JP2007281914A - Image copying apparatus, image data conversion device, image copying method, and image data conversion method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image copying apparatus and the like for quickly and properly copying an original image. <P>SOLUTION: When reading the original image and copying the image, image data read from a head part of the original image is analyzed to obtain information related to a paper color of the original image. After correcting a gradation value of the image data based on the paper color information, the original image is copied by forming dots on a print medium based on the image data after correction. By applying and analyzing the image data read for printing the original image, the paper information is immediately obtained, and the image can be printed by reflecting the result to correction of the image data, and thus, the original image can be quickly copied. Further, a ground color of a printing paper mostly appears on the head part in the original image, and thus the accurate paper information can be quickly detected from a few image data, and the original image can be quickly and properly copied. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a technology for copying a printed document image, and more particularly to a technology for obtaining a good copy image by performing appropriate correction according to the paper ground color on which the document image is printed.

With the advancement of digital technology represented by computers, it is now possible to easily handle high-quality images even in a general home. For example, if a computer and a color printer are used, an image created by various application programs on a computer or an image taken by a digital camera can be easily color-printed with sufficient image quality. Further, if a printed document image is read by a color scanner, image data corresponding to the document image can be generated. If the obtained image data is subjected to predetermined image processing and then printed by a color printer, it can be used in the same manner as a color copying machine.

When copying an original image in this way, it does not mean that the background color of the paper of the original image needs to be accurately reproduced as it is and printed. For example, when the original image is printed on colored paper, it is considered that the colored paper is intentionally used, so printing (that is, copying) so that the ground color of the paper is accurately reproduced. It is desirable to do. On the other hand, if the original image is printed on a non-quality paper such as recycled paper, it is desirable to print with the ground color portion of the paper skipped white.

Therefore, before copying the document image, the background color of the paper is detected by pre-scanning the entire document image with a coarse resolution, and then the image data read by the main scan is determined according to the background color of the paper. There has been proposed a technique for appropriately copying a manuscript image by adding correction (Patent Document 1 and Patent Document 2).

Japanese Patent Laid-Open No. 11-155044 JP 2001-197269 A

However, in the proposed technique, since the pre-scan and the main scan are performed in order to copy the original image, the original image must be read twice, and it is difficult to quickly copy the original image. there were. Of course, the entire original image is read with the same fine resolution as the main scan, the image data is analyzed to detect the ground color of the paper, and the image data is corrected according to the obtained detection result. However, this requires a large memory capacity because the image data of the entire original image must be stored once, which leads to a new problem. In addition, since the amount of image data to be analyzed becomes large, analysis takes time, and eventually the effect of speeding up the copying of the original image is not so great.

The present invention has been made to solve the above-described problems in the prior art,
An object of the present invention is to provide a technique capable of appropriately and quickly copying a document image without increasing a necessary memory capacity.

In order to solve at least a part of the problems described above, the image copying apparatus of the present invention employs the following configuration. That is,
An image copying apparatus for copying a document image by reading a document image, generating image data, and printing the image based on the generated image data,
Paper color information acquisition means for acquiring information relating to the paper color of the document image by analyzing the image data;
A gradation value correcting means for correcting a gradation value of the image data based on the acquired paper color information;
Dot data generating means for generating dot data as data representing the original image by the presence or absence of dot formation by performing predetermined image processing on the corrected image data;
Image forming means for forming the original image by forming dots on a print medium according to the dot data;
The summary of the paper color information acquisition means is the means for acquiring the paper color information by taking out and analyzing the image data of the head portion of the document image from the read image data.

The image copying method of the present invention corresponding to the above image copying apparatus is as follows.
An image copying method for copying an original image by reading an original image, generating image data, and printing the image based on the generated image data,
A first step of obtaining information relating to a paper color of the document image by analyzing the image data;
A second step of correcting a gradation value of the image data based on the acquired paper color information;
A third step of generating dot data, which is data representing the original image by the presence or absence of dot formation, by performing predetermined image processing on the corrected image data;
A fourth step of forming the original image by forming dots on a print medium according to the dot data,
The gist of the first step is that the paper color information is obtained by taking out and analyzing the image data of the head portion of the document image from the read image data.

In the image copying apparatus and the image copying method of the present invention, when the original image is read and the image is copied, the image data read from the original image is analyzed in advance to obtain information on the paper color of the original image. Keep it. Then, after correcting the gradation value of the image data based on the obtained paper color information, the original image is copied by forming dots on the print medium based on the corrected image data. Further, when the paper color information is obtained by analyzing the image data, the paper color information is obtained by taking out and analyzing the image data of the head portion of the document image.

As described above, if the image data used for acquiring the paper color information is used as the image data of the head portion of the document image, the image data read for printing the document image is used for analysis, and immediately analyzed. Since the paper color information is acquired and the result can be reflected in the correction of the image data and the image can be printed, the original image can be quickly copied. In most original images, the background color of the printing paper appears at the top. Therefore, by analyzing the image data of the head portion, it is possible to acquire accurate paper color information to the extent that it is comparable to the case of analyzing the image data of the entire original image.

In addition, if the image data at the beginning of the original image is analyzed, even if the image data is read at a fine resolution to print the image, the amount of data is not so large. Will not increase. In addition, the amount of data to be analyzed can be reduced compared to the case of analyzing the image data of the entire original image, so that the analysis can be performed quickly, and the original image can be quickly copied. It becomes possible to do.

In such an image copying apparatus of the present invention, the average value of saturation is calculated from the image data of the head portion of the original image, and when the obtained average saturation is equal to or less than a predetermined value, the paper color information is acquired. Also good.

The document image may be printed on a so-called colored paper such as pale yellow, light blue, or pink. When copying such an original image, it is desirable to copy so that the background color of the paper is reproduced as it is. Therefore, if the average saturation obtained from the image data at the beginning of the original image is greater than or equal to a predetermined value, it is determined that the original image is printed on colored paper and paper color information is not acquired. On the contrary, when the average saturation is equal to or less than the predetermined value, it is determined that the color is not printed on the paper with color, and the paper color information is acquired. And if paper color information is obtained,
If the image data is printed by correcting the gradation value of the image data, the original image can be appropriately copied.

In such an image copying apparatus, when the average saturation calculated from the head portion of the document image is not more than a predetermined value, the paper color information may be acquired as follows. That is, an area having a predetermined luminance or higher is extracted from the head portion of the document image. And after calculating the average brightness | luminance in the extracted area | region, it is good also as acquiring paper color information based on the obtained average brightness | luminance.

A date, time, figure, or the like may be printed at the beginning of the original image. Of course, such a portion does not represent the background color of the paper. Therefore, if an area having a predetermined luminance or higher is extracted from the head portion of the original image and paper color information is acquired based on the average luminance in the extracted area, an appropriate value corresponding to the ground color of the paper on which the original image is printed is obtained. Since accurate paper color information can be acquired, it is possible to appropriately copy a document image.

In the various image copying apparatuses described above, the paper color information may be acquired as follows. That is, instead of scanning the entire original image at once and printing the image, the gradation value correction is performed on the image data of the already read area while reading the original image for each area separately. In addition, a series of processes such as dot data generation and image formation are performed to copy the original image. And from the first scanned area in the original image,
The paper color information may be acquired by analyzing the first predetermined amount of image data.

Instead of printing the entire original image at once and then printing the image, a series of processing is performed on the image data in the already read area while reading the original image divided into a plurality of areas in this way. If an image is formed, the required amount of memory can be greatly reduced as compared with the case where the entire original image is read at once and then the image is printed. Since the first portion of the area read first is considered to be the portion where the ground color of the paper on which the original image is printed, the paper color information is obtained by analyzing the image data of this portion. Then, it is possible to acquire paper color information with sufficient accuracy without increasing the necessary memory amount.
In addition, if the image data of the predetermined amount of data at the head is analyzed instead of analyzing the image data of the entire area read first, the paper color information is quickly obtained by the amount of data to be analyzed. Furthermore, paper color information can be acquired at the earliest timing in a series of processes for copying a document image. As a result, the original image can be copied by reflecting the acquired paper color information, so that it can be quickly and appropriately copied.

