JP5915224B2 - Image processing apparatus, image forming apparatus, and image processing method - Google Patents

Description

  The present invention relates to an image processing apparatus, an image forming apparatus, and an image processing method.

  Currently, when a color image is output by a color copying machine, the output color image should be glossy in order to obtain a color reproducibility that is close to the color gamut of photographic paper and computer displays. It is getting done.

  When giving gloss to an output color image, it is required to eliminate a gloss difference and gloss unevenness on the image, and to form a natural color image that is faithful to the original image and has no sense of incongruity. In order to form such a color image, a process color (Y, M, C, K) signal is supplied, and a total amount of color material (toner) per unit area of a region where the color image is formed is determined. A technique for forming an image by controlling a preset amount of transparent color material (clear toner) is known (for example, Patent Document 1).

  However, in conventional image forming apparatuses that form an image including a transparent color material plate, when forming a color image on previously glossy paper such as coated paper, the type of transparent color material to be used, and image output If the image forming conditions such as the fixing temperature according to the mode are determined, the direction and range of the gloss control for the color image output due to the addition of the transparent color material are determined, so that the image cannot be formed by freely adjusting the glossiness. There was a problem.

  The present invention has been made in view of the above, and is not limited to image forming conditions such as the properties of recording paper, the type of transparent color material to be used, and image forming conditions (image output mode). An object is to enable image formation by adjusting the degree freely.

In order to solve the above-described problems and achieve the object, the image processing apparatus of the present invention is a process corresponding to each pixel of input image data that is an object of image formation according to an image forming condition at the time of image formation. Gloss control plane data to which process color total amount regulating means for regulating the total amount of toner by regulating the output level of color and density information of a special color for obtaining gloss corresponding to each pixel of the input image data Or a special color signal with its data level set to equalize the height of the toner surface formed by the process color and the special color according to the total amount regulation result for the process color as gloss control plane data. Spot color signal generating means for generating and outputting, and process color and spot color from the process color total amount regulating means and the spot color signal generating means Special color signal adaptive total amount regulating means for regulating the total amount of toner of the process color and the special color by regulating the output level of the process color or the special color when the sum of the force levels is larger than the total amount regulation value for the process color and the special color; , And the total toner amount of the process color corresponding to the input image data exceeds the reference total toner amount corresponding to the arbitrarily set glossiness, the process color total amount regulating means controls the process color When the total toner amount of the process color corresponding to the input image data does not satisfy the standard, the total color toner amount of the process color corresponding to the input image data and the standard are controlled by the spot color signal generation unit. Is the amount of the special color toner corresponding to the image data. By, and it performs gloss processing for equalizing the height of the toner surface formed by the process and spot colors.

The present invention also relates to an image processing method in an image processing apparatus comprising a process color total amount regulating means, a spot color signal generating means, and a spot color signal adaptive total quantity regulating means, wherein the process color total quantity regulating means is used when an image is formed. The total amount of toner is regulated by regulating the output level of the process color corresponding to each pixel of the input image data that is the object of image formation according to the image forming conditions, and the spot color signal generating means controls the input image. Acquire gloss control data corresponding to each pixel of data and assign density information of special color to obtain gloss, or process color and special color as gloss control data according to the total amount regulation result for the process color Generate and output a spot color signal in which the data level is set so that the height of the formed toner surface is uniform, When the total sum of output levels of the process color and the spot color from the process color total amount regulation unit and the spot color signal generation unit is larger than the total amount regulation value for the process color and the spot color by the color signal adaptive total amount regulation unit, the process color Alternatively, by regulating the output level of the special color, the total toner amount of the process color and the special color is regulated, and the total toner amount of the process color corresponding to the input image data becomes a reference toner corresponding to the arbitrarily set glossiness If the total amount exceeds the total amount, the total amount of process color toner is regulated by the process color total amount regulating means, and if the total amount of process color toner corresponding to the input image data does not satisfy the standard, the spot color signal is generated. A process corresponding to the input image data by means The difference between the total amount of toner color and the reference, by the amount of toner features corresponding to the image data, performing the gloss processing for equalizing the height of the toner surface formed by the process and spot colors It is characterized by.

  According to the present invention, there is an effect that an image can be formed by freely adjusting glossiness in an image without being limited by image forming conditions such as the properties of recording paper, the type of transparent color material to be used, and image forming conditions. .

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. FIG. 2 is an overall configuration diagram of the image processing apparatus provided in the image forming apparatus. FIG. 3 is a diagram showing a detailed block configuration of the total amount restriction processing unit of the image processing apparatus. FIG. 4 is a diagram illustrating an example of the forward deposition amount conversion table. FIG. 5 is a diagram schematically showing input image data as corresponding CMYK toner overlap. FIG. 6 is a diagram for explaining a normal process color total amount regulating process. FIG. 7 is a diagram illustrating an example of the reverse adhesion amount conversion table. FIG. 8 is a diagram for explaining the total amount regulating process by the pile height uniformizing process for uniformizing the height of the toner surface formed with five colors including the special color (transparent). FIG. 9 is a diagram showing the relationship between the total amount of process color (CMYK) toner and a transparent color material plate (αo data) obtained by a uniform pile height process. FIG. 10 is a diagram showing the relationship between the total amount of toner under an arbitrary image forming condition and the glossiness obtained by the pile height uniformization process of FIG. FIG. 11 is a diagram illustrating the relationship between the total amount of toner under an arbitrary image forming condition and the gloss level when output is uniformly performed with a set gloss level. FIG. 12 is a conceptual diagram of the pile height equalization processing and mat processing shown in FIG. FIG. 13 is a diagram showing the gloss characteristics of the clear toner plate with respect to changes in the cluster size. FIG. 14 is a flowchart for explaining an overview of the flow of processing in the total amount restriction processing unit. FIG. 15 is a diagram illustrating a hardware configuration (electrical configuration) of the image forming apparatus.

  Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. The image forming apparatus according to the present embodiment applies yellow (Y), magenta (M), cyan (C), black (K), and transparent (W) toner images to the peripheral surfaces of a plurality of image carriers. This is a color image forming apparatus which forms an image by forming it, superimposing it on an intermediate transfer member and transferring it (primary transfer), and then transferring it again to the transfer material (secondary transfer).

