JP2011061328A - Image processing method, image processor, image forming device, program, storage medium, and image forming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein visibility falls off about cutout characters except for a white cutout character. <P>SOLUTION: It is determined whether a RGB value for image data (character part background) is "255". When the image data is character image data composed of a background part of a first color and a character part of a second color different from the first color, saturation St of the character part is compared with saturation Sb of the background part. Then, it is determined whether Sb>St is met to determine the necessity of bold letter processing. If the character saturation is lower than the background saturation, bold letter processing is executed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image processing method, an image processing apparatus, an image forming apparatus, a program, a storage medium, and an image forming system.

  As an image forming apparatus such as a printer, a facsimile machine, a copying apparatus, a plotter, and a complex machine of these, for example, an ink jet recording apparatus is known as an image forming apparatus of a liquid discharge recording method using a recording head for discharging ink droplets. . This liquid discharge recording type image forming apparatus ejects ink droplets from a recording head onto a conveyed paper to form an image (recording, printing, printing, and printing are also used synonymously). Serial type image forming device that forms an image by ejecting droplets while the recording head moves in the main scanning direction, and a line type that forms images by ejecting droplets without the recording head moving There is a line type image forming apparatus using a head.

  In the present application, an “image forming apparatus” is an apparatus that forms an image by landing ink on a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics (simple liquid ejection apparatus) In addition, “image formation” not only gives an image having a meaning such as a character or a figure to a medium but also gives an image having no meaning such as a pattern to the medium. It also means (including what is simply referred to as a droplet discharge device or a liquid discharge device). In addition, the term “ink” is not limited to what is called ink, but is any liquid that can form an image, such as a recording liquid, a fixing liquid, a liquid, a DNA sample, or a patterning material. Used as a general term. The term “paper” is not limited to paper, but includes the above-described OHP sheet, cloth, and the like, and means that ink droplets adhere to the recording medium, recording medium, recording paper, recording It is used as a general term for what includes what is called paper.

  As a liquid discharge head (droplet discharge head) used as a recording head, a piezoelectric head or the like is used to displace a diaphragm and change the volume in the liquid chamber to increase the pressure to discharge the liquid droplet. There is known a thermal type head in which a heating element that generates heat is provided, the pressure in the liquid chamber is increased by bubbles generated by the heat generation of the heating element, and droplets are discharged.

  By the way, when creating a document with application software, in order to emphasize the character of the part, the extracted character comprised by the background part and the character part of a different color from a background part may be used. For example, a character (referred to as a “white character”) composed of a character part formed with white or a color close to white (white color) in a black background (which may be a color other than black) (background part). May be used.

  When such a white character is recorded using a liquid recording liquid (ink) as in an ink jet recording apparatus, the ink in the black portion bleeds into the white character portion due to ink bleeding, and as a result, the white character is There is a problem that it is thinned or partly collapsed. In particular, in the case of small characters and thin characters such as Mincho, the characters tend to be particularly crushed.

  Therefore, when the image is white or a white character with a color close to white, a process of adding a blank dot to the background portion adjacent to the dot forming the character image to thicken the white character (bold character processing) (Patent Document 1) is known. Pattern matching is used as the blank dot addition processing.

JP 2007-125826 A

  However, although the image quality of white characters can be improved by the above-described processing, there is a problem in that character crushing occurs because the character characters other than white characters are not subjected to thickening processing.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to improve the image quality of extracted characters.

In order to solve the above problems, an image processing method according to the present invention includes:
In an image processing method for generating image data of the image to be output by an image forming apparatus that includes a recording head that discharges droplets and forms an image,
When the image data is character image data composed of a background portion of a portion that is a first color and a character portion of a portion that is a second color different from the first color,
A characteristic calculation step of calculating characteristics of the background part and the character part based on the RGB values of the background part and the character part;
A bolding determination step for determining the presence or absence of the bolding process based on at least one of the hue characteristic and the saturation characteristic of the background part and the character part;
According to the bold character determination, a bolding process execution step is performed in which a bolding process is performed by adding dots of the same color as the character part to the outline part of the character part.

  Here, in the bolding determination step, the presence or absence of the bolding process may be determined based on the hue characteristic or the saturation characteristic and the brightness characteristic of the background part and the character part.

  In the bolding determination step, the presence or absence of the bolding process may be determined based on the hue characteristics, saturation characteristics, and brightness characteristics of the background portion and the character portion.

An image processing apparatus according to the present invention includes:
In an image processing apparatus that generates image data of the image to be output by an image forming apparatus that forms an image with a recording head that discharges droplets.
When the image data is character image data composed of a background portion of a portion that is a first color and a character portion of a portion that is a second color different from the first color,
A characteristic calculating means for calculating characteristics of the background portion and the character portion based on the RGB values of the background portion and the character portion;
Bolding determination means for determining the presence or absence of bolding processing based on at least one of hue characteristics and saturation characteristics of the background part and the character part;
In accordance with the bold character determination, a bolding process execution unit that performs a bolding process by adding a dot of the same color as the character part to the outline of the character part is provided.

An image forming apparatus according to the present invention includes:
In an image forming apparatus that forms an image with a recording head that discharges droplets,
When the image data is character image data composed of a background portion of a portion that is a first color and a character portion of a portion that is a second color different from the first color,
A characteristic calculating means for calculating characteristics of the background portion and the character portion based on the RGB values of the background portion and the character portion;
Bolding determination means for determining the presence or absence of bolding processing based on at least one of hue characteristics and saturation characteristics of the background part and the character part;
In accordance with the bold character determination, a bolding process execution unit that performs a bolding process by adding a dot of the same color as the character part to the outline of the character part is provided.

