be described.
First, an outline of the operation of the multifunction machine will be described with reference to FIGS. 1 and 2. An example of a copying process in which an image of a document read by the multifunction peripheral 100 is printed on a medium will be described.
The multifunction device 100 reads the document placed on the placement table 102 or the ADF 105 by the user with the image sensor 103. A document reading unit 202 of the image processing apparatus 200 provided in the multifunction peripheral 100 generates image data of a document read by the image sensor 103 and stores it in the temporary data storage unit 203.
The ACS determination unit 204 reads the image data of the original document stored in the temporary data storage unit 203 and performs ACS determination using the ACS threshold value registered by the threshold value registration unit 206.

The multifunction peripheral 100 prints the image data of the original read by the image sensor 103 by the printer 108 based on the ACS determination result of the ACS determination unit 204 of the image processing apparatus 200.
At this time, the multifunction peripheral 100 prints the image data determined to be a color document by the ACS determination on a medium using color toners such as yellow, magenta, cyan, and black by the printer 108.
In addition, the multi-function device 100 converts the image data determined to be a monochrome original by the ACS determination into monochrome image data, and the converted image data is printed on a medium using a black toner or the like by the printer 108.

Next, the ACS threshold adjustment process performed by the image processing apparatus will be described with reference to FIGS. 1, 2, and 3 in accordance with the step represented by S in the flowchart showing the flow of the ACS threshold adjustment process in the embodiment of FIG. .
S101: When the user interface unit 201 of the image processing apparatus 200 detects that the operation button 13 for selecting the “ACS adjustment” function is pressed on the image quality adjustment screen 10 illustrated in FIG. 3A, the user interface unit 201 illustrated in FIG. The ACS threshold adjustment setting screen 20 is displayed on the operation panel 106.

When detecting that the “ACS threshold adjustment” selection button 23 is pressed on the ACS threshold adjustment setting screen 20 shown in FIG. 3B, the user interface unit 201 displays the ACS threshold adjustment original input screen 30 shown in FIG. The information is displayed on the operation panel 106, and the process proceeds to S102. On the other hand, when the basic level base or the registration mode base is selected on the ACS threshold adjustment setting screen 20 and the pressing of the “apply” button 24 is detected, the process proceeds to S109.
S102: It is assumed that the user sets a plurality of ACS threshold adjustment originals in the ADF 105 of the image processing apparatus 200 in accordance with the guide message displayed on the ACS threshold adjustment original input screen 30.

S103: Furthermore, it is assumed that the user presses the “color mode” selection button 32 or the “monochrome mode” selection button 33 for selecting a mode displayed on the ACS threshold adjustment original input screen 30.
When the user interface unit 201 detects that the “color mode” selection button 32 or the “monochrome mode” selection button 33 is pressed on the ACS threshold adjustment original input screen 30, the user interface unit 201 notifies the reading unit 202 of a reading command. When the user interface unit 201 detects that the “color mode” selection button 32 is pressed, the user interface unit 201 sets the color mode as adjustment mode information. When detecting that the “monochrome mode” selection button 33 is pressed, the user interface unit 201 sets the monochrome mode as adjustment mode information.

Upon receiving the reading command, the document reading unit 202 reads a plurality of documents placed on the ADF 105 and sends image data of the read documents to the temporary data storage unit 203. Further, the document reading unit 202 notifies the user interface unit 201 that the reading is completed.
When the user interface unit 201 receives the notification that the reading is completed, the user interface unit 201 notifies the temporary data storage unit 203 of the adjustment mode information of the image data of the plurality of read documents.
The temporary data storage unit 203 receives image data of a plurality of documents sent from the document reading unit 202. The temporary data storage unit 203 receives the adjustment mode information notified from the user interface unit 201. The temporary data storage unit 203 stores adjustment mode information together with image data of a plurality of documents.

S104: After reading a plurality of documents in S103, when the user interface unit 201 detects that the user presses the “start” button 34 on the ACS threshold adjustment document input screen 30, the process proceeds to S105. If the pressing of the “Start” button 34 is not detected, the process proceeds to S102 in order to continue reading the document.
S105: When the user interface unit 201 detects that the user presses the “start” button 34 on the ACS threshold value adjustment document input screen 30 in S103, the user interface unit 201 notifies the ACS determination unit 204 of an ACS determination start command.