  Yellow (Y), magenta (M), cyan (C), black (K) composed of a photosensitive drum 10 as an image carrier, a charger 11, an exposure optical system 12, a developing device 13, and a cleaning device 20. The transparent (W) image forming units 50Y, 50M, 50C, 50K and 50W are arranged from the upstream side in the rotation direction of the transfer belt 14 which is a belt-like intermediate transfer member. Transfer (primary transfer) so that the yellow (Y), magenta (M), cyan (C), and black (K) toner images formed in each image forming unit 50 sequentially overlap the peripheral surface of the transfer belt 14. ) To obtain a color toner image. Further, an image on which a transparent clear toner image is superimposed is formed on the uppermost layer by the image forming unit 50W.

  The clear toner image formed on the transfer belt 14 and the color toner image below the clear toner image are opposite to the toner of the transfer unit 17 on the surface of the recording paper P fed from the paper feed cassette 15 via the timing roller 16. The toner is welded in the fixing device 18 with the clear toner image on the recording paper P as the lowermost layer and the color toner image held on the upper layer on the recording paper P by the discharge action having polarity. After that, it turns in the horizontal direction and is discharged to the tray 19 at the top of the apparatus. After the transfer, the transfer belt 14 is cleaned by removing residual toner in the cleaning device 21. The arrangement (arrangement) of the image forming units 50Y, 50M, 50C, 50K and 50W for yellow (Y), magenta (M), cyan (C), black (K) and transparent (W) is shown in FIG. It is not limited to what is shown.

  FIG. 2 is an overall configuration diagram of the image processing apparatus provided in the image forming apparatus. This image processing apparatus generates necessary parameters with reference to glossiness information corresponding to image forming conditions and arbitrarily set gloss control information, and performs matte processing such as pile height uniformization processing and texture addition. By controlling the process, a combination of a process color material (CMYK toner plate) and a transparent color material (clear toner) plate that cannot be realized by the conventional inverse mask process is generated. The outline of each part will be described below.

(Input correction unit (1), (2))
The input correction unit (1) 110 and the input correction unit (2) 111 are processing modules (not shown) of the following binary → multi-value conversion unit, logic inversion unit, RGB → Gray conversion unit, and separated signal generation unit. ).

  The binary-to-multivalue conversion unit converts the input 1-bit / pixel data into 8-bit / pixel and outputs the converted data. The logic inversion unit inverts the image logic for the RGB + X image data (in this case, it is assumed that the logic inversion is performed with the logic of 0 for white and 255 for black). The RGB → Gray conversion unit performs graying and RGB development by switching channels on RGB + X image data. The separation signal generation unit internally generates a separation signal for the RGB + X image data. The image format referred to as RGB + X is a format in which additional information bits are added to each pixel with respect to image information in the well-known RGB image format.

(Synthesizer)
The synthesizing unit 120 synthesizes two image data (original image data and synthesized image data) from the input correcting unit (1) 110 and the input correcting unit (2) 111 each composed of RGB (8 bits / pixel) + X (2 bits). A multi-value composition module that performs processing and a special color signal selection module that outputs a composite input signal (RGB + X) as a special color (transparent) signal (8 bits × 1 ch) in order to handle the clear toner plane.

(Pattern generator)
The pattern generation unit includes two types of pattern generation units: a pattern generation unit (RGB) 130 and a pattern generation unit (CMYK) 131 described below.

  The pattern generator (RGB) 130 outputs various test patterns (8 bits × 3 ch) to a video path through which RGB image data flows. The pattern generator (CMYK) 131 outputs various test patterns (8 bits × 5ch) to a video path in which CMYKT image data (T is a special color (transparent)) flows.

(Filter part)
The filter unit 140 performs the following image quality improvement processing on the input RGB signal.

(1) A predetermined (or designated) filter process is performed on the input RGB signal.
(2) Output RGB data for hue determination for color correction.
(3) Output GCR feature data for generating black (K version).
(4) An isolated point removal process is performed on the input RGB signal.
(5) Thinning / thickening processing is performed on the input RGB signal.

(Skin correction part)
The background correction unit 150 dynamically detects the background level of the image signal, corrects the image signal based on the detected background level, and keeps the background level constant, resulting from variations in the background density and reading of the document. Perform processing to eliminate unevenness.

(Color correction part)
The color correction unit 160 includes the following processing modules (not shown) of a saturation adjustment unit, a hue division masking color conversion unit, a 3DLUT color conversion unit, a UCR / UCA processing unit, and an under color processing unit. The input RGB image data is subjected to color correction and color processing as described below using the input hue determination RGB data and GCR feature data.

  The saturation adjusting unit converts the RGB signal into a Yuv signal, then converts it back into an RGB signal, and outputs it. The hue division masking color conversion unit performs masking calculation processing according to the hue on the input RGB data, and converts the input RGB data into unified RGB data reflecting the requested color adjustment (color processing). The 3DLUT color conversion unit performs a memory map interpolation operation using the 3D LUT on the unified RGB data, and converts the data into a designated output color space. The UCR / UCA processing unit performs black processing (four-color separation processing) on the CMY data after the 3DLUT color conversion, and converts the data into CMYK data. The under color processing unit performs under color processing on the color-converted CMYK data.

(Magnifying part)
The scaling unit 170 performs main scanning scaling or sub-scanning scaling according to a specified enlargement or reduction request.

(Total amount regulation department)
The total amount regulating unit 180 is a main part in the present embodiment, and details thereof will be described later.

(Output tone correction unit)
The output tone correction unit 190 includes processing modules (not shown) of the following printer γ processing unit, halftone processing unit, binarization processing unit, thinning processing unit, unevenness correction unit, and clear toner dither processing unit. ) And performs gradation processing adapted to the number of output bits of the image processing apparatus. Further, processing related to mat processing described later is also performed.

  The printer γ processing unit corrects the output characteristics of the image forming apparatus with respect to the input data so as to obtain a desired output density. The halftone processing unit performs pseudo halftone processing. The binarization processing unit outputs a pixel value obtained by binarizing the input gradation value after γ conversion using a fixed threshold value. The thinning processing unit performs 1/2 thinning processing in the main scanning direction and 1/2 thinning processing in the sub-scanning direction on the binarized data. The unevenness correction unit performs unevenness correction on the data after the binarization processing. The clear toner dither processing section performs clear toner dither processing.

