JP2020167483A - Image processing apparatus, program, image forming apparatus, and control method - Google Patents

Abstract

To make it possible to perform accurate blank determination in one-time blank determination.SOLUTION: An image processing apparatus comprises an acquisition unit that acquires a multigradation image and a control unit. The control unit executes frequency acquisition processing of acquiring, for a determination target page included in the multigradation image, a first frequency that is the total sum of the frequencies of luminance values equal to or more than a first threshold, and a second frequency that is the total sum of the frequencies of luminance values less than the first threshold, single color/multicolor determination processing of determining that when the first frequency or the second frequency is equal to or more than a second threshold, the determination target page is in a single color, and in other cases, the page is in multicolor, and image output determination processing of outputting a binary image for the determination target page determined to be in multicolor, and not outputting an image for the determination target page determined to be in a single color.SELECTED DRAWING: Figure 1

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 of the image processing apparatus.

Conventionally, there are known image processing devices that perform a process of reading an image of a document and outputting the image to paper, a display, or the like. Further, such an image processing device can select output as a black-and-white image when outputting the 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 devices of this type are equipped with a blank paper determination function for determining whether or not the original is a blank original. However, when the above-mentioned binarization process is executed on an image that is determined not to be blank by the blank sheet judgment, the image is blanked by the binarization process, and the blank sheet may be output as it is. ..

In order to solve this problem, for example, in Patent Document 1, it is accurately determined whether or not the image is a blank document by performing a blank sheet determination on each of the images before and after the image is converted to black and white by the binarization process. An image processing device equipped with a function is disclosed.

JP-A-2015-65638

With respect to the technique described in Patent Document 1, it is necessary to perform a blank sheet determination a plurality of times in order to perform a blank sheet determination after the binarization process. If accurate blank paper determination can be performed with or without binarization processing by one blank page determination, the time required for blank page determination can be expected to be shortened.

Therefore, one aspect of the present invention is to provide an image processing apparatus or the like capable of accurately performing a blank sheet determination of an image to be binarized by a single blank sheet determination.

In order to solve the above-mentioned problems, the image processing apparatus according to one aspect of the present invention includes an acquisition unit for reading a document and acquiring a multi-gradation image and a control unit, and the control unit includes the multiple unit. One page included in the gradation image is set as a judgment target page, and for the judgment target page, the first frequency, which is the total frequency of pixels having a luminance value equal to or higher than the first threshold value, and the first frequency, which is less than the first threshold value, are described. If at least one of the frequency acquisition process for acquiring the second frequency, which is the sum of the frequencies of the pixels having the luminance value, and the first frequency and the second frequency is the second threshold value or more, the determination target page is If the first frequency and the second frequency are both less than the second threshold value, the determination target page is determined to be multicolored, that is, the monochromatic / multicolor determination process and the monochromatic / multicolor determination. For the determination target page determined to be multicolored by the processing, the multi-gradation image related to the page is converted into a binary image based on the comparison between the first threshold value and the brightness value. The binary image is output, and the image output corresponding to the multi-gradation image related to the page is not output for the determination target page determined to be monochromatic by the monochromatic / multicolor determination process. Judgment processing and execution.

According to the above configuration, the first threshold value used for image conversion to a binary image is also used in the monochromatic / multicolor determination process. Therefore, the monochromatic / multicolor determination process calculates the frequency of the brightness value of each pixel in the binary image after image conversion, and uses the calculation result to determine whether or not the binary image after image conversion is monochromatic. it can. Therefore, although it is determined that the judgment target page in the multi-gradation image is not monochromatic, the phenomenon that the binary image after image conversion becomes monochromatic can be suppressed by only one monochromatic / multicolor determination process.

In order to solve the above problems, the control method according to one aspect of the present invention is a control method of an image processing apparatus including an acquisition unit that reads a document and acquires a multi-gradation image, and the multi-gradation image. The page included in the above is set as the determination target page, and for the determination target page, the first frequency, which is the sum of the frequencies of pixels having a luminance value equal to or higher than the first threshold value, and the luminance value, which is less than the first threshold value, are set. If at least one of the frequency acquisition step for acquiring the second frequency, which is the sum of the frequencies of the pixels, and the first frequency and the second frequency is equal to or higher than the second threshold value, the determination target page is monochromatic. If both the first frequency and the second frequency are less than the second threshold value, the determination target page is determined to be multicolored in the monochromatic / multicolor determination step and the monochromatic / multicolor determination step. With respect to the determination target page determined to be multicolored, the multi-gradation image related to the page is converted into a binary image based on a comparison between the first threshold value and the luminance value, and the second value is obtained. The value image is output, and the determination target page determined to be monochromatic in the monochromatic / multicolor determination step is an image output determination step in which the image corresponding to the multigradation image related to the page is not output. ,including.

