JP2011166765A - Image forming device and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To apply a smoothing technique using a conventional pattern matching method to image data obtained by RIP processing that outputs multi-level gray scales. <P>SOLUTION: An image forming device includes: a determination part (34) for generating determination data, which indicate the result of determining whether the following conditions are satisfied or not: a grayscale of a target pixel in first image data is greater than or equal to a predetermined value, and attribute data indicates a predetermined type, from the first image databased on PDL data and the attribute data of the first image data; a gray level processing part (31) for generating second image data by applying gray level processing, corresponding to the attribute data, to the first image data; a smoothing part (33) for generating third image data by smoothing image data generated by binarizing the first image data; and a switching part (35) that outputs a target pixel in the second image data as print data when the determination data do not satisfy the determination conditions, and outputs a target pixel in the third image data as print data when the determination data satisfy the determination conditions. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  In an image forming apparatus such as a digital multifunction peripheral (MFP: Multi Function Peripheral) or a printed matter by a printer, it is necessary to improve the occurrence of image quality failure called jaggy. Jaggy is a jagged shape that occurs at the edge of printed characters or graphics. This jaggy occurs due to the fact that the bitmap image is composed of dots at regular intervals.

  In the printing field, for example, a smoothing technique has been devised in which jaggies are smoothly corrected by using a pattern matching method for binary data after RIP (Raster Image Processing) processing.

Japanese Unexamined Patent Publication No. 2009-100288

  However, unlike the conventional RIP process for outputting binary data, an RIP process in which the number of output gradations is multivalued (for example, 256) has been proposed. Therefore, there is a need to apply the smoothing technique using the conventional pattern matching method even in such a case in order to inherit the accumulated technology.

  According to an embodiment for solving the above problem, the first image data is generated from first image data generated based on PDL (Page Description Language) data and attribute data of the first image data. Determination data representing a determination result is determined by determining whether or not a determination condition that a gradation value of a pixel of interest is equal to or greater than a predetermined value and the attribute data represents a predetermined type is satisfied. A determination unit to generate, a gradation processing unit for generating second image data by performing gradation processing corresponding to the attribute data on the first image data, and binarizing the first image data A smoothing processing unit that performs a smoothing process on the image data to generate third image data; and, if the determination data does not satisfy the determination condition, outputs a target pixel in the second image data as print data; Above When the determination data satisfies the determination condition, an image forming apparatus is provided that includes a switching unit that outputs the target pixel in the third image data as print data.

1 is a diagram illustrating a system configuration using an MFP according to a first embodiment. FIG. FIG. 2 is a block diagram illustrating a configuration example of a printer controller in the MFP according to the first embodiment. FIG. 2 is a block diagram illustrating a configuration example of an image processing unit in the MFP according to the first embodiment. The figure explaining the pattern matching process implemented in the smoothing process of 1st Embodiment. The figure which illustrates the image before and after the smoothing process of 1st Embodiment. The flowchart which shows the process sequence of the attribute information determination part of 1st Embodiment. FIG. 9 is a block diagram illustrating a configuration example of an image processing unit in an MFP according to a second embodiment.

[First Embodiment]
FIG. 1 is a diagram illustrating a system configuration using the MFP 12 according to the first embodiment.
In the system shown in FIG. 1, a computer terminal (PC) 11 connected to a network 10 provides PDL (Page Description Language) data or raster data indicating the structure of image data to a printer 120 which is a partial function in the MFP 12. Forward. That is, the PC 11 transfers PDL data or raster data from the printer driver 21 to the printer controller 121 according to the interface characteristics with the printer 120.

  In the printer 120, the printer controller 121 drives and controls the printer engine 122. The printer controller 121 expands the PDL data sent from the PC 11 into a bitmap and executes each image processing, and then stores the image data in the data storage unit. The printer engine 122 converts bitmap image data from the printer controller 121 into a drive signal, and performs a printing operation by carrying a sheet, controlling laser drive, and the like.

