JP7211209B2 - IMAGE PROCESSING APPARATUS, PROGRAM, IMAGE FORMING APPARATUS, AND CONTROL METHOD - Google Patents

Description

The present invention relates to an image processing apparatus, a program for controlling the image processing apparatus, an image forming apparatus, and a control method for the image processing apparatus.

2. Description of the Related Art Conventionally, there is known an image processing apparatus that reads an image of a document and outputs the image to a sheet of paper, a display, or the like. Further, such an image processing apparatus can select a black-and-white image output when outputting a read image, and may have a function of outputting a black-and-white image converted by a black-and-white binarization process.

Some image processing apparatuses of this type are equipped with a blank sheet determination function for determining whether or not a document is a blank document. However, when the above-described binarization processing is performed on an image that has been determined not to be blank in the blank page determination, the image may be blanked by the binarization processing, and the blank page may be output as it is. .

In order to solve this problem, for example, Japanese Patent Application Laid-Open No. 2002-200000 discloses that blank page determination is performed on images before and after conversion to black and white by binarization processing, so that whether or not the document is a blank page is accurately determined. An image processing apparatus equipped with functions is disclosed.

JP 2015-65638 A

With the technique described in Patent Document 1, it was necessary to perform blank page determination multiple times in order to perform blank page determination after binarization processing. If accurate blank page determination can be made by one blank page determination regardless of the presence or absence of binarization processing, the time required for blank page determination can be expected to be shortened.

SUMMARY OF THE INVENTION Accordingly, it is an object of one aspect of the present invention to provide an image processing apparatus and the like that can accurately perform blank page determination for an image to be subjected to binarization processing by one blank page determination.

In order to solve the above problems, an image processing apparatus according to an aspect of the present invention includes an acquisition unit that acquires a multi-tone image by reading a document, and a control unit. One page included in the gradation image is defined as a determination target page, and for the determination target page, a first frequency that is the sum of frequencies of pixels having a luminance value that is equal to or greater than the first threshold, and the above that is less than the first threshold a frequency acquisition process for acquiring a second frequency that is the sum of frequencies of pixels having luminance values; a single-color/multi-color determination process for determining that the page to be determined is multi-color if it is monochrome and both the first frequency and the second frequency are less than a second threshold, and the single-color/multi-color determination For the determination target page determined to be multicolored in the process, the multi-tone image related to the page is subjected to image conversion into a binary image based on the comparison between the first threshold value and the luminance value. and outputting the binary image, and for the determination target page determined to be monochrome in the monochrome/multicolor determination process, image output not outputting the image corresponding to the multi-tone image related to the page. Execute judgment processing.

According to the above configuration, the first threshold used for image conversion to a binary image is also used for monochrome/multicolor determination processing. Therefore, the monochrome/multicolor determination process calculates the frequency of the luminance value of each pixel in the binary image after image conversion, and uses the calculation result to determine whether the binary image after image conversion is monochrome. can. Therefore, it is possible to suppress the phenomenon that the page to be judged in the multi-tone image is not monochromatic, but the binary image after the image conversion is monochromatic only by performing the monochromatic/multicolor judging process once.

In order to solve the above problems, a control method according to one aspect of the present invention is a control method for an image processing apparatus including an acquisition unit that acquires a multi-tone image by reading a document, comprising: A page included in is a determination target page, and for the determination target page, a first frequency that is the sum of frequencies of pixels having a luminance value that is equal to or greater than a first threshold, and the luminance value that is less than the first threshold a frequency acquiring step of acquiring a second frequency that is the sum of the frequencies of the pixels having the a single-color/multi-color determination step, wherein if both the first frequency and the second frequency are less than a second threshold value, the page to be determined is determined to be multi-color; and the single-color/multi-color determination step. For the determination target page determined to be multicolored, the multi-tone image of the page is subjected to image conversion into a binary image based on the comparison between the first threshold value and the luminance value. an image output determination step of outputting a value image and not outputting an image corresponding to the multi-tone image of the determination target page determined to be monochrome in the monochrome/multicolor determination step; ,including.