Further, if the image copying apparatus and the image copying method of the present invention described above convert the image data read from the document image prior to copying the document image, the present invention is as follows. It can also be grasped as an image data conversion device and an image data conversion method. That is, the image data conversion apparatus of the present invention is
An image data conversion device that reads a document image to generate image data, performs predetermined image processing on the image data, and converts the document image into dot data represented by the presence or absence of dot formation,
Paper color information acquisition means for acquiring information relating to the paper color of the document image by analyzing the image data;
A gradation value correcting means for correcting a gradation value of the image data based on the acquired paper color information;
Dot data generating means for generating dot data as data representing the original image by the presence or absence of dot formation by performing predetermined image processing on the corrected image data;
The summary of the paper color information acquisition means is the means for acquiring the paper color information by taking out and analyzing the image data of the head portion of the document image from the read image data.

Further, the image data conversion method of the present invention corresponding to the above-described image data conversion apparatus,
An image data conversion method for reading a document image to generate image data and performing predetermined image processing on the image data, thereby converting the document image into dot data represented by the presence or absence of dot formation,
(A) obtaining information relating to the paper color of the document image by analyzing the image data;
A step (B) of correcting a gradation value of the image data based on the acquired paper color information;
A step (C) of generating dot data as data representing the original image by the presence or absence of dot formation by performing predetermined image processing on the corrected image data;
The summary of the step (A) is a step of acquiring the paper color information by taking out and analyzing the image data of the head portion of the document image from the read image data.

In the image data conversion apparatus and the image data conversion method of the present invention, after analyzing the image data read from the head portion of the document image and obtaining the paper color information, the gradation of the image data based on the paper color information Correct the value. Then, the corrected image data is converted into dot data. As described above, if the paper color information is acquired from the image data of the head portion of the document image, it is not necessary to read the document image in order to acquire the paper color information. In addition, the background color of the paper often appears at the beginning of the original image. As a result, the image data of the document image can be quickly and appropriately converted into dot data. Then, if dots are formed on the print medium according to the dot data obtained in this way, the original image can be copied quickly and appropriately.

Furthermore, the present invention can be realized using a computer by causing a computer to read a program for realizing the above-described image copying method or image data conversion method and executing a predetermined function. Therefore, the present invention includes the following program or a mode as a recording medium on which the program is recorded. That is, the program of the present invention corresponding to the image copying method described above is
A program for realizing, using a computer, a method of copying a document image by reading a document image, generating image data, and printing the image based on the generated image data,
A first function of acquiring information relating to a paper color of the document image by analyzing the image data;
A second function for correcting a gradation value of the image data based on the acquired paper color information;
A third function for generating dot data, which is data representing the original image according to the presence or absence of dot formation, by performing predetermined image processing on the corrected image data;
By forming dots on the print medium according to the dot data, the fourth function for forming the document image is realized by a computer, and
The gist of the first function is to obtain the paper color information by taking out and analyzing the image data of the head portion of the document image from the read image data.

The recording medium of the present invention corresponding to the above program is
A recording medium which records a program for copying a document image by reading a document image, generating image data, and printing the image based on the generated image data.
A first function of acquiring information relating to a paper color of the document image by analyzing the image data;
A second function for correcting a gradation value of the image data based on the acquired paper color information;
A third function for generating dot data, which is data representing the original image according to the presence or absence of dot formation, by performing predetermined image processing on the corrected image data;
A program for realizing a fourth function for forming the original image by using a computer by forming dots on a print medium according to the dot data is recorded, and
The gist of the first function is to obtain the paper color information by taking out and analyzing the image data of the head portion of the document image from the read image data.

Furthermore, the program of the present invention corresponding to the above-described image data conversion method is as follows:
A method for converting a document image into dot data represented by the presence or absence of dot formation by reading a document image, generating image data, and performing predetermined image processing on the image data.
A program for realizing using a computer,
A function (A) for obtaining information on the paper color of the document image by analyzing the image data;
A function (B) for correcting a gradation value of the image data based on the acquired paper color information;
By performing predetermined image processing on the corrected image data, a function (C) for generating dot data as data representing the original image by the presence or absence of dot formation is realized by a computer,
The gist of the function (A) is that the paper color information is acquired by taking out and analyzing the image data of the head portion of the document image from the read image data.

The recording medium of the present invention corresponding to the above program is
A computer image is generated by reading a document image, generating image data, and performing predetermined image processing on the image data, thereby converting the document image into dot data represented by the presence or absence of dot formation. A recording medium,
A function (A) for obtaining information on the paper color of the document image by analyzing the image data;
A function (B) for correcting a gradation value of the image data based on the acquired paper color information;
A program for realizing, using a computer, a function (C) for generating dot data, which is data representing the original image by the presence or absence of dot formation, by performing predetermined image processing on the corrected image data. As well as recording
The gist of the function (A) is that the paper color information is acquired by taking out and analyzing the image data of the head portion of the document image from the read image data.

If these programs are read into a computer and the various functions described above are realized, it is possible to generate dot data quickly and appropriately from a document image and obtain a good copy image.

Hereinafter, in order to clarify the contents of the present invention described above, examples will be described in the following order.
A. Summary of Examples:
B. Device configuration :
B-1. overall structure :
B-2. Internal configuration:
B-2-1. Internal configuration of the scanner unit:
B-2-2. Internal configuration of the printer unit:
C. Overview of image copy processing:
D. Paper color information detection process:
E. Modified example:

A. Summary of Examples:
Prior to detailed description of the embodiment, an outline of the embodiment will be described with reference to FIG. FIG. 1 shows an image copying apparatus 1 according to the present embodiment, which includes a scanner 20 and a printing apparatus 30.
FIG. The printing apparatus 30 is a so-called inkjet printer that prints an image by forming ink dots by ejecting ink droplets onto the print medium P. The printing apparatus 30 is equipped with various electronic circuits centering on the CPU, and is configured to execute predetermined image processing inside the printing apparatus 30. The scanner 20 optically reads an original image to generate image data, and then supplies the image data to the printing apparatus 30. Printing device 30
The received image data is subjected to predetermined image processing to print an image, whereby a copy image of the original image can be obtained.

When attention is paid to various functions performed inside the printing apparatus 30 for copying a document image, the printing apparatus 30 of this embodiment includes a “paper color information acquisition module”, a “tone value correction module”, “
It can be considered that it is composed of modules such as “dot data generation module” and “image forming module”. The “module” is a function that categorizes the functions performed in the printing apparatus 30 for convenience. The “module” can be realized as a part of the program or has a specific function. It is also possible to realize a “module” by using a logic circuit and further combining them.

When the image data read from the document image by the scanner 20 is supplied to the printing apparatus 30, it is first determined whether or not the image data is the head portion of the document. To the color information acquisition module. When the document image is read in a plurality of times and is divided into a plurality of image data from the scanner 20 and supplied to the printing apparatus 30, it may be determined whether or not the document includes the leading portion of the document. The “paper color information acquisition module” obtains information on the paper color of the paper on which the original image is printed by analyzing the image data corresponding to the head portion of the received image data. The paper color information is supplied to the gradation value correction module.

Upon receipt of the paper color information, the “tone value correction module” corrects the tone value of the image data supplied from the scanner 20 based on the paper color information, and then the “dot data generation module”.
To supply. Here, the dot data is data representing the original image by the presence or absence of dot formation. The “dot data generation module” generates dot data by performing predetermined image processing on the image data corrected based on the paper color information, and then converts the obtained dot data into the “image formation module”. To supply. The “image forming module” drives the ink ejection head 32 in accordance with the received dot data to form ink dots on the print medium P to form an image. By doing so, the original image is copied on the print medium.