The program according to the present invention is:
In a program that causes a computer to perform processing for generating image data of the image that is output by an image forming apparatus that includes a recording head that discharges droplets and forms an image.
When the image data is character image data composed of a background portion of a portion that is a first color and a character portion of a portion that is a second color different from the first color,
A characteristic calculation process for calculating characteristics of the background part and the character part based on RGB values of the background part and the character part;
A bolding process for determining the presence or absence of the bolding process based on at least one of the hue characteristic and the saturation characteristic of the background part and the character part;
According to the bold character determination, the computer is configured to perform a bolding process execution process in which a bolding process is performed by adding a dot of the same color as the character part to the outline part of the character part.

  The storage medium according to the present invention stores the program according to the present invention.

  The image forming system according to the present invention includes the image processing apparatus according to the present invention and an image forming apparatus that includes a recording head that discharges droplets to form an image.

  According to the image processing method, the image processing apparatus, the image forming apparatus, the program, the storage medium, and the image forming system according to the present invention, the background portion of the portion where the image data is the first color is different from the first color. When the character image data is composed of the character portion of the portion having the color 2, the characteristics of the background portion and the character portion are calculated based on the RGB values of the background portion and the character portion, and the hue characteristics of the background portion and the character portion And whether to perform bolding based on at least one of the saturation characteristics, and to perform bolding by adding dots of the same color as the character part to the outline part of the character part according to the determination Therefore, it is possible to improve the visibility even for non-white characters, and to improve the image quality, and because bolding is determined based on at least one of the hue characteristic and the saturation characteristic of the background part and the character part. It is possible to improve the image quality can be improved more visibility.

1 is an external perspective view illustrating an example of an image forming apparatus according to the present invention that outputs image data generated by an image processing method according to the present invention. It is side surface explanatory drawing of the mechanism part of the apparatus. It is a plane explanatory drawing similarly. It is a block diagram which shows the outline | summary of the control part of the apparatus. 1 is a block diagram illustrating an example of an image forming system including image processing and an image forming apparatus according to the present invention. It is a block explanatory view showing an example of an image processing device in the system. It is a flowchart with which it uses for description of 1st Embodiment of this invention. It is a flowchart with which it uses for description of 2nd Embodiment of this invention. It is explanatory drawing which shows an example of the table with which description of the embodiment is provided. It is explanatory drawing which shows the other example of the table similarly provided for description of the same embodiment. It is a flowchart with which it uses for description of 3rd Embodiment of this invention. It is explanatory drawing which shows an example of the table with which description of the embodiment is provided. It is explanatory drawing with which it uses for description of the calculation formula of a hue characteristic, a saturation characteristic, and a brightness characteristic from RGB value. It is a flowchart with which it uses for description of 4th Embodiment of this invention. It is explanatory drawing with which it uses for description of the chart for table setting and determination pattern setting. It is a flowchart of an example of the pattern matching process which shows an example of a bolding process execution process. It is explanatory drawing with which it uses for description of the specific example of the window similarly used for pattern matching. It is explanatory drawing with which it uses for description of the specific example of the pattern matching using the same window. It is explanatory drawing with which it uses for description of the other example of a bolding process execution process. It is explanatory drawing with which it uses for description of the output example which does not perform bolding. It is explanatory drawing with which it uses for description of the example of an output which performed bolding.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of an image forming apparatus according to the present invention including a program according to the present invention for performing an image processing method according to the present invention will be described with reference to FIGS. 1 is an external perspective view of the image forming apparatus, FIG. 2 is a side view of the mechanism of the apparatus, and FIG. 3 is a plan view of the same.

  As shown in FIG. 1, the image forming apparatus includes an image reading unit (scanner unit) 2 that reads an image on an upper part of an apparatus main body 1 that performs image formation. The apparatus main body 1 is detachably mounted with a paper feed cassette 3 for stocking paper to be fed to the mechanism unit, and a paper discharge tray for stocking paper to be discharged after an image is formed above the paper feed cassette 3. 4 is installed. Further, on the front side of the apparatus main body 1, there is a cartridge mounting portion 5 for mounting an ink cartridge, and an operation / display portion (operation panel) 6 for inputting various operation signals and displaying display information is arranged.

  As shown in FIGS. 2 and 3, the main body 1 has a carriage 33 with main and slave guide rods 31 and 32 which are guide members horizontally mounted on the left and right side plates 21 </ b> A and 21 </ b> B of the main body 1. It is slidably held in the scanning direction, and is moved and scanned in the direction indicated by the arrow (carriage main scanning direction) via a timing belt by a main scanning motor (not shown).

  The carriage 33 is provided with recording heads 34a and 34b composed of liquid ejection heads for ejecting ink droplets of yellow (Y), cyan (C), magenta (M), and black (K). The “recording head 34” is arranged in a sub-scanning direction orthogonal to the main scanning direction, and the ink droplet ejection direction is directed downward.

  Each of the recording heads 34 has two nozzle rows. One nozzle row of the recording head 34a has black (K) droplets, the other nozzle row has cyan (C) droplets, and the recording head 34b has one nozzle row. One nozzle row ejects magenta (M) droplets, and the other nozzle row ejects yellow (Y) droplets. As the recording head 34, a recording head having a nozzle row of each color in which a plurality of nozzles are arranged on one nozzle surface can be used.

