JP2012253775A - Image forming device and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device that prevents lack of information even in a small character or a pattern close to a Nyquist frequency by switching color conversion according to the size of a character or a graphic.SOLUTION: An image forming device comprises: an extraction unit that analyzes print data to extract a specific object; a detection unit that detects the size of the object; a color conversion unit that makes an output color different according to the size of the object detected by the detection unit; and a printer unit that performs printing according to the designated output color.

Description

  Embodiments described herein relate generally to an image forming apparatus.

  Conventionally, an outline font such as True Type (registered trademark) or Open Type (registered trademark) is used for a character image in an output image of a printer. Smoothing techniques such as RET (Resolution Enhanced technology) are used as means for smoothly reproducing these characters. This technique is mainly a technique for improving the position controllability of a binary printer and correcting jaggies of characters and lines.

  However, in recent years, dither patterns and lines have been used for characters and lines due to the widespread use of multi-value printers. In particular, since halftone dots and lines are used for thin color characters and color thin lines, there is a problem that characters and lines are interrupted and information is lost when the line is close to the Nyquist frequency of the printer engine.

JP 2005-94397 A

  The problem to be solved by the present invention is to provide an image forming apparatus and an image forming method in which color conversion is switched depending on the size of characters and graphics so that information is not lost even in small characters or patterns close to the Nyquist frequency. It is.

  In order to solve the above-described problem, an image forming apparatus according to an embodiment analyzes a print data and extracts a specific object, a detection unit that detects the size of the object, and a detection unit that detects the size. A color conversion unit that varies an output color depending on an object size; and a printer unit that performs printing according to the designated output color.

1 is a configuration diagram of an MFP according to the present embodiment. FIG. 3 is a block diagram related to image processing of the MFP. The flowchart for demonstrating switching of color conversion with the classification and size of an object. The figure which showed typically the positional relationship on the chromaticity diagram of the output color by each table.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4.
(This embodiment)

  FIG. 1 is a block diagram schematically showing a signal flow for electrical connection and control of a multifunction peripheral as an image forming apparatus equipped with an image recognition unit 125 in the present embodiment. The multifunction machine is a so-called MFP (Multi Functional Peripheral) 100, and includes a main control unit 101, a scanner unit 102, a printer unit 103, and an operation panel 104.

  A shared bus 111 shown in FIG. 1 connects CPUs (Central Processing Units) and the like to be described later, whereby program I / O transfer via the CPU or a peripheral device controls the bus as a bus master, and directly to a memory or the like. Data transfer by the accessing bus master is possible.

  The main control unit 101 includes a main CPU 110, a storage unit 112, an image processing unit 116, a page memory control unit 117, and a page memory 118.

  The main CPU 110 controls the entire main control unit 101.

  The storage unit 112 performs bidirectional communication between the main CPU 110 and a printer CPU 130 of the printer unit 103 described later, and stores a control program and various data for the main CPU 110. The storage unit 112 is an aggregate of read-only memory (hereinafter referred to as ROM) and rewritable memory (hereinafter referred to as RAM), and implements the procedure of the present embodiment together with a program and fixed data for performing the procedure of the present embodiment. Stores data generated or changed in the process. The former corresponds to a data ROM 205 described later.

  The image processing unit 116 performs image processing. The page memory control unit 117 stores or reads image data in the page memory 118. The page memory 118 has an area where image data for a plurality of pages can be stored, and is formed so that data obtained by compressing image data from the scanner unit 102 described later can be stored for each page.

  The operation panel 104 includes various operation keys 141, a liquid crystal display unit 142 having software keys (touch panel), and a panel CPU 140 to which these are connected. Panel CPU 140 is connected to main CPU 110. Various commands are input from the operation keys 141 or the soft keys of the liquid crystal display unit 142 and transmitted from the panel CPU 140 to the main CPU 110.

  A scanner unit 102, which is an image reading unit, is connected to the main CPU 110, and under the control of the scanner unit 120, controls the scanner unit 102, a storage unit 122 that stores a control program and various data, and a document for reading documents and the like. A CCD driver 123 that drives a line sensor such as a CCD; a scanning motor driver 124 that controls the rotation of a scanning motor that moves a carriage (not shown) carrying a line sensor, an exposure lamp, a mirror, and the like; an image recognition unit 125; And an image correction unit 126.