According to one aspect of the present invention, it is possible to provide an image processing apparatus and the like that can accurately perform blank page determination for an image to be binarized by one blank page determination.

1 is a block diagram showing an example configuration of an MFP (Multi-Function Peripheral) according to an embodiment of the present invention; FIG. 7 is a flowchart showing an example of monochrome page removal processing; FIG. 4 is a diagram showing an example of dividing a document into a plurality of blocks; 8 is a flowchart illustrating an example of frequency acquisition processing; FIG. 4 is a diagram showing an example of a histogram of luminance values; 7 is a flowchart illustrating an example of binary image necessity determination processing; 6 is a flowchart showing an example of blank page removal processing;

An embodiment of the present invention will now be described in detail with reference to FIGS.

<Hardware configuration>
An MFP (Multi-Function Peripheral) 1 as an example of an image processing apparatus includes an image forming section 10, an image reading section 20, an operation panel 30, and a network interface (I/F) 40, as shown in FIG. , and a control unit 50 .

An image forming unit 10, which is an example of a processing unit, executes printing (color printing or monochrome printing) based on image data, and forms a developer image based on the image data on a recording medium such as printing paper. An image forming method may be an electrophotographic method or an inkjet method. The image forming section 10 may also generate digital image data to be output to an external PC or the like connected via the network interface 40 .

An image reading unit 20, which is an example of an acquisition unit, reads an image of a document and generates image data. The reading method may be an ADF (Auto Document Feeder) method that reads the image of the document while conveying the document, or an FB (Flat Bed) method that reads the image of the document by placing the document on the contact glass. ) method may be used.

The operation panel 30 has a touch panel. Various types of information such as the state of the MFP 1 are displayed on the touch panel. Moreover, various inputs by the user are possible by performing a touch operation on the touch panel. The operation panel 30 may be provided with input keys such as numeric keys.

Since the MFP 1 includes a network interface 40, it can communicate with an external device such as a PC (personal computer) connected to a LAN (Local Area Network) via the LAN.

The control unit 50 includes a CPU 51 , a ROM 52 , a RAM 53 , an NVRAM (Non Volatile RAM) 54 and an ASIC 55 . The CPU 51 controls the image forming section 10 , the image reading section 20 , and the operation panel 30 by executing programs for various processes, and controls data communication via the network interface 40 . The ROM 52 stores programs executed by the CPU 51 and various data. The RAM 53 is used as a work area when the CPU 51 executes programs. The NVRAM 54 stores various setting values and the like input from the operation panel 30 .

<Functions and Settings>
The MFP 1 reads an image of a document using an image reading unit 20, and outputs image data based on the read image to a print sheet or the like using the image forming unit 10, or outputs the image data to an external PC or the like via a network interface 40. It has a reading function.

When using this reading function, the user can operate the operation panel 30 to change the output settings. As output settings, for example, three types of BW (black and white), gray, and color are prepared. The image reading unit 20 reads the image of the document as a multi-gradation image, which is multi-gradation digital image data, regardless of which output setting is set. A multi-tone image includes at least multi-tone luminance value data. Also, the manuscript may include a plurality of pages. In this case, the multi-tone image includes multiple pages of digital image data.

When "output setting: BW" is set, the MFP 1 performs image conversion to convert the read multi-tone image into a black and white binary image, and outputs the binary image. When "output setting: gray" or "output setting: color" is set, for example, a gray Jpeg image or a color Jpeg image with 256 gradations is output.

Also, the MFP 1 has a monochrome image removing function. The single-color image removal function determines whether or not the image of the document read by the image reading unit 20 is a single-color image such as white or black, and outputs the image if it is a single-color image. It is a function that does not Note that the MFP 1 can enable a blank page removal function, which does not output an image only when the original is blank, among monochrome image removal functions. The user can operate the operation panel 30 to set whether to enable or disable the monochrome image removal function or the blank page removal function.