  The printer controller 121 can analyze the attributes of each object, perform optimum image processing on each of them, synthesize them, and output them.

  The PC 11 and the printer 120 are not necessarily connected via a network, but may be connected using a USB or may be connected in a one-to-one relationship. The interface between the printer controller 121 and the printer engine 122 depends on the printer architecture.

  FIG. 2 is a block diagram illustrating a configuration example of the printer controller 121 in the MFP 12 according to the first embodiment. The printer controller 121 includes an image attribute analysis unit 22, a raster operation unit 23, a color conversion unit 24, a data encoding unit 25, a data storage unit 26, a data decoding unit 27, and an image processing unit 28.

  The PDL data transferred from the printer driver 21 by a print command in the application program 20 of the PC 11 is transferred to the printer controller 121 via the network. In the printer controller 121, the image attribute analysis unit 22 analyzes image attributes from the received PDL data and classifies the types. Basically, image data is roughly divided into attributes of characters, photographs, graphics 1 and graphics 2. Graphics 1 represents that the image is a graphics outline. Graphics 2 represents that the image is inside the graphics. The attribute of the classified data is assigned to each type of attribute as a tag, and is passed to subsequent processing. For example, in the case of having the above four types of attributes, 2-bit tag data is required.

  The raster computing unit 23 converts the PDL data into bitmap data. For example, in the case of monochrome printing, PDL data is converted into monochrome 8-bit bitmap data. In the case of color printing, the PDL data is converted into 8-bit bitmap data for each color. Tag data corresponding to the position is also assigned to each bitmap data.

  The color conversion unit 24 converts a standard RGB color signal into a CMY color or a CMYK color that is a color reproduction color in the printer, using a monitor of converted 8-bit colors. R, G, and B indicate red, green, and blue colors, and C, M, Y, and K indicate cyan, magenta, yellow, and black colors. In the embodiment of FIG. 2, the color conversion unit 24 switches the color conversion process according to the attribute of each image based on the tag data. If the output device is a monochrome printer, it is converted to a K color signal.

The color-converted image is then sent to the data encoding unit 25 where data compression is performed. The compression method may be a method for compressing multivalued image data. The compression method may be irreversible. The compressed image data is then temporarily stored in a data storage unit 26 such as a memory or HDD. By compressing, the capacity of data stored in the data storage unit 26 can be suppressed, and the performance of the entire system can be improved. Further, once stored in the data storage unit 26, functions such as electronic sorting can be used effectively.
The data decoding unit 27 reads data from the data storage unit 26 and decodes the encoded data.

  The image processing unit 28 performs a process for smoothly correcting jaggy according to the image characteristics and tag data for each object, and a halftone process. In the halftone process, for example, filtering using a threshold matrix converts data of one pixel into image data having the number of gradations of bits that matches the printing capability of the printer 120. The halftoning unit 30 performs halftoning according to image characteristics and tag data for each object.

  The printer engine 122 converts the image data into a PWM (Pulse Wide Modulation) signal for driving the laser, and forms an image.

  FIG. 3 is a block diagram illustrating a configuration example of the image processing unit 28 in the MFP 12 according to the first embodiment. The image processing unit 28 includes a gradation processing unit 31, a binarization processing unit 32, a smoothing processing unit 33, an attribute information determination unit 34, and a switching processing unit 35.

  The gradation processing unit 31 performs halftone processing. The binarization processing unit 32 binarizes the image data. The smoothing processing unit 33 smoothly corrects jaggy included in the image data. The attribute information determination unit 34 generates a determination signal from the image data and the attribute data. The switching processing unit 35 switches between the output image data of the binarization processing unit 32 and the output image data of the smoothing processing unit 33 based on the determination signal and outputs it to the print engine.

  Note that the RIP process illustrated in FIG. 3 represents a process executed by the image attribute analysis unit 22 and the raster calculation unit 23.