In the scanner unit 102 configured as described above, a document is set on a conventionally known automatic document feeder (not shown) or a document table (not shown) of the multifunction peripheral 100, and an operation key 141 or a liquid crystal provided on the operation panel 104 is set. Reading of the original is instructed by a soft key of the display unit 142.

  When the panel CPU 140 detects an image reading command, the reading command is transmitted to the main CPU 110 via the shared bus 111, and an operation command is given from the scanner CPU 120 of the scanner unit 102 to the CCD driver 123 and the scanning motor driver 124. Execute. The read image data is stored in the page memory 118.

  The image processing unit 116 executes the image processing process of the present embodiment. The image processing unit 116 executes processing of image data read by the line sensor of the scanner unit 102 and stored in the page memory 118, or supplied from a client terminal or the like. A desired process is performed on the obtained data. Details of the image processing will be described later with reference to FIG.

  The image correction unit 126 includes an A / D conversion circuit that converts an analog signal from the line sensor into a digital signal, and a line memory, and performs a filtering process and the like.

  The printer unit 103 illustrated in FIG. 1 has, for example, a conventionally known configuration, and includes a printer CPU 130, a storage unit 132, a fixing control unit 133, a laser driver 134, a polygon motor driver 135, a conveyance control unit 136, and a process control unit. 137. The well-known configuration described below is not shown.

The printer CPU 130 is connected to the main CPU and controls the entire printer unit 103 under the control of the printer CPU 130.
The storage unit 131 stores a control program and various data.
The laser driver 133 drives a known semiconductor laser transmitter and controls the laser beam based on the read image data of the document.

  The polygon motor driver 134 drives a polygon motor of a known laser exposure apparatus having a polygon mirror, and scans the laser beam from the semiconductor laser transmitter with a rotating polygon mirror.

  The conveyance control unit 135 controls drive motors of various rollers to control conveyance of a recording medium accommodated in a known paper cassette from the paper cassette along the paper conveyance path.

  The process control unit 136 controls a known charging charger, developing device, and transfer charger. The charging charger, for example, charges the surface of a drum-shaped photoconductor and forms an electrostatic latent image of a document image read by a laser beam scanned by the polygon mirror on the photoconductor. The developing device contains toner, and develops the electrostatic latent image on the photosensitive member into a visible image (toner image) with the toner. The transfer charger transfers the toner image on the photosensitive member to a recording medium supplied from the paper cassette via the paper conveyance path.

  Next, the color conversion selection process will be described. FIG. 2 is a diagram showing electrical connection between the image processing unit 112 and peripheral parts related to processing. As shown in this figure, a file created by using an application 201 on a personal computer (PC) 200 is converted into a printer language using a printer driver 202, and a network line such as a local area network (LAN) is connected. To the MFP or a printer (hereinafter collectively referred to as MFP).

  The data sent to the MFP 100 shown in FIG. 1 is analyzed by the extraction unit 203 in the image processing unit 116 and is discriminated into three types of objects: characters, graphics, and normal images. The size of characters and figures is determined. According to the object type and the size of characters and figures, the color conversion table 205 switches the reference area of the color conversion table stored in the storage unit 112, and the color conversion unit 205 executes color conversion suitable for each. Further, the color-converted data is output to the printer unit 103.

  FIG. 3 is an example of a flowchart for executing optimum color conversion table selection. Data is received from the PC 200 (300), and the type of the object is determined. First, it is determined whether or not the object is a character (301). If the target object is not a character (301: N), it is further determined whether or not the object is a graphic (302). If the target object is not a figure (302: N), the object target is set to 0 in the table number NTBL to select a color conversion table capable of faithfully reproducing the luminance as a normal image (303).

When it is determined that the object is a character or a figure, a table to be used is further selected according to the size. If the target is a character (301: Y), it is first determined whether the character size is 2 points or less (304). If it is determined that the character is larger than 2 points (304: N), it is further determined whether the size is 8 points or less (305). In these determinations, if the character size is 2 points or less (304: Y), 3 is set in the table number NTBL (306), and if it is greater than 2 points and 8 points or less (305: Y), the table The number NTBL is set to 2 (307), and if it exceeds 8 points (305: N), the table number NTBL is set to 1 (308).

  Further, when the object is a figure (302: Y), it is determined whether or not the line width is 0.25 point or more (309). If the line width of the figure exceeds 0.25 points (309: Y), 1 is set in the table number NTBL as in the case where the character size exceeds 8 points (308). On the other hand, when it is 0.25 points or less (309: N), 4 is set in the table number NTBL.

