JP2010173221A - Image formation device, image formation method, program, and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a character of good quality to be printed irrespective of the characteristic against the ink bleeding of a recording medium. <P>SOLUTION: An image formation device has a bleeding detection means for detecting the degree of ink bleeding on the recording medium, a corrected dot size selection means for choosing the dot size used at making a jaggy correction according to the degree of ink bleeding detected by the bleeding detection means, a jaggy detection means for detecting the pixel position needing the jaggy correction by making a pattern matching between a character outline and a reference pattern prepared beforehand, and a jaggy correction means for making the jaggy correction by making addition or permutation of dot to the pixel position detected by the jaggy detection means. The jaggy correction means uses the dot size chosen by the corrected dot size selection means at the jaggy correction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, an image forming method, a program, and a storage medium for eliminating jaggies that occur in black characters.

  The ink jet recording method is capable of high-speed recording, does not require special fixing processing when recording on plain paper, and has been attracting attention for office use because noise generation during recording is so small that it can be ignored. Yes. Various schemes have been proposed so far, and various schemes have already been commercialized and put into practical use. The ink jet recording method uses a recording head constituted by an ink liquid chamber and a nozzle communicating with the ink chamber. Pressure is applied to ink in the ink liquid chamber according to image information, and ink droplets are ejected from the nozzle. An image is formed by adhering to a recording material such as paper or film. Such an ink jet image forming apparatus discharges ink from a recording head and forms an image in a non-contact manner, so that it can record on various recording media.

  There are two types of inkjet printers with different head configurations, which are called a serial inkjet printer and a line inkjet printer, respectively. The serial ink jet printer forms an image while scanning the ink jet head in the width direction of the paper (main scan), and after one or more scans are completed, the paper is transported to form the next recording line. Is.

  On the other hand, in the line inkjet printer, since the nozzles are formed over almost the entire width direction of the paper, printing is performed while transporting the paper without performing scanning in the width direction. A line inkjet printer has the advantage of a high recording speed because it forms one line in the width direction at a time, but on the other hand, the size of the entire printer increases because the head itself becomes large. In addition, in order to perform high resolution recording, it is necessary to increase the density of the nozzles themselves, which increases the manufacturing cost of the head.

  In contrast, serial inkjet printers have the advantage that the cost of the apparatus is low because images are formed with a relatively small head. For this reason, many serial ink jet printers are currently in practical use.

  In the case of a serial inkjet printer, the printing speed is determined by the resolution of the image, the nozzle density, the driving frequency for forming dots, the sub-scanning speed, and the like. Among these, the nozzle density is limited by the processing accuracy of the nozzle, liquid chamber, flow path, and actuator.

  In order to improve the printing speed, it is preferable to form the printing area by one main scanning. For example, when creating an image with a resolution of 300 dpi in the sub-scanning direction using a head with a nozzle density of 300 dpi, the image is created by scanning once in the moving direction of the head (main scanning direction). However, in order to create an image with a resolution of 600 dpi in the sub-scanning direction, it is necessary to fill the image by a so-called interlace method in which two main scans and one sub-scan (paper conveyance) are performed. There is. Naturally, the method of creating an image by one scan (non-interlace method) is faster in creating an image. Also in the main scanning direction, as a method of forming one line in the main scanning direction, a method of forming by one main scanning (one pass printing) and a method of forming by a plurality of times of main scanning (so-called multi-scanning). Pass printing). Naturally, the printing speed is faster in the one-pass printing that can be formed by one main scanning.

  However, when an image is created by the 1-pass non-interlace method in order to increase the recording speed, the resolution of the image is inevitably reduced because the resolution of the image is determined by the resolution of the head. When the image density is low, a method of multi-value one pixel is effective for improving the image quality. Examples of the multivalued method include a method of changing the size of one dot itself, a method of forming one pixel by discharging a plurality of small dots, or a method of changing the density of the ink itself. However, high image quality by multi-value is effective for images such as photographs, but is hardly effective for graphics and characters. This is because, in the case of characters and graphics, a dot size larger than that of the background portion is necessary, and if small dots are used, characters and graphics images of low density are formed. Therefore, in binary images such as characters and graphics, a problem peculiar to low resolution occurs. In particular, in the case of characters, the character quality deteriorates and the characters are difficult to read.

  In order to improve the head resolution, in addition to improving the head nozzle density itself, there is a method of improving the apparent resolution by shifting and assembling a plurality of nozzle rows. However, both methods cannot avoid an increase in the manufacturing cost of the head, and the improvement in resolution causes a number of problems such as an increase in the amount of image data processing and complication of the device control system. It also leads to cost increase of the main body. These are particularly problematic when considering the use of a longer head for improving the printing speed. Also, regarding the line printer, not only the head length problem, but unlike serial printers, interlace and multi-pass operations are not possible, so the print resolution in the main scanning direction is fixed at the nozzle resolution of the head. . For this reason, the problem of lower resolution becomes more serious.

