JP2011109581A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively the suppress cost expended for full-color output. <P>SOLUTION: An image forming apparatus includes a color-determining means 55 for determining whether an original document is a full-color image or a monochromatic image; a selecting means 561 for selecting one from among a plurality of color processing means; and an image processing means 564 for executing image processing for the original document, on the basis of the selected one color processing method, when the original document is the full-color image. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus having an auto color select function and an image forming method.

When copying a document, a color copying machine or the like determines in advance whether the document is a full-color image or a monochrome image. Some images are provided with a so-called automatic color select (ACS) function (hereinafter referred to as an ACS or ACS function) for monochrome copying when an image is determined.
As an application of ACS, when a document is determined to be a full-color image and there is a character area exceeding a predetermined threshold in the document, another color processing method (for example, two-color color processing) is used. Some color copiers can be selected (for example, see Patent Document 1).

JP 2004-297610 A

However, the conventional image forming apparatus disclosed in Patent Document 1 performs color reduction on a full-color original having a large number of character areas, and the target is very limited.
In particular, there are various types of manuscripts (characters, photographs, graphs, CAD, etc.) handled by the image forming apparatus, such as differences in business types and sections in companies, etc., individual usage, etc. It's hard to say.
For this reason, there has been a demand for an image forming apparatus that performs color reduction control in a general and effective manner regardless of the usage mode.

  The present invention has been proposed in order to solve the above-described problems of the prior art, and full-color output is performed by selecting a color processing method for a full-color original or selecting and controlling a color processing method according to a color ratio. An object of the present invention is to provide an image forming apparatus and an image forming method for effectively performing a color reduction process by suppressing the above-described problem.

  In order to achieve the above object, the image forming apparatus of the present invention selects a color determination unit that determines whether a document is a full-color image or a monochrome image, and selects one color processing method from a plurality of color processing methods. And an image processing means for performing image processing on the original based on the selected one color processing method when the original is a full-color image.

  The image forming method of the present invention includes a step of determining whether a document is a full color image or a monochrome image, a step of selecting one color processing method from a plurality of color processing methods, In the case of an image, the method includes a step of performing image processing on the original based on the selected one color processing method.

  According to the image forming apparatus and the image forming method of the present invention, the cost of full color output can be effectively reduced.

1 is a schematic cross-sectional view showing an internal configuration of a digital color copying machine according to an embodiment of the present invention. FIG. 3 is a block diagram for explaining the flow of image processing of the digital color copying machine according to the present embodiment. It is a functional block diagram which shows the functional structure of the selection circuit which concerns on this embodiment. 3 is a flowchart showing a first image forming method of the digital color copying machine according to the embodiment. 6 is a flowchart showing a second image forming method of the digital color copying machine according to the embodiment. 6 is a flowchart showing a third image forming method of the digital color copying machine according to the embodiment. 10 is a flowchart showing a fourth image forming method of the digital color copying machine according to the embodiment. 10 is a flowchart showing a fifth image forming method of the digital color copying machine according to the embodiment.

Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings.
Here, the digital color copying machine 1 according to the embodiment of the present invention described below is realized by processing, means, and functions executed by a computer in accordance with instructions of a program (software). The program sends a command to each component of the computer to perform predetermined processing and functions as shown below. That is, the digital color copying machine of this embodiment is realized by specific means in which a program and a computer cooperate.
Note that all or part of the program is provided by, for example, a magnetic disk, optical disk, semiconductor memory, or any other computer-readable recording medium, and the program read from the recording medium is installed in the computer and executed. The The program can also be loaded and executed directly on a computer through a communication line without using a recording medium.

FIG. 1 is a schematic sectional view showing an internal configuration of a digital color copying machine 1 according to an embodiment of the present invention.
The digital color copier 1 uses cyan (C), magenta (M), yellow (Y), and black (K) single color toners on a sheet based on the color image data of the document read by the document reading unit 2. By superimposing them, a monochrome, two-color or full-color image can be formed by a so-called electrophotographic method.