In the image copying apparatus 10 described above, the image data of the head portion is used as image data to be analyzed in order to acquire the paper color information of the document image, not the image data of the entire document image. In most cases, since the background color of the paper appears at the beginning of the document image, accurate paper color information can be quickly acquired even by using only the image data of the beginning. In addition, if the image data of only the head portion, not the entire original image, is analyzed, paper color information can be acquired by diverting the head portion of the image data read at a fine resolution for copying. It is not necessary to read the entire original image with a rough resolution for analysis in advance. As a result, the original image can be copied appropriately and quickly. Hereinafter, such an image copying apparatus 10 will be described in detail based on examples.

B. Device configuration :
B-1. overall structure :
FIG. 2 is a perspective view showing the external shape of the image copying apparatus 10 of this embodiment. As shown in the figure, the image copying apparatus 10 of this embodiment includes a scanner unit 100, a printer unit 200, an operation panel 300 for setting the operation of the scanner unit 100 and the printer unit 200, and the like. The scanner unit 100 has a scanner function of reading a printed original image and generating image data, and the printer unit 200 has a printer function of receiving image data and printing an image on a print medium. Yes. Further, if a document image read by the scanner unit 100 is output from the printer unit 200, a copy function can be realized. In other words, the image copying apparatus 10 of this embodiment is a so-called scanner / printer / copy combined apparatus (hereinafter referred to as an SPC combined apparatus) that can independently realize a scanner function, a printer function, and a copy function.

FIG. 3 is an explanatory diagram showing a state in which the document table cover 102 provided on the upper part of the image copying apparatus 10 is opened in order to read the printed document image. As shown in the drawing, when the platen cover 102 is opened upward, a transparent platen glass 104 is provided,
Various mechanisms described later for realizing the scanner function are mounted. When reading a printed document image, the document table cover 102 is opened as shown in FIG.
A document image is placed on the button 4, the document table cover 102 is closed, and then the buttons on the operation panel 300 are operated. In this way, it is possible to read a document image and immediately convert it into image data.

The scanner unit 100 is entirely housed in an integrated case, and the scanner unit 100 and the printer unit 200 are connected to a hinge mechanism 204 (on the back side of the image copying apparatus 10.
(See FIG. 4). For this reason, by lifting the front side of the scanner unit 100, it is possible to rotate only the scanner unit 100 at the hinge portion.

FIG. 4 is a perspective view illustrating a state in which the front side of the scanner unit 100 is lifted and rotated. As shown in the figure, in the image copying apparatus 10 of the present embodiment, the upper surface of the printer unit 200 can be exposed by lifting the front side of the scanner unit 100. Printer unit 20
0 includes various mechanisms to be described later for realizing the printer function, a control circuit 260 to be described later for controlling the operation of the entire image copying apparatus 10 including the scanner unit 100, and
A power supply circuit (not shown) for supplying power to the scanner unit 100 and the printer unit 200 is also provided. Also, as shown in FIG. 4, an opening 202 is provided on the upper surface of the printer unit 200, which makes it easy to replace consumables such as ink cartridges, handle paper jams, and perform minor repairs. It is possible to do it.

B-2. Internal configuration:
FIG. 5 is an explanatory diagram conceptually showing the internal configuration of the image copying apparatus 10 of this embodiment. As described above, the image copying apparatus 10 includes the scanner unit 100 and the printer unit 200, and various configurations for realizing the scanner function are mounted inside the scanner unit 100.
Various configurations for realizing a printer function are installed in the printer unit 200.
In the following, the internal configuration of the scanner unit 100 will be described first, and then the printer unit 200 will be described.
The internal structure of will be described.

B-2-1. Internal configuration of the scanner unit:
The scanner unit 100 includes a transparent platen glass 104 on which a printed document image is set,
A document table cover 102 for holding the set document image, a reading carriage 110 for reading the set document image, and the reading carriage 110 in the reading direction (main scanning direction).
A driving belt 120 that is moved to the driving belt 120, and a driving motor 122 that supplies power to the driving belt 120.
And a guide shaft 106 that guides the movement of the reading carriage 110.
The operations of the drive motor 122 and the reading carriage 110 are controlled by a control circuit 260 described later.

When the drive motor 122 is rotated under the control of the control circuit 260, the movement is transmitted to the reading carriage 110 via the driving belt 120. As a result, the reading carriage 110 is
While being guided by the guide shaft 106, it moves in the reading direction (main scanning direction) according to the rotation angle of the drive motor 122. Further, the driving belt 120 is constantly adjusted to be in a moderately tensioned state by the idler pulley 124. Therefore, if the driving motor 122 is rotated in the reverse direction, the reading carriage 110 is moved in the reverse direction by a distance corresponding to the rotation angle. It is also possible to make it.

Inside the reading carriage 110 are a light source 112, a lens 114, a mirror 116, and a CC.
A D sensor 118 and the like are mounted. Light from the light source 112 is applied to the platen glass 104 and reflected by a document image set on the platen glass 104. Reflected light from the document image is guided to the lens 114 by the mirror 116, condensed by the lens 114, and detected by the CCD sensor 118. The CCD sensor 118 is configured by a linear sensor in which photodiodes that convert light intensity into an electrical signal are arranged in a row in a direction orthogonal to the moving direction (main scanning direction) of the reading carriage 110. For this reason, the reading carriage 11
If the original image is irradiated with light from the light source 112 while moving 0 in the main scanning direction and the reflected light intensity is detected by the CCD 118, an electrical signal corresponding to the original image can be obtained.

The light source 112 is composed of light emitting diodes of three colors of RGB, and can sequentially irradiate light of R color, G color, and B color at a predetermined cycle. C
In CD118, the reflected light of R color, G color, and B color is detected sequentially. In general, the red portion of the image reflects R light, but hardly reflects G or B light.
The reflected color light represents the R component of the image. Similarly, the reflected light of G color is G in the image.
The B color reflected light represents the B component of the image. Accordingly, if the original image is irradiated while switching the light of three colors of RGB at a predetermined cycle and the reflected light intensity is detected by the CCD 118 in synchronization therewith, the R component, G component and B component of the original image can be detected. It is possible to read a color image. Note that since the reading carriage 110 is moved even while the color of the light emitted by the light source 112 is switched, the position of the image for detecting each component of RGB corresponds to the movement amount of the reading carriage 110 strictly. However, this deviation can be corrected by image processing after reading each component.

B-2-2. Internal configuration of the printer unit:
Next, the internal configuration of the printer unit 200 will be described. The printer unit 200 includes a control circuit 260 that controls the overall operation of the image copying apparatus 10, a print carriage 240 for printing an image on a print medium, a mechanism that moves the print carriage 240 in the main scanning direction, A mechanism for feeding the print medium is mounted.

The print carriage 240 includes an ink cartridge 242 that stores K ink, an ink cartridge 243 that stores various inks of C ink, M ink, and Y ink, a print head 241 provided on the bottom surface side, and the like. The print head 241 is provided with an ink discharge head for discharging ink droplets for each ink. When the ink cartridges 242 and 243 are mounted on the print carriage 240, each ink in the cartridge is supplied to the ink discharge heads 244 to 247 for each color through an introduction pipe (not shown), and ink droplets are discharged from the respective ink discharge heads. . In the printer unit 200 shown in FIG. 5, the C ink, the M ink, and the Y ink are described as being integrally stored in one ink cartridge 243, but these inks are formed separately. It can also be stored in a dedicated ink cartridge. In addition to these inks, low density C ink (LC ink), low density M ink (LM ink), and low density K ink.
It is also possible to mount ink (LK ink) or the like.

The mechanism that moves the print carriage 240 in the main scanning direction includes a carriage belt 231 for driving the print carriage 240, a carriage motor 230 that supplies power to the carriage belt 231, and an appropriate tension is constantly applied to the carriage belt 231. Tension pulley 232 for holding the carriage, and carriage guide 233 for guiding the movement of the print carriage 240
And an origin position sensor 234 for detecting the origin position of the print carriage 240. When the carriage motor 230 is rotated under the control of the control circuit 260 described later,
The print carriage 240 can be moved in the main scanning direction by a distance corresponding to the rotation angle. Further, if the carriage motor 230 is rotated in the reverse direction, the print carriage 240 can be moved in the reverse direction.