  Further, the sub tanks 35a and 35b, which are sub tanks as the second ink supply unit for supplying ink of each color corresponding to the nozzle row of the recording head 34, are referred to as the “sub tank 35” when they are not distinguished. ) Is installed. In the sub tank 35, ink cartridges (main tanks) 10y, 10m, 10c, and 10k of various colors that are detachably attached to the cartridge loading unit 4 are supplied from the ink supply tubes 36 of the respective colors by the supply pump unit 24. The recording liquid is replenished and supplied.

  On the other hand, as a paper feeding unit for feeding the papers 42 stacked on the paper stacking unit (pressure plate) 41 of the paper feeding tray 2, a half-moon roller (feeding) that separates and feeds the papers 42 one by one from the paper stacking unit 41. A separation pad 44 made of a material having a large friction coefficient is provided facing the paper roller 43) and the paper feed roller 43, and the separation pad 44 is urged toward the paper feed roller 43 side.

  In order to feed the paper 42 fed from the paper feeding unit to the lower side of the recording head 34, a guide member 45 for guiding the paper 42, a counter roller 46, a transport guide member 47, and a tip pressure roller. And a conveying belt 51 that electrostatically attracts the fed paper 42 and conveys it at a position facing the recording head 34.

  The transport belt 51 is an endless belt, and is configured to wrap around the transport roller 52 and the tension roller 53 and circulate in the belt transport direction (sub-scanning direction). Further, a charging roller 56 that is a charging unit for charging the surface of the transport belt 51 is provided. The charging roller 56 is disposed so as to come into contact with the surface layer of the transport belt 51 and to rotate following the rotation of the transport belt 51. The transport belt 51 rotates in the belt transport direction when the transport roller 52 is rotationally driven through timing by a sub-scanning motor (not shown).

  Further, as a paper discharge unit for discharging the paper 42 recorded by the recording head 34, a separation claw 61 for separating the paper 42 from the conveying belt 51, a paper discharge roller 62, and a spur 63 that is a paper discharge roller. And a paper discharge tray 3 below the paper discharge roller 62.

  A duplex unit 71 is detachably mounted on the back surface of the apparatus body 1. The duplex unit 71 takes in the paper 42 returned by the reverse rotation of the conveyance belt 51, reverses it, and feeds it again between the counter roller 46 and the conveyance belt 51.

  Further, a maintenance / recovery mechanism 81 for maintaining and recovering the nozzle state of the recording head 34 is disposed in the non-printing area on one side of the carriage 33 in the scanning direction. The maintenance / recovery mechanism 81 includes cap members (hereinafter referred to as “caps”) 82a and 82b (hereinafter referred to as “caps 82” when not distinguished from each other) for capping the nozzle surfaces of the recording head 34, and nozzle surfaces. A wiper member (wiper blade) 83 for wiping the recording medium, an empty discharge receiver 84 for receiving liquid droplets when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge the thickened recording liquid, and a carriage And a carriage lock 87 for locking 33. A waste liquid tank 100 for storing waste liquid generated by the maintenance recovery operation is mounted on the lower side of the head recovery mechanism 81 in a replaceable manner with respect to the apparatus main body.

  Further, in the non-printing area on the other side of the carriage 33 in the scanning direction, there is an empty space for receiving liquid droplets when performing empty discharge for discharging liquid droplets that do not contribute to recording in order to discharge the recording liquid thickened during recording or the like. A discharge receiver 88 is disposed, and the idle discharge receiver 88 includes an opening 89 along the nozzle row direction of the recording head 34.

  In this image forming apparatus configured as described above, the sheets 42 are separated and fed one by one from the sheet feed tray 2, and the sheet 42 fed substantially vertically upward is guided by the guide 45, and includes the transport belt 51 and the counter. It is sandwiched between the rollers 46 and conveyed, and the leading end is guided by the conveying guide 37 and pressed against the conveying belt 51 by the leading end pressing roller 49, and the conveying direction is changed by approximately 90 °. Then, the sheet 42 is attracted to the charged conveyance belt 51, and the sheet 42 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 51.

  Therefore, by driving the recording head 34 according to the image signal while moving the carriage 33, ink droplets are ejected onto the stopped paper 42 to record one line, and after the paper 42 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 42 has reached the recording area, the recording operation is finished and the paper 42 is discharged onto the paper discharge tray 3.

  When performing the maintenance and recovery of the nozzles of the recording head 34, the nozzle 33 performs the suction from the nozzles by moving the carriage 33 to a position facing the maintenance and recovery mechanism 81 which is the home position and performing capping by the cap member 82. By performing a maintenance and recovery operation such as idle ejection for ejecting droplets that do not contribute to image formation, image formation by stable droplet ejection can be performed.

Next, an outline of the control unit of the image forming apparatus will be described with reference to FIG. This figure is an overall block diagram of the control unit.
The control unit 100 includes a CPU 101 that controls the entire apparatus, a ROM 102 that stores programs executed by the CPU 101 and other fixed data, a RAM 103 that temporarily stores image data, and the power supply of the apparatus. A rewritable non-volatile memory 104 for holding data, an image processing for performing various signal processing and rearrangement on image data, and other input / output signals for controlling the entire apparatus, scanner means 2 and a scanner control unit 116 for controlling 2.

  Further, a print control unit 108 including a data transfer unit for driving and controlling the recording head 34 and a driving signal generating unit, a head driver (driver IC) 109 for driving the recording head 34 provided on the carriage 33 side, An AC bias is applied to the charging roller 56, a main scanning motor 154 that moves and scans the carriage 33, a sub-scanning motor 155 that moves the conveyor belt 51 in a circular motion, a motor drive unit 110 that drives the maintenance / recovery motor 156 of the maintenance / recovery mechanism 81. An AC bias supply unit 111 and the like are provided.