An original for reading an image by the original reading unit 2 is set on the contact glass 3 disposed on the upper surface of the digital color copying machine 1 so that the image faces downward.
An openable / closable cover 4 is disposed above the contact glass 3 so that the original can be set on the contact glass 3 one by one by opening and closing the cover 4. Yes.
The document reading unit 2 includes a light source 21 for illuminating a document set on the contact glass 3 from below, a CCD image sensor 22 for detecting reflected light from the document and converting it into an electrical signal, and a document The first, second and third reflecting mirrors 231 to 233 for guiding the reflected light to the detection surface of the CCD image sensor 22 and the optical image of the original on the detection surface of the CCD image sensor 22 And a lens 24. The main scanning of the document is achieved by electrical scanning in the CCD image sensor 22.

  The light source 21 and the first reflecting mirror 231 are held by the first holding member 251, and the second and third reflecting mirrors 232 and 233 are held by the second holding member 252. The two holding members 251 and 252 can move in the left-right direction (sub-scanning direction) in FIG. 1 along the lower surface of the contact glass 3. The first and second holding members 251 and 252 move in the same direction so that the speed of the second holding member 252 is half that of the first holding member 251 by the rotational drive of the stepping motor. ing. The original set on the contact glass 3 is sub-scanned by the movement of the light source 21 and the reflecting mirrors 231 to 233 accompanying the movement of the first and second holding members 251 and 252.

  On the detection surface of the CCD image sensor 22, reading lines 22R, 22G, and 22B (not shown) for detecting each color of red (R), green (G), and blue (B) are arranged along the main scanning direction. Thus, they extend with a predetermined interval (for example, a distance of 4 lines). The light emitted from the light source 21 is reflected by the original, and the reflected light is reflected by the reflecting mirrors 231 to 233 and enters the detection surface of the CCD image sensor 22. An image signal based on each color component (RGB) detected by each reading line (red reading line 22R, green reading line 22G, blue reading line 22B) of the CCD image sensor 22 is provided in the digital color copying machine 1. It inputs into the control part 5 (refer FIG. 2).

  Based on the input image signal, the control unit 5 selects one color, two colors, three colors, or all colors selected from cyan (C), magenta (M), yellow (Y), and black (K). Digital image data is generated, and each digital image data is supplied to the laser scanning unit 6 (LSU). The laser scanning unit 6 separately irradiates irradiation light based on each given digital image data toward the surface of the substantially cylindrical photosensitive member 71 provided in the image forming unit 7.

In addition to the photoconductor 71, the image forming unit 7 stores a main charger 72 for charging the surface of the photoconductor 71 and toners of cyan, magenta, yellow, and black colors. Developing devices 73C, 73M, 73Y, and 73BK for forming each color toner image, and a cleaning device 73 for removing the toner remaining on the surface of the photoreceptor 71 after the toner image transfer are provided.
The surface of the substantially cylindrical transfer drum 75 is in contact with the surface of the photoreceptor 71. The transfer drum 75 is formed so that the outer circumference is longer than the length of the paper to be used. A transfer device 76 is provided in the transfer drum 75 at a position facing the photoconductor 71. In this digital color copying machine 1, a sheet is wound around a transfer drum 75 that rotates clockwise in FIG. 1, and the transfer position (between the photosensitive member 71 and the transfer drum 75) is passed from one to four times. The respective color toner images sequentially formed on the surface of the photoreceptor 71 can be transferred onto the paper one color at a time by the action of the transfer device 76.

  More specifically, at the time of image formation, first, the surface of the photoreceptor 71 that rotates counterclockwise in FIG. 1 is uniformly charged by the discharge of the main charger 72. Irradiation light based on the digital image data of the document read by the document reading unit 2 is irradiated from the laser scanning unit 6 to the charged surface of the photoreceptor 71, so that the surface of the photoreceptor 71 is selectively selected. As a result of exposure, an electrostatic latent image corresponding to any one of cyan, magenta, yellow and black is formed on the surface of the photoreceptor 71. Then, the surface of the photoreceptor 71 on which the electrostatic latent image is formed is attached with toner by a developing device corresponding to the one color toner, thereby forming a one color toner image to be transferred onto the paper.

