JP4548302B2 - Image output system, image output control device, image output method, image output program, and storage medium storing this program in a computer-readable manner - Google Patents

Description

  The present invention relates to an image output system, an image output control device, an image output method, an image output program, and a storage medium that stores the program in a computer-readable manner.

  In the printing plate making industry, color laser printers and multifunction machines have been used for comps. Here, the multifunction peripheral is a device having a printer function, a scanner function, a copier function, a facsimile function, and the like (hereinafter simply referred to as a color laser printer). This color laser printer is an example of an electrophotographic image forming apparatus that forms a color image on recording paper based on image data for each of a plurality of recording colors cyan C, magenta M, and yellow Y (and black K). is there.

  In recent years, color laser printers have achieved higher image quality, enabling inexpensive, high-speed, high-quality color output, so that not only conventional comp uses, but also proof uses for image data calibration, There is a growing demand for using color laser printers for printing final finished products such as small lot printing.

  Color laser printers generally have a lower resolution than printing methods such as offset printing. For this reason, many image output systems using color laser printers have multi-value screens (white with a gradation value of 0 for each pixel) in order to realize both the number of lines and gradation expression similar to other printing methods. In many cases, a screen capable of setting at least two gradation values is applied.

  Therefore, it is known that such an image output system causes a problem in image quality when outputting an image of an object composed of halftones in combination with the characteristics of the image forming process.

  For example, as described in Patent Documents 1 and 2, when the output image shifts from the halftone portion to the background portion in the sub-scanning direction due to the nonlinear and asymmetric image output characteristics of the color laser printer, A phenomenon occurs in which the density at the rear end of the halftone part in contact decreases (in Patent Document 2, this phenomenon is called “fading of the rear end of the image”).

  Here, “halftone” means a gradation in an intermediate area excluding the minimum value 0 and the maximum value of the gradation. In addition, the image data formed by selecting the gradation value of each pixel from the gradation value 0 and at least two other gradation values may be referred to as “multi-value image data”. For example, image data representing each recording color of cyan C, magenta M, yellow Y (, black K) with 256 gradations (gradation values 0 to 255) is an example of multi-value image data. The halftone in the tone is in the range of gradation values 1 to 254.

  An image of an object composed of a halftone may be referred to as a “halftone object image”. Further, the image data including the image data of the halftone object image may be simply referred to as “image data including the halftone object image”. Similarly, image data including image data of a background image of a halftone object image may be referred to as “image data including a background image”. Note that this background image includes a white background, that is, a background in which the gradation values of all the pixels are zero.

  FIG. 12 shows an example of a halftone object image and a background image. An image G shown in the figure includes halftone object images O1, O2, and O3 and a background image B. The above-mentioned blur at the rear end of the image occurs in the vicinity of the boundary between the halftone object images O1, O2, and O3 and the background image B.

  In Patent Document 1, in order to solve the problem of blur at the rear end of an image, an edge where multi-valued image data for each recording color changes from halftone image data to background image data in the sub-scanning direction on the recording medium is disclosed. A configuration is disclosed that operates to extract and change the value of the extracted background image data near the edge in the multi-valued image data to a set value near the image reproduction start point.

  In Patent Document 2, a predetermined test pattern image is formed on an image carrier, a physical quantity distribution of the test pattern image is measured, and a blur at the rear end of the test pattern image is detected from the measured physical quantity distribution. Then, based on the detection result, predetermined image processing is performed on the input image data, thereby solving the problem of blurring of the rear end of the image.

  By the way, when a halftone object image such as a figure is halftoned, the halftone dot at the boundary between the halftone object image and the background image is not a perfect halftone dot, but a halftone dot with a part missing. Formed as. FIG. 13 shows a halftone dot mode of one of (a part of) halftone object images O1, O2, and O3 of FIG.

  The halftone dot P completely included in the halftone object image O is formed as a perfect halftone dot including all the pixels S forming the halftone dot, but the halftone object image O and the background image ( A halftone dot P ′ formed so as to be in contact with a boundary portion with a halftone object image O (a boundary with a background image) is a part of all the pixels forming the halftone dot (not shown). The halftone dot image is formed as a halftone dot lacking three pixels S0) located outside the halftone object image O.

  In addition, since the color laser printer has a lower resolution than the offset printing as described above, when the halftone object image is output as a halftone dot, the edge portion cannot be expressed smoothly and is not smooth. There was a problem of giving an impression. Such jagged edges are called “jags”.