In addition, in the conventional MFP, when "output setting: BW" is set, even if the single-color image removal function is set to be effective, the output image may be in white or black. was there. For example, when it is determined whether or not a multi-tone image read by the MFP is a monochrome image, it is determined that the image is not a monochrome image, but after image conversion to a binary image, almost all This is the case where an image with white or black pixels is generated and output.

On the other hand, according to the MFP 1 according to the present embodiment, when "output setting: BW" is set, determination of whether or not the image is a monochrome image is performed using image conversion to a binary image as described later. Refers to the luminance value threshold for As a result, the MFP 1 can determine whether or not the binary image after the image conversion is monochromatic, so that when the monochromatic image removal function is set to be valid, the monochromatic image is not output.

Further, according to the MFP 1, in order to solve the above-mentioned problems, it is determined whether or not the multi-tone image is a monochrome image before image conversion to a binary image, and furthermore, it is converted to a binary image. It is not necessary to determine whether the binary image is a monochrome image after the image conversion of . Therefore, for example, it is not necessary to provide a dedicated circuit or the like for determining whether a binary image is a monochrome image, and the configuration of the MFP 1 can be simplified. Also, it is expected that the time required for determining whether or not the image is a monochrome image can be shortened.

<Processing in Monochromatic Image Removal Function>
In order to implement the single-color image removal function, the CPU 51 of the control unit 50 executes a program to perform single-color page removal processing including frequency acquisition processing, single-color/multicolor determination processing, and image output determination processing. Run. Each of these processes will be described below as an example of the control method of the MFP 1 .

(Single color page removal processing)
The monochrome page removal process will be described below with reference to FIG. The CPU 51 sets one page included in the multi-tone image read by the image reading section 20 as a determination target page. As shown in FIG. 3, the CPU 51 divides the determination target page into a plurality of blocks in a grid pattern (S1). At this time, the size of each block is expressed as blk_sizex×blk_sizey. The CPU 51 appropriately sets the values of blk_sizex and blk_sizey according to the number of blocks obtained by division.

Next, the CPU 51 executes frequency acquisition processing for each block and acquires the mode value (S2). The frequency acquisition process will be described later. The CPU 51 executes single-color/multi-color determination processing for determining whether or not the mode value is equal to or greater than the single-color determination threshold hindo_th (S3, single-color/multi-color determination step). Note that the monochrome determination threshold hindo_th is an example of a second threshold. If the mode value is greater than or equal to the single-color determination threshold value hindo_th (YES in S3), the CPU 51 sets the attribute of the block for which the determination was performed as a single-color block (S4), and determines that the mode value is less than the single-color determination threshold value hindo_th. If so (NO in S3), the attribute of the block for which the determination has been executed is set as a multicolor block (S5). The CPU 51 stores the set attribute of the block in the RAM 53 .

If only the first frequency and the second frequency are acquired in the frequency acquisition process to be described later, and the mode frequency value is not acquired, the CPU 51 determines that each of the first frequency and the second frequency is greater than or equal to the single-color determination threshold hindo_th. It may be determined whether or not In this case, if at least one of the first frequency and the second frequency is greater than or equal to the single-color determination threshold hindo_th, the CPU 51 sets the attribute of the block for which the determination was performed as a single-color block.

Next, the CPU 51 determines whether or not the determination of S3, that is, whether the block is a single-color block or a multi-color block, has been performed for all blocks included in the determination target page (S6). If the determination of S3 has not been completed for all blocks (NO in S6), the CPU 51 executes the processes from S2 to S5 until the determination of all blocks is completed. On the other hand, if the determination in S3 has been completed for all blocks (YES in S6), the CPU 51 counts the number of blocks whose attribute is set to monochromatic block (S7).