The paper to be used can be set in, for example, the paper cassette 8 or the manual feed tray 9, and the paper is guided from the paper cassette 8 and the manual feed tray 9 to the image forming unit 7 in the digital color copying machine 1. The branched paper conveyance path 10 is arranged so that it is possible.
The paper cassette 8 can store, for example, a plurality of sheets, and can feed the stored sheets one by one to the sheet conveyance path 10 by the pickup roller 81. On the other hand, the sheets set one by one on the manual feed tray 9 are sent out to the sheet conveyance path 10 by the sheet feeding roller 91.

  The sheet sent from the sheet cassette 8 or the manual feed tray 9 to the image forming unit 7 side through the sheet conveyance path 10 is temporarily stopped when the leading edge reaches the registration roller 11. Then, the rotation of the registration roller 11 is performed so that the timing when the one color toner image formed on the surface of the photoconductor 71 comes to a position facing the transfer drum 75 and the timing when the paper reaches the transfer position are matched. Resumed. At this time, static electricity is applied to the surface of the transfer drum 75 by the discharge of the discharge device 12 arranged to face the surface of the transfer drum 75, and the sheet fed from the registration roller 11 is applied to the transfer drum 75 by electrostatic force. It is designed to be wrapped around. The sheet fed from the registration roller 11 moves toward the transfer position while being wound around the transfer roller 75, and the one color toner image formed on the surface of the photoreceptor 71 is transferred to the sheet.

  Subsequently, when the transfer of other colors is continued, the toner 71 after the toner image is transferred is uniformly charged again by the main charger 72 after the toner remaining on the surface is collected by the cleaning device 73. The An electrostatic latent image corresponding to a toner image of a color to be formed next is formed on the surface of the charged photoreceptor 71 by irradiation light from the laser scanning unit 6. On the surface of the photoreceptor 71 on which the electrostatic latent image is formed, toner is attached by a developing device corresponding to the color, and a toner image of the next one color to be transferred to the paper is formed. Then, the toner image formed on the surface of the photoreceptor 71 is wound around the transfer drum 75 and transferred to the paper that has reached the transfer position again.

In this way, the paper is wound around the transfer drum 75 and passed through the transfer position 1 to 4 times, and the toner image is transferred to the paper every time the paper passes through the transfer position, so that cyan, magenta, yellow, and black are transferred. The selected toner images of 1 to 4 colors are transferred onto the paper (overlaid when there are 2 or more colors).
When the toner images of 1 to 4 colors are transferred onto the paper, the static electricity on the surface of the transfer drum 75 is removed by the discharge of the discharge device 12, and the paper is separated from the transfer drum 75. Then, the toner adhering to the surface of the transfer drum 75 after the paper is separated is collected by the cleaning brush device 77.

  The toner image transferred paper separated from the transfer drum 75 is placed on the surface of the rotating endless conveying belt 13 and conveyed to the fixing device 14. Then, the sheet after a predetermined fixing process is performed by the fixing device 14 is discharged to a sheet discharge unit 17 disposed outside the apparatus through a conveyance roller 15 and a discharge roller 16.

FIG. 2 is a block diagram for explaining the flow of image processing in the digital color copying machine according to the present embodiment.
The digital color copier 1 is provided with a control unit 5 constituted by a microcomputer or the like. The control unit 5 includes a color image reading circuit 51, an input correction circuit 52, a region separation processing circuit 53, a UCR / black generation circuit 54, a color / monochrome original discrimination circuit 55, a selection circuit 56, a spatial filter processing circuit 57, an output gradation. A processing circuit 58 and the like are functionally included.

