JP4642245B2 - Image forming apparatus, image forming method, and storage medium storing image forming procedure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus, an image forming method, and a storage medium storing an image forming procedure.
[0002]
More specifically, the present invention relates to an image forming apparatus suitable for forming a color image by, for example, an electrophotographic method, an image forming method, and a storage medium storing an image forming procedure.
[0003]
[Prior art]
Conventionally, in an electrophotographic color printer, if the “toner amount” of output image data of C (cyan), M (magenta), Y (yellow), and K (black) is too large for the entire image, the printer engine may be damaged. This is known to cause toner scattering. Therefore, when the “toner paste amount” is large, the value of each color data is converted to a low value, and image processing is performed to reduce the amount of toner used.
[0004]
On the other hand, if the “toner paste amount” is large for only a part of a photographic image or the like, the print engine will not be damaged. Rather, the intended density can be obtained by printing the image data as it is. Whether or not to do this can be switched for each print job. This option to switch for each print job is determined by whether the “toner reduction” processing mode is “on” or “off” (ie, toner reduction = on / off).
[0005]
[Problems to be solved by the invention]
However, in a conventional color image forming apparatus, when a business document mainly composed of black characters is printed while the “toner reduction” processing mode is set to “off” (that is, toner reduction = off), “toner scattering” "Is conspicuous.
[0006]
In contrast, when a photographic image is printed with the “toner reduction” processing mode set to “on” (that is, toner reduction = on), the black in the image is caused by the “toner reduction” processing. There is a case where the density of the portion of is reduced.
[0007]
Therefore, in view of the above points, an object of the present invention is to store an image forming apparatus, an image forming method, and an image forming procedure that can appropriately control the amount of a coloring material according to the contents of an image to be imaged. It is to provide a storage medium.
[0008]
Another object of the present invention is to provide an image forming apparatus, an image forming method, and a storage medium storing an image forming procedure that automatically determine whether or not to perform “toner reduction” processing according to the contents of a print job. Is to provide.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is an image forming apparatus for forming an image based on image data including a character portion and a photographic image portion, and the photographic image area occupied in the image data In response to the determination result by the image characteristic determination unit, an image characteristic determination unit that determines the ratio of the image data, and when the ratio of the photographic image portion in the image data exceeds a predetermined value, toner reduction with respect to the image data And a processing unit that performs toner reduction processing on the image data when the ratio of the photographic image portion in the image data does not exceed a predetermined value .
[0010]
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the image characteristic determining unit determines a ratio of a photographic image region in the image data for each page of the image.
[0011]
According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the image characteristic determination means is a ratio of the image area in the image data for each area composed of a plurality of adjacent pixels in one page of the image. Determine.
[0012]
According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, the image characteristic determining means is a ratio of the image area in the image data based on the number of character objects and photographic image objects included in the image. Determine.
[0013]
According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the image data is image data having a plurality of color element data for each pixel.
[0014]
The invention according to claim 6 is an image forming apparatus including an image forming unit that forms an image based on image data including a character portion and a photographic image portion and having a plurality of color element data for each pixel.
Image adjustment means for performing a predetermined conversion process on the plurality of color element data so that the sum of the plurality of color element data does not exceed a prescribed value, and a ratio of the photographic image portion in the image data exceeds a predetermined value Control means for executing processing by the image adjusting means when the ratio of the photographic image portion in the image data does not exceed a predetermined value without executing the processing by the image adjusting means. It is a thing.
[0015]
According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, the image adjusting means performs a conversion process so as to maintain a ratio of multi-value data of several color elements .
[0016]
According to an eighth aspect of the present invention, in the image forming apparatus according to the sixth aspect, the image adjusting unit performs a conversion process so as to maintain a ratio of multi-value data of color elements other than black .
[0017]
According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the sixth to eighth aspects, the image forming unit forms an image by an electrophotographic method .
[0018]
The invention according to claim 10 is an image forming method for forming an image on the basis of image data including a character portion and a photographic image portion, and an image characteristic determining step for determining a proportion of a photographic image area in the image data. And according to the determination result in the image characteristic determination step, if the ratio of the photographic image portion in the image data exceeds a predetermined value, the photographic image in the image data is not subjected to toner reduction processing. And a processing step of performing toner reduction processing on the image data when the ratio of the copies does not exceed a predetermined value .
