JP7277238B2 - image forming device - Google Patents

Description

The present invention relates to an image forming apparatus having a wide color gamut image forming mode for controlling the amount of developer supplied to an image carrier by a developer supplying member.

There is a color gamut as one of image quality indices in an image forming apparatus. The color gamut of an image forming apparatus is a color reproduction range that can be output by the image forming apparatus, and the wider the color gamut, the wider the color reproduction range, which means that the image forming apparatus is superior. As a method for expanding the color gamut, a method of separately adding a dark YMCK developer in addition to the YMCK four-color developer, a method of increasing the amount of the developer on the recording material, and the like are conceivable. Japanese Patent Application Laid-Open No. 2002-101002 discloses a proposal to adjust the tint of a secondary color by changing the rotational speed of a developer supply member. Although the purpose of this configuration is to adjust the color tone and not to increase the amount of developer on the recording material, it is possible to expand the color gamut by applying this technique. That is, it is possible to increase the amount of developer by increasing the rotation speed of the developer supply member.

Japanese Patent Laid-Open No. 8-227222

However, the conventional technology described above has the following problems.
The configuration in which the amount of developer is increased by increasing the rotation speed of the developer supply means as disclosed in Japanese Patent Application Laid-Open No. 2002-300300 increases the amount of developer even for a text image that does not require expansion of the color gamut. On the other hand, if an attempt is made to expand the color gamut by increasing the maximum amount of toner on paper, if image formation is performed under the image formation conditions in the normal image formation mode, text images such as splattering and distorted characters will result. I had a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems. The purpose is to prevent splattering of text images and garbled characters.

An image forming apparatus according to the present invention includes a controller that generates post-conversion image information based on input image information input from the outside, a rotatable image carrier, and a developer that is carried on its surface and faces the image carrier. in the developing section, a developer carrier that supplies the developer to the electrostatic latent image formed on the surface of the image carrier based on the converted image information; and a developing voltage is applied to the developer carrier. a developing voltage applying unit, wherein the controller comprises developing means for developing the input image information into a vector image or a raster image; and first developed image information of the vector image developed by the developing means. and control means for performing color adjustment control on each of the second developed image information of the raster image and the peripheral speed ratio of the developer carrier to the image carrier at a predetermined peripheral speed ratio. A normal image forming mode for developing the electrostatic latent image formed on the image carrier and a peripheral speed ratio larger than that in the normal image forming mode are used to increase the color gamut of the image formed on the recording material. In an image forming apparatus capable of executing a wide color gamut image forming mode that expands more than the normal image forming mode, the control means controls the first expansion of the vector image when the normal image forming mode is executed. When color adjustment control is performed using a first color conversion condition for performing color conversion with the post-image information and the second post-development image information for the raster image, and the wide color gamut image formation mode is executed, Using a second color conversion condition for color conversion with the first rasterized image information for the vector image and a third color conversion condition for color conversion with the second rasterized image information for the raster image , It is characterized by performing color adjustment control.

As described above, according to the present invention, when the wide color gamut image forming mode is used, different color conversion conditions are used according to the image data, thereby reducing the size and cost of the apparatus. It can be prevented, and the above object can be achieved by a simple method.

FIG. 2 is an explanatory diagram of the configuration of a controller including color conversion conditions of the image forming apparatus according to the first embodiment; Sectional view of the image forming apparatus of the first embodiment FIG. 1 is a schematic configuration diagram of a drive source for a photosensitive drum and a developing roller in Embodiment 1; Schematic explanatory drawing of the photosensitive drum layer structure of Example 1. Schematic explanatory diagram of the surface potential of a photosensitive drum in Example 1. FIG. Explanatory diagram of γ correction in the normal print mode of the first embodiment Explanatory drawing when gamma correction of the normal print mode is applied in the wide color gamut print mode of the first embodiment. Explanatory diagram of a case where gamma correction different from gamma correction in normal print mode is applied to vector image data and raster image data in wide color gamut print mode of the first embodiment. Flowchart for explaining color conversion conditions used in each print mode of the first embodiment Schematic diagram of the color gamut of the wide color gamut print mode of the first embodiment Schematic explanatory diagram of the surface potential of a photosensitive drum in Example 3.