  Further, a signal from an operation unit 18 arranged on the upper surface of the digital color copying machine 1 is input to the control unit 5. The user operates the operation unit 18 to start an image forming operation in the digital color copying machine 1 or select whether to perform monochrome processing, two-color processing, or full-color processing. be able to. Further, it is possible to allow the user to select a threshold value for determining whether or not a color area exists in the document at a ratio equal to or higher than the threshold value, for example, “color determination: strong / medium / weak”.

When red (R), green (G), and blue (B) image signals are input from the CCD image sensor 22 to the control unit 5, the control unit 5 is stored in advance in a predetermined medium such as a ROM or a hard disk. Various processing in each processing circuit is performed using existing program software.
Specifically, first, the color image reading circuit 51 takes in input image signals of each color, and converts red, green, and blue image signals into cyan, magenta, and yellow digital image data (for example, 256th floor). The signal is quantized and converted to the input correction circuit 52. The input correction circuit 52 performs line correction for correcting a shift in the timing of capturing each color, and the light distribution characteristics (the both ends in the main scanning direction) of the optical system such as the light source 21 differ between the central portion and the end portion in the main scanning direction. In addition to the shading correction process for correcting the sensitivity variation of the reading line due to the characteristic that the brightness of the image is reduced), the gamma correction process for providing the gradation characteristic proportional to the density of the original, and the digital image Processing for enlarging or reducing data in the sub-scanning direction, processing for enlarging or reducing data in the main scanning direction, and the like are performed.

The area separation processing circuit 53 extracts character areas, photograph areas (halftone dot areas), graphs and other graphic areas from the original image, separates them into respective image signals, and sends them to the UCR / black generation circuit 54. .
The area separation processing circuit 53 can also extract a color area from the document image.
The UCR / black generation circuit 54 performs black generation processing by extracting only the same component (level) from cyan, magenta, and yellow and replacing it with a black component. Thus, black (BK) digital image data is added to the digital image data given to the laser scanning unit 6.

A color / monochrome original determination circuit (color determination means) 55 determines whether the original is full color or monochrome using an ACS (auto color select) function.
The selection circuit 56 selects a color processing method according to the determination result and color ratio by the color / monochrome original determination circuit 55 or according to an input operation.
Detailed functions of the selection circuit 56 will be described later.
The spatial filter processing circuit 57 performs processing for converting a document image into an image of only a selected color when performing two-color processing. Further, when performing monochrome processing, processing for converting a document image into a black image is performed. Further, filter processing (so-called edge enhancement processing, smoothing processing, etc.) is performed. Note that the above-described conversion processing is not performed when full-color processing is performed.

  The digital image data processed by the above circuits is subjected to output gradation processing by the output gradation processing circuit 58, and is sent to the laser scanning unit 6 through the output device 59 after the output gradation processing. . The output gradation processing includes, for example, intermediate value processing (so-called error diffusion processing, dither processing, etc.).

FIG. 3 is a functional block diagram showing a functional configuration of the selection circuit according to the present embodiment.
As shown in the figure, the selection circuit 56 according to this embodiment includes a selection unit 561, a color ratio calculation unit 562, a display unit 563, and an image processing unit 564.

The selection unit 561 selects one color processing method from a plurality of color processing methods. In the case of this embodiment, the selection unit 561 selects automatically or manually from full color processing, two-color processing, or monochrome processing. . The image processing means 564 performs image processing based on the color processing method selected by the selection means 561.
Specifically, when the color determination unit 55 determines that the document is a full color image, the selection unit 561 can select a color processing method according to the color ratio.
For example, full-color processing is selected for a full-color image document whose color ratio is less than 30%, and monochrome processing or two-color processing is selected for a full-color image document whose color ratio is 30% or more. Can be set to.
On the other hand, when the document is determined to be a monochrome image, the selection unit 561 selects monochrome processing.
That is, full color printing (color reduction processing) is promoted by such selection control.