The mechanism for feeding the print medium includes a platen 236 that supports the print medium from the back side, a paper feed motor 235 that feeds the paper by rotating the platen 236, and the like. If the paper feed motor 235 is rotated under the control of a control circuit 260 described later, the print medium can be fed in the sub-scanning direction by a distance corresponding to the rotation angle.

The control circuit 260 has a CPU, a ROM, a RAM, a D / A converter that converts digital data into an analog signal, and a peripheral device interface PIF for exchanging data with peripheral devices. It is composed of The control circuit 260 controls the overall operation of the image copying apparatus 10, and controls these operations while exchanging data with the light source 112 mounted on the scanner unit 100, the drive motor 122, and the CCD 118.

In addition, the control circuit 260 drives the carriage motor 230 and the paper feed motor 235 to perform main scanning and sub scanning of the print carriage 240, and the ink ejection head 2 for each color
Control is also performed to discharge ink droplets by supplying drive signals to 44 to 249. The drive signal supplied to the ink discharge heads 244 to 247 is generated by reading image data from the computer 50, the digital camera 40, or the like and then performing image processing to be described later. Of course, by performing image processing on the image data read by the scanner unit 100,
It is also possible to generate a drive signal. In this way, under the control of the control circuit 260, the ink droplets are ejected from the ink ejection heads 244 to 247 to form the ink dots of the respective colors on the print medium while performing the main scanning and the sub scanning of the printing carriage 240. It is possible to print an image. Of course, instead of performing image processing in the control circuit 260, the ink ejection head 24 receives data subjected to image processing from the computer 50 and performs main scanning and sub-scanning of the print carriage 240 according to this data.
It is also possible to drive 4 to 247.

The control circuit 260 is also connected to the operation panel 300 so as to be able to exchange data. By operating various buttons provided on the operation panel 300, detailed operation modes of the scanner function and the printer function are set. It is possible to set. Furthermore, it is possible to set a detailed operation mode from the computer 50 via the peripheral device interface PIF.

FIG. 6 is an explanatory diagram showing a state in which a plurality of nozzles Nz for ejecting ink droplets are formed on the ink ejection heads 244 to 247 for each color. As shown in the figure, on the bottom surface of each color ink ejection head, four sets of nozzle rows for ejecting ink droplets for each color are formed.
In the set of nozzle rows, 48 nozzles Nz are arranged in a staggered manner with an interval of the nozzle pitch k. A drive signal is supplied from the control circuit 260 to each of these nozzles Nz.
Each nozzle Nz forms ink dots on the print medium by ejecting ink droplets of the respective ink according to the drive signal.

Various methods can be applied to the method of ejecting ink droplets from the ink ejection head. That is, a method of ejecting ink using a piezoelectric element, a method of ejecting ink droplets by generating bubbles in the ink passage with a heater arranged in the ink passage, and the like can be used. Also, instead of ejecting ink, adopt a method of forming ink dots on the print medium using a phenomenon such as thermal transfer, or a method of attaching toner powder of each color on the print medium using static electricity. Is also possible.

C. Overview of image copy processing:
As described above, the printer unit 200 prints an image by forming dots on a print medium. For this reason, in order to copy a document image with the image copying apparatus 10 of the present embodiment, data (dots) expressing the document image with dots by performing appropriate image processing on the image data generated by reading the document image. Data). In the following, an outline of processing (image copying processing) in which image data read from a document image is converted into dot data and then dots are formed on a printing medium to copy the image will be described. In the image copying apparatus 10 of this embodiment, dot data is generated by performing image processing in the control circuit 260 incorporated in the printer unit 200. However, the image processing is performed by a computer provided outside. It is also possible to read the obtained dot data from the peripheral device interface PIF and copy the original image.

FIG. 7 is a flowchart showing the flow of image copying processing for reading a document image and copying the image. Hereinafter, it demonstrates according to a flowchart. When the image copying process is started, first, a process of reading an image having a predetermined bandwidth from the head of the document image is performed (step S100).
). This is the following process. In the image copying process, when the scanner unit 100 reads an original image to generate image data, various image processing described later is applied to the read image data, and then a process for printing the image is performed. The image data read by the scanner unit 100 is temporarily stored in the RAM in the control circuit 260, and in the subsequent image processing, the RAM is stored in the RAM.
Is performed on the image data stored. Here, in the simplest case, it is conceivable to read the entire original image, temporarily store the image data in a RAM, perform image processing on the image data, and print the image. However, in practice, the RA that can be mounted on the control circuit 260.
Since the capacity of M is limited, it is impossible to store image data of the entire document image. Therefore, the original image is read within the range allowed by the RAM capacity, image data is stored, image processing is performed on the image data, and the image is printed. When the image is printed in this way, a new document image is read and stored in the RAM, and image processing is performed on the image data to print the image. In this way, image processing is performed while reading the original image little by little, and the image is printed.

FIG. 8 is an explanatory diagram conceptually showing how a document image is read little by little to copy a document image. A large rectangle indicated by hatching in the drawing indicates an area (printing area) where an original image is printed. A large rectangle drawn with a solid line outside the print area represents a print sheet on which a document image is printed. A horizontally long rectangle drawn in the upper part of the drawing is a reading carriage 110 for reading a document image. The scanner unit 100 generates image data by reading a document image while moving the reading carriage 110 in a reading direction indicated by an arrow in the drawing. Note that the dashed-dotted rectangle shown in the figure indicates the reading range of the scanner unit 100.

The operation of copying the document image by the image copying apparatus 10 of the present embodiment is roughly performed as follows. First, the reading carriage 110 is moved in the reading direction from the uppermost end of the document image, and an image in a predetermined range is read within a range that can be stored in the RAM. Here, “a” in FIG.
It is assumed that an image having a predetermined width is read. The image data read in this way is
After being temporarily stored in the RAM of the control circuit 260, predetermined image processing, which will be described later, is performed, and an image is printed by forming dots based on dot data obtained by the image processing.

In this way, while image processing is performed on the image data in the area “a”, the reading carriage 110 reads the original image of the portion indicated by “b” in FIG. 8 and stores the image data in the RAM.
To remember. Then, the reading carriage 110 reads the “b” area at the speed at which the image data of the previously read “a” area is subjected to image processing and the image is printed. The speed is set to be That is, when the reading of the area “b” having the predetermined width is completed, the image processing and the dot formation for the area “a” read earlier are finished, and the image processing and the dot formation for the area “b” are completed. By the end, reading of the next area “c” is completed. In this way, even if the reading carriage 110 continuously moves and appears to read a document image, the reading carriage 110 is read by a predetermined width and supplied to the control circuit 260. Inside the control circuit 260, the image is read by a predetermined width. Processing is performed and an image is printed. In step S100 in FIG. 7, a process of reading image data having a predetermined width (bandwidth) from the head portion of the document image is performed.

Thus, processing (paper color information detection processing) for detecting information relating to the paper color of the printing paper on which the document image is printed is performed on the band image data read from the head portion of the document image (step S102). Details of the paper color information detection process will be described later.

In the image copying process of FIG. 7, following the paper color information detection process, the tone value correction process is started (step S104). Here, the gradation value correction process is a process for correcting the gradation value of the image data read from the document image based on the detection result of the information on the paper color of the paper on which the document image is printed. By correcting the gradation value of the image data based on the paper color information, it is possible to appropriately copy the document image. Since the content of the gradation value correction process is determined depending on the paper color information detected in the paper color information detection process, details of the process will be described in detail later together with the paper color information detection process. In the image copying process according to the present embodiment, since the paper color information is detected by analyzing only the image data of the leading band, the original image can be quickly copied and the control circuit 260 can be used. There is no increase in the capacity of the RAM that should be built in.
This point will also be described in detail later together with the description of the paper color information detection process and the gradation value correction process.