According to one aspect of the present invention, it is possible to provide an image processing apparatus or the like capable of accurately performing a blank sheet determination of an image to be binarized by a single blank sheet determination.

It is a block diagram which shows an example of the structure of the MFP (Multi-Function Peripheral) which concerns on one Embodiment of this invention. It is a flowchart which shows an example of the monochromatic page removal process. It is a figure which shows an example which divides a document into a plurality of blocks. It is a flowchart which shows an example of a frequency acquisition process. It is a figure which shows an example of the histogram of the luminance value. It is a flowchart which shows an example of the binary image necessity determination processing. It is a flowchart which shows an example of a blank page removal process.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5.

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

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

The image reading unit 20 as an example of the acquisition unit reads the image of the original and generates the image data. The scanning method may be an ADF (Auto Document Feeder) method that reads the image of the document while transporting the document, or an FB (Flat Bed) that reads the image of the document by placing the document on the contact glass. ) Method may be used.

The operation panel 30 includes a touch panel. Various information such as the status of the MFP1 is displayed on the touch panel. In addition, various inputs can be made by the user by touching the touch panel. The operation panel 30 may be provided with an input key such as a numeric keypad.

Since the MFP 1 is provided with the network interface 40, it is possible to communicate with an external device such as a PC (personal computer) connected to the 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 unit 10, the image reading unit 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 a program executed by the CPU 51, various data, and the like. The RAM 53 is used as a work area when the CPU 51 executes a program. Various setting values and the like input from the operation panel 30 are stored in the NVRAM 54.

<Functions and settings>
The MFP 1 reads the image of the original by the image reading unit 20, outputs the image data based on the read image to a print paper or the like by the image forming unit 10, or outputs the image data to an external PC or the like via the 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 setting. As output settings, for example, three types of BW (black and white), gray, and color are prepared. The image reading unit 20 reads the original image as a multi-gradation image, which is multi-tone digital image data, regardless of which output setting is set. The multi-gradation image includes at least multi-gradation luminance value data. Further, the manuscript may include a plurality of pages. In this case, the multi-gradation image includes a plurality of pages of digital image data.

Then, when "output setting: BW" is set, the MFP 1 performs image conversion for converting the read multi-gradation 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 of 256 gradations is output.

Further, the MFP 1 has a single color image removal function. The monochromatic image removal function determines whether or not the image of the original document read by the image scanning unit 20 is a monochromatic image such as white monochromatic or black monochromatic, and outputs the image if it is a monochromatic image. It is a function that does not. The MFP1 can enable the blank image removal function, which does not output an image only when the original is blank, among the single color 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 the conventional MFP, when "output setting: BW" is set, there is a problem that the output image may be a single white color or a single black color even if the single color image removal function is enabled. was there. For example, when it was determined whether or not the multi-gradation image read by the MFP was a monochromatic image, it was determined that it was not a monochromatic image, but by the subsequent image conversion to a binary image, almost all of them were determined. This is a case where an image in which the pixels are white or black is generated and the image is output.

On the other hand, according to the MFP 1 according to the present embodiment, in determining whether or not the image is a monochromatic image when "output setting: BW" is set, it is used for image conversion to a binary image as described later. Refer to the threshold value of the brightness value to be obtained. As a result, the MFP1 can determine whether or not the binary image after image conversion is monochromatic, so that the monochromatic image is not output when the monochromatic image removal function is enabled.

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

<Processing in the single color image removal function>
In order to realize the single color image removal function, the CPU 51 of the control unit 50 executes a program to perform a single color page removal process including a frequency acquisition process, a single color / multicolor determination process, and an image output determination process. Execute. Each of these processes will be described below as an example of the control method of the MFP1.

(Single color page removal process)
The monochromatic page removal process will be described below with reference to FIG. The CPU 51 uses one page included in the multi-gradation image read by the image reading unit 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 the division.

Next, the CPU 51 executes a frequency acquisition process for each block and acquires the value of the maximum frequency value (S2). The frequency acquisition process will be described later. The CPU 51 executes a single color / multicolor determination process for determining whether or not the maximum frequency value is equal to or greater than the single color determination threshold value hidden_th (S3, single color / multicolor determination step). The single color determination threshold value hidden_th is an example of the second threshold value. When the maximum frequency value is equal to or higher than the single color determination threshold value hidden_th (YES in S3), the CPU 51 sets the attribute of the block that executed the determination as a single color block (S4), and the maximum frequency value is less than the single color determination threshold value hidden_th. If (NO in S3), the attribute of the block that executed the determination is set as a multicolor block (S5). The CPU 51 saves the set block attributes in the RAM 53.