When the ACS determination unit 204 receives the ACS determination start command, the ACS determination unit 204 acquires the image data and the adjustment mode of the plurality of documents read in S103 from the temporary data storage unit 203, and calculates the number of color pixels in the image data of the plurality of documents. To do.
The color pixel is determined using gradation information in the RGB color space (for example, a monochrome pixel when the gradation value is close, or a color pixel when the gradation value is separated) or CIEL. It is assumed that this is performed using a known technique such as a method of determining whether a color pixel or a monochrome pixel using the * a * b * color space.

S106: The ACS determination unit 204 compares the number of color pixels calculated from the image data of a plurality of documents with the color document threshold value as the adjustment threshold value in the ACS threshold value adjustment process, and determines the number of color pixels larger than the color document threshold value. An ACS determination is performed in which the document having the color pixel number smaller than the color document threshold is determined to be a monochrome document.
When the ACS determination is completed, the ACS determination unit 204 notifies the ACS threshold adjustment unit 205 of the determination results of the image data of a plurality of documents and the adjustment mode information.

S107: When the ACS threshold value adjustment unit 205 receives the determination result of the image data of a plurality of documents and the information of the adjustment mode in S106, the ACS threshold value adjustment unit that the determination result of the image data of the plurality of documents becomes the adjustment mode. ACS threshold value determination processing is performed to determine the ACS threshold value so that When the ACS threshold value determination process is completed, the ACS threshold value adjustment unit 205 notifies the user interface unit 201 of the result of the determination of the image data of a plurality of documents performed using the determined ACS threshold value and the ACS threshold value. Details of the ACS threshold value determination process will be described later.
When the user interface unit 201 receives the determination result of the image data of a plurality of documents and the ACS threshold value, the user interface unit 201 displays the ACS threshold value adjustment result display screen 40 shown in FIG.

S108: The user refers to the ACS threshold adjustment result display screen 40 displayed on the operation panel 106, and presses the “apply” button 43 or the “delete” button on the ACS threshold adjustment result display screen 40.
When the user interface unit 201 detects that the “apply” button 43 on the ACS threshold value adjustment result display screen 40 is pressed by the user, the user interface unit 201 proceeds to S109 and detects that the “delete” button is pressed. The process proceeds to S102.

S109: When the user interface unit 201 detects that the “apply” button 43 on the ACS threshold adjustment result display screen 40 is pressed by the user, the user interface unit 201 displays the ACS threshold registration screen 50 shown in FIG. To do.
Further, when the user interface unit 201 detects that the “apply” button 55 on the ACS threshold value registration screen 50 is pressed by the user, the user interface unit 201 notifies the ACS threshold value adjustment unit 205 and the threshold value registration unit 206 of a threshold value registration command. When the ACS threshold adjustment unit 205 receives the threshold registration command, the ACS threshold adjustment unit 205 notifies the threshold registration unit 206 of the adjusted threshold information. Upon receiving the adjusted threshold value information, the threshold value registration unit 206 registers the threshold value information in the image processing apparatus 200, and ends this processing.

When the user interface unit 201 detects that the basic level base or the registration mode base is selected on the ACS threshold adjustment setting screen 20 and the “Apply” button 24 is pressed in S101, the selected basic level base or The registration mode base information is notified to the threshold value registration unit 206, and the threshold value registration unit 206 registers the information in the image processing apparatus 200, and the process ends.
In this way, the image processing apparatus 200 performs ACS threshold value adjustment processing.

Next, ACS threshold determination processing performed by the image processing apparatus will be described.
First, an explanatory diagram of the ACS threshold value determining method in the embodiment of FIG. 6 will be described.
In FIG. 6, a table 60 for explaining the ACS threshold value determining method includes an adjustment document 61, a color pixel number 62, a user-specified adjustment mode 63, a color document threshold range 64, a color document threshold (Thd2) 65, and a matching rate 66. , And a determination result 67.

The adjustment document 61 represents a plurality of ACS threshold adjustment document names used in this embodiment. In this embodiment, four color originals (1 to 4) and three monochrome originals (1 to 3) are set in the ADF 105 of the image processing apparatus 200 and read twice.
The number of color pixels 62 represents the number of color pixels detected from document image data obtained by reading each document of the adjustment document 61.