Further, in FIG. 7, it is assumed that the paper color information detection process is performed after the image data of the predetermined bandwidth at the head is read. Therefore, in the example shown in FIG. 8, the paper color information detection process is performed while the next region “b” is being read after the first bandwidth region “a” is read. However, as will be described later, in the paper color information detection process, the image data of the entire bandwidth is not always used, and in many cases, the head image data is further used in the head bandwidth. Therefore, when the image data of the portion to be used is read, the paper color information detection process may be started before the reading of the area “a” is completed.

As described above, when the gradation value of the image data is corrected based on the paper color information detected from the image data having a predetermined bandwidth at the head of the document image (step S104), the control circuit 260 performs color conversion processing. Is started (step S106). The color conversion process is a process of converting color image data expressed by a combination of R, G, and B gradation values into data corresponding to the amount of each color ink used in the printer unit 200. As described above, since the printer unit 200 prints an image using four colors of C, M, Y, and K, in the color conversion process of this embodiment, RGB color image data is converted into C, A process of converting to gradation value data corresponding to the usage amount of each color ink of M, Y, and K is performed. Of course, in addition to the four colors C, M, Y, and K, low density C ink (LC ink), low density M ink (LM ink), or low density K ink (LK ink) are installed. In such a case, the RGB color image data may be converted into gradation value data corresponding to the amount of ink used for each color including these light inks.

The color conversion process is performed by referring to a three-dimensional numerical table called a color conversion table (LUT). FIG. 9 is an explanatory diagram conceptually showing a color conversion table (LUT) referred to for color conversion processing. Considering a color space in which gradation values of R, G, and B colors are taken on three orthogonal axes as shown in FIG. 9, the gradation values of RGB colors can take values from 0 to 255. .
Then, all the RGB image data can be associated with points inside a cube (color solid) whose origin is the vertex and whose length of one side is 255. From this point of view, change the way of viewing and change the color solid to R
When a plurality of grid points are generated in the color space by subdividing into a grid perpendicular to each axis of GB, each grid point is
Each can be considered to correspond to RGB image data. Therefore, a combination of gradation values corresponding to the usage amount of each color ink such as C, M, Y, and K is stored in advance at each grid point. By doing this, it is possible to quickly convert the RGB color image data into data (CMYK image data) corresponding to the amount of each color ink used by reading out the gradation values stored in the grid points.

For example, if the R component of the image data is RA, the G component is GA, and the B component is BA,
This image data is associated with a certain point (point A in the figure) in the color space (see FIG. 9). Therefore, a cube dV containing point A is detected from the fine cubes that subdivide the color solid, and the gradation values of the color inks stored in the lattice points of the cube dV are read out. Then, by performing an interpolation calculation from the gradation values of these grid points, the gradation value at point A (that is, CMYK image data) can be obtained. As described above, the color conversion table LUT is R
It can be considered as a three-dimensional number table in which combinations of gradation values corresponding to the amount of ink used for each color such as C, M, Y, and K are stored at each grid point indicated by a combination of gradation values for each color of GB. By referring to the color conversion table, it is possible to quickly convert the RGB color image data into gradation data (CMYK image data) corresponding to the amount of each color ink used.

When the color conversion process is completed as described above, halftone processing is performed in the image copying process as shown in FIG. 7 (step S108). Halftone processing is the following processing. The CMYK data obtained by the color conversion process is data that can take values from the gradation value 0 to the gradation value 255 for each pixel. On the other hand, since the printer unit 200 displays an image by forming dots, each pixel can only take a state of whether or not to form dots. Therefore, it is necessary to convert CMYK image data having 256 gradations into data (dot data) representing the presence or absence of dot formation for each pixel. Halftone processing is processing for converting CMYK image data into dot data in this way.

As a method for performing the halftone process, various methods such as an error diffusion method and a dither method can be applied. The error diffusion method is to determine whether or not dots are formed for a certain pixel so as to diffuse an error in gradation expression generated in that pixel to surrounding pixels and to eliminate the error diffused from the surroundings. This is a method of determining the presence or absence of dot formation for each pixel. Also, the dither method uses a threshold value and CM that are randomly set in the dither matrix.
Each pixel is compared with the YK image data, and it is determined that dots are formed in the pixels having the larger CMYK image data, and conversely, it is determined that no dots are formed in the pixels having the larger threshold value. This is a technique for obtaining dot data for a pixel.

FIG. 10 is an explanatory diagram illustrating an enlarged part of the dither matrix. In the illustrated matrix, threshold values that are uniformly selected from the range of gradation values 0 to 255 are randomly stored in a total of 4096 pixels, 64 pixels in all directions. Here, the threshold gradation value is 0.
In the present embodiment, the CMYK image data is 1-byte data and the gradation value can take a value from 0 to 255. The size of the dither matrix is not limited to 64 pixels in the vertical and horizontal directions as illustrated in FIG. 10, and can be set to various sizes including those having different numbers of vertical and horizontal pixels. It is.

FIG. 11 is an explanatory diagram conceptually showing a state in which the presence / absence of dot formation is determined for each pixel with reference to the dither matrix. This determination is made for each color of CMYK, but in the following, in order to avoid complicated explanation, each color of the CMYK image data is simply referred to as image data.

When determining the presence or absence of dot formation, first, the gradation value of the image data for the pixel of interest (the pixel of interest) as the object of determination is compared with the threshold value stored at the corresponding position in the dither matrix. . The thin broken arrow shown in the figure schematically represents that the image data of the pixel of interest is compared with the threshold value stored at the corresponding position in the dither matrix. If the image data of the pixel of interest is larger than the threshold value of the dither matrix, it is determined that a dot is formed on that pixel. On the other hand, when the threshold value of the dither matrix is larger, it is determined that no dot is formed in the pixel.
In the example shown in FIG. 11, the image data of the pixel at the upper left corner of the image is “97”, and the threshold value stored at the position corresponding to this pixel on the dither matrix is “1”. Accordingly, for the pixel at the upper left corner, the image data is larger than the threshold value of the dither matrix, and therefore it is determined that a dot is formed on this pixel. An arrow indicated by a solid line in FIG. 11 schematically shows a state in which it is determined that a dot is to be formed in this pixel and the determination result is written in the memory. On the other hand, for the pixel on the right side of this pixel, the image data is “97”, the threshold value of the dither matrix is “177”, and the threshold value is larger, so it is determined that no dot is formed for this pixel. In this way, by comparing the image data with the threshold value set in the dither matrix, it is possible to determine whether or not dots are formed for each pixel. In the halftone process (step S108 in FIG. 7), the above-described dither method is applied to the gradation data (CMYK image data) corresponding to the usage amount of each of the C, M, Y, and K inks. A process of generating dot data by determining the presence or absence of dot formation for each time is performed.

After the gradation data of each color of CMYK is converted into dot data by performing the halftone process, this time, the interlace process is started (step S110). The interlacing process is a process in which the print head 241 rearranges the dot data in the order in which dots are formed and supplies them to the ink discharge heads 244 to 247 for each color. That is, as shown in FIG. 6, since the nozzles Nz provided in the ink discharge heads 244 to 247 are provided at an interval of the nozzle pitch k in the sub-scanning direction, the ink is moved while the print carriage 240 is main-scanned. When droplets are ejected, dots are formed at intervals of the nozzle pitch k in the sub-scanning direction. Therefore, in order to form dots in all the pixels, the relative position between the print carriage 240 and the print medium is moved in the sub-scanning direction, and new dots are formed in the pixels between the dots separated by the nozzle pitch k. Necessary. As described above, when an image is actually printed, dots are not formed in order from the upper pixel on the image. Furthermore, for pixels in the same row in the main scanning direction, dots are not formed by one main scanning, but are formed by dividing the main scanning into a plurality of times due to image quality requirements. In this main scanning, dots are also widely formed at the pixels at the skipped positions.