When only the first frequency and the second frequency are acquired and the maximum frequency value is not acquired in the frequency acquisition process described later, the CPU 51 determines the single color determination threshold value of hint_th or more for each of the first frequency and the second frequency. It may be determined whether or not it is. In this case, the CPU 51 sets the attribute of the block that executed the determination as the monochromatic block if at least one of the first frequency and the second frequency is equal to or higher than the monochromatic determination threshold threshold_th.

Next, the CPU 51 determines whether or not the determination of S3, that is, the determination of whether the block is a monochromatic block or a multicolor block, has been executed for all the blocks included in the determination target page (S6). If the determination of S3 is not completed for all blocks (NO in S6), the CPU 51 executes the processes S2 to S5 until the determination of all blocks is completed. On the other hand, when the determination of S3 is completed for all the blocks (YES in S6), the CPU 51 counts the number of blocks whose attributes are set to the monochromatic blocks (S7).

Then, the CPU 51 determines whether or not the ratio of the monochromatic blocks among all the blocks included in the determination target page is equal to or greater than the monochromatic block threshold plane_blk_weight (S8). When the ratio of the monochromatic blocks included in the determination target page is equal to or greater than the monochromatic block threshold plane_blk_weight (YES in S8), the CPU 51 sets the attribute of the determination target page as the monochromatic page (S9) and includes the determination target page. When the ratio of the monochromatic block is less than the monochromatic block threshold plane_blk_weight (NO in S8), the attribute of the determination target page is set as the multicolor page (S10).

Next, the CPU 51 executes an image output determination process (S11), and ends the monochromatic page removal process.

As described above, the CPU 51 determines that the determination target page is monochromatic and the first frequency and the second frequency are monochromatic if either the first frequency or the second frequency is equal to or higher than the single color determination threshold threshold_th for the entire determination target page. If both are less than the single color determination threshold value hidden_th, the process of determining that the determination target page is multicolored is executed.

The value of the single-color block threshold plane_blk_weight is a value that allows the judgment target page to contain multi-color blocks with an error level, and the ratio of the multi-color blocks included in the judgment target page falls within the error range. It is preferable to have. Examples of such values include, but are not limited to, 99% and 98%.

When a plurality of pages are included in the multi-gradation image, the CPU 51 executes the above-mentioned single color page removal process for all the pages.

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

The CPU 51 generates a histogram of the 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. When the gradation of the luminance value included in the multi-gradation image is larger than 6 bits, the CPU 51 may convert the gradation of the luminance value into 6 bits. As shown in FIG. 5, the luminance value histogram is represented by a luminance value k on the horizontal axis and a frequency h (k) representing the frequency of pixels having the luminance value k on the vertical axis. The CPU 51 stores the generated histogram of the luminance value in the RAM 53.

Next, the CPU 51 determines whether or not all the pixels in the block have been scanned (S22). When the CPU 51 has not scanned all the pixels in the block in S21 and determines that there is a pixel whose luminance value is not reflected in the histogram (NO in S22), the CPU 51 completes scanning of all the pixels in the block. The process of S21 is repeated until the above. On the other hand, when all the pixels are scanned and it is determined that the luminance values of all the pixels are reflected in the histogram (YES in S22), the CPU 51 determines whether or not the MFP1 is set to "output setting: BW", that is, the final output. Is BW (black and white) or not (S23).

When the MFP1 is not set to "output setting: BW" (NO in S23), that is, when the output setting is set to gray or color, the CPU 51 has the mode value h (k) in the histogram. The mode k_max, which is the value of the high luminance value k, is acquired as the "mode". On the other hand, when the MFP1 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 value k which is equal to or higher than the binarization threshold bw_th in the histogram. The calculated value is acquired as the "first frequency" (S25, frequency acquisition step). Further, the CPU 51 calculates the sum of the frequency values h (k) corresponding to the luminance value k which is less than the binarization threshold value bw_th in the histogram, and acquires the obtained value as the “second frequency” (S26, frequency acquisition). Step).

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

The CPU 51 acquires the larger value of the obtained first frequency and the second frequency as the "most frequency value" (S27), stores the most frequency value in the RAM 53, and ends the frequency acquisition process. According to the configuration for acquiring the maximum frequency value in this way, the CPU 51 does not need to compare both the first frequency and the second frequency with the single color determination threshold value hidden_th described later in the single color page removal process. Therefore, the CPU 51 can determine whether the original is monochromatic or multicolored only by comparing the most frequent value and the monochromatic threshold value hidden_th once. Therefore, it can be expected that the processing of the CPU 51 will be reduced in load and speeded up. The CPU 51 may store each of the first frequency and the second frequency in the RAM 53 without acquiring the maximum frequency value.