The selection unit 561 can automatically select a color processing method corresponding to the overall color page ratio for a plurality of documents including full-color images.
For example, full-color processing is selected for a full-color image document having a color page ratio of less than 30%, and monochrome processing or two-color processing is performed for a full-color image document having a color page ratio of 30% or more. Can be set to select.
This method can also promote the color reduction process as described above.
The color ratio and the color page ratio are calculated by the color ratio calculation unit 562.

Furthermore, when the document is determined to be a full-color image, the selection unit 561 can select one color processing method in accordance with a user input operation.
Specifically, selection is made from full-color processing, two-color processing, or monochrome processing according to the user's touch panel operation or the like.

The color ratio calculation unit 562 calculates the ratio of the color area in the document (hereinafter referred to as the color ratio).
Here, “color ratio” refers to the ratio of the area of the full color area in the area of one page of the document.

In addition, the color ratio calculation unit 562 can determine the ratio (color page ratio) of the original of the full color image in all the originals.
Here, the “color page ratio” refers to the ratio of pages occupied by a full-color original in all originals.
For example, if there are two pages in a 10-page document that are determined to be full-color images, the color ratio calculation unit 562 calculates the color page ratio as 20%.

Further, the color ratio calculation means 562 can also obtain the ratio of the full color area area in the entire original as the “color page ratio”.
In this case, for example, if a full-color area of 1 to 5 pages is 20% and a full-color area of 6 to 10 pages is 40% in a 10-page document, the color page ratio is calculated to be 30%.
Further, the ratio of the area of the full color area in all the full color documents can be obtained as the “color page ratio”.
In this case, for example, if there are 5 pages of a document determined as a full-color image in a 10-page document, and the full-color area of each page is 20%, the color page ratio is calculated as 10%. Is done.

The display unit 563 notifies the user of various items to be notified via a panel screen included in the operation unit 18.
In particular, the display unit 563 according to the present embodiment can display an image having a color ratio equal to or greater than a threshold value from a full-color image document prior to the image forming process.
Furthermore, the display unit 563 can display page images having a color ratio equal to or greater than a threshold value from the full-color image document in order of increasing color ratio by assigning a number corresponding to the color ratio to each page of the document. .
In this case, not only the preview is performed, but only the document image that is predicted to be greatly affected by the color reduction is displayed. Therefore, the user can efficiently select the color processing.

The image processing unit 564 performs image processing on a document based on either full color processing, two-color processing, or monochrome processing.
Specifically, image processing is performed on the target document based on the color processing method selected by the selection unit 561.

  Next, an image forming method of the digital color copying machine according to the present embodiment will be described with reference to FIGS.

FIG. 4 is a flowchart showing a first image forming method of the digital color copying machine according to the present embodiment.
As shown in the figure, first, the document reading unit 2 reads image data of a document (A1).
Next, the color determination means 55 determines whether the document is a full color image or a monochrome image using the ACS function (A2).

As a result, when it is determined that the document is a monochrome image (A3: monochrome document), the selection unit 561 selects monochrome processing, and the image processing unit 564 performs monochrome processing on the image data of the target document to perform image formation processing. (A4).
On the other hand, when it is determined that the document is a full color image (A3: color document), the selection unit 561 selects the color processing method selected by the user, and the image processing unit 564 performs image processing based on the color processing method. Do.

In this case, the user can select one of (a) “full color”, (b) “two-color”, and (c) “monochrome”.
For example, as shown in FIG. 4, when (a) is selected by the user, the selection unit 561 selects full color processing, and the image processing unit 564 performs full color processing on the image data of the target document and performs image formation processing. Perform (A5).
The selection of the color processing method by the user can be changed not only in advance through the operation unit 18 but also in the middle.
The image forming data formed in steps A4 and A5 is sent to the output device 59.
Then, the output device 59 performs a printing process based on the received image formation data (A6).

As described above, according to the first image forming method described above, the monochrome image is automatically printed in monochrome by the ACS function, and the full color image is printed after being subjected to the color processing selected by the user. .
For this reason, for example, it is possible to output a full-color image original by performing two-color processing or monochrome processing. This can reduce the cost for printing.
Of course, it is also possible to output a full color image original in full color.
Therefore, according to this image forming method, it is possible to maintain the output quality while reducing the output cost.