  From the above, in order to obtain better images while maintaining low cost and high-speed printing, it is an important issue to consider how to achieve good image quality within the limited head resolution. I understand that.

  Next, problems specific to low resolution will be described in detail. The recorded image of the ink jet printer is represented by dots formed in a matrix in the scanning direction of the head and the transport direction of the recording paper, which is a direction orthogonal to the head scanning direction. Here, when a character is printed as a dot image, the quality of the character varies greatly depending on the resolution of the image to be printed. For example, when a character of the same size is printed at 300 dpi × 300 dpi and when printed at 600 dpi × 600 dpi, the number of dots constituting the character differs by about four times, and therefore when printed at 600 dpi × 600 dpi. It is possible to express to a finer detail, and of course the character quality is good. In particular, in the hatched portion of the character, dots increase (or decrease) in a staircase pattern according to the resolution. Therefore, the hatched portion is recognized as jagged (jaggy) when printed at 300 dpi × 300 dpi. It becomes easy to be done.

  In the ink jet recording apparatus, there is a smoothing method called anti-aliasing as a method for reducing the jaggy of the contour appearing at the low resolution. However, since this method changes the dot in the contour with a very large number of gradations, high-accuracy smoothing can be performed, but the processing is very complicated and requires processing time. For this reason, it is not suitable when high throughput is required as in a recent ink jet recording apparatus.

  Further, as a jaggy correction processing method in the ink jet recording apparatus, there is a processing method described in Patent Document 1. This is to reduce jaggy by detecting the jaggy of the character outline by pattern matching the font data of the developed characters with a plurality of predetermined reference patterns, and replacing the center pixel in the reference pattern with smaller dots. It is.

  As a method for changing the dot diameter of the character outline portion in accordance with the degree of bleeding of the recording medium, there is a method described in Patent Document 2.

  However, in Japanese Patent Application Laid-Open No. 2004-26853, since the ink bleeding method varies depending on the recording medium, even if printing is performed with the same jaggy correction dots, the blurring on the recording medium is small, so There may be cases where the character portion is divided, or conversely, the blurring is large and the details are crushed or feathered, and thus jaggies cannot be reduced satisfactorily.

  Further, in Patent Document 2, only the dot in the outline portion of the character is changed, which is not effective for the jaggy correction dot, and only the dot diameter is reduced according to the degree of bleeding. No consideration is given to the case where there is little bleeding on the non-recording medium.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to enable printing of characters of good quality regardless of the characteristics of the recording medium against ink bleeding. To do.

  In order to solve the above-described problems, an image forming apparatus according to the present invention has a blur detection unit that detects the degree of blur of ink on a recording medium, and a dot size that is used for jaggy correction is detected by the blur detection unit. Correction dot size selection means for selecting according to the degree of ink bleeding, jaggy detection means for detecting pixel positions that require jaggy correction by pattern matching between a character outline portion and a reference pattern prepared in advance, and the jaggy detection means And jaggy correction means for performing jaggy correction by performing dot addition or dot replacement at the detected pixel position, and the jaggy correction means uses the correction dot size selection means during jaggy correction. The selected dot size is used.

  The image forming method according to the present invention includes a blur detection step for detecting the degree of ink bleeding on a recording medium, and the degree of ink bleeding detected by the blur detection unit for the dot size used for jaggy correction. A correction dot size selection step that is selected by: a jaggy detection step that detects a pixel position that requires jaggy correction by pattern matching between a character outline portion and a reference pattern prepared in advance; and A jaggy correction step for performing jaggy correction by adding a dot to or replacing a dot at a pixel position, and the jaggy correction means is a dot selected by the correction dot size selection means at the time of jaggy correction. Characterized by using size.

  Further, the program according to the present invention causes the image forming apparatus to detect the degree of ink bleeding on the recording medium, and the ink detected by the bleeding detection unit for the dot size used for the jaggy correction. A correction dot size selection means for selecting according to the degree of bleeding, a jaggy detection means for detecting a pixel position requiring jaggy correction by pattern matching between a character outline portion and a reference pattern prepared in advance, and detection by the jaggy detection means Functioning as jaggy correction means for performing jaggy correction by performing dot addition or dot replacement at the pixel position, and the jaggy correction means was selected by the correction dot size selection means during jaggy correction. Causes the computer to use the dot size.

  Further, in the storage medium according to the present invention, the image forming apparatus is detected by the blur detection unit that detects the degree of blur of ink on the recording medium and the blur detection unit that detects the dot size used for the jaggy correction. Correction dot size selection means for selecting according to the degree of ink bleeding, jaggy detection means for detecting pixel positions that require jaggy correction by pattern matching between a character outline and a reference pattern prepared in advance, and the jaggy detection means. It is made to function as jaggy correction means for performing jaggy correction by adding or replacing dots at the detected pixel position, and the jaggy correction means is selected by the correction dot size selection means at the time of jaggy correction. A program to make the computer execute using the correct dot size , It is a computer-readable.

  According to the present invention, it is possible to print characters of good quality regardless of the characteristics of the recording medium against ink bleeding.