  This jaggy naturally occurs when an image is output using a halftone dot, and even in offset printing using a halftone dot, a jaggy is seen at the edge portion. However, in offset printing or the like, since the resolution is relatively high, such a degree of jaggies is permitted as a quality of a general printed matter.

  However, when a multi-value screen is applied to image formation by an electrophotographic color laser printer, the theoretical spacing and size of halftone dots obtained from device resolution, such as offset printing, are not equal, and the resolution is relatively low. Since it is low, it gives an impression that the smoothness of the edge is inferior to that of offset printing or the like. This is not a big problem in the case of a conventional comp application, but there is a quality problem when used for printing a proof or a final product.

  This problem is considered to be caused by the following circumstances. In electrophotographic image formation, in order to avoid a situation in which a gap is generated between pixels having a large gradation value, that is, a portion having a high density, and the density is lowered, the size of a pixel to be actually formed is theoretically determined. In general, adjustments are made so as to be larger than the pixel size.

  FIG. 14 shows a schematic form of a theoretical pixel and a pixel actually formed in the vicinity of the edge E of the halftone object image O shown in FIG. As shown in the figure, the actually formed pixels (simply called “actual pixels”) S ′ are formed in a size larger than each theoretical pixel S by a predetermined area.

  The size of the jaggy is determined in accordance with the distance between the edge E and the halftone dot P that is completely included in the halftone object image O and has the smallest distance to the edge E, for example. In FIG. 14, the actual depth d ′ is theoretically the same as the difference Δw (for example, one half of the difference Δw) between the actual pixel S ′ width w ′ and the theoretical pixel S width w. It becomes deeper than the upper depth d. Here, the edge E represents a theoretical edge, and the edge E ′ represents an actual edge.

  As described above, when electrophotographic image formation is performed, the depth from the edge of the halftone object image is increased and the smoothness of the edge is reduced, so that jaggies are conspicuous compared to offset printing or the like.

JP 2000-125135 A (claim, specification paragraph [0004]) JP 2004-54103 A (claim, specification paragraph [0002])

  The present invention has been made to solve the above-described problems, and is an image output capable of improving the smoothness of the edge of a halftone object image in an image formed using an electrophotographic method. It is an object of the present invention to provide a system, an image output control device, an image output method, an image output program, and a storage medium storing the program in a computer-readable manner.

In order to achieve the above object, the invention described in claim 1 is an electrophotographic image forming an image on a recording sheet while changing a laser exposure amount based on multi-value image data for each of a plurality of recording colors. An image output system comprising: a forming apparatus; and an image output control apparatus that includes halftone object images and a background image, and transmits halftone-processed multi-value image data to the image forming apparatus via a network The image output control device includes: extraction means for extracting pixels of the halftone object image in contact with the boundary between the halftone object image and the background image of the halftone image data subjected to the halftone processing; and laser exposure the size of each pixel of the extracted said halftone object image is formed a to equalize the pixel size of the theoretical, the complement to reduce the tone value of the each pixel Means for transmitting halftone-processed multi-valued image data including the halftone object image with the gradation value reduced and the background image to the image forming apparatus, and the image forming apparatus The halftone object image and the background image are formed on the recording paper while reducing the laser exposure amount when forming the extracted pixels based on the multivalued image data subjected to the halftone processing. It is characterized by that.

According to a second aspect of the present invention, there is provided an electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multi-value image data for each of a plurality of recording colors, and a halftone image. An image output system including an object image and a background image, and including an image output control device that transmits halftone-processed multi-value image data to the image forming apparatus via a network, and a user interface The image output control device includes a halftone image that is in contact with a boundary between a halftone object image and a background image of multivalued image data subjected to halftone processing in response to a correction instruction made by the user interface. extraction means for extracting a pixel of the tone object image, the difference in each pixel of the extracted said halftone object image formed by laser exposure To equalize the figure pixel size theoretical, and a correction means for reducing the gradation values of the respective pixels, and a the background image and the halftone object image gray scale value is reduced The halftoned multi-value image data is transmitted to the image forming apparatus, and the image forming apparatus is configured to form the extracted pixel based on the half-tone image multi-valued image data. The halftone object image and the background image are formed on a recording sheet while reducing the laser exposure amount.

  The invention according to claim 3 is the image output system according to claim 1 or 2, wherein the correction means is a gradation of pixels of the halftone object image extracted by the extraction means. It is characterized in that the amount of decrease in gradation value is changed according to the value.

  According to a fourth aspect of the present invention, in the image output system according to the third aspect, the correction means increases the amount of decrease as the gradation value of the extracted pixel increases. It is a feature.