Then, the CPU 51 determines whether or not the ratio of single-color blocks to all blocks included in the determination target page is equal to or greater than the single-color block threshold value plane_blk_weight (S8). When the proportion of monochrome blocks included in the determination target page is equal to or greater than the monochrome block threshold value plane_blk_weight (YES in S8), the CPU 51 sets the attribute of the determination target page as a monochrome page (S9), and the page is included in the determination target page. If the ratio of single-color blocks is less than the single-color block threshold value plane_blk_weight (NO in S8), the attribute of the determination target page is set as a multicolor page (S10).

Next, the CPU 51 executes image output determination processing (S11), and terminates the monochrome page removal processing.

As described above, if either one of the first frequency and the second frequency is greater than or equal to the single-color determination threshold hindo_th for the entire determination target page, the CPU 51 determines that the determination target page is monochrome, and the first frequency and the second frequency are less than the single-color determination threshold value hindo_th, a process for determining that the page to be determined is multi-color is executed.

Note that the monochrome block threshold value plane_blk_weight is a value that allows the page to be judged to include multi-colored blocks with a margin of error, and that the ratio of multi-colored blocks included in the page to be judged is within the error range. Preferably. Examples of such values include, but are not limited to, 99% and 98%.

Note that when the multi-tone image includes a plurality of pages, the CPU 51 executes the above-described single-color page removal processing for all pages.

(Frequency acquisition process)
The frequency acquisition process executed in S1 of the monochrome page removal process shown in FIG. 2 will be described below with reference to FIGS. 4 and 5. FIG.

The CPU 51 generates a histogram of luminance values of each pixel in the block (S21). Here, a case where the gradation of the luminance value included in the multi-gradation image is 6 bits (0 to 63) will be described as an example. Note that if the gradation of the luminance value included in the multi-gradation image is greater than 6 bits, the CPU 51 may convert the gradation of the luminance value to 6 bits. As shown in FIG. 5, the luminance value histogram is expressed with the luminance value k on the horizontal axis and the frequency value h(k) representing the frequency of pixels having the luminance value k on the vertical axis. The CPU 51 stores the generated luminance value histogram in the RAM 53 .

Next, the CPU 51 determines whether or not all pixels in the block have been scanned (S22). If the CPU 51 determines in S21 that all the pixels in the block have not been scanned and there is a pixel whose brightness value is not reflected in the histogram (NO in S22), the CPU 51 completes the scanning of all the pixels in the block. The process of S21 is repeated until it does. On the other hand, when it is determined that all pixels have been scanned and the luminance values of all pixels have been reflected in the histogram (YES in S22), the CPU 51 determines whether the MFP 1 is set to "output setting: BW", that is, determines whether the final output is BW (black and white) (S23).

If the MFP 1 is not set to "output setting: BW" (NO in S23), that is, if the output setting is set to gray or color, the CPU 51 determines the most frequent value h(k) in the histogram. A mode value k_max, which is the value of the luminance value k with a high value, is acquired as a "mode value". On the other hand, when the MFP 1 is set to "output setting: BW" (YES in S23), the CPU 51 calculates the sum of the frequency values h(k) corresponding to the luminance values k equal to or greater than the binarization threshold bw_th in the histogram. The calculated value is obtained as the "first frequency" (S25, frequency obtaining step). The CPU 51 also calculates the sum of the frequency values h(k) corresponding to the luminance values k that are less than the binarization threshold bw_th in the histogram, and acquires the obtained value as the "second frequency" (S26, frequency acquisition step).

Note that the binarization threshold bw_th is an example of a first threshold, and is a luminance value threshold used in image conversion to a binary image. In the image conversion, the CPU 51 converts pixels whose luminance values are equal to or greater than the binarization threshold bw_th to white, and converts pixels whose luminance values are less than the binarization threshold bw_th to black. This results in a binary image with only black or white pixels. In FIG. 5, the binarization threshold bw_th is set to the 51st luminance value k (k=50) from among the luminance values k of 64 gradations, but the binarization threshold bw_th is not limited to this.