1 is a schematic configuration diagram of an entire mechanism unit of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 2 is a plan view illustrating a main part of the ink jet recording apparatus according to the embodiment of the invention. FIG. 2 is a perspective explanatory view illustrating a head configuration of the ink jet recording apparatus according to the embodiment of the invention. FIG. 3 is a schematic cross-sectional explanatory diagram of a conveyance belt of the ink jet recording apparatus according to the embodiment of the invention. FIG. 3 is a diagram illustrating an example of a nozzle array of a recording head. FIG. 3 is a diagram illustrating an example of a nozzle array of a recording head. FIG. 3 is a diagram illustrating an example of a nozzle array of a recording head. FIG. 3 is a diagram illustrating an example of a nozzle array of a recording head. FIG. 4 is a diagram illustrating a state where ink droplets ejected from a recording head are fixed on a recording medium. It is the figure which showed simply an example of the processing system which performs jaggy correction which concerns on embodiment of this invention. It is the figure which showed an example of the processing flow with respect to 1 character in the font processor which concerns on embodiment of this invention. It is the figure which showed the example of dot arrangement | positioning of the shaded part where jaggy generate | occur | produced. It is the figure which showed the example of the jaggy correction | amendment for making jaggy of a diagonal line inconspicuous. It is a flowchart figure which shows an example of the process sequence of the jaggy correction based on embodiment of this invention using only a small dot. It is a figure which shows an example of the relationship of the attention pixel and the reference pattern in the case of the pattern matching which concerns on embodiment of this invention. It is a figure which shows an example of the state by which jaggy correction was carried out with the small dot. It is a figure which shows an example of the reference pattern which concerns on embodiment of this invention. It is the figure which showed an example of the process at the time of changing the dot size used for a jaggy correction based on the degree of the ink bleeding based on embodiment of this invention. It is the figure which showed an example of the process at the time of changing the dot size used for a jaggy correction based on the degree of the ink bleeding based on embodiment of this invention. It is the figure which showed an example of the process at the time of changing the dot size used for a jaggy correction based on the degree of the ink bleeding based on embodiment of this invention. It is a figure which shows an example of the image for determining the degree of ink bleeding based on embodiment of this invention. It is the figure which showed an example of the flow of the process in selection of a jaggy correction dot size based on embodiment of this invention. It is the figure which showed an example of the flow of the process in selection of a jaggy correction dot size based on embodiment of this invention. FIG. 6 is a diagram showing the degree of ink bleeding when the resolution differs between the main scanning direction and the sub-scanning direction.

  Next, embodiments for carrying out the invention will be described in detail with reference to the drawings.

  First, as an image forming apparatus to which the present invention is applied, an example of an ink jet recording apparatus will be described with reference to FIGS. 1 is a schematic configuration diagram of the entire mechanism of the ink jet recording apparatus, FIG. 2 is an explanatory plan view of a main part of the ink jet recording apparatus, FIG. 3 is a perspective explanatory view illustrating a head configuration of the ink jet recording apparatus, and FIG. FIG. 3 is a schematic cross-sectional explanatory diagram of a conveyance belt of a recording apparatus.

  This ink jet recording apparatus has an image forming unit 2 and the like inside the apparatus main body 1, and a paper feed tray 4 on which a large number of recording media (hereinafter referred to as “paper”) 3 can be stacked below the apparatus main body 1. The sheet 3 fed from the sheet feeding tray 4 is taken in, and a required image is recorded by the image forming unit 2 while the sheet 3 is conveyed by the conveying mechanism 5, and then mounted on the side of the apparatus main body 1. The paper 3 is discharged to the paper discharge tray 6.

  In addition, the ink jet recording apparatus includes a duplex unit 7 that can be attached to and detached from the apparatus main body 1. When performing duplex printing, the sheet 3 is transported in the reverse direction by the transport mechanism 5 after completion of one-surface (front surface) printing. The sheet is taken into the duplex unit 7, reversed, and sent to the transport mechanism 5 again as the other side (back side) as a printable side, and the sheet 3 is discharged to the discharge tray 6 after the other side (back side) printing is completed.

  Here, the image forming unit 2 slidably holds the carriage 13 on the guide shafts 11 and 12, and moves the carriage 13 in a direction orthogonal to the conveyance direction of the paper 3 (main scanning) by a main scanning motor (not shown). . The carriage 13 is equipped with a recording head 14 composed of a droplet discharge head in which nozzle holes 14n (see FIG. 3) as a plurality of discharge ports for discharging droplets are arranged. The ink cartridge 15 for supplying the ink is detachably mounted. Note that a sub tank may be mounted in place of the ink cartridge 15 so that ink is replenished and supplied from the main tank to the sub tank.

  Here, as the recording head 14, for example, as shown in FIGS. 2 and 3, droplets that eject ink droplets of each color of yellow (Y), magenta (M), cyan (C), and black (K). Although the four independent inkjet heads 14y, 14m, 14c, and 14k, which are ejection heads, are used, one or a plurality of heads having a plurality of nozzle arrays that eject ink droplets of each color may be used.