  Next, the operation of each block of the image processing unit 28 will be described.

  The gradation processing unit 31 performs halftone processing to reproduce intermediate colors for image data. Halftone means that printing is possible by expressing an intermediate color with a pattern of small dots (dots). By this halftone processing, it is possible to represent a continuous tone image with a small tone output.

  The gradation processing unit 31 converts the continuous gradation image data into a halftone image using a dither matrix prepared in advance. The gradation processing unit 31 has a plurality of dither matrices (halftone patterns) in order to execute halftone processing according to the purpose of obtaining desired image quality such as gradation reproduction emphasis, fine character reproduction emphasis, and roughness reduction. ing. That is, processing is performed by switching the halftone pattern corresponding to the attribute of the image.

The smoothing processing unit 33 smoothly corrects jaggy included in the image data with respect to the image data binarized by the binarization processing unit 32.
FIG. 4 is a diagram illustrating the pattern matching process performed in the smoothing process according to the first embodiment. The binarized image data is processed as a plurality of input images 41 divided into a 5 × 5 matrix.

  The smoothing processing unit 33 compares the template images 40-1, 40-2,..., 40-m in the template database 40 with the input image 41, and determines the matching of the pixel arrangement of each image for each pixel. Judgment. In the example shown in FIG. 4, the template image 40-2 matches the input image 41. If there is a template image that matches the input image 41 as a result of pattern matching, the pixel value is converted in accordance with a smoothing process that is predetermined according to the template image.

  FIG. 5 is a diagram illustrating images before and after the smoothing process according to the first embodiment. The pre-smoothing image 43 is represented as a binary image in a matrix of 3 rows × 3 columns. In the image 44 after the smoothing process, the lower right block of the 1 × 2 block and the lower right block of the 2 × 1 block are replaced with the black value (= 1) of the binary data. Yes. This reduces the jaggy at the boundary of the figure.

FIG. 6 is a flowchart illustrating a processing procedure of the attribute information determination unit 34 according to the first embodiment.
In step S01, the attribute information determination unit 34 inputs image data of a block represented by a matrix and its attribute data. And the attribute information determination part 34 determines whether the following conditions are satisfied. Condition (1) The gradation value of the target pixel (pixel at the center of the block) is within a predetermined range. Condition (2) The attribute data is character or graphics 1, that is, the image in the block includes a graphics outline.

  When both the condition (1) and the condition (2) are satisfied (step S01 Yes), the attribute information determination unit 34 outputs a determination signal as “1” in step S02. If at least one of the condition (1) or the condition (2) is not satisfied (No in step S01), the attribute information determination unit 34 outputs a determination signal as “0” in step S03.

  Condition (1) determines whether the density of the target pixel is equal to or higher than a predetermined value. That is, when gradation value = 0 is white and gradation value = 255 is black, for example, if the gradation value is in the range of 150 to 255, it is determined that the pixel has a density close to black. it can. Even if the attribute data includes a graphics contour, if the gradation value is small, the presence of jaggy is not noticeable. However, when the gradation value is large, the presence of jaggy is strongly recognized.

  Condition (2) determines whether or not it is necessary to perform the smoothing process. Of the four types of attribute data, the picture is deteriorated in image quality by performing a smoothing process. Further, it is not necessary to perform the smoothing process on the inside of the graphics which is the graphics 2. On the other hand, the outline portion of characters and graphics is data to be smoothed.

  The switching processing unit 35 outputs the value of the target pixel in the image data output from the gradation processing unit 31 to the print engine 122 when the determination signal is “0”, and when the determination signal is “1”, The value of the target pixel in the image data output by the smoothing processing unit 33 is output to the print engine 122.