The CPU 51 acquires the larger one of the obtained first frequency and second frequency as the "modal frequency value" (S27), saves the modal frequency value in the RAM 53, and ends the frequency obtaining process. According to the configuration for acquiring the mode value in this way, the CPU 51 does not need to compare both the first frequency and the second frequency with the below-described single-color determination threshold hindo_th in the single-color page removal process. Therefore, the CPU 51 can determine whether the document is monochrome or multicolor by simply comparing the mode value and the monochrome determination threshold value hindo_th once. Therefore, it can be expected that the processing of the CPU 51 will be reduced in load and speeded up. Note that the CPU 51 may store each of the first frequency and the second frequency in the RAM 53 without acquiring the mode value.

As described above, in the frequency acquisition process, the CPU 51 sets one page included in the multi-tone image as a determination target page, and sums up the frequency of pixels having luminance values equal to or higher than the binarization threshold bw_th for the entire determination target page. and a second frequency that is the sum of frequencies of pixels having luminance values less than the binarization threshold bw_th.

The values of the binarization threshold bw_th, the single-color determination threshold hindo_th, and the single-color block threshold plane_blk_weight may be set to predetermined values when the MFP 1 is shipped from the factory, or may be set as arbitrary values by the user through the operation panel 30. good too. The binarization threshold bw_th, the single-color determination threshold hindo_th, and the single-color block threshold plane_blk_weight may be stored in the ROM 52 as initial setting values, or may be stored in the NVRAM 54 as user setting values.

(Image output determination processing)
Next, the image output determination process executed in S11 of the monochrome page removal process shown in FIG. 2 will be described below with reference to FIG. First, the CPU 51 refers to the attribute of the determination target page stored in the RAM 53 (S31).

Next, the CPU 51 determines whether or not the attribute of the determination target page is set to monochrome page (S32, image output determination step). If the attribute of the determination target page is not set to monochrome page (NO in S32), the CPU 51 converts the multi-tone image of the page into a binary image based on the comparison between the binarization threshold value and the luminance value. Image conversion is performed (S33), the generated binary image is output to the image forming section 10 (S34), and the image output determination process ends. The image forming unit 10 outputs the input binary image to a print sheet or the like, or outputs it to an external PC or the like via the network interface 40 .

On the other hand, if the attribute of the determination target page is set to monochrome page (YES in S32), the CPU 51 ends the image output determination process without outputting the image corresponding to the multi-tone image related to the page. do. In this case, the CPU 51 may or may not perform image conversion to a binary image for the page to be determined that has been set as a monochrome page.

Here, when image conversion to a binary image is performed, the CPU 51 image-converts all pages included in the multi-tone image to a binary image regardless of the result of the single-color/multi-color determination process. According to this, the CPU 51 can store a low-capacity binary image in the RAM 53 when temporarily storing the multi-tone image in the RAM 53, so that the necessary capacity of the RAM 53 can be saved. Further, when image conversion to a binary image is not performed, the CPU 51 can execute image conversion to a binary image only when necessary. Therefore, it can be expected that the load on the CPU 51 will be reduced and the processing speed will be increased.

<Processing in blank page removal function>
As described above, the single-color image removing function of the MFP 1 includes the blank page removing function. Blank page removal processing executed by the CPU 51 of the control unit 50 to realize the blank page removal function will be described below. Note that the blank page removal process is an example of the monochrome page removal process. Further, since the frequency acquisition process included in the blank page removal process is the same as in the case of the single-color page removal process, description thereof will be omitted here.

(Blank page removal processing)
The blank page removal process will be described below with reference to FIG. The CPU 51 sets one page included in the multi-tone image read by the image reading section 20 as a determination target page. As shown in FIG. 3, the CPU 51 divides the determination target page into a plurality of blocks in a grid pattern (S41). The size of each block is as described above.