  The control unit 100 is connected to an operation panel 114 for inputting and displaying information necessary for the apparatus.

  The control unit 100 has an I / F 106 for transmitting and receiving data and signals to and from the host side. From the host 200 side such as an information processing device such as a personal computer and an imaging device such as a digital camera, a cable or The data is received by the I / F 106 via the network. Further, reading information of the original image from the scanner 2 is taken in via the scanner control unit 116.

  Then, the CPU 101 of the control unit 100 reads and analyzes the print data in the reception buffer included in the I / F 106 with respect to the reception data from the host side, and processes the extracted characters according to the present invention by the program according to the present invention. The ASIC 105 performs other necessary image processing, data rearrangement processing, and the like, and transfers the image data to the print control unit 108. Note that the generation of dot pattern data for image output is performed by the printer driver 101 on the host 200 side. Further, the read data of the original image from the scanner 2 is subjected to necessary input correction processing and output processing to generate image data, which is transferred to the print control unit 108.

  The print control unit 108 transfers the above-described image data to the head driver 109 as serial data, and outputs a transfer clock, a latch signal, a control signal, and the like necessary for transferring the image data and confirming the transfer to the head driver 109. In addition to the above, it includes a D / A converter that performs D / A conversion on the drive pulse pattern data stored in the ROM 102, a drive signal generation unit including a voltage amplifier, a current amplifier, and the like. A drive signal composed of a plurality of drive pulses is output to the head driver 109.

  The head driver 109 selectively selects a drive pulse that constitutes a drive signal provided from the print control unit 108 based on image data corresponding to one line of the print head 34 that is input serially, and drops droplets of the print head 34. The recording head 34 is driven by applying it to a driving element (for example, a piezoelectric element) that generates energy to be discharged. At this time, by selecting a driving pulse constituting the driving signal, for example, dots having different sizes such as a large droplet, a medium droplet, and a small droplet can be sorted.

  The I / O unit 113 acquires information from the various sensor groups 115 mounted on the apparatus, extracts information necessary for printer control, the print control unit 108, the motor control unit 110, and the AC bias supply unit. Used to control 111. The sensor group 115 includes an optical sensor for detecting the position of the paper, a thermistor for monitoring the temperature in the machine, a sensor for monitoring the voltage of the charging belt, an interlock switch for detecting opening and closing of the cover, and the like. The I / O unit 113 can process various sensor information.

Next, an image forming system according to the present invention including the image processing apparatus according to the present invention will be described with reference to FIG.
This printing system (image forming system) is configured by connecting one or a plurality of image processing apparatuses 400 such as a personal computer (PC) and the inkjet recording apparatus 500 via a predetermined interface or network.

  As shown in FIG. 6, in the image processing apparatus 400, a CPU 401 and various ROMs 402 and RAM 403, which are memory means, are connected by a bus line. The bus line is connected to a storage device 406 using a magnetic storage device such as a hard disk, an input device 404 such as a mouse and a keyboard, a monitor 405 such as an LCD or a CRT, and the like via a predetermined interface. A storage medium reading device for reading a storage medium such as an optical disk is connected, and a predetermined interface (external I / F) 407 for communicating with a network such as the Internet or an external device such as a USB is connected.

  An image processing program including a program according to the present invention is stored in the storage device 406 of the image processing apparatus 400. This image processing program is installed in the storage device 406 by being read from the storage medium according to the present invention by a storage medium reader or downloaded from a network such as the Internet. By this installation, the image processing apparatus 400 becomes operable to perform image processing. Note that this image processing program may operate on a predetermined OS. Further, it may be a part of specific application software.

  The ink jet recording apparatus 500 may be the image forming apparatus described above, or the ink jet recording apparatus alone may not have a function of generating a dot pattern by image drawing or a character printing command.

  Here, a print command from application software or the like executed by the image processing apparatus 400 as a host is subjected to image processing by a printer driver incorporated as software in the image processing apparatus 400 (host computer), and the inkjet recording apparatus 500 performs the image processing. Multi-value dot pattern data (print image data) that can be output is generated.

  It is assumed that the data is rasterized and transferred to the ink jet recording apparatus 500, and the ink jet recording apparatus 500 is printed out.

  Specifically, in the image processing apparatus 400, an image drawing or character recording command from an application or operating system (for example, a description of the position and thickness and shape of a line to be recorded, a typeface of a character to be recorded, and the like) (Which describes the size, position, etc.) is temporarily stored in the drawing data memory.

  Note that these instructions are written in a specific print language. The command stored in the drawing data memory is interpreted by the rasterizer, and if it is a line recording command, it is converted into a recording dot pattern corresponding to the designated position and thickness. If it is a character recording command, the outline information of the corresponding character is called from the font outline data stored in the image processing apparatus 400, converted into a recording dot pattern corresponding to the designated position and size, and the image If it is data, it is directly converted into a recording dot pattern.

  Thereafter, these recorded dot patterns (image data) are subjected to image processing and stored in a raster data memory. At this time, the image processing apparatus 400 rasterizes the recording dot pattern data with the orthogonal grid as the basic recording position. Examples of the image processing include color management processing (CMM) for adjusting colors, γ correction processing, halftone processing such as dithering and error diffusion, further background removal processing, total ink amount regulation processing, and the like.

  Then, the recording dot pattern stored in the raster data memory is transferred to the ink jet recording apparatus 500 via the interface.

  The program according to the present invention is stored in the ROM 102 of the image forming apparatus described with reference to FIGS. 1 to 4 described above, or stored in the ROM 402 of the image processing apparatus 400 and the like. Performs processing related to characters.