Hereinafter, the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

In this embodiment, the image forming apparatus includes an image carrier, developing means, and a developer for carrying an electrostatic latent image formed on the image carrier. is applied with a development potential. When the development potential is applied, the developer is supplied to the developing portion facing the image carrier and the developing means, and the electrostatic latent image formed on the image carrier based on the converted image information and the development potential. Development is performed according to the development contrast. A controller that generates post-conversion image information based on input image information that is input from the outside includes rasterization means that rasterizes the image information into a raster image. Further, the controller has a color matching section that adjusts the color reproducibility of the raster image, and a color separation section that converts the color space data adjusted for color reproduction by the color matching section into developer colors. Further, the controller includes a gamma correction section for faithfully reproducing the data converted by the color separation section to the color data of the image information, and a halftoning section for performing gradation expression processing on the color data after gamma correction. prepare with department.

The image forming apparatus has a normal image forming mode, a wide color gamut image forming mode in which an image is formed by changing the supply amount of the developer in the normal image forming mode, and a developer supply to the image carrier. and variable toner supply means for changing the supply amount by changing the rotation speed of the means. The controller discriminates whether the image information before development is raster image data or vector image data, and in the case of the wide color gamut image forming mode, divides the raster image data and vector image data after RIP processing. Set different color conversion conditions. This will be described in detail below.

[Configuration of Image Forming Apparatus and Outline of Image Forming Operation]
FIG. 1 shows an example of the configuration of the controller section in this embodiment.

A print job described in a page description language (PDL) such as PCL or PostScript is generally sent from the host PC 101 to the controller 102 of the image forming apparatus. The controller 102 is mainly composed of a RIP section 104 , a color conversion section 105 , a γ correction section 106 and a halftoning section 107 . The color conversion conditions of this embodiment refer to color adjustment processing performed on the image information after expansion by the color conversion unit 105 , the γ correction unit 106 and the halftoning unit 107 .

A RIP (Raster Image Processor) unit 104 analyzes (interprets) a print job including PDL sent from the host computer 101 . The RIP unit 104 is a unit that generates raster image data, which is RGB bitmap format image data corresponding to the resolution of the image forming apparatus (for example, 600 dpi).

In this embodiment, an image data discrimination section 110 for discriminating between raster image data and vector image data in a print job is provided before the RIP section 104, and different color conversion conditions are used according to the data format.

A color conversion unit 105 takes into account the difference in color reproduction range between devices and performs conversion to match colors as much as possible and to match the appearance of colors. This is the part that converts.

The color conversion unit 105 includes a color matching unit 108 that performs color matching between devices, and a color separation unit 109 that converts the color space data subjected to color matching into each color toner data YMCK of the image forming apparatus.

In general, when printing a file created by an application (image software, office suite software, etc.) on a computer while viewing the LCD monitor, the following can be said. That is, the color reproduction range (R'G'B') of the electrophotographic printer is narrower than the color reproduction range (RGB) of the liquid crystal monitor. It is the color matching department that performs color matching conversion that matches the color appearance of the input device (LCD monitor) and the output device (electrophotographic printer) as much as possible to match the difference in color gamut between the input device (LCD monitor) and the output device (electrophotographic printer). 108.

As shown in FIG. 1, the difference in processing performed by the color conversion unit 105, γ correction unit 106, and halftoning unit 107 is used as a color conversion condition.

Next, the color-matched R'G'B' is converted into color data YMCK of each developer by the color separation unit 109 .