Next, the CPU 51 executes the above-described frequency acquisition process for each block and acquires the mode value (S42). The CPU 51 executes single-color/multi-color determination processing for determining whether or not the mode value is equal to or greater than the single-color determination threshold hindo_th (S43, single-color/multi-color determination step). If the mode frequency value is greater than or equal to the single-color determination threshold hindo_th (YES in S43), the CPU 51 determines whether or not the brightness value corresponding to the mode frequency value is greater than or equal to the white page brightness threshold white_th (S44).

Here, the "luminance value corresponding to the mode frequency value" when the MFP 1 is set to "output setting: BW" means the frequency value h(k) among the luminance values k included in the mode frequency value. indicates the largest luminance value k. For example, in S27 of the frequency acquisition process shown in FIG. 4, when the CPU 51 acquires the first frequency as the mode frequency value, the CPU 51 selects the frequency value h ( The luminance value k for which k) is the largest is used as the "luminance value corresponding to the most frequent value" in S44.

When the brightness value corresponding to the mode frequency value is equal to or greater than the blank page determination threshold value white_th (YES in S44), the CPU 51 sets the attribute of the block for which the determination was performed as a blank page block (S45), and the mode frequency value is monochrome determination. If it is less than the threshold hindo_th (NO in S44), or if the brightness value corresponding to the mode frequency value is less than the white page determination threshold white_th (NO in S45), set the attribute of the block for which the determination was performed as a color block. (S46). The CPU 51 stores the set attribute of the block in the RAM 53 .

Next, the CPU 51 determines whether or not the determination of S43 and/or S44, that is, whether the block is a blank block or a color block, has been performed for all blocks included in the determination target page (S47). If the determination of S43 and/or S44 has not been completed for all blocks (NO in S47), the CPU 51 executes the processes of S42 to S46 until the determination of all blocks is completed. On the other hand, if the determination in S43 and/or S44 has been completed for all blocks (YES in S47), the CPU 51 counts the number of blocks whose attribute is set to blank block (S48).

Then, the CPU 51 determines whether or not the ratio of blank blocks to all blocks included in the determination target page is equal to or greater than the monochrome block threshold value plane_blk_weight (S49). If the percentage of blank blocks included in the page to be determined is equal to or greater than the monochrome block threshold value plane_blk_weight (YES in S49), the CPU 51 sets the attribute of the page to be determined as a blank page (S50). If the ratio of blank blocks is less than the monochrome block threshold plane_blk_weight (NO in S49), the attribute of the page to be determined is set as a color page (S51).

Next, the CPU 51 executes image output determination processing, which will be described later (S52), and ends the blank page removal processing.

(Image output determination processing)
The image output determination process in the blank page removal process is the same as the image output determination process in the monochrome page removal process, but in S32 of FIG. 6, it is determined whether the attribute of the page to be determined is set to monochrome page. The only difference is that it is determined whether or not the page is set to a blank page. Other processes are the same as the image output determination process in the single-color page removal process, so the description is omitted here.

As described above, in the blank page removal process, only when the page to be judged becomes a monochrome binary image by image conversion into a binary image and the page to be judged before the image conversion is judged to be blank , the CPU 51 determines that image conversion to a binary image is necessary. That is, if the page to be judged is not blank, the CPU 51 converts the page to be judged into a binary image, and even if the binary image is monochromatic, the image forming section 10 outputs a monochromatic binary image. . Therefore, when a monochrome binary image is output from the MFP 1, the user can recognize that the document is a page other than a blank page. In this case, the user can determine, for example, that there is a problem with image conversion into a binary image, and change the output settings of MFP 1 so that an appropriate image is output from MFP 1 .
<Modification>
Although one embodiment of the present invention has been described above, the present invention can also be implemented in other forms.