[0019]
According to an eleventh aspect of the present invention, in the image forming method according to the tenth aspect, in the image characteristic determining step, a ratio of a photographic image area in the image data is determined for each image page .
[0020]
According to a twelfth aspect of the present invention, in the image forming method according to the tenth aspect, in the image characteristic determining step, a ratio of the image area to the image data for each area composed of a plurality of adjacent pixels in one page of the image. Determine .
[0021]
According to a thirteenth aspect of the present invention, in the image forming method according to the tenth aspect, in the image characteristic determining step, the ratio of the image area in the image data according to the number of character objects and photographic image objects included in the image. Determine .
[0022]
According to a fourteenth aspect of the present invention, in the image forming method according to any one of the tenth to thirteenth aspects, the image data is image data having a plurality of color element data for each pixel .
[0023]
The invention according to claim 15 is an image forming method using image forming means for forming an image based on image data including a character portion and a photographic image portion and having a plurality of color element data for each pixel, In accordance with the characteristics of the image data, it is determined whether or not to activate an image adjustment unit that performs a predetermined conversion process on the plurality of color element data so that the sum of the plurality of color element data does not exceed a predetermined value. A control step, and when the ratio of the photographic image portion in the image data exceeds a predetermined value, the control step does not operate the processing by the image adjustment means and occupies the photographic image in the image data. When the ratio of the parts does not exceed a predetermined value, the processing by the image adjusting means is activated .
[0024]
According to a sixteenth aspect of the present invention, in the image forming method according to the fifteenth aspect, the image adjusting unit performs a conversion process so as to maintain a ratio of multi-value data of several color elements .
[0025]
According to a seventeenth aspect of the present invention, in the image forming method according to the fifteenth aspect, the image adjusting unit performs a conversion process so as to maintain a ratio of multi-value data of color elements other than black .
[0026]
According to an eighteenth aspect of the present invention, in the image forming method according to any one of the fifteenth to seventeenth aspects, the image forming means forms an image by an electrophotographic method .
[0027]
The invention according to claim 19 is a storage medium storing a program for causing a computer to execute an image forming procedure for forming an image based on image data including a character portion and a photographic image portion, the image forming procedure. The image characteristic determination step for determining the proportion of the photographic image area in the image data, and the proportion of the photographic image portion in the image data exceeds a predetermined value according to the determination result in the image characteristic determination step And a processing step of performing toner reduction processing on the image data when toner reduction processing on the image data is not performed and a ratio of a photographic image portion in the image data does not exceed a predetermined value .
[0028]
The invention according to claim 20 is a program for causing a computer to execute an image forming procedure for forming an image based on image data including a character portion and a photographic image portion, and the image forming procedure occupies the image data. An image characteristic determination step for determining a ratio of a photographic image area, and toner reduction with respect to the image data when a ratio of a photographic image portion in the image data exceeds a predetermined value according to a determination result in the image characteristic determination step And a processing step of performing toner reduction processing on the image data when the ratio of the photographic image portion in the image data does not exceed a predetermined value .
[0045]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0046]
(About system configuration)
FIG. 2 shows a system configuration according to this embodiment. In this figure, reference numeral 203 denotes a network composed of 100BaseT Ethernet, to which a personal computer (PC) 201 and a color copying machine 202 are connected. Other devices are also connected to the network 203, but are omitted in this figure. The color copier 202 functions as a postscript printer compatible with the network, and prints a color image output from the PC 201.
[0047]
(About internal block)
FIG. 1 is an internal block diagram of a color copying machine 202 according to the present embodiment. In this figure, reference numeral 101 denotes a scanner, which optically reads a document and converts it into an electrical signal, and generates RGB (Red, Green, Blue) digital data in which each pixel has 8-bit luminance information. This data is raster data having a resolution of 400 dpi in both the main scanning direction and the sub-scanning direction.
[0048]
An image processing unit 102 performs input masking processing, log conversion processing from RGB to CMYK, output masking processing, and the like.
[0049]
A lookup table (LUT) 103 has a conversion table from 8 bits to 8 bits. The LUT 103 has an independent table for each of CMYK. This is used for calibration to adjust individual printer differences.