Next, the gamma correction unit 106 performs gamma correction, the halftoning unit 107 performs gradation expression processing such as dither, and a signal is sent to the image forming engine controller 103 .

FIG. 2 is a schematic diagram of the image forming apparatus. As shown in the figure, the image forming apparatus has a plurality of photosensitive drums 5 (5Y, 5M, 5C, 5K) (image carriers) which are first image carriers, and sequentially carries second image carriers. Multiple transfer is continuously performed on an intermediate transfer belt 3 (transfer target) which is a body. This is a four-drum system (in-line system) for obtaining a so-called full-color print image. The transfer means in this embodiment consists of means for primary transfer from the photosensitive drum to the intermediate transfer belt and means for secondary transfer from the intermediate transfer belt to the recording material.

The intermediate transfer belt 3 is an endless belt, suspended by a drive roller 12, a tension roller 13, an idler roller 17, and a secondary transfer counter roller 18, and rotated in the direction of the arrow in the drawing at a process speed of 100 mm/sec. are doing. As a material for the intermediate transfer belt 3, polyimide, polyamide, polycarbonate (PC), polyvinylidene fluoride (PVDF), or the like is used. The drive roller 12 , tension roller 13 , and secondary transfer counter roller 18 are support rollers that support the intermediate transfer belt 3 .

Four photosensitive drums 5 (5Y, 5M, 5C, 5K) are arranged in series in the moving direction of the intermediate transfer belt 3, corresponding to each color. A photosensitive drum 5Y having a yellow developer (developing means) is uniformly charged to a predetermined polarity and potential by a primary charging roller (charging means) 7Y in the course of rotation. Then, an electrostatic latent image corresponding to the first color (yellow) component image of the intended color image is formed by receiving image exposure 4Y from image exposure means (exposure means) 9Y. Next, the electrostatic latent image is developed with a first color yellow toner (developer) by the developing roller 8Y. Such a method in which toner is developed on the portion where the electrostatic latent image is formed by image exposure is called a "reversal development method". A yellow image formed on the photosensitive drum 5</b>Y enters the primary transfer nip portion with the intermediate transfer belt 3 . At the primary transfer nip portion, a voltage application member (primary transfer roller) 10Y is brought into contact with the back side of the intermediate transfer belt 3 . The voltage applying member 10Y has a primary transfer bias power source (not shown) so that bias can be applied independently at each port. The intermediate transfer belt 3 first transfers yellow at the port of the first color, and then from the photosensitive drums 5M, 5C, and 5K corresponding to the respective colors that have undergone the above-described processes, the respective colors of magenta, cyan, and black are sequentially transferred at each port. do. The four-color toner image transferred onto the intermediate transfer belt 3 rotates along with the intermediate transfer belt 3 in the direction of the arrow (clockwise) in FIG.

On the other hand, the recording material P stacked and stored in the paper feed cassette 1 is fed by the paper feed roller 2, conveyed to the nip portion of the registration roller pair 6, and temporarily stopped. The temporarily stopped recording material P is supplied to the secondary transfer nip by the registration roller pair 6 in synchronization with the timing when the four-color toner image formed on the intermediate transfer belt 3 reaches the secondary transfer nip. Then, the toner image on the intermediate transfer belt 3 is transferred onto the recording material P by applying a voltage (approximately +1.5 kV) between the secondary transfer roller 11 and the secondary transfer opposing roller 18 . The recording material P onto which the toner image has been transferred is separated from the intermediate transfer belt 3 and sent to the fixing device 14 via a conveying guide 19, where it is heated and pressed by a fixing roller 15 and a pressure roller 16. The toner image is fused and fixed to the surface. As a result, a four-color full-color image is obtained. After that, the recording material P is discharged from the paper discharge roller pair 20 to the outside of the apparatus, and one cycle of printing is completed. On the other hand, the toner remaining on the intermediate transfer belt 3 without being transferred onto the recording material P at the secondary transfer portion is removed by a cleaning unit 21 arranged downstream from the secondary transfer portion.