Next, a second image forming method of the digital color copying machine according to this embodiment will be described with reference to FIG.
FIG. 5 is a flowchart showing a second image forming method of the digital color copying machine according to the present embodiment.
As shown in the figure, first, the document reading unit 2 reads image data of a document (B1).
Next, the color determination means 55 determines whether the document is a full color image or a monochrome image using the ACS function (B2).

As a result, when it is determined that the document is a monochrome image (B3: monochrome document), the selection unit 561 selects monochrome processing, and the image processing unit 564 performs monochrome processing on the image data of the target document to perform image formation processing. (B4).
On the other hand, if it is determined that the document is a full-color image (B3: color document), then the color ratio determining unit 561 calculates the ratio of the color area in the document (B5).

As a result, when a color ratio equal to or greater than a predetermined threshold is calculated (B6: greater than or equal to the threshold), the selection unit 561 selects monochrome processing, and the image processing unit 564 performs monochrome processing on the image data of the target document to form an image. Processing is performed (B4).
On the other hand, when the color ratio less than the threshold is calculated (B6: less than the threshold), the selection unit 561 selects full color processing, and the image processing unit 564 performs image formation processing by performing full color processing on the image data of the target document. (B7).
The image forming data formed in steps B4 and B7 is sent to the output device 59.
Then, the output device 59 performs a printing process based on the received image formation data (B8).

As described above, according to the second image forming method described above, the monochrome image is automatically printed in monochrome by the ACS function, and the original with a low color ratio is automatically printed in full color for the full color image. High originals are automatically printed in monochrome.
That is, full color output is allowed for a document with a relatively small color area, and full color output is restricted for a document with a large color area.
For this reason, unlike the first image forming method described above, full-color output can be forcibly limited to some extent regardless of user independence.
However, by changing the color ratio threshold, it is possible to loosen or increase the restriction on full color output.
Therefore, according to this image forming method, the output cost can be further reduced.

Next, a third image forming method of the digital color copying machine according to this embodiment will be described with reference to FIG.
FIG. 6 is a flowchart showing a third image forming method of the digital color copying machine according to the present embodiment.
As shown in the figure, first, the document reading unit 2 reads image data of a document (C1).
Next, the color determination means 55 determines whether the document is a full color image or a monochrome image using the ACS function (C2).

As a result, when it is determined that the document is a monochrome image (C3: monochrome document), the selection unit 561 selects monochrome processing, and the image processing unit 564 performs monochrome processing on the target document to perform image formation processing ( C4).
On the other hand, if it is determined that the document is a full-color image (C3: color image), then the color ratio determination unit 561 calculates the ratio of the color area in the document (C5).

As a result, when a color ratio less than a predetermined threshold is calculated (C6: less than threshold), the selection unit 561 selects monochrome processing, and the image processing unit 564 performs monochrome processing on the target document to perform image formation processing. (C4).
On the other hand, when the color ratio equal to or greater than the threshold is calculated (C6: greater than or equal to the threshold), the selection unit 561 selects the two-color processing, and the image processing unit 564 performs the two-color processing on the target document and performs image formation processing. (C7).
The image forming data formed in steps C4 and C7 is sent to the output device 59.
Then, the output device 59 performs a printing process based on the received image formation data (C8).

As described above, according to the third image forming method described above, monochrome images are automatically output in monochrome by the ACS function. For full-color images, a document with a low color ratio is automatically printed in monochrome. A high original is automatically printed in two colors.
That is, in this image forming method, full color processing is not performed at all.
For this reason, the output cost can be further reduced as compared with the image forming method described above.