[0050]
A printer 104 forms a color image by electrophotography based on the received frame sequential CMYK data.
[0051]
A frame buffer 105 is a synchronous DRAM having a size of 139 MB. Raster image data fetched from the scanner 101 is stored or written under the control of the CPU 106.
[0052]
Reference numeral 106 denotes a CPU bus.
[0053]
Reference numeral 107 denotes a CPU for controlling the color copying machine, which uses Intel Pentium III, 600 MHz. The CPU 107 executes the procedure shown in FIGS. 3 and 4 (detailed later).
[0054]
Reference numeral 108 denotes an I / O port connected to the CPU bus 106, which controls the scanner 101 and the printer 104 and inputs signals from various sensors (not shown).
[0055]
Reference numeral 109 denotes a ROM which stores a program that operates when the system is booted and the procedure shown in FIGS. The ROM 109 is connected to the CPU bus 106.
[0056]
Reference numeral 110 denotes a work RAM, which is a 117 MB synchronous DRAM. Actually, it is configured as a 256 MB synchronous DRAM memory module together with the frame buffer 105. The work RAM 110 is connected to the CPU bus 106.
[0057]
A SCSI controller 111 is connected to the CPU bus 106.
[0058]
Reference numeral 112 denotes a 3.5 inch 9.1 GB hard disk drive (HDD) connected to the SCSI controller 111.
[0059]
A network I / F controller 113 is connected to the CPU bus 106. It is connected to an external 10BaseT, 100BaseT, or 10Base5 Ethernet network to exchange data.
[0060]
Reference numeral 114 denotes an operation unit of the color copying machine, which includes an LCD panel, a touch panel, and buttons (all not shown).
[0061]
(About copy operation)
A copy operation according to the present embodiment will be described with reference to FIG.
[0062]
When copying is performed, first, the scanner 101 reads a document and generates RGB raster image data. The image processing unit 102 converts the data into any of C, M, Y, and K data, develops it in the printer 104 via the LUT 103, and outputs it to a recording sheet. This operation is repeated in the order of MCYK to form a color image.
[0063]
In the case of a copying operation, when the processing in the image processing unit 102 is performed, an operation is performed so that the “toner paste amount” of each color does not exceed a specified value, so there is no need to consider the toner reduction processing.
[0064]
(About print operation)
A printing operation according to the present embodiment will be described with reference to FIG.
[0065]
When the user executes printing from the PC 201 (see FIG. 2) to the color copying machine 202 (see FIG. 2) using a printer driver, the color copying machine 202 executes a job described in a postscript via the network I / F 113. Received and stored in the work RAM 110. Then, the CPU 107 interprets the description of the postscript, generates a raster image, and stores it in the frame buffer 105. The raster image is developed by the printer 104 via the LUT 103 and output to a recording sheet. This operation is repeated in the order of MCYK to form a color image.
[0066]
(About switching the toner reduction processing mode)
The automatic switching of the toner reduction processing mode that is characteristic in the present embodiment will be described with reference to FIG. The processing procedure shown in this figure is executed under the control of the CPU 107 based on a program stored in the ROM 109 (or HDD 112).
[0067]
The toner reduction processing mode is one of the options that can be selected by the user using the printer driver. In this embodiment, the toner reduction processing mode has three options of off, on, and auto. Information selected by the printer driver is described in the PostScript job as part of the print job.
[0068]
When a raster image is generated in the printer operation described in the previous section, toner reduction processing is also performed. The process of FIG. 3 is performed for each page of the print job.
[0069]
First, in step S301, it is checked whether or not the toner reduction processing mode of the job is turned off. If it is turned off, the variable TR is set to 0 in step S307, and the process proceeds to rasterizing the page in step S308. If it is not off, it is checked in step S302 whether the toner reduction processing mode is on. If it is on, the variable TR is set to 1 in step S306, and the process proceeds to rasterization in step S308. If it is not on, it is auto that remains, so the process proceeds to step S303. In step S303, the postscript description of the page is checked to find an image operator that means raster image data, and the sum S of raster images occupied on the page is calculated.