As described above, when an image is actually printed, dots are not formed according to the order of arrangement of pixels on the image. Therefore, C, M, Y can be used before actually starting the dot formation. ,
It is necessary to rearrange the dot data obtained for each color of K in the order in which the ink ejection heads 244 to 247 form dots. Such a process is a process called interlace.

In the image copying process, when the interlace process is completed, a process for actually forming dots on the print medium based on the data obtained by the interlace process (dot formation process)
Is started (step S112). That is, while the carriage motor 230 is driven to cause the print carriage 240 to perform main scanning, the rearranged dot data (print data) is supplied to the ink ejection heads 244 to 247. As described above, the print data is data indicating whether or not dots are formed in each pixel. Therefore, the ink discharge heads 244 to 247 can appropriately apply ink to each pixel by discharging ink droplets according to the print data. Dots can be formed.

When one main scan is completed, the paper feed motor 235 is driven to feed the print medium in the sub-scanning direction, and the carriage motor 230 is driven again to print the print carriage 2.
The ink discharge head 244 converts the dot data rearranged in the order while 40 is main-scanned.
To 247 to form dots.

Subsequently, it is determined whether or not the above processing has been performed on the image data of all the bands included in the document image (step S114). If an unprocessed band remains, after reading the image data of that bandwidth (step S116 in FIG. 7), a series of processes subsequent to the gradation value correction process are performed. When it is determined that the above-described processing has been completed for all bands by repeating such operations (step S114: yes), the image copying processing of this embodiment shown in FIG. 7 is terminated. As a result, C, M, Y, and K dots are formed on the print medium with an appropriate distribution according to the gradation value of the image data, and an image corresponding to the original image is copied. Become.

As described above, in order to properly print a document image, it is desirable to detect on which printing paper the document image is printed. For example, if the original image is printed on paper with a color such as pale yellow or light blue, it is desirable to copy it so that the background color of the paper is reproduced as accurately as possible. If it is printed on a slightly dull paper, it is desirable to copy the paper so that the ground color of the paper is white. However, if the background color of the paper is normally detected, it is difficult to quickly copy the original image. Therefore, in the image copying process of this embodiment, in order to obtain an appropriate copy image while minimizing an increase in the time required for copying, a paper color information detection process as described below is performed. Based on the above, gradation value correction processing is performed.

D. Paper color information detection process:
FIG. 12 is a flowchart showing the flow of processing (paper color information detection processing) performed to detect information relating to the paper color of the document image during the image copying processing of this embodiment. Such processing is
This process is executed in the control circuit 260 when image data having a predetermined bandwidth is read from the head portion of the document image.

When the paper color information detection process is started, first, image data of a predetermined number of lines (for example, 5 lines) at the head portion is extracted from the image data of a predetermined bandwidth, and the average saturation is calculated (step) S200). As described above, since the image data read by the reading carriage 110 is RGB image data, the saturation can be obtained by applying a known conversion formula. Therefore, in step S200, an average value of saturation is calculated for image data of a predetermined number of lines.

Subsequently, it is determined whether or not the obtained average saturation is equal to or less than a predetermined value (step S202). what if,
If the original image is printed on so-called colored paper such as pale yellow, light blue, and pink, the average saturation should be some value. When the original image is printed on a colored paper, it is desirable to print the original image as it is without detecting the paper color of the paper and correcting the image data for printing. Alternatively, if the document image is an image in which the outer edge portion where the paper background color appears does not exist, the paper color of the paper cannot be detected, and the image data cannot be corrected according to the paper color. . Therefore, in such a case (that is, when the average saturation is equal to or less than a predetermined value), the fact that the paper color is not detected is stored as paper color information (step S208).
).

On the other hand, if the average saturation is equal to or less than the predetermined value (step S202: yes), the paper background color portion outside the print area is detected, and the paper is not considered to be colored paper. Therefore, the paper color of the paper can be detected. However, instead of immediately detecting the paper color from a predetermined number of lines of image data, a process for extracting a region having a luminance equal to or higher than the predetermined luminance is performed as a preparation for detecting the paper color (step S204). This is processing performed for the following reason.

FIG. 13 is an explanatory diagram conceptually showing an area of a predetermined number of lines used for detecting the paper color from the image data of the predetermined bandwidth at the head of the document image. Note that a rectangle indicated by a one-dot chain line in the drawing represents an area having a predetermined hand width at the beginning, and a hatched area represents a print area where an original image is printed. As shown in the drawing, the paper color of the paper is detected based on the image data of a partial area at the head in the image data of the head with a predetermined bandwidth. However, some original images have date, time, or some graphic printed in this area. In such a case, if the paper color is detected including the date, time, figure, etc., the accurate paper color cannot be detected. Therefore, as a preparation for detecting the paper color, a process for removing the date, time, figure, etc. is performed by extracting only the area whose luminance is equal to or higher than the predetermined luminance. It should be noted that the objects to be removed such as date, time, figure, etc. are clearly printed in black or the like so that they can be clearly recognized, and as a result, they are considered to have a considerably low luminance. Therefore, the value of the predetermined luminance used for determining whether or not to extract in step S204 can be set to a lower value (for example, the gradation value 200).

After calculating the average brightness for the image data of the area thus extracted, the obtained average brightness is stored as paper color information indicating the paper color of the paper on which the document image is printed (step S2).
06). As described above, since the image data is obtained in the form of RGB image data, it is possible to obtain the average luminance by converting the RGB image data into luminance values by applying a known conversion formula.

In the paper color information detection process shown in FIG. 12, the average luminance of the low saturation area is calculated and the paper color information of the paper is acquired. However, the paper color information is not limited to such values, and the following values may be acquired as the paper color information. That is, except for the low luminance region (for example, less than the gradation value 200) that cannot be applied to the paper color of the paper from the low saturation region, the remaining region has a relatively high luminance ( For example, it is detected at what ratio an area having a gradation value of 230 or more) exists. The higher the high luminance ratio, the more the paper color corresponds to white. Therefore, the paper color information may be acquired based on the high luminance ratio thus obtained. From experience, the paper color information obtained based on the high luminance ratio more appropriately reflects the paper color of the paper than the paper color information based on the average luminance.

In the paper color information detection process of this embodiment, the paper color information of the paper on which the original image is printed is obtained by performing the above-described processing on the image data of the predetermined bandwidth at the beginning of the original image. To do. Subsequently, a gradation conversion characteristic is selected based on the acquired paper color information (step S21).
0). The control circuit 260 of this embodiment stores a plurality of types of gradation conversion characteristics in advance, and performs a process of selecting the gradation conversion characteristics according to the acquired paper color information.

FIG. 14 is an explanatory diagram illustrating the gradation conversion characteristics stored in advance. As shown in the figure, the gradation conversion characteristic describes the output gradation value with respect to the input gradation value. Therefore,
By referring to the gradation conversion characteristics, the gradation value of the image data can be immediately converted. Here, when the gradation value is converted using the characteristics shown in FIG. 14A, if the contrast of the image data is slightly enhanced and the gradation value of the image data is 245 or more, the upper limit value ( It is converted into image data that is pasted to the gradation value 255). In addition, when the image data is converted using the characteristics shown in FIG. 14B, the upper limit value (tone value 255) is obtained when the contrast is emphasized slightly stronger and the image data has a gradation value of 235 or more. Will stick to. Furthermore, when the characteristics shown in FIG. 14C or the characteristics shown in FIG. 14D are obtained, the contrast is further enhanced, and the gradation value of the image data is 220 or more in the characteristics shown in FIG. If it exists, the image data is pasted to the upper limit value. If the gradation value of the image data is 205 or more, the image data is converted to image data to be pasted to the upper limit value.