  Note that the number, type, and arrangement order of colors are not limited to this, and recording that can be used with this apparatus to prevent so-called "bidirectional color differences" in which the color tone varies slightly depending on the order in which ink droplets overlap. The head has a plurality of nozzle rows each having a plurality of nozzles arranged in the sub-scanning direction in the main scanning direction, and has two or more nozzle rows that eject the same color ink, and ejects the same color ink. It is also possible to adopt a configuration in which one or more nozzle rows that eject different color inks are arranged between the nozzle rows.

  In addition, the recording head that can be used in this apparatus has a plurality of nozzle rows that are composed of a plurality of nozzles arranged in the sub-scanning direction in the main scanning direction, and has two or more nozzle rows that eject the same color ink. In addition, one or more nozzle rows that discharge different color inks may be arranged between the nozzle rows that discharge the same color ink.

  As another form of the recording head that can be used in this apparatus, a plurality of nozzle arrays composed of a plurality of nozzles arranged in the sub-scanning direction are arranged in the main scanning direction, and nozzle arrays that eject the same color ink are arranged. There are two or more rows, one or more nozzle rows that eject different color inks are arranged between the nozzle rows that eject the same color ink, and the same color ink centering on the axis orthogonal to the main scanning direction It is also possible to adopt a configuration in which the nozzle rows that discharge the nozzle are arranged symmetrically.

  This apparatus can take any of the above forms, and by taking these forms, it is possible to prevent the occurrence of color difference during bidirectional printing. Hereinafter, prevention of bidirectional color difference occurrence will be described with reference to the drawings.

  First, as shown in FIG. 5, in a head in which nozzle rows of each color are arranged one by one in the printing direction (for example, a head arranged as YMCK), when bidirectional printing is performed, bidirectional printing is performed at a portion where a plurality of recording liquids are overlapped. Color difference will occur.

  However, this can be solved by arranging two or more nozzle rows that eject ink of the same color and arranging one or more nozzle rows that eject another color ink to be overlapped between them. For example, as shown in FIG. 6, by arranging the nozzle rows for ejecting C and M inks between the nozzle rows for ejecting Y ink, they are superimposed in the order of C → Y regardless of the forward path and the backward path. It is also possible to superimpose them in the order of Y → C. Moreover, it is possible to superimpose in the order of M → Y regardless of the forward path and the return path, and it is also possible to superimpose in the order of Y → M. Accordingly, bidirectional printing can be performed while expanding the color reproduction range, and a color print having a wide color reproduction range can be printed at high speed.

  Furthermore, as shown in FIG. 7, by arranging nozzle rows that eject ink of the same color symmetrically around the K nozzle, two types of more colors can be placed in any overlapping order regardless of the forward or backward path. The above color inks can be overlaid. As a result, bidirectional printing can be performed while obtaining a wider color gamut, and a color print having a wider color gamut can be printed at high speed.

  Further, as shown in FIG. 8, in addition to normal yellow, magenta, cyan, and black inks, low-density yellow, magenta, cyan, and black inks can be used (photo yellow, photo magenta, photo cyan, and photo ink). gray). By using an ink having a low color density, it is possible to print a color printed matter in which graininess (roughness) is suppressed in addition to expanding the color reproduction range.

As the ink-jet head constituting the recording head 14, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a metal phase change caused by a temperature change. A shape memory alloy actuator to be used, an electrostatic actuator using an electrostatic force, or the like provided as energy generating means for discharging ink can be used.

  The paper 3 in the paper feed tray 4 is separated one by one by a paper feed roller (half-moon roll) 21 and a separation pad (not shown), fed into the apparatus main body 1 and sent to the transport mechanism 5.

  The transport mechanism 5 guides the fed paper 3 along the guide surface 23 a and guides the paper 3 fed from the duplex unit 7 along the guide surface 23 b and the paper 3. A conveying roller 24 that conveys, a pressure roller 25 that presses the sheet 3 against the conveying roller 24, a guide member 26 that guides the sheet 3 toward the conveying roller 24, and a sheet 3 that is returned when duplex printing is performed on the duplex unit 7. And a pressing roller 28 that presses the paper 3 fed from the conveying roller 24.

  Further, the transport mechanism 5 charges the transport belt 33 between the drive roller 31 and the driven roller 32 and the transport belt 33 so that the recording head 14 transports the paper 3 while maintaining the flatness of the paper 3. A charging roller 34 that is opposed to the charging roller 34, a guide member 35 (not shown) that guides the conveying belt 33 at a portion facing the image forming unit 2, and a conveying belt 33. A cleaning roller made of a porous material or the like, which is a cleaning means for removing the recording liquid (ink) adhering to the recording medium.

  Here, the conveyance belt 33 is an endless belt, is stretched between the driving roller 31 and the driven roller (tension roller) 32, and circulates in the direction of arrow A in FIG. 1 (paper conveyance direction). It is configured as follows.