Next, FIG. 3 shows the driving sources of the photosensitive drums 5 (5Y, 5M, 5C, 5K), the developing rollers 8 (8Y, 8M, 8C, 8K), and the driving rollers 12 of the intermediate transfer belt 3 in this embodiment.

The photosensitive drums 5 (5Y, 5M, 5C, 5K) and the driving roller 12 of the intermediate transfer belt 3 are rotated in the direction of the arrow by a common driving motor M1, and the developing rollers 8Y, 8M, 8C, 8K are driven by a common driving motor M2. Rotate uniformly in the direction of the arrow. Since the photosensitive drum 5 and the developing roller 8 are separate driving sources, they can be rotated at desired rotational speeds.

In this configuration, there is a wide color gamut print mode as a wide color gamut image forming mode in addition to a normal print mode as a normal image forming mode, and the image forming apparatus can execute a plurality of these image forming modes. In the wide color gamut print mode, the rotation speed of the developing roller 8 with respect to the rotation speed of the photosensitive drum 5 (hereinafter referred to as peripheral speed difference) is increased compared to the normal print mode. Increase the amount of toner to achieve a wider color gamut.

[Structure of photosensitive drum 1, potential setting, and peripheral speed difference of developing roller]
FIG. 4 shows the layer structure of the photosensitive drum 5. As shown in FIG. The main components of the photosensitive drum 5 are, from the bottom layer, a drum substrate 501 made of a conductive material such as aluminum, an undercoat layer 502 that suppresses light interference and improves the adhesiveness of the upper layer, a charge generation layer 503 that generates carriers, and a charge generation layer 503 that generates carriers. and a charge transport layer 504 for transporting carriers. The drum base body 501 is grounded, and when the surface of the photosensitive drum 5 is charged by the charging roller 7, an electric field is formed from the inside to the outside of the photosensitive drum 5 . When the photosensitive drum 5 is irradiated with light from the scanner unit 9 , carriers are generated in the charge generation layer 503 . The carriers move due to the electric field and pair with charges on the surface of the photosensitive drum 5 to change the surface potential of the photosensitive drum 5 .

The surface potential of the photosensitive drum 5 in the normal print mode and the wide color gamut print mode will be described with reference to FIG. First, the potential at which the surface of the photosensitive drum 5 is charged by the charging roller 7 is defined as a charging potential Vd. After that, the surface potential of the photosensitive drum 5 changes to the exposure potential Vl by exposure. A voltage is applied to the developing roller 8 by a high voltage power source (not shown) so as to have a developing potential Vdc. Since the development potential Vdc is set between the exposure potential Vl and the charging potential Vd, the electric field is generated in the direction opposite to the direction in which the toner coated on the surface of the development roller 8 is developed onto the photosensitive drum 5 in the non-exposed portion. is formed, and an electric field is formed in the developing direction on the photosensitive drum 5 side in the exposed portion. The electric field develops the toner in the exposed portion, but the electric field in the exposed portion weakens because the surface potential of the photosensitive drum 5 increases due to the toner charge as the toner develops. With the toner supply amount in the normal print mode, the entire area K of Vdc cannot be used as the density of the image portion having a relatively large area (hereinafter referred to as solid density) with respect to the line image, and Vdc appears to be smaller than Vdc. ' is the region T. Therefore, by increasing the peripheral speed difference and increasing the toner supply amount, it is possible to use the photosensitive drum 5 up to a region K where the toner amount on the photosensitive drum 5 is saturated at a certain peripheral speed difference.

As described above, the peripheral speed difference is 140% in the normal print mode and 280% in the wide color gamut print mode in the configuration of this embodiment.

[Regarding color conversion conditions for wide color gamut print mode]
Color conversion conditions (gamma correction) in the normal print mode in this embodiment will be described with reference to FIG.