In the above-described embodiment, the case where the CPU 51 executes each process has been described. However, the ASIC 55 may execute each process, or the CPU 51 and the ASIC 55 may cooperate to execute each process. Moreover, the control unit 50 may include a plurality of CPUs, and the plurality of CPUs may cooperate to execute each process.

Alternatively, a PC (computer) connected to the Internet may be installed with a program for each process executed by the CPU 51 of the MFP 1 , and the PC may execute the same process as the process executed by the CPU 51 .

Furthermore, the program for each process executed by the CPU 51 of the MFP 1 is installed in a PC (not shown) connected to the MFP 1 via a LAN (Local Area Network), not limited to a PC connected to the Internet. In the PC, processing similar to each processing executed by the CPU 51 may be executed.

Further, in the above-described embodiment, the MFP 1 as an image forming apparatus having a printing function by the image forming unit 10 and a reading function by the image reading unit 20 was taken as an example of the image processing apparatus. It may be a single-function device, such as a reading device with a function.

The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. is also included in the technical scope of the present invention.

1 MFP (image processing device, image forming device)
10 image forming unit (process unit)
20 image reading unit (acquisition unit)
50 control unit

Claims (5)

an acquisition unit that reads a document and acquires a multi-tone image;
a control unit;
The control unit
One page included in the multi-tone image is defined as a determination target page, and for the determination target page, a first frequency that is the sum of frequencies of pixels having a luminance value equal to or greater than a first threshold, and a frequency acquisition process for acquiring a second frequency that is the sum of frequencies of pixels having a certain luminance value;
If at least one of the first frequency and the second frequency is equal to or greater than the second threshold, the page to be determined is monochrome, and if both the first frequency and the second frequency are less than the second threshold, the a single-color/multi-color determination process for determining that the page to be determined is multi-colored;
For the determination target page determined to be multicolor in the single-color/multicolor determination process, the multi-tone image related to the page is a binary image based on the comparison between the first threshold value and the luminance value. Output the binary image by converting the image to
an image output determination process of not outputting an image corresponding to the multi-tone image of the page determined to be monochrome in the monochrome/multicolor determination process; An image processing device characterized by: In the frequency acquisition process, one of the first frequency and the second frequency, which has a larger value, is acquired as a mode frequency value;
In the monochrome/multicolor determination process, if the mode frequency value is equal to or greater than the second threshold value, the page to be determined is determined to be monochrome, and if the mode frequency value is less than the second threshold value, 2. The image processing apparatus according to claim 1, wherein the determination target page is determined to be multicolor. 3. A program that causes a computer to execute each process in the control unit provided in the image processing apparatus according to claim 1 or 2, and causes the computer to function as the control unit. An image processing device according to claim 1 or 2;
In the image output determination process, a developer image is formed on a recording medium based on the binary image after the image conversion is performed for the multicolor page determined to require the image conversion to the binary image. and a process unit for forming an image. A control method for an image processing apparatus including an acquisition unit that acquires a multi-tone image by reading a document,
One page included in the multi-tone image is defined as a determination target page, and for the determination target page, a first frequency that is the sum of frequencies of pixels having a luminance value equal to or greater than a first threshold, and a frequency obtaining step of obtaining a second frequency that is the sum of frequencies of pixels having a certain luminance value;
If at least one of the first frequency and the second frequency is equal to or greater than the second threshold, the page to be determined is monochrome, and if both the first frequency and the second frequency are less than the second threshold, the a single color/multicolor determination step for determining that the page to be determined is multicolor;
For the determination target page determined to be multicolor in the single-color/multicolor determination step, the multi-tone image related to the page is a binary image based on the comparison between the first threshold value and the luminance value. Output the binary image by converting the image to
and an image output determination step of not outputting an image corresponding to the multi-tone image of the determination target page determined to be monochrome in the monochrome/multicolor determination step. control method.

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