(ACS determination unit)
The ACS determination unit 200 determines whether the original is a color original or a monochrome original from the input RGB image data.

(Blank paper detection unit)
The blank page detection unit 210 compares the binarized data (counting continuity) with the threshold for the area defined by the register, and determines that the page is blank when all predetermined conditions are satisfied.

(Output control unit)
The output control unit 220 controls the output of image data (CMYK + α) to the engine unit.

  Next, FIG. 3 shows a detailed block configuration of the total amount restriction processing unit corresponding to the gloss control information (gloss control plane data). Hereinafter, detailed specifications (usage parameters, processing, etc.) will be described for each functional module. The following various parameters are set in predetermined registers according to the image output conditions set by the user.

(Forward deposition amount conversion part)
The forward adhesion amount conversion unit 181 is a functional module that converts input image data into image data converted into toner adhesion amount (forward adhesion amount conversion). The signals that are input to and output from this module and the parameters that are used are shown below. FIG. 4 shows an example of the forward deposition amount conversion table (the horizontal axis is input and the vertical axis is output).

(Input / output and parameters used)
<Input>
Ci: Input C data signal (8bit)
Mi: Input M data signal (8bit)
Yi: Input Y data signal (8bit)
Ki: Input K data signal (8bit)
αi: Input α data signal (8bit)
Sep: Separation signal (2bit)

<Output>
Co (Ct): Output C data signal (8bit) after conversion of forward adhesion amount
Mo (Mt): Output M data signal (8bit) after conversion of the forward adhesion amount
To (Yt): Output Y data signal (8bit) after conversion of forward adhesion amount
Ko (Kt): Output K data signal (8bit) after conversion of the forward deposition amount
αo (αt): Output α data signal (8bit) after forward adhesion amount conversion

<Use parameters>
conv _ * _ text: Forward-attachment conversion table for characters (* is c, m, y, k, or α)
conv _ * _ phot: Forward deposition amount conversion table for patterns (* is c, m, y, k, or α)
conv_luton: Forward deposition amount conversion table control

(Select parameters to use)
The selection of the 5st (CMYK + α) forward deposition amount conversion table (hereinafter, *: c, m, y, k, or α) based on the separation signal Sep is performed as follows.

(A) When Sep = “character” or “other than image”: Conv _ * = conv _ * _ text
(B) When Sep = “Picture” or “Image”: Conv _ * = conv _ * _ phot

  The separation signal Sep is a signal indicating the result of the image area separation of the input image into characters / pictures / images or the like by the input correction unit (1) 110 and the input correction unit (2) 111.

(Adhesion amount conversion of input signal (forward deposition amount conversion))
When the forward deposition amount conversion table control (conv_luton) is ON (1), the input Ci, Mi, Yi, Ki, and αi image data are supported for each color plate based on the separation signal Sep as follows. By using the forward adhesion amount conversion LUT (8 bits), the converted values are converted into adhesion amount conversion values Ct, Mt, Yt, Kt, and αt (8 bits) (for toner and ink).

  When conv_luton is ON (1): Ct = Conv_c [Ci], Mt = Conv_m [Mi], Yt = Conv_y [Yi], Kt = Conv_k [Ki], αt = Conv_a [αi]

  When the forward deposition amount conversion table control (conv_luton) is OFF (0), the input is output as it is as follows.

  When conv_luton is OFF (0): Ct = Ci, Mt = Mi, Yt = Yi, Kt = Ki, αt = αi

[Process Color (CMYK) Total Volume Regulations]
The process color total amount restriction unit 182 is a functional module that performs a total amount restriction process for a normal process color (four colors: CMYK). The signals that are input to and output from this module and the parameters that are used are shown below.

(Input / output and parameters used)
<Input>
Ci (Ct): Input C data signal (8bit) after conversion of adhesion amount
Mi (Mt): Input M data signal after conversion of adhesion amount (8bit)
Yi (Yt): Input Y data signal after conversion of adhesion amount (8 bits)
Ki (Kt): Input K data signal after conversion of adhesion amount (8bit)
Sep: Separation signal (2bit)

<Output>
Co (Cs): Output C data signal (8bit) after regulation of total process color
Mo (Ms): Output M data signal (8bit) after regulation of total process color
Yo (Ys): Output Y data signal after regulation of total process color (8bit)
Ko (Ks): Output K data signal (8bit) after regulation of total process color
kisei_h: Total amount regulation judgment result (1 bit)

<Use parameters>
max_4st_text: Total amount regulation value for character process colors (CMYK) (maximum adhesion amount)
max_4st_phot: Total amount regulation value for pattern process colors (CMYK) (maximum adhesion amount)
kisei_4st_enbl: Total amount restriction enable for process color (CMYK)

(Select parameters to use)
The total amount regulation value (maximum adhesion amount) of the process color (CMYK) based on the separation signal Sep is selected as follows.

(a) When Sep = “character” or “non-image”: MAX_4st = max_4st_text
(b) When Sep = “Picture” or “Image”: MAX_4st = max_4st_phot

(Total amount restriction processing (conversion of CMYK data associated with total amount restriction))
When the total amount regulation process is ON (kisei — 4st_enbl = 1), the process color (CMYK) is calculated using the image data values (Ct, Mt, Yt, Kt) converted into the adhesion amount by the above-described forward adhesion amount conversion unit 181. Regulate the total amount. For example, FIG. 5 schematically shows the input image data as the overlap of the corresponding CMYK toners, but the sum of the total amount regulation value MAX_4st (250% in the example of FIG. 6) and Ct, Mt, Yt, Kt. When the total is larger than MAX_4st, the data level is regulated (see FIG. 6). FIG. 6 is a diagram for explaining a normal process color total amount restriction process.

  In order to preserve the black (K) reproduction level as much as possible (brightness preservation), the total amount restriction implemented here is set to a value obtained by subtracting Kt from MAX_4st as the restriction value for CMY as follows. The portion is erased according to the ratio of CMY. Data Cs, Ms, Ys, and Ks after total amount regulation calculated as follows are each 8 bits. In division, only the integer part is valid and the decimal part is rounded down.