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

The values of the binarization threshold value bw_th, the single color determination threshold value hidden_th, and the single color block threshold value plane_blk_weight may be set to predetermined values at the time of shipment from the factory of the MFP 1, and the user sets them as arbitrary values by the operation panel 30. May be good. The binarization threshold value bw_th, the single color determination threshold value hidden_th, and the single color block threshold value 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 judgment processing)
Next, the image output determination process executed in S11 of the monochromatic page removal process shown in FIG. 2 will be described below with reference to FIG. First, the CPU 51 refers to the attributes 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 the monochrome page (S32, image output determination step). When the attribute of the determination target page is not set to the monochromatic page (NO in S32), the CPU 51 converts the multi-gradation image related to the page into a binary image based on the comparison between the binarization threshold value and the brightness value. Image conversion is performed (S33), the generated binary image is output to the image forming unit 10 (S34), and the image output determination process is completed. The image forming unit 10 outputs the input binary image to a print paper or the like, or outputs the input binary image to an external PC or the like via the network interface 40.

On the other hand, when the attribute of the determination target page is set to a single color page (YES in S32), the CPU 51 ends the image output determination process without outputting the image corresponding to the multi-gradation image related to the page. To do. In this case, the CPU 51 may or may not perform image conversion to a binary image for the determination target page set as the monochromatic page.

Here, when performing image conversion to a binary image, the CPU 51 converts all the pages included in the multi-gradation image into a binary image regardless of the result of the monochromatic / multicolor determination processing. According to this, when the multi-gradation image is temporarily stored in the RAM 53, the CPU 51 can store the low-capacity binary image in the RAM 53, so that the required capacity of the RAM 53 can be saved. Further, when the image conversion to the binary image is not performed, the CPU 51 can execute the image conversion to the binary image only when necessary. Therefore, regarding the processing of the CPU 51, it can be expected that the load is reduced and the processing speed is increased.

<Processing in the blank paper removal function>
As described above, the monochromatic image removing function included in the MFP 1 includes a blank page removing function. Hereinafter, the blank page removal process executed by the CPU 51 of the control unit 50 in order to realize the blank page removal function will be described. The blank page removal process is an example of the single color 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, the description thereof is omitted here.

(Blank page removal process)
The blank page removal process will be described below with reference to FIG. 7. The CPU 51 uses one page included in the multi-gradation image read by the image reading unit 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-mentioned frequency acquisition process for each block to acquire the value of the maximum frequency value (S42). The CPU 51 executes a single color / multicolor determination process for determining whether or not the maximum frequency value is equal to or higher than the single color determination threshold value hidden_th (S43, single color / multicolor determination step). When the highest frequency value is equal to or higher than the single color determination threshold value (YES in S43), the CPU 51 determines whether or not the brightness value corresponding to the highest frequency value is equal to or higher than the blank sheet brightness threshold value white_th (S44).

Here, the "luminance value corresponding to the highest frequency value" when the MFP 1 is set to "output setting: BW" is the frequency value h (k) among the brightness values k included in the highest 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 maximum frequency value, the CPU 51 has a frequency value h (of the brightness value k that is equal to or higher than the binarization threshold value bw_th). The luminance value k having the largest k) is used as the "luminance value corresponding to the most frequent value" in S44.

When the luminance value corresponding to the highest frequency value is equal to or higher than the blank paper determination threshold value white_th (YES in S44), the CPU 51 sets the attribute of the block that executed the judgment as a blank paper block (S45), and determines that the highest frequency value is a single color. If it is less than the threshold threshold_th (NO in S44), or if the luminance value corresponding to the most frequent value is less than the blank judgment threshold white_th (NO in S45), the attribute of the block that executed the judgment is set as a color block. (S46). The CPU 51 saves the set block attributes in the RAM 53.

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

Then, the CPU 51 determines whether or not the ratio of the blank block among all the blocks included in the determination target page is equal to or greater than the monochromatic block threshold plane_blk_weight (S49). When the ratio of blank pages included in the determination target page is equal to or greater than the single color block threshold plane_blk_weight (YES in S49), the CPU 51 sets the attribute of the determination target page as a blank page (S50) and includes it in the determination target page. When the ratio of blank blocks is less than the single color block threshold plane_blk_weight (NO in S49), the attribute of the page to be determined is set as the color page (S51).