[0070]
In step S305, it is determined whether or not the sum S exceeds 20% of the page size. If it exceeds, the variable TR is set to 0 in step S307 in the same manner as “toner reduction = off”. If not, the variable TR is set to 1 in step S306 as in “toner reduction = on”.
[0071]
In step S308, the page is rasterized and raster image data is developed in the frame buffer 105. In step S309, if the variable TR is not 0 (that is, 1), toner reduction processing for the page is performed in step S310. If it is 0, toner reduction processing is not performed.
[0072]
In this way, in the case of “toner reduction = auto”, the toner reduction processing mode is automatically switched on / off according to the contents of the page for each page.
[0073]
(Toner reduction process)
Next, the toner reduction process in step S310 shown in FIG. 3 will be described with reference to FIG. The processing procedure shown in this figure is executed under the control of the CPU 107 based on a program stored in the ROM 109 (or HDD 112).
[0074]
The toner reduction process is performed for each pixel of the raster image on the frame buffer 105.
[0075]
First, in step S401, the sub-scanning line pointer PY is initialized to zero. In step S402, the main scanning pixel pointer PX is initialized to zero. A pixel to be processed is specified by PX and PY.
[0076]
In step S403, the values of the pixel data C, M, Y, K of the pixel (PX, PY) are extracted from the frame buffer 105. This is 8-bit data for each color.
[0077]
In step S404, it is determined whether or not the sum of the values of C, M, Y, and K exceeds 256 × 2.1, that is, 210% of the “toner amount”. “Toner paste amount” is defined as 100% when a certain color of toner is fully applied. In the printer engine of the present embodiment, it is preferable to keep it to 210% or less. If the pixel is 210% or less, there is no problem and the process proceeds to step S407. If greater than 210%, a coefficient A = (256 × 2.1−K) / (C + M + Y) is calculated in step S405, and pixel data is obtained by multiplying coefficient C only in C, M, and Y in step S406. Store in the frame buffer 105. K is not converted at this time.
[0078]
As a result, the “toner paste amount” is rounded to a total of 210% while maintaining the balance of C, M, and Y.
[0079]
In step S407, the main scanning pixel pointer PX is advanced by one. In step S408, it is determined whether or not the processing of the line has been completed. If it has not been completed, the process loops to step S403. The process moves to step S409 so as to move.
[0080]
In step S409, the sub-scanning line pointer PY is advanced by one. In step S410, it is determined whether or not the entire line processing has been completed. If it has not been completed, the process loops to step S402.
[0081]
By performing this series of processing, toner reduction processing can be performed on one page image on the frame buffer 105.
[0082]
In the above-described embodiment, the determination is made for each page and recognized. However, the determination may be made for each area in one page, or may be switched for each object.
[0083]
(Modification of the present embodiment)
(1) Image information input means: Acquires image information to be formed.
[0084]
Image characteristic determination means: It is determined from the image information obtained by the image information input means whether the image is mainly a character or a photographic image.
[0085]
Raster image generation means: generates raster image data from image information obtained by the image information input means. The raster image data has multi-value data for each of a plurality of color elements in each pixel.
[0086]
Raster image adjustment means: Converts multi-value data of a plurality of color elements so that the sum of the multi-value data of a plurality of color elements does not exceed a specified value in each pixel of the raster image data generated by the raster image generation means. To do.
[0087]
Control means: Based on the determination result of the image characteristic determination means, control is performed so that the adjustment by the raster image adjustment means is performed if the image is mainly a character, and the adjustment by the raster image adjustment means is not performed if the image is mainly a photographic image.
[0088]
Image forming means: forms an image of the raster image data finally obtained by the above processing.
[0089]
{Circle around (2)} In the above {circle around (1)}, the image characteristic determination means makes a determination for each page of the image, and the control means also switches for every page of the image.
[0090]
{Circle around (3)} In the above {circle around (1)}, the image characteristic determination means makes a determination for each area composed of a plurality of adjacent pixels in one page of the image, and the control means also switches for each area.
[0091]
{Circle around (4)} In the above {circle around (1)}, the raster image adjusting means adjusts so as to maintain the ratio of multi-value data of several color elements.
[0092]
(5) In the above (4), the raster image adjusting means adjusts so as to maintain the ratio of the multi-value data of the color elements other than black.