(a) When Ct + Mt + Yt + Kt ≦ MAX_4st:
Total amount regulation judgment OFF (kisei_h = 0),
Cs = Ct, Ms = Mt, Ys = Yt, Ks = Kt

(b) When Ct + Mt + Yt + Kt> MAX_4st and MAX_4st <Kt:
Total amount regulation determination ON (kisei_h = 1),
Cs = 0, Ms = 0, Ys = 0, Ks = MAX_4st

(c) When Ct + Mt + Yt + Kt> MAX_4st and MAX_4st ≧ Kt:
Total amount regulation determination ON (kisei_h = 1),
Cs = (Ct * (MAX_4st-Kt)) / (Ct + Mt + Yt),
Ms = (Mt * (MAX_4st-Kt)) / (Ct + Mt + Yt),
Ys = (Yt * (MAX_4st-Kt)) / (Ct + Mt + Yt),
Ks = Kt
However, when Ct + Mt + Yt = 0, Cs = 0, Ms = 0, Ys = 0, and Ks = Kt.

  At this time, MAX_4st (10 bits) is applied with different total amount regulation values for the character area and the picture area, and max_4st_text (10 bits) is referred to for the character area, and max_4st_phot (10 bits) is referred to for the picture area. The total amount restriction determination result (kisei_h) is output to the output selector 186 (overall selector) at the subsequent stage.

  When the total amount restriction process is OFF (kisei_4st_enbl = 0), the through output is as follows.

Total amount regulation judgment OFF (kisei_h = 0),
Cs = Ct, Ms = Mt, Ys = Yt, Ks = Kt

[Spot color signal generator]
The spot color signal generation unit 183 is a clear toner (α) signal generation module for setting a clear toner (α) data level having a high degree of freedom corresponding to various use cases. The signals that are input to and output from this module and the parameters that are used are shown below.

(Input / output and parameters used)
<Input>
Ci (Cs): Input C data signal (8bit) after regulation of total process color
Mi (Ms): Input M data signal (8bit) after regulation of total process color
Yi (Ys): Input Y data signal (8bit) after regulation of total process color
Ki (Ks): Input K data signal (8bit) after regulation of total process color
αi (αt): Input α data signal after conversion of adhesion amount (8bit) (Gloss control data)
Sep: Separation signal (2bit)

<Output>
αs: Output α data signal after clear toner signal generation (10bit)

<Use parameters>
target_alpha_text: Clear toner for character (α) data target adhesion amount
target_alpha_phot: Clear toner for image (α) data target adhesion amount
lut_alpha_text: Character clear toner (α) data generation table
lut_alpha_phot: Pattern clear toner (α) data generation table
max_4st_text: Total amount regulation value for character process colors (CMYK) (maximum adhesion amount)
max_4st_phot: Total amount regulation value for pattern process colors (CMYK) (maximum adhesion amount)
self_gen_enbl: Clear toner (α) data internal generation enable
zero_mask_enbl: Clear toner (α) zero input mask processing enable

(Select parameters to use)
Selection of the clear toner (α) data target adhesion amount based on the separation signal Sep is performed as follows.

(A) When Sep = “character” or “non-image”: Target_alpha = target_alpha_text
(B) When Sep = “Picture” or “Image”: Target_alpha = target_alpha_phot

  Selection of the clear toner (α) data generation table based on the separation signal Sep is performed as follows.

(A) When Sep = “character” or “non-image”: LUT_alpha = lut_alpha_text
(B) When Sep = “Picture” or “Image”: LUT_alpha = lut_alpha_phot

  The process color (CMYK) total amount regulation value (maximum adhesion amount) based on the separation signal Sep is selected as follows.

(A) When Sep = “character” or “non-image”: MAX_4st = max_4st_text
(B) When Sep = “Picture” or “Image”: MAX_4st = max_4st_phot

(Input value setting for clear toner (α) data generation table)
In accordance with the internal generation enable (self_gen_enbl) for the clear toner (α) data, the setting value of the data input to the clear toner (α) data generation table is changed.

  When clear toner (α) data is generated internally, the LUT input (Lut_in) is obtained by dividing the sum of the process colors by the total amount restriction value (MAX — 4st) for four colors as described below.

When internal generation is ON (self_gen_enbl = 1): sum_CMYK = Ct + Mt + Yt + Kt
Lut_in = (sum_CMYK << 8) / MAX_4st (However, when Lut_in> 255, Lut_in = 255. “<<” is a bit shift operator.)

  When clear toner (α) data is not generated internally, the clear toner (α) data after the adhesion amount conversion input to the module is used as LUT input (Lut_in) as described below.

  When internal generation is OFF (self_gen_enbl = 0): Lut_in = αt

(Clear toner (α) signal generation and unit axis conversion)
Using the clear toner (α) data generation table (LUT_alpha), clear toner (α) data for the LUT input (Lut_in) set by the input value calculation for the spot color (α) data generation table is obtained. Further, when the total amount is calculated by the total amount regulation module adapted to the clear toner signal at the subsequent stage, the clear toner (α) data level is the maximum (= 255) so that the 5st (CMYK + α) signal level is matched. α) The unit axis is converted so that the data target adhesion amount is obtained.

αtt = (LUT_alpha [Lut_in] × Target_alpha) >> 8
In the above equation, αtt is 255/256 with respect to Target_alpha (target adhesion amount) when LUT_alpha [Lut_in] = 255. Note that “>>” is a bit shift operator.

(Zero input mask)
When the clear toner (α) zero input mask processing enable is ON (zero_mask_enbl = 1), the module-input α data (zero input) is referred to, and the internally generated clear toner (α) data is masked and output. .

(A) When zero input mask is ON (zero_mask_enbl = 1) and zero input (αt = 0): αs = 0
(B) When zero input mask is ON (zero_mask_enbl = 1) and non-zero input (αt ≠ 0): αs = αtt
(C) When zero input mask is OFF (zero_mask_enbl = 0): αs = αtt

[Special color signal adaptive total amount regulation department]
The spot color signal adaptive total amount restriction unit 184 is a total amount restriction processing module adapted to 5st (CMYK + α) having a high degree of freedom corresponding to various use cases. The signals that are input to and output from this module and the parameters that are used are shown below.