The user-specified adjustment mode 63 represents a determination mode (color (color mode) / mono (monochrome mode)) of the read ACS threshold value adjustment document. In this embodiment, it is a determination mode (color mode / monochrome mode) of a document input on the ACS threshold adjustment document input screen 30 shown in FIG.
The color document threshold range 64 represents an ACS threshold adjustment range for each document to be in the determination mode represented by the user-specified adjustment mode 63. For example, when the adjustment document 61 is the color document 4, the ACS threshold adjustment range is less than 610, and when the adjustment document 61 is the monochrome document 1, the ACS threshold adjustment range is greater than 700.

A color document threshold (Thd2) 65 represents an ACS threshold for allowing each document to enter the determination mode represented by the user-specified adjustment mode 63. For example, when the adjustment original 61 is the color original 4, the ACS threshold is 609, and when the adjustment original 61 is the monochrome original 1, the ACS threshold is 701.
The coincidence rate 66 is the coincidence between the ACS determination result (color or monochrome) of each document that has been subjected to ACS determination with the threshold value represented by the color document threshold (Thd2) 65 and the mode (color or monochrome) of the user-specified adjustment mode 63 Represents the rate.

  For example, when the color original threshold (Thd2) 65 is set to 799, the color original 1 (color pixel number 62 = 800) having a color pixel number 62 greater than 799 is determined as “color”, and the color pixel number 62 is Color originals 2 to 4 and monochrome originals 1 to 3 of 799 or less are determined as “mono”. Therefore, in this case, the color original 1 and the monochrome originals 1 to 3 have the same ACS determination result and the user-specified adjustment mode 63 mode, and the color originals 2 to 4 have the ACS determination result and the mode inconsistent, and the matching rate 66 Becomes 4/7.

  When the color document threshold (Thd2) 65 is 609, the color documents 1 to 4 and the monochrome document 1 in which the color pixel number 62 is larger than 609 are determined as “color”, and the color pixel number 62 is 609 or less. The monochrome originals 2 and 3 are determined to be “mono”. Therefore, in this case, the color originals 1 to 4 and the monochrome originals 2 and 3 have the same mode as the ACS determination result, and the monochrome original 1 has the ACS determination result and the user-specified adjustment mode 63 in the same mode, and the matching rate 66 Becomes 6/7.

  Further, when the color document threshold (Thd2) 65 is set to 701, the color document 1 having the color pixel number 62 larger than 701 is determined as “color”, and the color documents 2 to 4 having the color pixel number 62 of 701 or less are determined. The monochrome originals 1 to 3 are determined to be “mono”. Accordingly, in this case, the color original 1 and the monochrome originals 1 to 3 have the same ACS determination result and the user-specified adjustment mode 63 mode, and the color originals 2 to 4 have the ACS determination result and the user-specified adjustment mode 63 mode. The coincidence rate 66 is 4/7.

In this embodiment, the smallest color original threshold 65 (for example, Thd2 = 609) when the mode of the user-specified adjustment mode 63 is color and the largest color original threshold 65 (when the mode of the user-specified adjustment mode 63 is monochrome) ( For example, a color original threshold value (for example, Thd2 = 609) having the highest matching rate 66 among Thd2 = 701) is adopted as the ACS threshold value.
The determination result 67 represents the determination result at the adopted color document threshold (for example, Thd2 = 609).

Next, the ACS threshold value determining process performed by the image processing apparatus will be described with reference to FIGS. 1, 2, and 6 in accordance with the step represented by S in the flowchart showing the ACS threshold value determining process in the embodiment of FIG. .
S201: The ACS threshold adjustment unit 205 receives information about the number of color pixels and the adjustment mode of the image data of a plurality of documents from the ACS determination unit 204.

  When the ACS threshold value adjustment unit 205 receives the information on the number of color pixels and the adjustment mode of each document, the ACS threshold value adjustment unit 205 calculates the range of the color document threshold and the color document threshold based on the information on the number of color pixels and the adjustment mode. Here, the number of color pixels of each original corresponds to the number of color pixels 62 shown in FIG. 6, and the information of the adjustment mode of each original corresponds to the user-specified adjustment mode 63 shown in FIG.

  The ACS threshold value adjustment unit 205 sets the color document threshold value range to a range smaller than the number of color pixels when the information of the adjustment mode of each document is “color (color)”, and sets the adjustment mode of each document. When the information is “mono”, the color document threshold range is calculated for each document so that the color document threshold range is larger than the number of color pixels, and the color document threshold range is set to the range. Based on this, a color document threshold value for each document is calculated.