  The invention according to claim 5 is the image output system according to claim 3 or claim 4, wherein the correction means is a gradation value of a pixel of a halftone object image and a reduction amount of the gradation value. Storage means for preliminarily storing related information for associating with, selecting a reduction amount associated with the gradation value of the pixel extracted by the extraction means from the related information, and extracting the gradation of the pixel The value is reduced by the selected reduction amount.

According to a sixth aspect of the present invention, there is provided an electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multi-value image data for each of a plurality of recording colors, and a halftone image. Multi-valued image data including an object image and another halftone object image formed at a position overlapping with or in contact with the halftone object image and transmitted to the image forming apparatus via the network is transmitted to the image forming apparatus. An image output control device comprising: an image output control device comprising: a halftone object image of multi-valued image data that has undergone halftone processing and another halftone object image; Extracting means for extracting each pixel of the halftone object image and the other halftone object image in contact with the boundary; and the halftone object Images and one or both of the other halftone object image, so as to equalize the size of each pixel of the extracted is formed by a laser exposure to the pixel size of the theoretical, reduce the tone value of the each pixel Correction means for causing the halftone object image having one or both of the gradation values to be reduced and the halftoned multi-value image data including the other halftone object image to the image forming apparatus. And the image forming apparatus reduces the laser exposure amount when forming the extracted pixels based on the multi-valued image data subjected to the halftone processing, and reduces the halftone object image and the halftone object image. Another halftone object image is formed on a recording sheet.

According to a seventh aspect of the present invention, there is provided an electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multi-value image data for each of a plurality of recording colors, and a halftone image. Multi-valued image data including an object image and another halftone object image formed at a position overlapping with or in contact with the halftone object image and transmitted to the image forming apparatus via the network is transmitted to the image forming apparatus. An image output control system including a user interface, wherein the image output control apparatus performs halftone processing in response to a correction instruction issued by the user interface. The halftone object in contact with the boundary between the halftone object image of the multi-valued image data and the other halftone object image Extraction means for extracting respective pixel image and the other halftone object image, one or both of the halftone object image and the other halftone object image, each being the extracted is formed by a laser exposure Correction means for reducing the gradation value of each pixel so that the pixel size is equal to the theoretical pixel size, and the halftone object image in which one or both of the gradation values are reduced, and The multi-valued image data that has been halftoned including the other halftone object image is transmitted to the image forming apparatus, and the image forming apparatus performs the above-described multi-valued image data that has been halftoned. The halftone object image and the other halftone object image are formed on the recording paper while reducing the laser exposure amount when forming the extracted pixels. It is characterized in that.

  The invention according to claim 8 is the image output system according to claim 6 or 7, wherein the correction means is a gradation of pixels of the halftone object image extracted by the extraction means. Comparing means for comparing a value with a gradation value of a pixel of the other halftone object image, and reducing a gradation value of a pixel having a larger gradation value based on the comparison result It is said.

  The invention according to claim 9 is the image output system according to any one of claims 6 to 8, wherein the correction means is a gradation of pixels of the halftone object image extracted by the extraction means. The reduction amount of the gradation value is changed according to the value and / or the gradation value of the pixel of the other halftone object image.

  The invention described in claim 10 is the image output system according to claim 9, wherein the correction means increases the decrease as the gradation value of the extracted pixel increases. It is a feature.

  The invention according to claim 11 is the image output system according to claim 9 or claim 10, wherein the correcting means is a gradation value of a pixel of a halftone object image and a reduction amount of the gradation value. Storage means for preliminarily storing related information for associating with, selecting a reduction amount associated with the gradation value of the pixel extracted by the extraction means from the related information, and extracting the gradation of the pixel The value is corrected by the selected decrease amount.

According to a twelfth aspect of the present invention, an electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multivalued image data for each of a plurality of recording colors and a network. An image output control apparatus including a halftone object image and a background image, and transmitting halftone-processed multi-value image data to the image forming apparatus through the network, wherein the halftone processing is performed Extraction means for extracting pixels of the halftone object image in contact with the boundary between the halftone object image and the background image of the multivalued image data, and each pixel of the extracted halftone object image formed by laser exposure to equalize the sizes pixel size theoretical, and a correction means for reducing the gradation values of the respective pixels, the halftone gray scale value is reduced The halftoned multi-value image data including the object image and the background image is transmitted to the image forming apparatus, and the halftone image is reduced while reducing the laser exposure amount when forming the extracted pixels. An object image and the background image are formed on a recording sheet.