  The transport belt 33 can be configured as a single layer, or as shown in FIG. 4, a two-layer configuration of a first layer (outermost layer) 33a and a second layer (back layer) 33b, or a configuration of three or more layers. For example, the transport belt 33 is a surface layer that is a sheet adsorbing surface formed of a pure resin material having a thickness of about 40 μm that is not subjected to resistance control, for example, ETFE pure material, and resistance control by carbon using the same material as the surface layer. It consists of the back layer (medium resistance layer, earth layer) performed.

The charging roller 34 is disposed so as to come into contact with the surface layer of the transport belt 33 and to rotate following the rotation of the transport belt 33. A high voltage is applied to the charging roller 34 in a predetermined pattern from a high voltage circuit (high voltage power source) (not shown).

  Further, on the downstream side from the transport mechanism 5, a paper discharge roller 38 for sending the paper 3 on which an image is recorded to the paper discharge tray 6 is provided.

  In the ink jet recording apparatus configured as described above, the conveyor belt 33 circulates in the direction of arrow A, and is positively charged by coming into contact with the charging roller 34 to which a high potential applied voltage is applied. In this case, the charging roller 34 is charged at a predetermined charging pitch by switching the polarity at predetermined time intervals.

  Here, when the paper 3 is fed onto the conveying belt 33 charged at this high potential, the inside of the paper 3 is in a polarized state, and the electric charge having the opposite polarity to the electric charge on the conveying belt 33 is connected to the belt 33 of the paper 3. The charge on the belt 33 and the charge on the transported paper 3 are electrostatically attracted to each other, and the paper 3 is electrostatically attracted to the transport belt 33. . In this way, the sheet 3 strongly adsorbed to the transport belt 33 is calibrated for warpage and unevenness, and a highly flat surface is formed.

  Accordingly, the recording belt 14 is moved around the conveyor belt 33 and the recording head 14 is driven in accordance with the image signal while moving and scanning the carriage 13 in one direction or in both directions, as shown in FIGS. As shown, a droplet 14i is ejected (jetted) from the recording head 14, and ink droplets, which are droplets, are landed on the stopped paper 3 to form dots Di, thereby recording one line. After the predetermined amount of paper 3 is conveyed, the next line is recorded. When the recording end signal or the signal that the rear end of the paper 3 reaches the recording area is received, the recording operation is ended. FIG. 9B is an enlarged view of the dot Di formation portion of FIG.

  In this way, the sheet 3 on which the image is recorded is discharged to the discharge tray 6 by the discharge roller 38.

  FIG. 10 shows a simplified example of a processing system that performs jaggy correction on characters.

  In FIG. 10, an image or character print command (for example, image line position / thickness / shape, character font / size / position, etc.) issued from the application software 200 is temporarily stored in the drawing data memory 201. The rasterizer 202 reads and interprets the print command stored in the drawing data memory 201, and if it is a line drawing command, converts it into a dot pattern according to the designated position, thickness, etc. For example, the corresponding font data is fetched from the font data memory 207 and raster data that can be recorded by the inkjet recording apparatus 100 is generated. The raster data is temporarily stored in the raster data memory 203 and is output to the ink jet recording apparatus 1 through an interface unit (not shown).

  In the example of the processing system shown here, development of characters into a dot pattern is performed by the font processor 204 independent of the rasterizer 202. However, the font processor 204 and the rasterizer 202 can be integrated. The rasterizer 202 and the font processor 204 are generally realized as software such as a printer driver, but one or both of them can be realized as hardware. Further, the font data memory 207 may be the same physical memory as the drawing data memory 201 or an independent physical memory.

  The font processor 204 includes jaggy correction means 206 for performing jaggy correction processing for recording dots for jaggy correction on the character outline portion in addition to the dot development means 205 for developing characters into font data (bitmap data). Including.

  An example of a processing flow for one character in the font processor 204 will be described with reference to FIG. First, it is checked whether or not the font data of the designated size of the character to be processed exists in the font data memory 207 (step S1). Only when it does not exist, the dot development means 205 develops the font data. Processing is executed (step S2). The generated font data is stored in the font data memory 207. The font data is subjected to jaggy correction processing (step S3) by the jaggy correction means 206.

  Before describing the processing procedure of the jaggy correction process (step S3), first, a specific example of jaggy correction will be described.

  FIG. 12 shows an example of dot arrangement in the shaded area where jaggy has occurred. As shown in FIG. 12, since the dot row forming the outline is stepped in the hatched portion, the outline of the line becomes discontinuous at the joint (change point), and so-called jaggy occurs.

  FIG. 13 shows an example of jaggy correction for making such a slanted jaggy inconspicuous. The example shown here is an example of correcting jaggy by adding small dots to a blank part of a character line formed with large dots (replacement with a blank small dot), but adding medium dots to the blank part Alternatively, it is also possible to use replacement of large dots with small and medium dots in the image portion.

  Next, the procedure of the jaggy correction process (step S3 in FIG. 11) will be described.