The upper left graph in FIG. 6 is the raw γ curve 1 . Since the raw γ-curve 1 is not linear with respect to the image data, γ-correction is performed to make it linear. γ correction is performed using an LUT (look up table).

For example, if it is desired to produce a reflection density of 0.8 for image data 80h, it can be seen from the raw γ curve 1 that actual image data A0h should be used in order to produce a reflection density of 0.8. . Therefore, when the input image data is 80h, the actual image data uses A0h. Similarly, a series of input image data and image data to be actually used are associated with each other to create an LUT. The LUT created in this manner is LUT1 shown in the upper right graph of FIG.

By using this LUT1, the post-correction γ-curve 1 becomes linear as shown in the lower left graph of FIG.

Next, FIG. 7 will be used to explain the case where the conventional LUT 1 for the normal print mode is used in the wide color gamut print mode.

In the wide color gamut print mode, the maximum amount of toner on the recording material is increased, so the raw γ curve 2 is as shown in the upper left graph of FIG. The dashed line is the raw γ curve 1 in normal print mode. The raw γ curve 2 in the wide color gamut print mode has a higher reflection density than the raw γ curve 1 in the normal print mode.

Therefore, when gamma correction is performed using LUT1 in the normal print mode, the raw gamma curve 1 in the image data FFh has a reflection density of 1.45, whereas the raw gamma curve 2 has a reflection density of 1.75. Become. As a result, text images, fine lines, etc., for which there is no need to increase the amount of toner, are scattered or (characters) are blurred. In addition, since the input image data is 80h, LUT1 is corrected so that the actual image data A0h is used. Therefore, the density increases from raw γ curve 2 to 1.2, and the γ curve after correction is also linear. It's gone. As a result, there is a problem that the photographic image becomes darker as a whole, the gradation is lost, and the appearance of colors changes.

Moreover, these problems appear conspicuously depending on the image data. Text images and thin lines that cause scattering are vector image data that describe graphics with numerical (vector) data. In addition, photographic images that lose gradation are raster paper that expresses squares of various colors and shades in a mesh pattern so finely that it is almost impossible to see with the naked eye, just like painting each square of grid paper. image data. Therefore, by changing the gamma correction according to the image data, an LUT that does not cause scattering, etc., is adopted for vector image data, and an LUT that does not destroy gradation or change the appearance of colors is adopted for raster image data. There is a need to.

Next, the case of the first embodiment in which different color conversion conditions are used according to the image data in the wide color gamut print mode will be described with reference to FIG.

The first embodiment is characterized in that color conversion conditions (LUT2, LUT3) different from the color conversion conditions (LUT1) in the normal print mode are used according to the image data in the wide color gamut print mode.

LUT2 (solid line) is used for vector image data used for text images and thin lines. The LUT 2 makes the reflection density in the image data FFh the same as in the normal print mode, and makes the γ curve after correction in the medium and low density areas the same as the γ curve after correction in the normal print mode, The color gamut is kept from widening in high-density areas that are almost solid.

Next, LUT3 (one-dot dashed line) is used for raster image data used for photographic images. The LUT 3 makes the γ-curve after correction the same as the γ-curve after correction in the normal image forming mode in middle and low density areas, and widens the color gamut in high-density areas close to solid.

Next, the color conversion conditions in the wide color gamut print mode will be described with reference to the flow chart of FIG.

First, the controller 102 determines the image forming mode specified in the print job received in step S1.

When the wide color gamut print mode is specified as the image forming mode, the image data discriminating unit 110 discriminates whether the image data is vector image data or raster image data based on the input image information before being developed by the RIP unit 104. . If it is determined to be raster image data, processing for raster image data is started in step S3, and if it is determined to be vector image data, processing for vector image data is started in step S4.

After that, according to the image data format determined by the image data determination unit 110 through RIP processing (development processing) and color conversion, gamma correction is performed using LUT2 for vector image data and LUT3 for raster image data. Finally, halftoning processing is performed and an image is output.