[0093]
(6) In the above (1), the plurality of color elements are composed of four colors of cyan, magenta, yellow, and black.
[0094]
(7) In the above (1), the image information obtained by the image information input means is written in a page description language.
[0095]
(8) In the above item (1), the image characteristic determining means makes a determination based on the number of character objects and photographic image objects in the image information.
[0096]
(9) In the above item (1), the image forming means performs image formation by electrophotography.
[0097]
Other embodiments In the present invention, a storage medium storing software program codes for realizing the functions of the above-described embodiments is supplied to a system or apparatus, and the computer (or computer) of the system or apparatus is used. Needless to say, this can also be achieved by the CPU and MPU) reading and executing the program code stored in the storage medium.
[0098]
In this case, the program code itself read from the storage medium realizes the novel function of the present invention, and the storage medium storing the program code constitutes the present invention.
[0099]
As a storage medium for supplying the program code, for example, a floppy disk, a hard disk, a magneto-optical disk, an optical disk, a CD-ROM, a CD-R, a magnetic tape nonvolatile memory card, a ROM, or the like can be used.
[0100]
In addition, the functions of the above-described embodiments are realized by executing the program code read by the computer, and the OS running on the computer is one of the actual processes based on the instruction of the program code. The functions of the above-described embodiment can be realized by performing some or all of the processes.
[0101]
Further, after the program code read from the storage medium is written to a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. The CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments can be realized by the processing.
[0102]
It goes without saying that the present invention can also be applied to a case where the program is distributed to a requester via a communication line such as personal computer communication from a storage medium in which the program code of the software realizing the functions of the above-described embodiments is recorded. Yes.
[0103]
(Effects of this embodiment)
According to the above-described embodiment, an operation mode in which the toner reduction processing mode is switched according to the content of each page of the print job can be realized. In many cases, this mode is set to “toner reduction = on”, which can suppress toner scattering for text-based business documents, and sufficient density reproduction for image-based pages. Automatically switched to “toner reduction = off”. Thereby, the operativity can be improved.
[0104]
【The invention's effect】
As described above, according to the present invention, the image forming apparatus, the image forming method, and the storage medium storing the image forming procedure, which can appropriately control the amount of the coloring material according to the content of the image to be imaged. Can be realized.
[0105]
Furthermore, it is possible to realize an image forming apparatus, an image forming method, and a storage medium storing an image forming procedure that automatically determine whether or not to perform “toner reduction” processing according to the contents of a print job. .
[Brief description of the drawings]
FIG. 1 is a block diagram showing an internal configuration of a color copying machine according to an embodiment.
FIG. 2 is a system configuration diagram according to the present embodiment.
FIG. 3 is a flowchart showing a procedure for switching toner reduction processing in the present embodiment;
FIG. 4 is a flowchart illustrating toner reduction processing according to the present exemplary embodiment.
[Explanation of symbols]
101 Scanner 102 Image Processing Unit 103 LUT (Look Up Table)
104 Printer 105 Frame buffer 107 CPU
109 ROM
110 RAM
112 HDD (Hard Disk Drive)

Claims (20)

An image forming apparatus that forms an image based on image data including a character portion and a photographic image portion ,
Image characteristic determining means for determining a ratio of a photographic image area in the image data;
In response to the determination result by the image characteristic determination means, when the ratio of the photographic image portion in the image data exceeds a predetermined value, the image occupying the image data is not subjected to toner reduction processing. An image forming apparatus comprising: a processing unit that performs toner reduction processing on the image data when the ratio of the image portion does not exceed a predetermined value . The image forming apparatus according to claim 1.
The image forming apparatus according to claim 1, wherein the image characteristic determining unit determines a ratio of a photographic image area in the image data for each page of the image. The image forming apparatus according to claim 1.
The image forming apparatus according to claim 1, wherein the image characteristic determining unit determines a ratio of an image area in the image data for each area including a plurality of adjacent pixels in one page of the image. The image forming apparatus according to claim 1.