(Input / output and parameters used)
<Input>
αi (αs): Input α data signal (10 bits) after clear toner signal generation
Ci (Cs): Input C data signal (8bit) after regulation of total process color
Mi (Ms): Input M data signal (8bit) after regulation of total process color
Yi (Ys): Input Y data signal (8bit) after regulation of total process color
Ki (Ks): Input K data signal (8bit) after regulation of total process color
Sep: Separation signal (2bit)

<Output>
αo (αd): Output α data signal (8bit) after regulation of special color signal adaptive total amount
Co (Cd): Output C data signal (8bit) after regulation of special color signal adaptive total amount
Mo (Md): Output M data signal (8bit) after regulation of special color signal adaptive total amount
Yo (Yd): Output Y data signal (8bit) after special color signal adaptive total amount regulation
Ko (Kd): Output K data signal (8bit) after regulation of special color signal adaptive total amount

<Use parameters>
max_5st_text: Total amount regulation value for 5st character (CMYK + α)
max_5st_phot: Total amount regulation value for 5st (CMYK + α) for design
target_alpha_text: Clear toner for character (α) data target adhesion amount
target_alpha_phot: Clear toner for image (α) data target adhesion amount
sp_ucr _ * _ text: Character clear toner UCR coefficient (* is c, m, y, or k)
sp_ucr _ * _ phot: Clear toner UCR coefficient for design (* is c, m, y, or k)
sp_exc _ * _ text_enbl: Erase for character clear toner (* is c, m, y, or k)
sp_exc _ * _ phot_enbl: Erase for clear toner for design (* is c, m, y, or k)
kisei_5st_mode: 5st total amount regulation mode
kisei_5st_enbl: Total amount restriction enable for 5st (CMYK + α)

(Select parameters to use)
Selection of the total amount regulation value (maximum adhesion amount) of 5st (CMYK + α) based on the separation signal Sep is performed as follows.

(A) When Sep = “character” or “non-image”: MAX_5st = max_5st_text
(B) When Sep = “Picture” or “Image”: MAX_5st = max_5st_phot

  Selection of the clear toner (α) data target adhesion amount based on the separation signal Sep is performed as follows.

(A) When Sep = “character” or “non-image”: Target_alpha = target_alpha_text
(B) When Sep = “Picture” or “Image”: Target_alpha = target_alpha_phot

  The selection of the clear toner UCR coefficient based on the separation signal Sep (in the following, * is c, m, y, or k) is as follows.

(A) When Sep = “character” or “non-image”: SP_ucr _ * = sp_ucr _ * _ text
(B) When Sep = “Picture” or “Image”: SP_ucr _ * = sp_ucr _ * _ phot

  Clear toner compatible erase (enable) selection based on the separation signal Sep (in the following, * is c, m, y, or k) is as follows.

(A) When Sep = “character” or “non-image”: SP_exc _ * _ enbl = sp_exc _ * _ text_enbl
(B) When Sep = “Picture” or “Image”: SP_exc _ * _ enbl = sp_exc _ * _ phot_enbl

(Regulation of total amount of special color signal)
When the total amount restriction processing is ON (kisei_5st_enbl = 1), the total amount restriction is performed when the sum of the output levels of process color (CMYK) and clear toner (α) is larger than the total amount restriction value (MAX_5st) for 5st (CMYK + α). Do. The total amount regulation here can change the version for regulating the data level according to the setting of the 5st total amount restriction mode (kisei_5st_mode). As shown below, the α data restriction mode (kisei_5st_mode = 0) and the process color The restriction mode (kisei_5st_mode = 1) can be selected.

When in alpha data restriction mode (kisei_5st_mode = 0)
(a) When Css + Mss + Yss + Kss + αs ≦ MAX_5st:
Total amount regulation judgment OFF (kisei_h = 0),
Cd = Css, Md = Mss, Yd = Yss, Kd = Kss,
αss = αs

(b) When Css + Mss + Yss + Kss + αs> MAX_5st:
Total amount regulation determination ON (kisei_h = 1),
Cd = Css, Md = Mss, Yd = Yss, Kd = Kss (where process color is not regulated)
αss = MAX_5st- (Css + Mss + Yss + Kss) (However, when αss <0, αss = 0)

When the process color regulation mode (kisei_5st_mode = 1)
MAX_5st_adap = MAX_5st-αs (However, when MAX_5st_adap <0, MAX_5st_adap = 0)
αss = αs // α data is not regulated

(a) When Css + Mss + Yss + Kss ≦ MAX_5st_adap:
Total amount regulation judgment OFF (kisei_h = 0),
Cd = Css, Md = Mss, Yd = Yss, Kd = Kss

(b) When Css + Mss + Yss + Kss> MAX_5st_adap and MAX_5st_adap <Kss:
Total amount regulation determination ON (kisei_h = 1),
Cd = 0, Md = 0, Yd = 0, Kd = MAX_5st_adap

(c) When Css + Mss + Yss + Kss> MAX_5st_adap and MAX_5st_adap ≧ Kss:
Total amount regulation determination ON (kisei_h = 1),
Cd = (Css * (MAX_5st_adapt-Kss)) / (Css + Mss + Yss),
Md = (Mss * (MAX_5st_adapt-Kss)) / (Css + Mss + Yss),
Yd = (Yss * (MAX_5st_adapt-Kss)) / (Css + Mss + Yss),
Kd = Kss

  In the above-mentioned special color signal adaptive total amount control, different total amount control values are applied to MAX_5st (10 bits) in the character area and the picture area. . Then, the total amount restriction determination result (kisei_h) is output to the output signal selection unit 186 at the subsequent stage. When the total amount restriction process is OFF (kisei — 4st_enbl = 0), the through output is as follows.

  When total amount restriction judgment is OFF (kisei_h = 0): Cd = Css, Md = Mss, Yd = Yss, Kd = Kss

(Inverse conversion of unit axis)
Since the α data (αss) after the 5th total amount regulation has been converted to the unit axis to 10 bits (refer to the spot color signal generation and unit axis conversion processing by the spot color (α) data generation table described above), here the 8-bit output Reverse transform to become data. In the following conversion formula, only the integer part is valid and the decimal part is rounded down.

  αd = (αss << 8) / Target_alpha

(Reverse adhesion amount conversion part)
The reverse adhesion amount conversion unit 185 is a reverse adhesion amount conversion function module that converts input image data into image data converted into an adhesion amount. The signals that are input to and output from this module and the parameters that are used are shown below. FIG. 7 shows an example of the reverse adhesion amount conversion table (the horizontal axis is input and the vertical axis is output).