By doing so, it is possible to widen the color gamut while ensuring halftone gradation in photographic images without scattering text images and fine lines or blurring (characters) images.

FIG. 10 shows the color gamut of this embodiment. The black line represents the wide color gamut print mode, and the gray line represents the color reproduction range of the normal print mode. It can be seen that the color gamut of the wide color gamut print mode of the first embodiment is wider than the color gamut of the normal print mode, and the color reproduction range that can be output is expanded. Therefore, even when a text image or the like is mixed in a photo image to be output in the wide color gamut print mode, it is possible to output a photo image with a wide color gamut without scattering or blurring of characters.

In this embodiment, in addition to the same control as in Embodiment 1, different color separation is performed for vector image data in the wide color gamut print mode, and when RGB color space data is converted into developer (toner) color data YMCK, , are characterized by different transformations. The image forming apparatus will be described below.

[About color separation in wide color gamut print mode]
The image forming apparatus used in this embodiment and the basic configuration and operation of the optimum rotational speed of the developer supplying means in the wide color gamut print mode are the same as those described in the first embodiment. Therefore, the detailed description for this embodiment will be omitted.

In this embodiment, when color-matched R'G'B' is converted into color data YMCK of each developer, the vector image data is converted so as to reduce the maximum toner amount. This conversion is performed by a conversion table. For example, Red-FFh (solid) is converted to Yellow-FFh (solid)+Magenta-FFh (solid) as Yellow-D0h+Magenta-D0h. Such color conversion from RGB to YMCK is performed in a high-density area so that the reflection density of 1.75 of the image data FFh in the wide color gamut print mode becomes the reflection density of 1.45 of the image data FFh in the normal print mode. , is thinned out by about 17% at the time of conversion. In this embodiment, Table 1 shows conversion of Red as an example. Conversion is performed in the red high-density region E0h or higher, and conversion is performed by linear interpolation in the regions between E0h, F0h, and FFh. Green and Blue are also converted in the same way.

By doing so, it is possible to prevent text images and fine lines from being scattered, and (characters) from being distorted. In this embodiment, as in the first embodiment, even when a photographic image output in the wide color gamut print mode includes a text image or the like, characters are not scattered or blurred. Photo images can be output.

In this embodiment, in addition to the same control as in the first embodiment, an image forming apparatus will be described in which the surface potential of the photosensitive drum in the wide color gamut print mode is optimized for density stability.

[Surface potential of photosensitive drum in wide color gamut print mode]
The image forming apparatus used in this embodiment and the basic configuration and operation of the optimum rotational speed of the developer supplying means in the wide color gamut print mode are the same as those described in the first embodiment. Therefore, the detailed description for this embodiment will be omitted.

FIG. 11 illustrates the surface potential of the photosensitive drum 5 in this embodiment.

The surface potential of the photosensitive drum 5 is determined by the charging potential Vd, the developing potential Vdc, and the exposure potential Vl as described in the first embodiment. Each potential in the print mode is set to a necessary and sufficient value for developing the toner coated on the surface of the developing roller 303 . Therefore, even if the potential fluctuates for some reason, the amount of toner to be developed does not change and the density is stabilized. However, if each potential of the wide color gamut print mode is adopted in the normal print mode, the density will not be stable because the amount of developed toner will also change when the potential fluctuates. As described above, in this embodiment, _Vdn , _Vdcn and _Vln are used instead of _Vdw , _Vdcw and _Vlw as the potentials in the normal print mode from the viewpoint of density stability. Therefore, in the normal print mode in the configuration of this embodiment, the peripheral speed difference is 140%, Vd _n =-500 V, Vdc _n =-350 V, and Vl _n =-100 V. In the wide color gamut print mode, a peripheral speed difference of 280%, Vd _w =−850 V, Vdc _w =−600 V, and Vl _w =−120 V are adopted.