  Next, the image processing method, the image processing method, the image processing apparatus, the image forming apparatus, the program, the storage medium, and the image processing related to the extracted characters performed in the image forming system according to the present invention are executed by the computer as described above. This will be explained with an example.

  In the image processing according to the present invention, when the image data is character image data composed of a background portion of a portion that is a first color and a character portion of a portion that is a second color different from the first color, Calculate the characteristics of the background part and the character part based on the RGB values of the background part and the character part, and determine whether or not the bolding process is performed based on at least one of the hue characteristic and the saturation characteristic of the background part and the character part. In accordance with the bold character determination, bolding processing is performed in which bolding processing is performed by adding dots of the same color as the character portion to the contour portion of the character portion.

  That is, an image of image data to be processed by the image processing according to the present invention is configured by a background portion and a character portion, and the background portion and the character portion are configured by different colors. As an example, a background portion (colored) and a character portion (color different from the background portion) can be mentioned.

Accordingly, a first embodiment of the present invention will be described with reference to the flowchart of FIG.
First, it is determined whether or not the RGB value of the image data (character portion background) is “255”. If the RGB value is “255”, it is not a blank character, and the process is exited. That is, the following processing is started when the image data is character image data composed of a background portion of the first color portion and a character portion of the second color portion different from the first color. The

  On the other hand, if the RGB value of the image data is not “255”, the saturation (character saturation) St of the character portion and the saturation (background saturation) Sb of the background portion are calculated based on the RGB values. Here, the character saturation St is 0 to 1 and the background saturation Sb is 0 to 1. That is, here, the characteristics of the background part and the character part are calculated based on the RGB values of the background part and the character part (characteristic calculation process, characteristic calculation means, characteristic calculation process). The calculation of the saturation characteristics based on the RGB values will be described later.

  Then, the character saturation St and the background saturation Sb are compared to determine whether or not Sb> St, and the presence / absence of the bolding process is determined. The character saturation St is 0 to 1 and the background saturation Sb is 0 to 1. That is, here, the presence / absence of the bolding process is determined based on the calculated saturation characteristics of the background part and the character part (a bolding determination process, a bolding determination unit, and a bolding determination process).

  At this time, if Sb> St is not satisfied, that is, if the character saturation is higher than the background saturation, the processing is exited.

  On the other hand, if Sb> St, that is, if the character saturation is lower than the background saturation, the thickening process (the bolding process executing step, the bolding process executing means, the thickening process executing process, and so on) ).

  That is, in this embodiment, the presence / absence of thickening processing is determined from the saturation characteristics of the background portion and the character portion, the saturation characteristics of the background portion and the character portion are compared, and the character portion has a saturation saturation. If it is high, the character is not thickened. Conversely, if the saturation is low, the thickening process is performed. At this time, it is also possible to change the degree (level) of performing thickening processing according to the difference in saturation between the background portion and the character portion.

Next, a second embodiment of the present invention will be described with reference to the flowchart of FIG.
First, it is determined whether or not the RGB value of the image data (character portion background) is “255”. If the RGB value is “255”, it is not a blank character, and the process is exited.

  On the other hand, if the RGB value of the image data is not “255”, the saturation (character saturation) St of the character portion and the saturation (background saturation) Sb of the background portion are calculated based on the RGB values. That is, here, the characteristics of the background part and the character part are calculated based on the RGB values of the background part and the character part (characteristic calculation process, characteristic calculation means, characteristic calculation process). The calculation of the saturation characteristics based on the RGB values will be described later.

  Then, the character hue Ht and the background hue Hb are calculated to obtain the hue difference ΔH, and the value (constant) A is obtained by referring to the ΔH → A conversion table as shown in FIG. It is determined whether or not the difference from the saturation Sb is larger than the value A (Sb−St> A), and the presence / absence of thickening processing is determined. That is, here, the presence / absence of bolding processing is determined based on the calculated saturation characteristics and hue characteristics of the background portion and the character portion (bold text determination step, bold text determination means, bold text determination processing). The calculation of hue characteristics based on RGB values will be described later.

  At this time, if Sb−St> A is not satisfied, that is, if the difference between the character saturation and the background saturation is not larger than the value A, the process is terminated.

  On the other hand, if Sb−St> A, that is, if the difference between the character saturation and the background saturation is larger than the value A, by adding a dot having the same color as the character portion to the contour portion of the character portion. Perform bolding process.

  That is, in this embodiment, the degree of thickening processing according to the difference between the saturation of the background portion and the saturation of the character portion and the constant determined from the difference of the hue of the background portion and the character portion (Level) is changed.

Here, the ΔH → A conversion table shown in FIG. 9 predetermines a value A as an enhancement coefficient corresponding to a hue difference ΔH obtained in advance from the character hue Ht (0 to 359 degrees) and the background hue Hb (0 to 359 degrees). It was created. Hue difference ΔH is
ΔH = | Ht−Hb | (when Ht−Hb | ≦ 180)
ΔH = 359− | Ht−Hb | (when Ht−Hb |> 180)
Is required.

  In this case, as shown in FIG. 10, the value A (constant) is preferably set so as to decrease as the hue difference increases. Also, the setting conditions can be experimentally determined from the visibility when the character part and the background part have arbitrary RGB values, fonts, and font sizes, and can be made different between the high resolution mode and the low resolution mode. preferable. FIG. 10 is a conversion table for converting a hue difference ΔH at a resolution of 600 × 300 dpi, 600 × 600 dpi, and 1200 × 1200 dpi into a hue difference enhancement coefficient Ah (value A) and a saturation difference ΔS into a saturation difference enhancement coefficient As (value A). An example is shown.