  FIG. 14 is a flowchart showing an example of a jaggy correction processing procedure using only small dots. In this process, pattern matching is used for recognizing a pixel position to be replaced with a small dot. A window of size m × n is used for this pattern matching. As an example, a jaggy correction processing procedure for a part of a character as shown in FIG. In this case, it is assumed that the pattern matching window is a window with m = 3 and n = 3 as shown in FIG.

  First, the first pixel of the font data is set as a target pixel (step S101). Font data (bitmap data) corresponding to a 3 × 3 window centered on the pixel of interest is acquired (step S102), and pattern matching with a 3 × 3 size reference pattern prepared in advance is performed (step S102). S103). If there is a match by this pattern matching (step S104, Yes), the target pixel is replaced with a small dot or replaced with a pixel of a predetermined gradation that generates a small dot (step S105). (Step S106), and the process is repeated from step S102. If the pattern matching does not match (No at Step S104), Step S105 is skipped and the process proceeds to Step S106. Such a process is repeated until all the pixels of the font data and its peripheral pixels have been processed (Yes in step S107).

  For example, as shown in FIG. 15, when a blank pixel located at the center of the window becomes the target pixel, the reference pattern shown in FIG. 17 is matched, so that the target pixel is replaced with a small dot as shown in FIG. (Addition) or a pixel of a predetermined gradation that generates a small dot.

  By making the size of the window and the reference pattern larger than the size of 3 × 3, the change point of the diagonal line near the horizontal or vertical is detected, and small dots are added (replaced) according to the inclination, and The quality can be further improved. The size of the window for matching and the reference pattern is determined in consideration of the extent to which replacement with small dots needs to be targeted and whether the processing time is in time for the recording speed. As this size increases, the amount of data used for pattern matching increases and the time required for pattern matching also increases. Therefore, from the viewpoint of processing time, the size of the window and the reference pattern should be as small as possible. On the other hand, the number of dots to be replaced with small dots before and after the change point depends on the required character quality. Therefore, it is necessary to determine an optimum size according to the required processing speed and character quality.

  Next, a process for changing the size of the jaggy correction dots in accordance with the degree of character blur will be described.

  At this time, it is assumed that five stages of dots can be formed.

  It is assumed that a jaggy correction pattern is applied to a character and a jaggy correction dot having a size of rank 3 is formed. At this time, when the degree of blur of the recording medium is large, the size of the jaggy correction dot is converted to a rank 2 size that is reduced by one step. When the degree of blur of the recording medium is small, the size of the jaggy correction dot is changed. It is converted into a dot of rank 4 that is increased by one step (see FIG. 18).

  In another implementation method, not only a jaggy correction pattern for forming rank 3 size dots but also a jaggy correction pattern for previously forming rank 2 size and rank 3 size dots as jaggy correction patterns corresponding to the respective reference patterns. A pattern is also prepared. When the recording medium has a large degree of bleeding, a jaggy correction pattern for forming a rank 2 size dot is used. When the recording medium has a low degree of bleeding, a rank 4 size dot is formed. By applying the jaggy correction pattern for forming the character to the character, the size of the jaggy correction dot is changed according to the degree of bleeding (see FIG. 19).

  Further, when the character is a black character, the degree of bleeding of the recording medium is small, and the J ink correction dot of K ink is added, by adding the CMY ink droplets in the same position as the jaggy correction dot, The size of the jaggy correction dot is changed greatly in a pseudo manner (see FIG. 20).

  FIG. 21 is an example of an image for determining the degree of ink bleeding. In FIG. 21, a line image patch (upper stage) with an interval of one dot and a solid image patch (lower stage) in which dots are formed at a resolution pitch are changed in the dot size (FIGS. 21 (1) to (5)). Applicable) Multiple formations. Since the dot size is changed, the appearance of the same line segment image and solid image on the input digital data is different on the paper. The image layout, the number of patches, the shape, the interval between line segments, and the like are not limited thereto.

  When the blur is visually determined, it is determined whether the line segment image has been reproduced without being crushed or the solid image has been filled, and an ink output configuration that is considered to be the best is selected. For example, the selection content may be displayed on the display unit of the apparatus and the user may select the selection content from the operation unit.

  When the image is read by a scanner or the like and the degree of blur is determined, the width information of the line segment can be acquired. Therefore, as shown in FIG. 22, the output configuration with the closest line width is selected from only the line segment image. In FIG. 22, first, line width information is acquired from the read image data (S201), and a difference from a desired line width in each line image is calculated (S202). The dot size used when printing the line image with the smallest difference from the desired line width is selected (S203).

  Alternatively, as shown in FIG. 23, a line width within a predetermined range and a line segment image patch or a solid image patch having the maximum density may be selected. In FIG. 23, first, line width information and density information are acquired from the read image data (S201). A dot size equal to or smaller than the dot size used when printing a line image having the smallest difference from the desired line width is selected (S203). The dot size for printing the solid image having the highest density among the dot sizes selected in S203 is selected (S204).