  As described above, the color conversion according to the selected table number is executed (311).

  The color conversion selection is as follows. In the color conversion for each object, the font size is small as described below, and the smaller the lowercase letters and thin lines, the closer to the primary or secondary color or black than the original color. Here, primary colors indicate cyan, magenta, and yellow, and secondary colors indicate red, green, and blue.

  That is, lowercase letters and thin lines are color-converted to the outermost shell color of a color solid that can be reproduced with color materials such as cyan, magenta, yellow, red, green, blue, and black that are closest in the color space. In other words, characters and fine lines that are small or thin are reduced in the number of colors as much as possible, converted to primary or secondary colors accordingly, and reproduced with colors that correspond to the solid color of the material used. Make sure that the thin wires are not interrupted or blurred. For normal images, color conversion including halftones faithful to the original is performed for all of luminance, saturation, and hue in order to emphasize color reproducibility.

  Next, a specific example of color conversion for characters and figures will be shown.

  FIG. 4 is a diagram schematically showing the positional relationship on the chromaticity diagram of the output color by each table. For example, characters having a size of more than 8 points are converted by the color conversion table 1 by determining the target color so as to match the lightness in a uniform color difference space represented by, for example, the CIE 1976 L * a * b * color system (tbl1). . In the case of characters exceeding 2 points and not exceeding 8 points, the color conversion table 2 keeps the saturation and lightness of characters exceeding 8 points and the color corresponds to the primary color, secondary color or achromatic color. (Tbl2). Furthermore, most of the characters of 2 points or less are converted by the color conversion table 3 into primary or secondary colors corresponding to the outermost contour of the output system (tbl3).

  By doing so, the CMYK value of the character data becomes 0 or the maximum value, and the color does not depend on the screen.

  On the other hand, graphic objects are classified into two types of objects, a line with a line width exceeding 0.25 points and a solid line, and a line width with a line width of 0.25 points or less. Color conversion is performed using the color conversion table 1 for matching the degree of saturation in the same manner as characters exceeding the point. Also, lines with a line width of 0.25 points or less may have their colors changed for color coding, such as wiring diagrams, so here the color is set so that the gamma is increased and the brightness is lowered without changing the hue angle. It is processed in the conversion table 4 (tbl4).

  As described above, it is possible to provide an image forming apparatus capable of reproducing thin thin lines and lowercase letters without interruption or fading by switching color conversion according to the type of object and the size of characters and figures.

  As mentioned above, although embodiment of this invention was described, this embodiment is shown as an example and is not intending limiting the range of invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

100 ... MFP (MFP)
103: Printer unit 110 ... Main CPU
112 ... Storage unit 116 ... Image processing unit 200 ... Personal computer 203 ... Extraction unit 204 ... Detection unit 205 ... Color conversion unit

Claims (8)

An extractor that analyzes the print data and extracts specific objects;
A detection unit for detecting the size of the object extracted by the extraction unit;
A color conversion unit that varies the output color depending on the size of the object detected by the detection unit;
An image forming apparatus comprising: a printer unit that performs printing according to an output color specified by the color conversion unit.   The image forming apparatus according to claim 1, wherein the specific object is a character and a figure.   The color conversion unit performs first color conversion when the size of the specific object is equal to or smaller than a predetermined value, and performs second color conversion when the size is larger than the predetermined value. 2. The image forming apparatus according to 2.   The color conversion unit sets the color conversion output so that the brightness of the output color when the size of the specific object is equal to or smaller than a predetermined size is lower than the brightness of the output color of the object larger than the predetermined size. The image forming apparatus according to claim 3. Analyzing the print data to extract specific objects,
Detect the size of the object,
Different output colors depending on the size of the object detected by the detection unit,
An image forming method for performing color conversion by color designation according to the output color.   6. The image forming method according to claim 5, wherein the specific object is a character and a figure.   7. The image forming method according to claim 6, wherein the first color conversion is performed when the size of the specific object is equal to or smaller than a predetermined value, and the second color conversion is performed when the size of the specific object is larger than the predetermined value. .   8. The color conversion output is set so that the brightness of an output color when the size of the specific object is equal to or smaller than a predetermined size is lower than the brightness of an output color of an object larger than the predetermined size. Image forming method.

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