FIG. 15 is an explanatory diagram showing a state in which which gradation conversion characteristic is to be selected is set according to the detected paper color information. As described above with reference to FIG. 14, the conversion characteristic A only slightly enhances the contrast. Therefore, when almost no gradation conversion is required, for example, since the original image is printed on colored paper, the paper color is changed. The selection may be made when it is not detected or when the original image is printed on high-quality paper and a sufficient copy image can be obtained even if the original image data is printed without correction. Corresponding to this, FIG. 15 shows the case where the paper color information is not detected or the average luminance obtained as the paper color information is the gradation value 245 or more, as shown in FIG. It is set that the gradation conversion characteristic A is selected. Also, the paper color information
When acquired based on the ratio of the relatively high luminance area, the gradation conversion characteristic A may be selected even when the high luminance ratio is high. In FIG. 15, it is set that the gradation conversion characteristic A is selected even when the average luminance of the paper color information is less than the gradation value 205. The reason will be described later.

On the other hand, when the average luminance obtained as the paper color information is in the range of the gradation value 235 to the gradation value 245, it is considered that the document image is printed on a relatively high-quality printing paper. Therefore, in FIG. 15, it is set that the gradation conversion characteristic B is selected for such paper color information. If the gradation value of the image data is converted with reference to the gradation conversion characteristic B, the image can be printed with the contrast enhanced so that the ground color portion of the paper will fly white.

When the average luminance obtained as the paper color information is in the range of the gradation value 220 to the gradation value 235, the original image is printed on a printing paper such as relatively high-quality recycled paper. it is conceivable that. Therefore, in FIG. 15, it is set that the gradation conversion characteristic C is selected for such paper color information. Further, the average luminance as the paper color information has a gradation value of 205 to a gradation value of 220.
If it is in the range, it is considered that the document image is printed on a sheet such as low-quality recycled paper. Therefore, in such a case, it is set to select the gradation conversion characteristic D.
These gradation conversion characteristics strongly emphasize the contrast, so even if the original image is printed on a dull printing paper such as recycled paper, It is possible to print an image with the contrast enhanced so that the color portions fly white.

When the average luminance detected as the paper color information is less than the gradation value 205, the copy is performed with the background color of the paper being whitened, and the gradation conversion characteristic D shown in FIG. In this embodiment, it is set that the gradation conversion characteristic A that slightly enhances the contrast is selected, as shown in FIG. this is,
The reason is as follows. If the average luminance detected as the paper color information is too low, the paper color may not be detected correctly for some reason. For example, as shown in FIG. 13, in order to detect the paper color excluding the date, time, figure, etc. described in the paper ground color portion outside the print area, only an area with a predetermined luminance or higher is extracted. The average brightness is calculated, but the date, time, figure, etc. are not black, but are printed in a very light gray color, and these areas may be extracted by mistake. Alternatively, as described above, the paper color information is obtained by detecting the ratio of areas having a relatively high luminance (for example, gradation value 230 or more) in an area having a certain level of luminance (for example, gradation value 200). If you are seeking,
There is no case where an area with a gradation value of 200 or more does not exist or only a few exist, so that an accurate ratio cannot be detected. As described above, when there is a possibility that the paper color is erroneously detected, it is not possible to obtain an appropriate copy image by copying with the contrast enhanced so that the paper ground color is white.

Alternatively, it is assumed that the document image is printed on a light gray printing paper. Even in such a case, there are only a few regions having a luminance value of 200 or more in the original image, and therefore, when obtaining paper color information based on the average luminance, or relatively high luminance (for example, , Gradation value 23
Even when the paper color information is acquired based on the ratio of the area of 0 or more), it is conceivable that correct paper color information cannot be acquired in any case. Therefore, in FIG. 15, the gradation conversion characteristic A that hardly enhances the contrast is selected even when the paper color information cannot be detected or when the average luminance detected as the paper color information is less than the gradation value 205. It is set.

In step S210 of the paper color information detection process shown in FIG. 12, after selecting an appropriate gradation conversion characteristic according to the detected paper color information as described above, the paper color information detection process is terminated. Returning to the image copying process shown in FIG.

As described above, when the gradation conversion characteristic is selected based on the paper color information, the process of converting the gradation value of the image data is performed in accordance with the selected gradation conversion characteristic thereafter (FIG. 7). Step S104). That is, when image data having a predetermined bandwidth at the beginning of the original image is read by the reading carriage 110, the above-described paper color information detection process is performed to select the gradation conversion characteristic, and then the image is read according to the conversion characteristic. Convert the gradation value of the data. When image data is read from the subsequent bands, the paper color information detection process is not performed, and the gradation value of the image data is converted according to the already selected gradation conversion characteristic. Thus, the above-described color conversion process (step S106 in FIG. 7), halftone process (step S108), interlace process (step S110), and dot formation process (step S112) are performed on the image data whose tone values have been converted. By performing the above, it is possible to finally obtain a copy image corresponding to the document image.

According to the image copying process described above, since the paper color information is detected by analyzing the image data of the head portion of the original image, the paper color information can be detected quickly. Images can be copied quickly. That is, when paper color information is to be detected by analyzing the image data of the entire original image, the original image is inevitably read at a coarse resolution due to memory capacity restrictions, and the paper color information is analyzed by analyzing the coarse image data. It is necessary to detect.
Since the image data read in this way has a low resolution, it cannot be used as it is to print a copy image, and this time, it is necessary to read the original image with a fine resolution for printing and print the image. Become. Eventually, it becomes necessary to read the original image twice, that is, the pre-scan for obtaining the paper color information and the main scan for printing the image, and it is difficult to make a quick copy.

On the other hand, if only the head portion of the document image is present, image data read at a fine resolution for printing can be stored in the memory and analyzed to detect the paper color information. In most cases, since the background color of the paper appears at the beginning of the original image, the paper color information can be detected with sufficient accuracy without forcibly analyzing the entire original image. For this reason, pre-scanning for acquiring paper color information is not necessary, and only main scanning for printing an image needs to be performed, so that an original image can be quickly copied.

In addition, the amount of data to be analyzed in order to obtain paper color information is less than that in the case of analyzing the entire document image at the head portion of the document image. For this reason, paper color information can be quickly acquired, and as a result, a document image can be quickly copied. Further, since the amount of data to be analyzed is small, the required memory amount does not increase.

Furthermore, in the image copying process of this embodiment, gradation conversion characteristics corresponding to the paper color information are set in advance, and when the paper color information is detected, the corresponding gradation conversion characteristics can be selected immediately. For this reason, since the gradation value correction process (step S104 in FIG. 7) can be started immediately, the original image can be quickly copied.

E. Modified example:
Several modifications can be considered for the image copying apparatus 10 described above. Hereinafter, these modified examples will be briefly described.

In the embodiment described above, the portion corresponding to the ground color of the paper is skipped white.
It has been described as enhancing the contrast of the entire image. For example, in the gradation conversion characteristic C shown in FIG. 14C, the gradation value in the range of gradation values 0 to 220 is set so that the output gradation value becomes the gradation value 255 with respect to the input having the gradation value 220 or more. The image data is also converted so that the contrast is enhanced. However, the maximum purpose of such gradation conversion is to convert the image data so that the gradation value becomes 255 for an input exceeding the predetermined gradation value. Only the image data may be converted to the gradation value 255, and the image data that does not satisfy the predetermined gradation value may not be subjected to gradation conversion.

FIG. 16 is an explanatory diagram illustrating the gradation conversion characteristics used in the first modification. FIG.
The gradation conversion characteristics shown in a) correspond to the gradation conversion characteristics shown in FIG. Similarly, the gradation conversion characteristic shown in FIG. 16B corresponds to the gradation conversion characteristic of FIG.
The conversion characteristic of FIG. 16C is the conversion characteristic of FIG. 14C, and the conversion characteristic of FIG.
This corresponds to the conversion characteristic (d). As apparent from a comparison between the gradation conversion characteristics shown in FIG. 16 and the gradation conversion characteristics shown in FIG. 14, the gradation values of the image data are obtained using the various gradation conversion characteristics shown in FIG. Since the contrast of the portion having a gradation value smaller than the background color of the paper, that is, the portion corresponding to the original image is not inadvertently emphasized, a natural copy image can be obtained. .