[Second Embodiment]
In the second embodiment, the image processing unit 28 is configured to process a color image signal. Accordingly, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 7 is a block diagram illustrating a configuration example of the image processing unit 28 in the MFP 12 according to the second embodiment. The image processing unit 28 includes a gradation processing unit 51, a binarization processing unit 52, a smoothing processing unit 53, an attribute information determination unit 54, and a switching processing unit 55.

  Image data for each color of cyan (C), magenta (M), yellow (Y), and black (K) and attribute data are input to the image processing unit 28. Each block constituting the image processing unit 28 executes the image processing operation in monochrome printing described in FIG. 3 for each color.

  As described above, according to the image forming apparatus of each embodiment described above, smoothing processing can be performed in monochrome printing and color printing, and the outline of characters and graphics can be smoothed without causing deterioration of images inside the photographs and graphics. can do.

  Each function described in the above embodiment may be configured using hardware, or may be realized by reading a program describing each function into a computer using software. Each function may be configured by appropriately selecting either software or hardware.

  Furthermore, each function can be realized by causing a computer to read a program stored in a recording medium (not shown). Here, as long as the recording medium in the present embodiment can record a program and can be read by a computer, the recording format may be any form.

Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage.
Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

  DESCRIPTION OF SYMBOLS 10 ... Network, 11 ... Computer terminal, 12 ... MFP, 20 ... Application program, 21 ... Printer driver m22 ... Image attribute analysis part, 23 ... Raster operation part, 24 ... Color conversion part, 25 ... Data encoding part, 26 ... Data storage unit 27 ... Data decoding unit 28 ... Image processing unit 30 ... Halftoning unit 31 ... Gradation processing unit 32 ... Binarization processing unit 33 ... Smoothing processing unit 34 ... Attribute information determination 35: switching processing unit, 51 ... gradation processing unit, 52 ... binarization processing unit, 53 ... smoothing processing unit, 54 ... attribute information determination unit, 55 ... switching processing unit, 120 ... printer, 121 ... printer controller 122. Printer engine.

Claims (6)

From the first image data generated based on PDL (Page Description Language) data and the attribute data of the first image data, the gradation value of the pixel of interest in the first image data is a predetermined value or more. A determination unit that determines whether or not the determination condition that the attribute data represents a predetermined type is satisfied, and generates determination data that represents a determination result; and
A gradation processing unit that performs gradation processing corresponding to the attribute data on the first image data to generate second image data;
A smoothing processing unit that generates a third image data by performing a smoothing process on the binarized image data of the first image data;
When the determination data does not satisfy the determination condition, the target pixel in the second image data is output as print data. When the determination data satisfies the determination condition, the target pixel in the third image data is output. An image forming apparatus comprising: a switching unit that outputs pixels as print data.   The image forming apparatus according to claim 1, wherein the predetermined type represented by the attribute data is a contour portion of a character or a graphic.   The PDL data is color data, and the determination unit, the gradation processing unit, the smoothing unit, and the switching unit process image data and attribute data of each color generated based on the PDL data. The image forming apparatus according to 2. From the first image data generated based on PDL (Page Description Language) data and the attribute data of the first image data, the gradation value of the pixel of interest in the first image data is a predetermined value or more. And determining whether or not the determination condition that the attribute data represents a predetermined type is satisfied, and generating determination data representing a determination result; and
A gradation processing step for generating second image data by performing gradation processing corresponding to the attribute data on the first image data;
A smoothing process step of performing a smoothing process on the image data obtained by binarizing the first image data to generate third image data;
When the determination data does not satisfy the determination condition, the target pixel in the second image data is output as print data. When the determination data satisfies the determination condition, the target pixel in the third image data is output. An image forming method comprising: a switching step of outputting pixels as print data.   The image forming method according to claim 4, wherein the predetermined type represented by the attribute data is a contour portion of a character or a graphic.   The PDL data is color data, and the determination step, the gradation processing step, the smoothing processing step, and the switching step process image data and attribute data of each color generated based on the PDL data. Item 6. The image forming method according to Item 5.

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