(Input / output and parameters used)
<Input>
Ci (Cd): Input C data signal (8bit) after the special color signal adaptive total amount regulation
Mi (Md): Input M data signal (8bit) after special color signal adaptive total amount regulation
Yi (Yd): Input Y data signal (8bit) after special color signal adaptive total amount regulation
Ki (Kd): Input K data signal (8bit) after special color signal adaptive total amount regulation
αi (αd): Input α data signal (8bit) after special color signal adaptive total amount regulation
Sep: Separation signal (2bit)

<Output>
Co (Cu): Output C data signal (8bit) after reverse adhesion amount conversion
Mo (Mu): Output M data signal (8bit) after reverse adhesion amount conversion
Yo (Yu): Output Y data signal (8bit) after reverse adhesion amount conversion
Ko (Ku): Output K data signal (8bit) after reverse adhesion amount conversion
αo (αu): Output α data signal after reverse adhesion amount conversion (8 bits)

<Use parameters>
inv _ * _ text: Reverse conversion amount conversion table for characters (* is c, m, y, k, or α)
inv _ * _ phot: Reverse drawing amount conversion table for picture (* is c, m, y, k, or α)
inv_luton: Reverse pulling adhesion amount conversion table control

(Selection of parameters used in the function module)
The selection of the reverse deposition amount conversion table for 5st (CMYK + α) based on the separation signal Sep (where * is c, m, y, k, or α) is as follows.

(A) When Sep = "character" or "other than image": Inv _ * = inv _ * _ text
(B) When Sep = "Picture" or "Image": Inv _ * = inv _ * _ phot

(Reverse conversion of adhesion amount to output signal (conversion of reverse toner amount))
When the reverse adhesion amount conversion table control (inv_luton) is ON (1), each image data of Cd, Md, Yd, Kd, αd that has been subjected to total amount restriction processing with the attached amount conversion value (for toner and ink) is separated. The output color control signals Cu, Mu, Yu, Ku, and αu (each 8 bits) are converted by a reverse drawing adhesion amount conversion LUT (8 bits × 8 bits) corresponding to each color plate based on the signal Sep.

(a) When inv_luton is ON (1):
Cu = Inv_c [Cd], Mu = Inv_m [Md], Yu = Inv_y [Yd], Ku = Inv_k [Kd], αu = Inv_a [αd]
(b) When inv_luton is OFF (0):
Cu = Cd, Mu = Md, Yu = Yd, Ku = Kd, αu = αd

[Output signal selector (overall selector)]
The output signal selection unit 186 is an output signal selection function module that selectively switches and outputs input image data from the reverse adhesion amount conversion unit 185 and input image data (attachment amount conversion through) input to the total amount regulating unit. . The signals that are input to and output from this module and the parameters that are used are shown below.

(Input / output and parameters used)
<Input>
Ci: Input C data signal (8bit) to the total amount regulation department
Mi: Input M data signal (8 bits) to the total amount control department
Yi: Input Y data signal (8 bits) to the total amount control unit
Ki: Input K data signal (8bit) to the total amount regulation department
αi: Input α data signal (8bit) to the total amount control unit
Cu: Input C data signal (8bit) after reverse adhesion amount conversion
Mu: Input M data signal (8bit) after reverse adhesion amount conversion
Yu: Input Y data signal (8bit) after reverse adhesion amount conversion
Ku: Input K data signal (8bit) after conversion of reverse adhesion amount
αu: Input α data signal (8bit) after conversion of reverse adhesion amount
kisei_h: Total amount regulation judgment result (1 bit)

<Output>
Co: Output C data signal (8bit) output from the total amount control unit
Mo: Output M data signal (8bit) output from the total amount control unit
Yo: Output Y data signal (8bit) output from the total amount control unit
Ko: Output K data signal (8bit) output from the total amount control unit
αo: Output α data signal (8bit) output from the total amount control unit

<Use parameters>
kisei_h_enbl: Total amount restriction determination enable
kisei_enbl: Total amount restriction overall processing enable

(Output signal selection)
When the total amount restriction determination enable is ON (kisei_h_enbl = 1) and the total amount restriction determination results output from the process color total amount restriction unit 182 and the special color signal adaptive total amount restriction are both OFF (kisei_h = 0), the total amount The input signal (Ci, Mi, Yi, Ki, αi) to the regulation part is output as it is, otherwise the total amount regulation result (Cu, Mu, Yu, Ku, αu) after the reverse adhesion amount conversion is displayed. Output.

  When the total amount restriction overall processing enable is OFF (kisei_enbl = 0), as shown below, the input signal (Ci, Mi, Yi, Ki, αi) to the total amount restriction unit is output unconditionally. .

(A) When kisei_enbl is ON (1): Co = Cu, Mo = Mu, Yo = Yu, Ko = Ku, αo = αu
(B) When kisei_enbl is OFF (0): Co = Ci, Mo = Mi, Yo = Yi, Ko = Ki, αo = αi

  In the present embodiment, the total amount regulation of the toner surface formed with five colors including α (spot color (transparent)) using each processing module described above, as shown in FIG. S101), spot color signal generation (step S102), spot color signal adaptive total amount regulation (step S103), and output gradation correction (step S104) are performed in order.

[Pile height uniform treatment]
When the above-described processing modules are used to realize the total amount regulating process for uniformizing the height of the toner surface formed with five colors including the clear toner as shown in the schematic diagram of FIG. In the data generation table, an α data level corresponding to the difference between the total amount of process toners (CMYK) and the total amount regulation value as shown in FIG. 9 is set.

  Here, self_gen_enbl (clear toner (α) data internal generation enable) is set to internal generation ON (setting: 1), and zero_mask_enbl (clear toner (α) zero input mask processing enable) is independently set according to the presence or absence of the zero mask. Set.

  FIG. 10 shows the relationship between the total toner amount and the glossiness under an arbitrary image forming condition. In this example, the total toner amount 250% corresponding to the set (target) glossiness is set as a reference, and 250% or more. For the input image data, the total amount restriction for the process color (CMYK) is applied by the process color total amount restriction unit, and for the input image data (CMYK) less than 250%, the spot color signal generation unit 183 applies. By setting the clear toner plane with the difference between the total value (C + M + Y + K) and 250% as the α data level, the toner surface formed with five colors including α (special color) as shown in the schematic diagram of FIG. An image with a uniform glossiness is formed with a uniform height.