  Here, A: enhancement coefficient, Ah: hue difference enhancement coefficient, As: saturation difference enhancement coefficient, A: max (Ah, As), ΔH: hue difference (0 to 180 degrees), Ht: character portion hue (0 to 0) 359 degrees), Hb: background portion hue (0 to 359 degrees), ΔS: saturation difference (0 to 1), St: character portion saturation (0 to 1), Sb: background portion saturation (0 to 1). At this time, the hue difference ΔH and the saturation difference ΔS are obtained as follows.

ΔH = | max (Ht, Hb) −min (Ht, Hb) | (when Ht−Hb | ≦ 180)
ΔH = 360− | max (Ht, Hb) −min (Ht, Hb) | (Ht−Hb |> 180

ΔS = | max (St, Sb) −min (St, Sb) | (when St−Sb | ≦ 0.5)
ΔS = 360− | max (St, Sb) −min (St, Sb) | (when St−Sb |> 0.5)

Next, a third embodiment of the present invention will be described with reference to the flowchart of FIG.
First, it is determined whether or not the RGB value of the image data (character portion background) is “255”. If the RGB value is “255”, it is not a blank character, and the process is exited.

  On the other hand, if the RGB value of the image data is not “255”, the character saturation St, the background side Sb, the lightness (character lightness) Lt of the character part, and the lightness (background lightness) Lb of the background part are based on the RGB values. To calculate. That is, here, the characteristics of the background part and the character part are calculated based on the RGB values of the background part and the character part (characteristic calculation process, characteristic calculation means, characteristic calculation process). The calculation of brightness characteristics based on RGB values will be described later.

  Then, the character saturation St and the background saturation Sb are compared to determine whether or not Sb> St, and the character lightness Lt and the background lightness Lb are compared to determine whether or not Lb <Lt. The character brightness Lt is 0 to 1, and the background brightness Ls is 0 to 1. That is, here, the first step of determining whether or not to perform the bolding process is performed based on the calculated saturation characteristics and hue characteristics of the background portion and the character portion.

  At this time, if Sb−St> A and Lb <Lt are not satisfied, the process is exited.

  On the other hand, if Sb−St> A and Lb <Lt, the difference between the character saturation St and the background saturation Sb is the ΔH → A conversion table shown in FIG. 12, as in the second embodiment. It is determined whether or not the value is larger than the value A obtained by reference. In other words, here, the second stage of the presence / absence of bolding processing is determined based on the calculated saturation characteristics and hue characteristics of the background portion and the character portion (in combination with the above-described saturation and lightness determination processing, (Characterizing determination step, bold character determining means, bold character determining process).

  At this time, if Sb−St> A is not satisfied, that is, if the difference between the character saturation and the background saturation is not equal to or greater than the value A, the process is terminated.

  On the other hand, if Sb−St> A, that is, if the difference between the character saturation and the background saturation is larger than the value A, the thickening process is performed.

  That is, in this embodiment, the presence / absence of thickening processing is determined from the saturation characteristics, hue, and brightness characteristics of the background portion and the character portion. When the background saturation is high compared to the text saturation and the background brightness is low compared to the text brightness, the difference between them is calculated from the difference in hue between the background and text. Compared with the constant to be determined, character thickening is not performed when it becomes smaller, and bolding processing is performed when it becomes larger.

Here, the ΔH → A conversion table shown in FIG. 12 predetermines a value A as an enhancement coefficient corresponding to the hue difference ΔH obtained in advance from the character hue Ht (0 to 359 degrees) and the background hue Hb (0 to 359 degrees). It was created. here,
ΔH = | Ht−Hb | (when Ht−Hb | ≦ 180)
ΔH = 359− | Ht−Hb | (when Ht−Hb |> 180)
Is required.

  At this time, as described above, the constant is set so as to decrease as the difference in hue between the background portion and the character portion increases. The setting conditions can be experimentally obtained from the visibility when the character and background are arbitrary RGB values, fonts, and font sizes, and can be different between the high resolution mode and the low resolution mode. Also, the thickening process is performed according to the difference between the saturation of the background portion and the saturation of the character portion, the difference between the constants, the difference between the lightness of the background portion and the lightness of the character portion, and the difference between the constants. It is also possible to change the degree of execution (level).

  In this way, any two or more of the hue characteristics and saturation characteristics of the character part and the background part, and any two or more including the brightness characteristic are detected and compared, and a dot is added to a desired position as described later. (Thickening process) is controlled.

  At this time, the hue characteristic, the saturation characteristic, and the lightness characteristic can be detected by calculating from the RGB values using the conversion formula shown in FIG. 13, and there is no need to provide a special detection device.

  In FIG. 13, H: Hue (0 to 359 degrees, where red is 0 degrees), L: Lightness (0 to 1), S: Saturation (0 to 1), R: 0 to 1, G: 0 to 1 , B: 0 to 1.

  Thus, when the image data is character image data composed of the background portion of the portion that is the first color and the character portion of the portion that is the second color different from the first color, the background portion and the character Based on the RGB value of the part, the characteristics of the background part and the character part are calculated, and the presence or absence of the bolding process is determined based on at least one of the hue characteristic and the saturation characteristic of the background part and the character part. By performing the bolding process by adding dots of the same color as the character portion to the contour portion of the portion, it is possible to improve the visibility even for a non-white character, and to improve the image quality.

Next, a fourth embodiment of the present invention will be described with reference to the flowchart of FIG.
First, it is determined whether or not the font of the character portion of the image data is a predetermined type (referred to as group A).