Here, the color document threshold is an adjustment threshold value, and is a value obtained by subtracting “1” from the minimum number of color pixels when a plurality of documents are read in the color mode. When read, it is a value obtained by adding “1” to the maximum number of color pixels.
The ACS threshold value adjustment unit 205 calculates the color document threshold value for each image of the document whose document type is designated as color by subtracting 1 from the number of color pixels for each image of the document calculated by the ACS determination unit 204, The color document threshold value for each document image designated as monochrome is calculated by adding 1 from the number of color pixels for each document image calculated by the ACS determination unit 204.

For example, as shown in FIG. 6, when the number of color pixels 62 determined from the color original 1 is 800 and the user-specified adjustment mode 63 is “color (color)”, the original is “color (color)”. The color document threshold range and the color document threshold value are calculated so that the color document threshold value is 799 pixels, which is one less than 800 pixels of 62 color pixels, and the color pixels determined from the monochrome document 1 When the number 62 is 700 and the user-specified adjustment mode 63 is “mono (monochrome)”, the color document threshold range and the color document threshold are calculated so that the document is determined to be “mono (monochrome)”. The color document threshold is set to 701 pixels, which is one more than 700 pixels having 62 color pixels.
As described above, the range of the color document threshold calculated by the ACS threshold adjustment unit 205 is the color document threshold range 64 shown in FIG. 6, and the color document threshold is the color document threshold 65 shown in FIG.

S202: The ACS threshold adjustment unit 205 determines whether each document is a color document or a monochrome document based on the color document threshold for each document calculated in S201, and the determination result and the user Calculate the match rate with the specified adjustment mode.
This match rate is the match rate 66 shown in FIG. 6, and the ACS threshold value adjustment unit 205 calculates the match rate 66 for each color document threshold value 65. The method for calculating the coincidence rate 66 is as described above.

S203: The ACS threshold adjusting unit 205 determines the ACS threshold value that has the highest match rate calculated in S202 from the smallest color document threshold value when the mode is color and the largest color document threshold value when the mode is monochrome. This process is terminated.
That is, the ACS threshold value adjustment unit 205 sets the first adjustment threshold value that is the smallest of the color document threshold values for each document image whose document type is specified as color, and each document image whose document type is specified as monochrome. The second adjustment threshold value having the largest value among the color original threshold values is calculated, and the matching rate of the first adjustment threshold value (matching rate calculated in S202) and the matching rate of the second adjustment threshold value (S202). The color original threshold value having a high matching rate is determined as the ACS threshold value.

For example, the smallest color original threshold value 65 (for example, Thd2 = 609) when the mode of the user-specified adjustment mode 63 shown in FIG. 6 is color and the largest color original threshold value 65 when the mode of the user-specified adjustment mode 63 is monochrome. Among the (for example, Thd2 = 701), the color original threshold value (for example, Thd2 = 609) with the highest matching rate 66 is determined as the ACS threshold value.
Thus, by determining the ACS threshold in consideration of the determination results of a plurality of documents, the accuracy of ACS determination is improved. By suppressing the determination of a monochrome original as a color original, color toner consumption can be reduced.

  The image processing apparatus 200 according to the present exemplary embodiment performs ACS determination by calculating the number of color pixels by the ACS determination unit 204 for each image of the document read by the document reading unit 202, and the document type in which the ACS determination result is designated. Color document threshold values are calculated so that they match, and the respective color document threshold values are set as ACS threshold values, and color / monochrome determination is performed for all document images, and the color / monochrome determination result matches the specified document type By calculating the rate and determining and adjusting the ACS threshold based on the color document threshold and the matching rate, the accuracy of color / monochrome determination can be improved.

In this embodiment, a plurality of ACS threshold adjustment originals are set on the ADF of the multifunction peripheral to read the original image, but may be set on a flat bed to read the original image. .
In this embodiment, a plurality of documents for ACS threshold adjustment are specified by inputting an adjustment mode separately for color and monochrome. However, images of a plurality of documents mixed with color and monochrome are read. Thereafter, an adjustment mode may be input for each original.