Of course, in such a case, since the gradation change becomes discontinuous at the portion corresponding to the gradation value of the background color of the paper, the hatching is shown in FIG. 16E or FIG. As described above, a transition area may be provided to continuously change the gradation value.

In the above-described embodiment, the reading carriage 110 reads a document image while moving at a constant speed, and the moving speed of the reading carriage 110 performs dot processing by performing image processing on bandwidth image data. It is set in consideration of the speed required to form,
explained. However, for the first band of the document image, processing for detecting paper color information is required in addition to image processing and dot formation. Therefore, while various processes are being performed in the control circuit 260 for the leading band, only the time required for detecting the paper color information is obtained.
The moving speed of the reading carriage 110 may be decreased. Since the detection of the paper color information is performed on the image data for the first band, the moving speed of the reading carriage 110 is limited only immediately after the start of reading. Then, immediately after the start of reading, even if the moving speed of the reading carriage 110 is somewhat slow, the operator of the image copying apparatus 10 does not feel uncomfortable. As a result, it is possible to quickly and appropriately copy the original image without making the operator feel that the paper color information is being read at all.

Although the printing apparatus of the present embodiment has been described above, the present invention is not limited to all the embodiments described above, and can be implemented in various modes without departing from the scope of the present invention.

It is explanatory drawing which showed the outline | summary of the image copying apparatus of a present Example. 1 is a perspective view showing an external shape of an image copying apparatus according to an embodiment. FIG. 6 is an explanatory diagram showing a state in which a document table cover provided at the upper part of the printing apparatus is opened to read a printed document image. It is the perspective view which showed a mode that the front side of the scanner part was lifted and rotated. 1 is an explanatory diagram conceptually showing an internal configuration of an image copying apparatus according to an embodiment. FIG. It is explanatory drawing which showed a mode that the several nozzle which discharges an ink drop to the ink discharge head was formed. 6 is a flowchart showing a flow of image copying processing for reading a document image and copying the image. FIG. 3 is an explanatory diagram conceptually showing how a document image is read by a predetermined bandwidth for copying a document image. It is explanatory drawing which showed notionally the color conversion table referred for a color conversion process. It is explanatory drawing which expanded and illustrated a part of dither matrix. It is explanatory drawing which showed notionally the mode that the presence or absence of dot formation was judged for every pixel, referring a dither matrix. 5 is a flowchart showing a flow of paper color information detection processing performed during image copying processing. FIG. 5 is an explanatory diagram conceptually showing an area of a predetermined number of lines used for detecting a paper color in image data having a predetermined bandwidth at the head of a document image. It is explanatory drawing which illustrated the gradation conversion characteristic previously matched with paper color information and memorize | stored. It is explanatory drawing which showed a mode that which gradation conversion characteristic to select was set according to the detected paper color information. It is explanatory drawing which illustrated the gradation conversion characteristic of the modification previously matched with paper color information and memorize | stored.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Image copying apparatus, 12 ... Ink discharge head, 100 ... Scanner part,
200: Printer unit, 240: Print carriage, 241: Print head,
242 ... Ink cartridge, 243 ... Ink cartridge,
260 ... control circuit, 300 ... operation panel

Claims (9)

An image copying apparatus for copying a document image by reading a document image, generating image data, and printing the image based on the generated image data,
Paper color information acquisition means for acquiring information relating to the paper color of the document image by analyzing the image data;
A gradation value correcting means for correcting a gradation value of the image data based on the acquired paper color information;
Dot data generating means for generating dot data as data representing the original image by the presence or absence of dot formation by performing predetermined image processing on the corrected image data;
Image forming means for forming the original image by forming dots on a print medium according to the dot data;
The paper color information acquisition means is an image copying apparatus which is means for acquiring the paper color information by taking out and analyzing image data of a head portion of the original image from the read image data. The image copying apparatus according to claim 1,
The paper color information acquisition means is an image copying apparatus which is means for acquiring the paper color information when the average saturation obtained from the image data of the head portion of the document image is not more than a predetermined value. The image copying apparatus according to claim 1,
The paper color information acquisition means includes
Average saturation calculating means for calculating an average saturation, which is an average value of saturation, based on image data of the head portion of the original image;
When the average saturation is equal to or less than a predetermined value, an area having a predetermined luminance or higher is extracted from the head portion of the document image, and average luminance calculating means for calculating an average luminance in the extracted area is provided.
An image copying apparatus which is means for acquiring the paper color information based on the average luminance. An image copying apparatus according to any one of claims 1 to 3,
Image data storage means for dividing the document image into a plurality of regions and storing image data read for each region;
The gradation value correcting means, the dot data generating means, and the image forming means are configured to read the image data of the already read area while reading the original image for each area. Means to perform each process according to the order,
The paper color information acquisition means is an image copying apparatus which is means for acquiring the paper color information by analyzing a predetermined amount of image data from an area where the image data is first read. An image data conversion device that reads a document image, generates image data, and performs predetermined image processing on the image data to convert the document image into dot data represented by the presence or absence of dot formation,
Paper color information acquisition means for acquiring information relating to the paper color of the document image by analyzing the image data;
A gradation value correcting means for correcting a gradation value of the image data based on the acquired paper color information;
Dot data generating means for generating dot data as data representing the original image by the presence or absence of dot formation by performing predetermined image processing on the corrected image data;
The paper color information acquisition means is an image data conversion apparatus which is means for acquiring the paper color information by taking out and analyzing the image data of the head portion of the original image from the read image data. An image copying method for copying an original image by reading an original image, generating image data, and printing the image based on the generated image data,
A first step of obtaining information on the paper color of the document image by analyzing the image data;
A second step of correcting a gradation value of the image data based on the acquired paper color information;
A third step of generating dot data, which is data representing the original image according to the presence or absence of dot formation, by performing predetermined image processing on the corrected image data;
A fourth step of forming the original image by forming dots on a print medium according to the dot data,
In the image copying method, the first step is a step of acquiring the paper color information by taking out and analyzing image data of a head portion of the document image from the read image data. An image data conversion method for reading a document image to generate image data and performing predetermined image processing on the image data, thereby converting the document image into dot data represented by the presence or absence of dot formation,
(A) obtaining information relating to the paper color of the document image by analyzing the image data;
A step (B) of correcting a gradation value of the image data based on the acquired paper color information;
A step (C) of generating dot data as data representing the original image by the presence or absence of dot formation by performing predetermined image processing on the corrected image data;
In the image data conversion method, the step (A) is a step of acquiring the paper color information by taking out and analyzing the image data of the head portion of the document image from the read image data. A program for realizing, using a computer, a method of copying a document image by reading a document image, generating image data, and printing the image based on the generated image data,
A first function of acquiring information relating to a paper color of the document image by analyzing the image data;
A second function for correcting a gradation value of the image data based on the acquired paper color information;
A third function for generating dot data, which is data representing the original image according to the presence or absence of dot formation, by performing predetermined image processing on the corrected image data;
By forming dots on the print medium according to the dot data, the fourth function for forming the document image is realized by a computer, and
The first function is a program for acquiring the paper color information by taking out and analyzing image data of a head portion of the document image from the read image data. A method for converting a document image into dot data represented by the presence or absence of dot formation by reading a document image, generating image data, and performing predetermined image processing on the image data.
A program for realizing using a computer,
A function (A) for obtaining information on the paper color of the document image by analyzing the image data;
A function (B) for correcting a gradation value of the image data based on the acquired paper color information;
By performing predetermined image processing on the corrected image data, a function (C) for generating dot data as data representing the original image by the presence or absence of dot formation is realized by a computer,
The function (A) is a program that obtains the paper color information by extracting and analyzing image data of a head portion of the document image from the read image data.

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