Next, the CPU 51 executes an image output determination process described later (S52), and ends the blank page removal process.

(Image output judgment processing)
The image output judgment process in the blank page removal process is the same as the image output judgment process in the single color page removal process, but in S32 of FIG. 6, it is determined whether or not the attribute of the page to be judged is set to the single color page. It differs only in determining whether or not it is set on a blank page. Since other processes are the same as the image output determination process in the single color page removal process, the description thereof is omitted here.

As described above, in the blank page removal process, only when it is determined that the judgment target page becomes a monochromatic binary image by image conversion to a binary image and the judgment target page before the image conversion is blank. , CPU 51 determines that image conversion to a binary image is necessary. That is, when the judgment target page is other than a blank page, the CPU 51 converts the judgment target page into a binary image, and even if the binary image becomes a single color, the image forming unit 10 outputs a single color binary image. .. Therefore, the user can recognize that the original is a page other than a blank page when the binary image of a single color is output from the MFP1. In this case, for example, the user can determine that there is a problem in image conversion to a binary image and change the output setting of the MFP1 so that an appropriate image is output from the MFP1.
<Modification example>
Although one embodiment of the present invention has been described above, the present invention can also be implemented in other embodiments.

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. Further, the control unit 50 may include a plurality of CPUs, and the plurality of CPUs may cooperate to execute each process.

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

Furthermore, not only the PC connected to the Internet but also the PC (not shown) connected to the MFP1 via the LAN (Local Area Network) is installed with the program of each process executed by the CPU 51 of the MFP1. In the PC, the same processing as each processing executed by the CPU 51 may be executed.

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

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

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

Claims (5)

An acquisition unit that reads a document and acquires a multi-gradation image,
With a control unit
The control unit
One page included in the multi-gradation image is set as a judgment target page, and for the judgment target page, the first frequency, which is the sum of the frequencies of pixels having a luminance value equal to or higher than the first threshold value, and the first frequency, which is less than the first threshold value, A frequency acquisition process for acquiring a second frequency, which is the sum of the frequencies of pixels having a certain luminance value, and
If at least one of the first frequency and the second frequency is equal to or higher than the second threshold value, the determination target page is a single color, and if both the first frequency and the second frequency are less than the second threshold value, the determination target page is described. Single color / multicolor judgment processing that determines that the judgment target page is multicolor,
Regarding the determination target page determined to be multicolored by the monochromatic / multicolor determination process, the multigradation image related to the page is a binary image based on the comparison between the first threshold value and the luminance value. The image is converted to and the binary image is output.
For the determination target page determined to be monochromatic by the monochromatic / multicolor determination process, it is possible to execute an image output determination process that does not output an image corresponding to the multigradation image related to the page. An image processing device as a feature. In the frequency acquisition process, one of the first frequency and the second frequency, which has a larger value, is acquired as the highest frequency value.
In the monochromatic / multicolor determination process, if the maximum frequency value is equal to or higher than the second threshold value, it is determined that the determination target page is monochromatic, and if the maximum frequency value is less than the second threshold value, it is determined. The image processing apparatus according to claim 1, wherein the determination target page is determined to have multiple colors. A program characterized by causing a computer to execute each process in the control unit of the image processing apparatus according to claim 1 or 2, and causing the computer to function as the control unit. The image processing apparatus according to claim 1 or 2,
A developer image is placed on the recording medium based on the binary image after the image conversion is performed on the multicolor page for which the image conversion to the binary image is determined to be necessary in the image output determination process. An image forming apparatus including a process unit for forming. It is a control method of an image processing device including an acquisition unit that reads a document and acquires a multi-gradation image.
One page included in the multi-gradation image is set as a determination target page, and the first frequency, which is the sum of the frequencies of pixels having a luminance value equal to or higher than the first threshold value, and the determination target page are less than the first threshold value. A frequency acquisition step of acquiring a second frequency, which is the sum of the frequencies of pixels having a certain luminance value, and
If at least one of the first frequency and the second frequency is equal to or higher than the second threshold value, the determination target page is a single color, and if both the first frequency and the second frequency are less than the second threshold value, the determination target page is described. A single color / multicolor judgment step that determines that the judgment target page is multicolor,
Regarding the determination target page determined to be multicolored in the monochromatic / multicolor determination step, the multi-gradation image related to the page is a binary image based on the comparison between the first threshold value and the luminance value. The image is converted to and the binary image is output.
The determination target page determined to be monochromatic in the monochromatic / multicolor determination step includes an image output determination step that does not output an image corresponding to the multigradation image related to the page. Control method.

Images