[Matte processing by adding texture to clear toner plate]
While increasing the gloss by making the toner height uniform in image formation, the output tone correction unit 190 in FIG. 2 applies a texture to the uniform surface above a certain toner total amount level to increase the gloss. Lower mat processing.

  FIG. 13 shows the change in glossiness with respect to the clear toner density for each cluster size. For example, when the clear toner is formed at a density of 50% by increasing the cluster size (per unit area), the glossiness is reduced by 50%. It is shown that.

  FIG. 11 shows the relationship between the total toner amount and glossiness under an arbitrary image forming condition. In this example, the special color is based on the total toner amount 80% and 150% corresponding to the set (target) glossiness. The signal generation unit 183 sets a clear toner plane for input image data (CMYK) less than 80% by setting the difference between the total value (C + M + Y + K) and 80% as an α data level (pile height uniformization processing I) For the input image data (CMYK) of 80% to 150%, a clear toner plane is set (pile height uniformization process II) with the difference between the total value (C + M + Y + K) and 150% as an α data level.

  Here, the restriction on the total amount of toner of process colors (CMYK) is not applied in order to keep the color reproduction of the image to be formed as much as possible. In this example, when the input image data (CMYK) is 150% or more, In the pile height process by forming a clear toner plate, the set (target) glossiness cannot be achieved, and if the total amount of the process color (CMYK) toner is regulated with a total amount value of 150%, the color reproduction of the image to be formed Therefore, when the input image data (CMYK) is 150% or more, the output tone correction unit 190 performs the mat processing by applying the texture of the clear toner plate after the above processing by the spot color signal adaptive total amount regulation unit 184. carry out.

  Here, the set (target) gloss level is X%, the gloss level is Y% with respect to the total toner amount of the input image data (CMYK) having a total amount value of 150% or more, and the density value when the maximum cluster size in FIG. 13 is selected. Is represented by Z%, and the gloss change rate K has the following relationship.

  K = -Z (where 0 <Z <50)

  When there is a relationship of the above formula, the product of the glossiness (Y × K / 100) with respect to the glossiness change rate and the total amount of input image data (CMYK) with a total amount value of 150% or more is the set (target) glossiness Since Z should be equal to the difference in glossiness with respect to the total amount of input image data (CMYK) having a total amount value of 150% or more, Z is expressed by the following equation.

  Z = (1-X / Y) × 100 (%)

  FIG. 12 shows a conceptual diagram of the total amount regulation process including the clear toner plate generation according to the above total toner amount value. In this way, by referring to the glossiness information with respect to the total amount of toner under the set image forming conditions, the total amount of toner having the set glossiness is searched, and when the toner amount is insufficient, the clear toner plate is used for clear toner. Give.

  Here, when the total amount of process colors (CMYK) exceeds the set total toner amount that gives the glossiness, the glossiness is lowered most with reference to the glossiness change characteristic by texture addition as shown in FIG. A suitable cluster size is selected based on the glossiness change rate of the region, and the density value corresponding to the extent to which the glossiness is reduced is calculated as described above, and texture is applied.

  If an image having the set glossiness cannot be formed even if the glossiness control by applying clear toner is performed with reference to the glossiness information described above, presentation (display or sound) is made via the operation unit. If the image forming condition or glossiness is not changed, the image formation is performed under the clear toner applying condition that gives the glossiness closest to the target glossiness.

  FIG. 15 is a block diagram illustrating a hardware configuration (electrical configuration) of the image forming apparatus according to the present embodiment. As shown in the figure, this image forming apparatus has a configuration in which a controller 310 and an engine unit (Engine) 360 are connected by a PCI (Peripheral Component Interface) bus. The controller 310 is a controller that controls the entire apparatus and controls drawing, communication, and input from an operation unit (not shown). The engine unit 360 is a printer engine that can be connected to a PCI bus. The engine unit 360 includes an image processing part such as error diffusion and gamma conversion in addition to a so-called engine part such as a plotter.

  The controller 310 includes a CPU 311, a north bridge (NB) 313, a system memory (MEM-P) 312, a south bridge (SB) 314, a local memory (MEM-C) 317, and an ASIC (Application Specific Integrated Circuit). 316 and a hard disk drive (HDD) 318, and the north bridge (NB) 313 and the ASIC 316 are connected by an AGP (Accelerated Graphics Port) bus 315. The MEM-P 312 further includes a ROM (Read Only Memory) 312a and a RAM (Random Access Memory) 312b.

  The CPU 311 performs overall control of the apparatus, has a chip set including the NB 313, the MEM-P 312 and the SB 314, and is connected to other devices via the chip set.

  The NB 313 is a bridge for connecting the CPU 311 to the MEM-P 312, SB 314, and AGP 315, and includes a memory controller that controls reading and writing to the MEM-P 312, a PCI master, and an AGP target.

  The MEM-P 312 is a system memory used as a memory for storing programs and data, a memory for developing programs and data, a memory for drawing printers, and the like, and includes a ROM 312a and a RAM 312b. The ROM 312a is a read-only memory used as a memory for storing programs and data, and the RAM 312b is a writable and readable memory used as a program and data development memory, a printer drawing memory, and the like.

  The SB 314 is a bridge for connecting the NB 313 to a PCI device and peripheral devices. The SB 314 is connected to the NB 313 via a PCI bus, and a network interface (I / F) unit and the like are also connected to the PCI bus.

  The ASIC 316 is an IC (Integrated Circuit) for image processing having hardware elements for image processing, and has a role of a bridge for connecting the AGP 315, the PCI bus, the HDD 318, and the MEM-C 317. The ASIC 316 includes a PCI target and an AGP master, an arbiter (ARB) that forms the core of the ASIC 316, a memory controller that controls the MEM-C 317, and a plurality of DMACs (Direct Memory) that rotate image data using hardware logic. Access Controller) and a PCI unit that performs data transfer between the engine unit 360 via the PCI bus. An FCU (Facsimile Control Unit) 30, a USB (Universal Serial Bus) 40, and an IEEE 1394 (the Institute of Electrical and Electronics Engineers 1394) interface 350 are connected to the ASIC 316 via a PCI bus. The operation display unit 320 is directly connected to the ASIC 316.