  The determination method will be described with reference to FIG. 21. If the line widths (3), (4), and (5) are within the allowable range, the density and the filling of the paper surface are the best (3). Is selected and jaggy correction processing is performed.

  Moreover, it is preferable that the determination of the degree of bleeding can be set for each printing mode. This is because if the print mode is different, the dot size, resolution, recording speed, and the like to be used change, so that the ink spreading characteristics on the paper also change. At this time, it is preferable that an image for determining bleeding is also formed with a print setting corresponding to the print mode. The blur determination image may be prepared for each printing mode. At this time, a determination image of a plurality of modes is included in one chart, or a plurality of charts are prepared for each mode. Also, the output configuration may be automatically set by predicting the degree of bleeding in other modes from the result of the bleeding determination in the reference mode.

  In line segment image formation, it is better to determine the direction of the line segment in consideration of the printing method. There are printing methods with different resolutions in the main scanning direction (recording head moving direction) and sub-scanning direction (paper transport direction) of the paper, for example, a printing mode in which the main scanning direction is 600 dpi and the sub-scanning direction is 300 dpi. In such a mode, since the main / sub resolutions are different, the filling of the paper surface is naturally different in the main / sub directions (see FIG. 24).

  In such a case, the line segment in the main scanning direction has a higher dot formation density and tends to be thicker than the line segment in the sub direction. For this reason, if the line width is determined based on the line segment in the sub direction, bleeding may be excessive during actual printing.

  In blur detection, the line segment image is mainly used to detect whether or not the details are crushed due to excessive blurring. Therefore, the line width is determined by the line segment in the dense direction where the blur tends to increase. It is better to make a decision. In the case of FIG. 24, it is better to determine the line width with a line segment extending in the main direction.

  In addition, when there is an element that changes the bleeding characteristics on the recording paper itself or the recording paper due to changes in paper settings, paper replenishment, paper replacement, device usage environment (temperature, humidity, etc.) By providing a function for prompting blur determination, it is possible to prompt the user to always form an image with a certain quality.

  In addition, by having a function that stores the recording paper and the environment in which the device is used (temperature, humidity, etc.), the printing mode and the degree of bleeding in advance, the printing conditions can be set without repeating the bleeding determination. A suitable output can be performed. The print condition may be changed manually or automatically.

  The above-described image processing method may be processed entirely on the computer as a program (printer driver), or a part of the image processing method is processed on the computer and the rest is converted to hardware and processed on the image forming apparatus side. You may do it. Further, all the processes can be realized as hardware and configured to be performed on the image forming apparatus side.

  Furthermore, when the above-described image processing method is programmed, it can be easily distributed in large quantities or copied by recording it on an inexpensive storage medium. Moreover, long-term preservation | save becomes possible by preserve | saving to a non-volatile storage medium. In addition, 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 install them in a computer using these storage media.

  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 a recording liquid other than the above, a data processing apparatus that supplies print data to the image forming apparatus, and a printer driver installed in the data processing apparatus.

  The present invention has been described above by the preferred embodiments of the present invention. While the invention has been described with reference to specific embodiments thereof, various modifications and changes can be made to these embodiments without departing from the broader spirit and scope of the invention as defined in the claims. is there.

  Further, in the image forming apparatus according to the present invention, the correction dot size selection unit has a dot size smaller than a predetermined dot size when the ink bleeding level detected by the bleeding detection unit is larger than a predetermined bleeding level. And the dot size larger than the predetermined dot size may be selected when the ink bleeding level detected by the blur detection means is smaller than the predetermined blur level.

  The image forming apparatus according to the present invention further includes a bleeding detection image output unit that outputs a bleeding detection image for detecting the degree of bleeding of ink on a recording medium, and a reading unit that reads the bleeding detection image. The blur detection means may detect the degree of ink blur by using the blur detection image read by the reading means.

  The image forming apparatus according to the present invention also receives a blur detection image output means for outputting a blur detection image for detecting the degree of blur of ink on a recording medium and a dot size used for jaggy correction by the user. Correction dot size input means, and the jaggy correction means may use the dot size input by the correction dot size input means for jaggy correction.

  In the image forming apparatus according to the present invention, the blur detection image output by the blur detection image output unit is configured by printing a plurality of line images and solid images with different dot sizes. The blur detection means may detect the degree of ink blur by using at least one of the line width of the line pattern constituting the blur detection image read by the reading means and the density of the solid coating pattern.

  The image forming apparatus according to the present invention further includes an environment measuring unit that measures at least one of ambient temperature and humidity, and an information display unit that displays information to the user, and the temperature measured by the environment measuring unit When at least one of the humidity reaches a predetermined value, a display that prompts the previous period information display means to detect the degree of bleeding again may be performed.