Next, a fourth image forming method of the digital color copying machine according to this embodiment will be described with reference to FIG.
FIG. 7 is a flowchart showing a fourth image forming method of the digital color copying machine according to the present embodiment.
As shown in the figure, first, the document reading unit 2 reads image data of a document (D1).
Here, it is assumed that image data relating to a plurality of documents is sequentially read.
Next, the color determination means 55 determines whether each original is a full color image or a monochrome image using the ACS function (D2).

As a result, for a document determined as a monochrome image (D3: monochrome document), the image processing unit 564 performs monochrome processing through the selection of the selection unit 561 to perform image formation processing (D4).
On the other hand, for a document determined as a full-color image (D3: color image), the color ratio determination unit 561 calculates the ratio of the color area in the document (D5).

As a result, for the document (D6: less than the threshold value) for which the color ratio less than the predetermined threshold is calculated, the image processing unit 564 performs monochrome processing through the selection by the selection unit 561 to perform image formation processing (D4). .
On the other hand, for a document (D6: greater than or equal to the threshold) for which the color ratio equal to or greater than the threshold is calculated, the display unit 563 displays a preview image of the full color image according to the order of the ratio.
That is, the user can confirm only the original having a high color ratio among all the originals by using the preview image.

Then, the user selects a color processing method for the displayed document via the operation unit 18 (D8).
This selection can be performed not only uniformly for all previewed full-color originals but also individually for each original.
Specifically, the user presses one of the selection keys of “full color processing”, “two-color processing” or “monochrome processing” displayed on the panel.

Here, when “monochrome processing” is selected (D8: monochrome), the selection unit 561 selects monochrome processing, and the image processing unit 564 performs monochrome processing on the target document to perform image formation processing (D4).
When “two-color” is selected (D8: two-color), the selection unit 561 selects two-color processing, and the image processing unit 564 performs two-color processing on the target document to perform image formation processing. (D9).
When “full color processing” is selected (D8: full color), the selection unit 561 selects full color processing, and the image processing unit 564 performs full color processing on the target document to perform image formation processing (D10).
The image formation data formed in steps D4, D9, and D10 is sent to the output device 59.
Then, the output device 59 performs a printing process based on the received image formation data (D11).

As described above, according to the fourth image forming method described above, a monochrome image is automatically output in monochrome by the ACS function. For a full color image, a document having a low color ratio is automatically printed in monochrome. High originals are displayed in descending order of color ratio so that the user can select the processing method.
This image forming method is the same as the first image forming method in that the user can select a color processing method. Further, the present invention is the same as the second or third image forming method in that the color processing method of the document having a high color ratio can be set other than the full color processing.
However, according to this image forming method, a document having a high color ratio among the full-color documents is displayed in advance as an image.
For this reason, as with the other image forming methods, the output quality can be effectively maintained while the output cost is reduced.

Next, a fifth image forming method of the digital color copying machine according to the present embodiment will be described with reference to FIG.
FIG. 8 is a flowchart showing a fifth image forming method of the digital color copying machine according to this embodiment.
As shown in the figure, first, the document reading unit 2 reads image data of a document (E1).
Here, it is assumed that image data relating to a plurality of documents is sequentially read.
Next, the color determination means 55 determines whether each original is a full color image or a monochrome image using the ACS function (E2).

As a result, for a document determined as a monochrome image (E3: monochrome document), the selection by the selection unit 561, the image processing unit 564 performs monochrome processing on the image data to perform image formation processing (E4).
On the other hand, for a document determined as a full color image (E3: color document), the color ratio determining means 561 calculates the ratio of the color area in the document (E5).

As a result, when a color ratio equal to or greater than a predetermined threshold is calculated (E6: greater than or equal to the threshold), the selection unit 561 selects monochrome processing, and the image processing unit 564 performs monochrome processing on the image data of the target document to form an image. Processing is performed (E4).
On the other hand, when the color ratio less than the threshold is calculated (E6: less than threshold), the selection unit 561 selects full color processing, and the image processing unit 564 performs full color processing on the image data of the target document and performs image formation processing. (E7).
The image forming data formed in steps E4 and E7 is sent to the output device 59.
Then, the output device 59 performs a printing process based on the received image formation data (E8).