The image forming apparatus according to claim 1, wherein the image characteristic determining unit determines a ratio of an image area in the image data based on the number of character objects and photographic image objects included in the image . The image forming apparatus according to any one of claims 1-4,
The image forming apparatus, wherein the image data is image data having a plurality of color element data for each pixel. An image forming apparatus comprising image forming means for forming an image based on image data including a character portion and a photographic image portion and having a plurality of color element data for each pixel,
Image adjusting means for performing a predetermined conversion process on the plurality of color element data so that the sum of the plurality of color element data does not exceed a prescribed value;
When the ratio of the photographic image portion in the image data exceeds a predetermined value, the processing by the image adjustment unit is not executed, and the ratio of the photographic image portion in the image data does not exceed the predetermined value. an image forming apparatus characterized by comprising a control means causes execution of processing by said image adjustment means. The image forming apparatus according to claim 6 .
The image forming apparatus according to claim 1, wherein the image adjusting unit performs a conversion process so as to maintain a ratio of multi-value data of several color elements. The image forming apparatus according to claim 6 .
The image forming apparatus according to claim 1, wherein the image adjusting unit performs a conversion process so as to maintain a ratio of multi-value data of color elements other than black. The image forming apparatus according to any one of claims 6-8,
An image forming apparatus, wherein the image forming means forms an image by electrophotography. An image forming method for forming an image based on image data including a character portion and a photographic image portion ,
An image characteristic determining step for determining a proportion of a photographic image area in the image data;
According to the determination result in the image characteristic determination step, when the ratio of the photographic image portion in the image data exceeds a predetermined value, toner reduction processing is not performed on the image data, and the photographic image portion in the image data And a processing step of performing toner reduction processing on the image data when the ratio does not exceed a predetermined value . The image forming method according to claim 10 .
In the image characteristic determining step, a ratio of a photographic image area in the image data is determined for each page of an image. The image forming method according to claim 10 .
In the image characteristic determining step, the ratio of the image area in the image data is determined for each area composed of a plurality of adjacent pixels in one page of the image. The image forming method according to claim 10 .
In the image characteristic determining step, the ratio of the image area in the image data is determined based on the number of character objects and photographic image objects included in the image . The image forming method according to any one of claims 10-13,
The image forming method, wherein the image data is image data having a plurality of color element data for each pixel. An image forming method using image forming means for forming an image based on image data including a character portion and a photographic image portion and having a plurality of color element data for each pixel,
In accordance with the characteristics of the image data, it is determined whether or not to activate an image adjustment unit that performs a predetermined conversion process on the plurality of color element data so that the sum of the plurality of color element data does not exceed a predetermined value. Comprising a control step ,
In the control step, when the ratio of the photographic image portion in the image data exceeds a predetermined value, the processing by the image adjustment unit is not activated, and the ratio of the photographic image portion in the image data has a predetermined value. An image forming method , comprising: activating a process performed by the image adjusting unit when not exceeding . The image forming method according to claim 15 .
An image forming method, wherein the image adjusting means performs a conversion process so as to maintain a ratio of multi-value data of several color elements. The image forming method according to claim 15 .
The image forming method according to claim 1, wherein the image adjusting unit performs a conversion process so as to maintain a ratio of multi-value data of color elements other than black. The image forming method according to any one of claims 15 to 17 ,
An image forming method, wherein the image forming means forms an image by electrophotography. A storage medium storing a program for causing a computer to execute an image forming procedure for forming an image based on image data including a character portion and a photographic image portion ,
The image forming procedure includes:
An image characteristic determining step for determining a proportion of a photographic image area in the image data;
According to the determination result in the image characteristic determination step, when the ratio of the photographic image portion in the image data exceeds a predetermined value, toner reduction processing is not performed on the image data, and the photographic image portion in the image data storage media ratio in if it does not exceed the predetermined value, and having a processing step of subjecting the toner reduction processing of the image data. A program for causing a computer to execute an image forming procedure for forming an image based on image data including a character portion and a photographic image portion ,
The image forming procedure includes:
An image characteristic determining step for determining a proportion of a photographic image area in the image data;
According to the determination result in the image characteristic determination step, when the ratio of the photographic image portion in the image data exceeds a predetermined value, toner reduction processing is not performed on the image data, and the photographic image portion in the image data And a processing step of performing toner reduction processing on the image data when the ratio does not exceed a predetermined value .

Images