  At this time, if the font is a type of group A, it is determined whether or not the font size is larger than 7 points, for example. If the font size is larger than 7 points, the process of the first embodiment described above (bold character processing pattern A). If the score is 7 points or less, the processing of the second embodiment described above (bold character processing pattern B) is performed.

  On the other hand, if the font is not the type of group A, it is determined whether or not the font size is larger than 7 points, for example. If the font size is larger than 7 points, the processing of the second embodiment described above (bold character processing pattern B). If the score is 7 points or less, the processing of the third embodiment described above (bold character processing pattern C) is performed.

  That is, here, the processes of the first to third embodiments described above are selected and performed according to the font type and size of characters. The condition in this case is experimentally obtained from the visibility when the character and background are arbitrary RGB values, fonts, and font sizes as shown in FIG.

  Specifically, as shown in FIG. 15, an evaluation image (font size: 3) in which characters having a hue Ht such that ΔH is 0 to 0.5 is arranged with respect to the hue Hb (0 to 359 degrees) of the background portion. -8 points, 1 point interval (Hb: 0-359 degrees, 10 degrees interval) print sample (table setting / determination pattern setting chart), the visibility of multiple people was evaluated at a distance of 30 cm, the value described above A (constant) is determined so that 100% is visible.

Next, the bolding process in the process described above will be described.
In the thickening process, the character portion is thickened by adding dots of the same color as the character portion to the contour portion of the character portion. As the thickening process, for example, a pattern matching process can be performed.

An example of this pattern matching process will be described with reference to the flowchart of FIG.
First, a target pixel is set at the head of the font data, and bitmap data of font data corresponding to the window is acquired around the target pixel. Then, by pattern matching, the acquired data is compared with data of a pattern (hereinafter referred to as “reference pattern”) to which character data (character part data) set in advance is added. Add a dot to In these processes, one pixel may be handled as 1-byte data or 1-bit data.

  For example, when pattern matching is performed with the font data shown in FIG. 18A using the m × n (3 × 3) reference patterns shown in FIGS. 17A to 17C, FIG. As shown in FIG. 17, since the dot state included in the window W when the pixel position (dot position) D45 of the font data is the target pixel matches the reference pattern in FIG. As shown in FIG. 18B, D45 is replaced from the background data to the character data (for convenience of illustration, the background is shown in black and the character is shown in white, but the character is actually white. Other than color data.)

  Similarly, when the window W moves to the right and the target pixel becomes D46, although not shown, since it matches the reference pattern in FIG. 17B, the target pixel D46 is changed from the background data to the character portion. When the window W is moved one place to the right and the pixel of interest becomes D47, the pixel coincides with the reference pattern of FIG. 17A, so that the pixel of interest D47 is changed from the background data to the character portion. Replaced with data.

  Here, the sizes of the window and the reference pattern are determined by appropriately determining how much dot replacement needs to be performed and whether the processing time is in time for the printing speed. Specifically, when the size of the reference pattern is increased, the pattern matching data is increased, so that pattern matching takes time. Therefore, from the processing time, the size should be as small as possible.

  On the other hand, the number of dots that should be replaced before and after the outline is determined by the character quality to be pursued by improving the collapse of the characters. That is, the optimum size is determined from the viewpoints of both processing speed and character quality.

  Further, the bolding process can be performed without using pattern matching. That is, it is a process of making a bold character by uniformly adding dots to the character part without performing pattern matching. For example, as shown in FIG. 19, this processing is performed by adding one dot to the right and one dot below to the image data shown in FIG. Fatten.

  In this case, if dots are added to the left and right or the top and bottom, respectively, in a small size character (for example, 6 points) with a narrow space between characters, the character itself may be crushed. Although dot addition is performed, it can be adjusted to change the additional pattern according to the character size.

  Further, as in the case of the above-described pattern matching, the additional pattern may be changed according to the character size, character type, and image resolution. For low resolution, characters are thickened using pattern matching, and for high resolution, uniform thickness. It may be possible to switch between them.

  It is also possible to change the level of character thickening by comparing the background portion and the character portion.

Next, specific examples of the case where the above bolding is not performed and the case where it is performed will be described with reference to FIGS.
FIG. 20A shows an output example when bolding is not performed, and FIG. 20B shows a partially enlarged view of this output example in dot size. In FIG. 20, the resolution of the image is formed at the same resolution as the nozzle pitch (300 dpi in this example) in the sub-scanning direction, and is higher in density in the main scanning direction than the sub-scanning direction (in this example, the sub-scanning direction). It is assumed that it is formed at 600 dpi twice as much as the scanning direction. In this case, since the main scanning direction has a resolution twice that of the sub-scanning direction, two dots in the main scanning direction correspond to one dot in the sub-scanning direction. The figure is enlarged twice as much as the scanning direction.

  As shown in FIG. 20, if thickening is not performed, dot selection is performed by mechanically selecting a width according to the shape of the character. It penetrates into the character part, blurring the outline part, and good visibility cannot be obtained.

  On the other hand, FIG. 21A shows an output example when bolding is performed, and FIG. 21B shows a partially enlarged view of the output example in dot size.

  As shown in FIG. 20, one dot in the sub-scanning direction, one dot in the main scanning direction, and a large (large) dot in the background color adjacent to the dots forming the character part have the same color as the character part. The ink is added using the ink, and the thickening process is performed.

  By this processing, the boundary part of the dot part of the background part with the character part is bolded, and even if the ink of the background part is blotted, the removed character part is thick, so it is crushed Good image quality can be obtained without disappearing.