As described above, according to the fifth image forming method described above, monochrome images are automatically printed in monochrome by the ACS function. For full-color images, a document with a low color ratio is automatically printed in full color. High originals are automatically printed in monochrome.
Therefore, the same actions and effects can be achieved by a method different from the above-described image forming methods.

As described above, according to the digital color copying machine 1 of the present embodiment, any one of monochrome processing, two-color processing, and full-color processing according to the ACS function and user selection is possible.
In particular, according to the digital color copying machine 1 of the present embodiment, the color ratio of a full-color original can be calculated and color processing corresponding to the calculated color ratio can be performed.
For this reason, the cost concerning full-color output can be effectively suppressed regardless of the usage mode of the user.
It is also possible to maintain user convenience and output quality.

The image forming apparatus of the present invention has been described with reference to the embodiment. However, the image forming apparatus according to the present invention is not limited to the above-described embodiment, and various modifications may be made within the scope of the present invention. It goes without saying that it is possible.
For example, the image forming apparatus and the image forming method of the present invention can be applied not only to a color complex machine but also to a color-compatible image forming apparatus such as a color printer or a color display.

Further, an aspect of selecting a color processing method according to a color ratio or a color page ratio threshold is not limited to the above-described embodiment.
For example, for a user who places importance on visibility, it may be set to perform full color processing when the color ratio or the like is equal to or greater than a threshold value.
It is also possible to set the threshold stepwise and automatically select a color processing method corresponding to each threshold range.
For example, full color processing is performed when the color ratio is less than 20%, two-color processing is performed when the color ratio is 20% or more and less than 60%, and monochrome processing is performed when the color ratio is 60% or more. Can do.

  The present invention can be suitably used for a full-color image forming apparatus such as a color complex machine or a color printer.

DESCRIPTION OF SYMBOLS 1 Digital color copying machine 55 Color determination means 561 Selection means 562 Color ratio calculation means 563 Display means 564 Image processing means

Claims (10)

Color determination means for determining whether the document is a full-color image or a monochrome image;
Selecting means for selecting one color processing method from a plurality of color processing methods;
An image forming apparatus comprising: an image processing unit configured to perform image processing on a document based on the selected one color processing method when the document is a full-color image. Color ratio calculation means for calculating the ratio of the color area in the document,
The selection means includes
The image forming apparatus according to claim 1, wherein the one color processing method is selected based on a predetermined threshold with respect to a color area ratio in a full-color image original. The selection means includes
The image forming apparatus according to claim 2, wherein full color processing is selected as the one color processing method when a ratio of color areas in a full color image original is less than a predetermined threshold. The image processing means includes
4. The image forming apparatus according to claim 2, wherein when the ratio of the color area in the original of the full-color image is equal to or greater than a predetermined threshold, the two-color processing or the monochrome processing is selected as the one color processing method. . The color ratio calculation means includes
Calculate the percentage of full-color images in a document consisting of one or more pages as the color page ratio,
The selection means includes
The image forming apparatus according to claim 2, wherein the one color processing method is selected based on a predetermined threshold with respect to the color page ratio. The selection means includes
The image forming apparatus according to claim 5, wherein full color processing is selected as the one color processing method when the color page ratio is less than a predetermined threshold. 7. The image forming apparatus according to claim 2, further comprising: a display unit configured to display a document image having a color area ratio equal to or greater than a predetermined threshold among documents determined to be full-color images. The display means includes
The image forming apparatus according to claim 7, wherein among the originals determined to be full-color images, original images having a color area ratio equal to or greater than a predetermined threshold are displayed in the order of the ratios. The selection means includes
The image forming apparatus according to claim 1, wherein one color processing method is selected from the plurality of color processing methods in accordance with an input operation. Determining whether the document is a full color image or a monochrome image;
Selecting one color processing method from a plurality of color processing methods;
And a step of performing image processing on the original based on the selected one color processing method when the original is a full-color image.

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