  An image forming apparatus according to the present invention includes a storage unit that stores a print mode in which print settings suitable for an image to be printed are set, a print mode input unit that receives a print mode selection input by a user, a temperature, Environment measuring means for measuring at least one of the humidity, and the storage means performs jaggy correction for each value of at least one of the printing mode, temperature, humidity, and type of recording medium to be used. The dot size suitable for use at the time is also stored, and the correction dot size selection means performs jaggy correction when at least one of the print mode, temperature, humidity, and type of recording medium used changes. As the dot size to be used, a dot size suitable for the change may be selected from the dot sizes stored in the storage means.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 3 Recording medium 14 Recording head

JP 2003-334938 A JP 2005-199608 A

Claims (10)

Blur detection means for detecting the degree of ink bleeding on the recording medium;
Correction dot size selection means for selecting the dot size to be used in the jaggy correction based on the degree of ink bleeding detected by the blur detection means;
Jaggy detection means for detecting a pixel position that requires jaggy correction by pattern matching between a character outline portion and a reference pattern prepared in advance;
And jaggy correction means for performing jaggy correction by performing dot addition or dot replacement at the pixel position detected by the jaggy detection means,
The image forming apparatus characterized in that the jaggy correction means uses the dot size selected by the correction dot size selection means at the time of jaggy correction.   The correction dot size selection unit selects a dot size smaller than a predetermined dot size when the ink bleeding level detected by the bleeding detection unit is larger than a predetermined bleeding level, and is detected by the bleeding detection unit. 2. The image forming apparatus according to claim 1, wherein a dot size larger than the predetermined dot size is selected when the degree of bleeding of the ink that has been applied is smaller than the predetermined bleeding degree. A blur detection image output means for outputting a blur detection image for detecting the degree of ink blur on the recording medium, and a reading means for reading the blur detection image,
3. The image forming apparatus according to claim 1, wherein the blur detection unit detects the degree of ink blur by using the blur detection image read by the reading unit. A blur detection image output means for outputting a blur detection image for detecting the degree of ink blur on the recording medium, and a correction dot size input means for receiving an input of a dot size used for jaggy correction by the user. ,
The image forming apparatus according to claim 1, wherein the jaggy correction unit uses the dot size input by the correction dot size input unit for jaggy correction. The blur detection image output by the blur detection image output means is configured by printing a plurality of line images and solid images with different dot sizes,
The blur detection unit uses at least one of a line width of a line pattern and a density of a solid coating pattern constituting the blur detection image read by the reading unit to detect the degree of ink blur. The image forming apparatus according to claim 3. Environmental measuring means for measuring at least one of ambient temperature and humidity;
Having information display means for displaying information to the user;
6. The display for prompting the previous period information display means to detect the degree of bleeding again when at least one of temperature and humidity measured by the environment measuring means reaches a predetermined value. The image forming apparatus according to any one of the above. Storage means for storing a print mode in which print settings suitable for an image to be printed are determined;
Print mode input means for receiving input of print mode selection by the user;
Environmental measurement means for measuring at least one of temperature and humidity,
The storage means also stores a dot size suitable for use in the jaggy correction for each value of at least one of the printing mode, temperature, and humidity and the type of recording medium to be used.
The correction dot size selection means stores the dot size stored in the storage means as the dot size used for jaggy correction when at least one of the printing mode, temperature, and humidity and the type of recording medium used changes. The image forming apparatus according to claim 1, wherein an image suitable for the change is selected. A blur detection step for detecting the degree of blur of the ink on the recording medium;
A correction dot size selection step for selecting a dot size to be used for jaggy correction according to the degree of ink bleeding detected by the blur detection means;
A jaggy detection step of detecting a pixel position that requires jaggy correction by pattern matching between a character outline portion and a reference pattern prepared in advance;
A jaggy correction step for performing jaggy correction by adding dots or replacing dots at the pixel positions detected by the jaggy detection means,
The image forming method according to claim 1, wherein the jaggy correction means uses the dot size selected by the correction dot size selection means at the time of jaggy correction. The image forming apparatus
Blur detection means for detecting the degree of ink bleeding on the recording medium;
Correction dot size selection means for selecting the dot size to be used in the jaggy correction based on the degree of ink bleeding detected by the blur detection means;
Jaggy detection means for detecting a pixel position that requires jaggy correction by pattern matching between a character outline portion and a reference pattern prepared in advance;
Function as jaggy correction means for performing jaggy correction by adding dots or replacing dots at the pixel positions detected by the jaggy detection means;
The jaggy correction means is a program for causing a computer to use the dot size selected by the correction dot size selection means during jaggy correction. The image forming apparatus
Blur detection means for detecting the degree of ink bleeding on the recording medium;
Correction dot size selection means for selecting the dot size to be used in the jaggy correction based on the degree of ink bleeding detected by the blur detection means;
Jaggy detection means for detecting a pixel position that requires jaggy correction by pattern matching between a character outline portion and a reference pattern prepared in advance;
Function as jaggy correction means for performing jaggy correction by adding dots or replacing dots at the pixel positions detected by the jaggy detection means;
The jaggy correction means is a computer-readable storage medium storing a program for causing a computer to use the dot size selected by the correction dot size selection means during jaggy correction.

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