  A MEM-C 317 is a local memory used as a copy image buffer and a code buffer, and an HDD (Hard Disk Drive) 318 is a storage for storing image data, programs, font data, and forms. It is.

  The AGP 315 is a bus interface for a graphics accelerator card that has been proposed to speed up graphics processing, and speeds up the graphics accelerator card by directly accessing the MEM-P 312 with high throughput. .

  Note that the configuration of the image forming apparatus in the above embodiment can be applied to a multi-function machine having at least two functions of a copy function, a printer function, a scanner function, and a facsimile function in addition to a printing apparatus having only a printer function. .

180 Total amount regulation unit 181 Forward deposition amount conversion unit 182 Process color total amount regulation unit 183 Special color signal generation unit 184 Special color signal adaptive total amount regulation unit 185 Reverse drawing adhesion amount conversion unit 186 Output signal selection unit 190 Output tone correction unit

Japanese Patent Laid-Open No. 10-055089

Claims (8)

A process color total amount regulating means for regulating the total amount of toner by regulating the output level of the process color corresponding to each pixel of the input image data that is the object of image formation according to the image forming conditions at the time of image formation; ,
Acquire gloss control plane data to which density information of a special color for obtaining gloss corresponding to each pixel of the input image data is assigned, or process color according to a total amount regulation result for the process color as gloss control plane data Spot color signal generating means for generating and outputting a spot color signal in which the data level is set so as to uniformize the height of the toner surface formed with the spot color;
When the total output level of the process color and the spot color from the process color total amount regulating unit and the spot color signal generating unit is larger than the total amount regulation value for the process color and the spot color, the process color or the spot color output level is regulated. A special color signal adaptive total amount regulating means for regulating the total amount of process color and special color toner,
Equipped with a,
When the total toner amount of the process color corresponding to the input image data exceeds the reference total toner amount corresponding to the arbitrarily set glossiness, the total process toner amount is regulated by the process color total amount regulating means. And
If the total amount of process color toner corresponding to the input image data does not satisfy the reference, the spot color signal generation means calculates the difference between the total amount of process color toner corresponding to the input image data and the reference. An image processing apparatus characterized by performing a gloss process for equalizing a height of a toner surface formed by a process color and a special color by using a toner amount of a special color corresponding to data . An output tone correction unit that applies a texture to the gloss control plane data indicated by the spot color signal from the spot color signal adaptive total amount regulation unit, and performs mat processing by changing the cluster size or density of the texture to be applied,
When the total toner amount of the process color corresponding to the input image data exceeds the reference total toner amount corresponding to the arbitrarily set glossiness, the matting process is performed by the output gradation correction unit, the image processing apparatus according to claim 1, wherein the gloss Ru dimming pollock. An image processing apparatus that determines a coating amount of a color material for each pixel constituting input image data,
Determining means for determining the application amount of the special color material corresponding to the target pixel;
When the total amount of the color material of the process color corresponding to the target pixel does not satisfy the first reference value, the determining unit determines the total amount of the color material of the process color and the first reference value for the target pixel. If the total amount of the color material of the process color for the target pixel is not less than the first reference value and does not satisfy the second reference value, the application amount of the special color material for the target pixel is determined based on the difference Based on the difference between the total amount of the color material of the process color for the pixel and the second reference value, the application amount of the special color material for the target pixel is determined, and when it is equal to or greater than the second reference value, A process for lowering the glossiness is performed on the target pixel,
The first reference value and the second reference value are values corresponding to one arbitrarily set glossiness,
An image processing apparatus. A gradation correction unit that applies a texture to the special color material corresponding to the target pixel when the total amount of the color material of the process color corresponding to the target pixel is equal to or greater than the second reference value; The image processing apparatus according to claim 3. When the total amount of the color material of the process color corresponding to the target pixel and the total amount of the special color material corresponding to the target pixel are larger than the total amount regulation value, the total amount of the color material of the process color or the special color The image processing apparatus according to claim 4, further comprising a total amount regulating unit that regulates a coating amount of the material. An image forming apparatus comprising the image processing apparatus according to claim 1. An image processing method in an image processing apparatus comprising a process color total amount regulating means, a spot color signal generating means, and a spot color signal adaptive total quantity regulating means,
The process color total amount regulating means regulates the total amount of toner by regulating the output level of the process color corresponding to each pixel of the input image data that is the object of image formation according to the image forming conditions at the time of image formation. Regulate,
The spot color signal generation means acquires gloss control plane data to which density information of a spot color for obtaining gloss corresponding to each pixel of the input image data is assigned, or controls the total amount for the process color as gloss control plane data Generate and output a spot color signal with the data level set to equalize the height of the toner surface formed by the process color and spot color according to the result,
When the sum of the output levels of the process color and the spot color from the process color total amount regulation unit and the spot color signal generation unit is larger than the total amount regulation value for the process color and the spot color by the spot color signal adaptive total amount regulation unit, a process By regulating the output level of color or spot color, the total amount of toner of process color and spot color is regulated ,
When the total toner amount of the process color corresponding to the input image data exceeds the reference total toner amount corresponding to the arbitrarily set glossiness, the total process toner amount is regulated by the process color total amount regulating means. And
If the total amount of process color toner corresponding to the input image data does not satisfy the reference, the spot color signal generation means calculates the difference between the total amount of process color toner corresponding to the input image data and the reference. An image processing method characterized by performing a gloss process for equalizing a height of a toner surface formed by a process color and a special color by using a toner amount of a special color corresponding to data . An image processing method in an image processing apparatus for determining a coating amount of a color material for each pixel constituting input image data,
The image processing apparatus includes a determining unit that determines a coating amount of the special color material corresponding to the target pixel.
By the determination means,
When the total amount of the color material for the process color corresponding to the target pixel does not satisfy the first reference value, based on the difference between the total amount of the color material for the process color for the target pixel and the first reference value, Determine the amount of the special color material applied to the target pixel;
When the total amount of the color material of the process color for the target pixel is not less than the first reference value and does not satisfy the second reference value, the total amount of the color material of the process color and the second reference value for the target pixel On the basis of the difference between the target color and the application amount of the special color material for the target pixel,
When the value is equal to or greater than the second reference value, the target pixel is subjected to a process for reducing the glossiness,
The first reference value and the second reference value are values corresponding to one arbitrarily set glossiness,
An image processing method .

Images