  As described above, in this embodiment, ACS determination is performed for each read document image, and the color document threshold value is calculated so that the result of the ACS determination matches the specified document type. By calculating the matching rate with the document type, and determining and adjusting the ACS threshold based on the calculated color document threshold and the matching rate, it is possible to improve the accuracy of color / monochrome determination. It is done.

In addition, since the ACS determination results of a plurality of documents are displayed on the display unit using the adjusted ACS threshold, the user can adjust to the appropriate ACS threshold while referring to the displayed ACS determination results. The effect that it can be obtained.
In this embodiment, the image forming apparatus including the scanner and the printer has been described as including the image processing apparatus. However, the present invention is not limited thereto, and the image reading apparatus including the scanner includes the image processing apparatus. It may be provided with.

DESCRIPTION OF SYMBOLS 100 Multifunction machine 101 Scanner 102 Mounting stand 103 Image sensor 104 Mounting stand cover 105 ADF
106 Operation Panel 108 Printer 109 Cassette 200 Image Processing Device 201 User Interface Unit 202 Document Reading Unit 203 Temporary Data Storage Unit 204 ACS Determination Unit 205 ACS Threshold Adjustment Unit 206 Threshold Registration Unit

Claims (9)

An operation unit for accepting an input operation for designating a color or monochrome document type for a plurality of documents to be read;
A reading unit for reading images of the plurality of documents;
For each document image read by the reading unit, the number of color pixels is calculated, and when the number of color pixels exceeds a threshold value, it is determined as color, and when the threshold value is not exceeded, color monochrome determination is performed. A determination unit to perform;
An adjustment threshold value is calculated for each document image so that the result of the color / monochrome determination matches the specified document type, and the color / monochrome determination is performed on the document image using the calculated adjustment threshold value as the threshold value. An adjustment unit that calculates a matching rate between the color / monochrome determination result and the designated document type, and determines the threshold based on the adjustment threshold and the matching rate;
A registration unit for registering the threshold value determined by the adjustment unit;
An image processing apparatus comprising: The image processing apparatus according to claim 1.
The adjustment unit is
The first adjustment threshold value that is the smallest value among the adjustment threshold values for each image of the document for which the document type is specified as color, and the adjustment threshold value for each image of the document for which the document type is specified as monochrome. The second adjustment threshold value with the largest value is calculated,
The image processing apparatus further compares the matching rate of the first adjustment threshold with the matching rate of the second adjustment threshold, and determines an adjustment threshold having a high matching rate as the threshold. The image processing apparatus according to claim 1 or 2,
The adjustment unit is
Calculating the adjustment threshold value for each image of the document in which the document type is specified as color by subtracting 1 from the number of color pixels for each image of the document calculated by the determination unit;
The image processing is characterized in that the adjustment threshold value for each image of the document whose document type is designated as monochrome is calculated by adding 1 from the number of color pixels for each image of the document calculated by the determination unit. apparatus. The image processing apparatus according to any one of claims 1 to 3,
The adjustment unit is
An image processing apparatus, wherein information for identifying the plurality of originals is classified into color or monochrome based on a color / monochrome determination result performed with the determined threshold value and displayed on a display unit. The image processing apparatus according to any one of claims 1 to 4,
The operation unit is
An image processing apparatus comprising means for changing a threshold value determined by the adjustment unit. The image processing apparatus according to claim 5.
The adjustment unit is
An image characterized in that information for identifying the plurality of documents is classified into color or monochrome based on the color / monochrome determination result performed by the determination unit with the threshold value changed by the operation unit and displayed on the display unit. Processing equipment.   An image forming apparatus comprising the image processing apparatus according to claim 1.   An image reading apparatus comprising the image processing apparatus according to claim 1. In the image processing method performed by the image processing apparatus,
Receiving an input operation for specifying a color or monochrome document type for a plurality of documents to be read;
Reading images of the plurality of documents;
For each document image read by the reading unit, the number of color pixels is calculated, and when the number of color pixels exceeds a threshold value, it is determined as color, and when the threshold value is not exceeded, color monochrome determination is performed. Steps to do,
An adjustment threshold value is calculated for each document image so that the result of the color / monochrome determination matches the specified document type, and the color / monochrome determination is performed on the document image using the calculated adjustment threshold value as the threshold value. Calculating a matching rate between the color / monochrome determination result and the designated document type, and determining the threshold based on the adjustment threshold and the matching rate;
Registering the threshold determined by the adjustment unit;
An image processing method comprising:

Images