By doing so, it is possible to set the optimum potential according to the print mode, and to ensure a stable density in each print mode. In this embodiment, as in the first embodiment, even when a photographic image output in the wide color gamut print mode includes a text image or the like, characters are not scattered or blurred. Photo images can be output.

101 host PC
102 Controller 103 Image Formation Engine Controller 104 RIP Section 105 Color Conversion Section 106 γ Correction Section 107 Halftoning Section 108 Color Matching Section 109 Color Separation Section 110 Image Data Discrimination Section 1 Paper Feed Cassette 2 Paper Feed Roller 3 Intermediate Transfer Belt 4 Image Exposure 5 Photosensitive Drum 501 Drum Substrate 502 Undercoat Layer 503 Charge Generation Layer 504 Charge Transport Layer 6 Registration Roller Pair 7 Charging Means 8 Development Roller 9 Exposure Means 10 Primary Transfer Roller 11 Secondary Transfer Roller 12 Driving Roller 13 Tension Roller 14 Fixing Device 17 idler roller 18 secondary transfer opposing roller M1 drive source for photosensitive drum M2 drive source for developing roller

Claims (6)

a controller that generates post-conversion image information based on input image information input from the outside;
a rotatable image carrier;
developer carrying on the surface of the image carrier, and supplying the developer to an electrostatic latent image formed on the surface of the image carrier on the basis of post-conversion image information in a developing section facing the image carrier; body and
a development voltage applying unit that applies a development voltage to the developer carrier;
The controller is
a rendering means for rendering the input image information into a vector image or a raster image;
control means for performing color adjustment control on each of the first developed image information of the vector image and the second developed image information of the raster image developed by the development means;
a normal image forming mode in which the electrostatic latent image formed on the image carrier is developed by setting the peripheral speed ratio of the developer carrier to the image carrier to a predetermined peripheral speed ratio; In an image forming apparatus capable of executing a wide color gamut image forming mode in which the color gamut of an image formed on a recording material is expanded more than in the normal image forming mode by making it larger than in the normal image forming mode,
When the normal image forming mode is executed, the control means performs color conversion using the first developed image information for the vector image and the second developed image information for the raster image. Color adjustment control is performed using color conversion conditions, and when the wide color gamut image formation mode is executed, a second color conversion condition for performing color conversion using the first developed image information for the vector image ; and a third color conversion condition for performing color conversion using the second developed image information for an image , and performing the color adjustment control. The control means is
a color matching unit that adjusts color reproducibility for the raster image;
a color separation unit that converts the color space data that has undergone color reproduction adjustment in the color matching unit into each color of the developer;
a gamma correction unit that corrects the data converted by the color separation unit;
a halftoning unit that performs gradation expression processing on the color data corrected by the γ correction unit;
2. The image forming apparatus according to claim 1, comprising: 3. A method according to claim 2, wherein said control means performs said color adjustment control by changing a γ curve of said γ corrector between said first developed image information and said second developed image information. image forming device. 3. The control device according to claim 2, wherein the control means performs the color adjustment control by changing the conversion table of the color separation section between the first developed image information and the second developed image information. image forming device. When the wide color gamut image forming mode is executed, the control means sets the maximum toner amount of the image data when color conversion is performed using the second color conversion condition in the first developed image information to 5. The toner amount is controlled so as to be smaller than the maximum toner amount of the image data when color conversion is performed using the third color conversion condition in the second developed image information. 1. The image forming apparatus according to item 1 or 1 . The control means sets a target maximum toner amount of image data when color conversion is performed using the second color conversion condition in the first developed image information when the wide color gamut image forming mode is executed. The value is controlled so as to be the same as the target value of the maximum toner amount of the image data when color conversion is performed using the first color conversion condition when the normal image forming mode is executed. 6. The image forming apparatus according to claim 5 .

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