  In addition, you may change the size of the dot to add according to the resolution. Further, the number of additional dots added to the character portion is not limited to one dot, but may be two dots or more. When the resolution is high, the addition of one dot is less likely to thicken the extracted characters, and may not be thick enough to sufficiently eliminate background blurring. Therefore, it is preferable to control the addition of dots appropriately. .

  That is, at the boundary between the background portion and the character portion, the amount of blur in the background portion is almost constant regardless of the resolution, whereas the thickness of the character portion due to the addition of one dot changes according to the resolution. Therefore, if the number of dots to be added is controlled / adjusted according to the resolution, appropriate bolding according to the resolution can be executed.

  The above-described processing related to bolding may be all processed as a program on a computer, or a part may be programmed and processed on a computer, and the rest may be processed as hardware.

  As described above, in the image processing method, the image processing apparatus, the image forming apparatus, the program, the storage medium, and the image forming system according to the present invention, the background portion and the first color of the portion in which the image data is the first color Is character image data composed of character parts of different second color parts, the characteristics of the background part and the character part are calculated based on the RGB values of the background part and the character part, and the background part and the character part Is determined based on at least one of the hue characteristic and the saturation characteristic, and the bolding process is performed by adding dots of the same color as the character part to the outline part of the character part according to the determination. As a result, it is possible to improve the visibility and improve the image quality even for non-white characters, and the bold text based on at least one of the hue characteristics and the saturation characteristics of the background portion and the character portion. Since determining the reduction, thereby improving the image quality can be improved more visibility.

  A program for causing a computer to execute the above-described image processing method can be easily distributed in large quantities or copied by recording it on a storage medium. In terms of storage of the program, it can be stored on a nonvolatile storage medium. Long-term storage is possible. Furthermore, since current computers include external storage medium reading means such as a floppy disk drive and a CD / DVD drive as standard or optional, it is possible to easily introduce them into the computer using these storage media. Further, it can be provided to the image processing apparatus or the image forming apparatus by a download method using the Internet.

  In the above embodiment, the present invention has been described with reference to an example in which the present invention is applied to an ink jet recording apparatus. However, the present invention can also be applied to a printer, a facsimile apparatus, a copying apparatus, a printer / fax / copier multifunction machine, etc. The present invention can also be applied to an image forming apparatus using other ink, an image processing apparatus that supplies print data (image data) to the image forming apparatus, and a program such as a printer driver installed in the image processing apparatus.

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Scanner 3 Paper feed tray 33 Carriage 34 Recording head 208 Print control part 400 Image processing apparatus 500 Inkjet recording apparatus

Claims (8)

In an image processing method for generating image data of the image to be output by an image forming apparatus that includes a recording head that discharges droplets and forms an image,
When the image data is character image data composed of a background portion of a portion that is a first color and a character portion of a portion that is a second color different from the first color,
A characteristic calculation step of calculating characteristics of the background part and the character part based on the RGB values of the background part and the character part;
A bolding determination step for determining the presence or absence of the bolding process based on at least one of the hue characteristic and the saturation characteristic of the background part and the character part;
An image processing method comprising: performing a bolding process by performing a bolding process by adding a dot having the same color as the character part to the outline part of the character part in accordance with the bold character determination.   2. The image processing method according to claim 1, wherein in the bolding determination step, the presence or absence of the bolding process is determined based on a hue characteristic or a saturation characteristic and a brightness characteristic of the background part and the character part. .   The image processing method according to claim 1, wherein in the bolding determination step, the presence or absence of the bolding process is determined based on a hue characteristic, a saturation characteristic, and a lightness characteristic of the background part and the character part. In an image processing apparatus that generates image data of the image to be output by an image forming apparatus that forms an image with a recording head that discharges droplets.
When the image data is character image data composed of a background portion of a portion that is a first color and a character portion of a portion that is a second color different from the first color,
A characteristic calculating means for calculating characteristics of the background portion and the character portion based on the RGB values of the background portion and the character portion;
Bolding determination means for determining the presence or absence of bolding processing based on at least one of hue characteristics and saturation characteristics of the background part and the character part;
An image processing apparatus comprising: a bolding process execution unit that performs a bolding process by adding a dot having the same color as the character part to the outline part of the character part according to the bold character determination. In an image forming apparatus that forms an image with a recording head that discharges droplets,
When the image data is character image data composed of a background portion of a portion that is a first color and a character portion of a portion that is a second color different from the first color,
A characteristic calculating means for calculating characteristics of the background portion and the character portion based on the RGB values of the background portion and the character portion;
Bolding determination means for determining the presence or absence of bolding processing based on at least one of hue characteristics and saturation characteristics of the background part and the character part;
An image forming apparatus comprising: a bolding process execution unit that performs a bolding process by adding a dot having the same color as the character part to the outline part of the character part according to the bold character determination. In a program that causes a computer to perform processing for generating image data of the image that is output by an image forming apparatus that includes a recording head that discharges droplets and forms an image.
When the image data is character image data composed of a background portion of a portion that is a first color and a character portion of a portion that is a second color different from the first color,
A characteristic calculation process for calculating characteristics of the background part and the character part based on RGB values of the background part and the character part;
A bolding process for determining the presence or absence of the bolding process based on at least one of the hue characteristic and the saturation characteristic of the background part and the character part;
A program for causing a computer to perform a bolding process execution process for performing a bolding process by adding a dot having the same color as the character part to the outline part of the character part according to the bold character determination.   A storage medium storing the program according to claim 6.   An image forming system comprising: the image processing apparatus according to claim 4; and an image forming apparatus that includes a recording head that discharges droplets to form an image.

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