According to a thirteenth aspect of the present invention, an electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multi-value image data for each of a plurality of recording colors and a network. Connected to the halftone object image, and another halftone object image formed at a position overlapping or in contact with the halftone object image. An image output control apparatus that transmits to the image forming apparatus, the halftone object image in contact with a boundary between a halftone object image of halftone image data and another halftone object image, and the halftone object image Extracting means for extracting each pixel of another halftone object image; the halftone object image; and the other halftone object With one or both of the-object image so as to equalize the size of each pixel of the extracted is formed by a laser exposure to the pixel size of the theoretical, and correction means for reducing the gradation values of the respective pixels, the The halftone object image including the halftone object image and the other halftone object image in which one or both of the gradation values are reduced is transmitted to the image forming apparatus, and the extraction is performed. The halftone object image and the other halftone object image are formed on a recording sheet while reducing the amount of laser exposure when forming the formed pixels.

According to a fourteenth aspect of the present invention, there is provided an electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multi-value image data for each of a plurality of recording colors, and a halftone image. An image output control method executed by an image output control device including an object image and a background image and transmitting halftone-processed multi-value image data to the image forming device via a network, the image output control A step of extracting pixels of the halftone object image in contact with the boundary between the halftone object image and the background image of the halftone image data subjected to the halftone processing; and the image output control device is formed by laser exposure. the size of each pixel of the extracted said halftone object image so as to equal the pixel size of the theoretical is, scan to reduce the tone value of the each pixel And the image output control device transmits halftone-processed multi-valued image data including the halftone object image with the gradation value reduced and the background image to the image forming device. And the halftone object image and the background image while the image forming apparatus reduces the laser exposure amount when forming the extracted pixels based on the multivalued image data subjected to the halftone processing. Forming on the recording paper.

According to a fifteenth aspect of the present invention, there is provided an electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multi-value image data for each of a plurality of recording colors, and a halftone image. Multi-valued image data including an object image and another halftone object image formed at a position overlapping with or in contact with the halftone object image and transmitted to the image forming apparatus via the network is transmitted to the image forming apparatus. An image output method executed by the image output control device, wherein the image output control device is arranged at a boundary between a halftone object image and other halftone object images of multivalued image data subjected to halftone processing. Extracting the respective pixels of the halftone object image and the other halftone object image in contact with each other; and the image output control device, Serial one or both of a halftone object image and the other halftone object image, so as to equalize the size of each pixel of the extracted is formed by a laser exposure to the pixel size of the theoretical floors of each of the pixels A step of decreasing a tone value, and the image output control device performs halftone processing including the halftone object image and the other halftone object image in which one or both of the tone values are reduced. Transmitting image data to the image forming apparatus; and reducing the laser exposure amount when the image forming apparatus forms the extracted pixels based on the multi-valued image data subjected to the halftone processing. And forming the halftone object image and the other halftone object image on a recording sheet.

According to a sixteenth aspect of the present invention, there is provided an electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multivalued image data for each of a plurality of recording colors, and a network. An image output program for controlling a computer including a halftone object image and a background image and having communication means for transmitting halftone-processed multi-value image data to the image forming apparatus through the network. , Causing the computer to function as extraction means for extracting pixels of the halftone object image in contact with the boundary between the halftone object image and the background image of the halftone image data subjected to halftone processing, and the computer is configured to perform laser exposure. equal to the pixel size of the theoretical size of each pixel of the extracted said halftone object image is formed by So that the, to function as a correction means for reducing the gradation values of the respective pixels, multivalued image data gray scale values have been processed halftone containing a reduced the halftone object image and the background image Is transmitted to the image forming apparatus by the communication unit, and the halftone object image and the background image are formed on a recording sheet while reducing the amount of laser exposure when forming the extracted pixels. It is characterized by that.

According to a seventeenth aspect of the present invention, there is provided an electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multi-value image data for each of a plurality of recording colors, and a network. Connected to the halftone object image, and another halftone object image formed at a position overlapping or in contact with the halftone object image. An image output program for controlling a computer having communication means for transmitting to the image forming apparatus, the computer comprising: a halftone object image of multi-valued image data subjected to halftone processing; and another halftone object image Extract each pixel of the halftone object image and the other halftone object image in contact with the boundary To function as a detecting means, the computer, the one or both of a halftone object image and the other halftone object image, the size of each pixel of the extracted is formed by a laser exposure to the pixel size of the theoretical A halftone dot that includes the halftone object image and the other halftone object image in which the gradation value of one or both of them is reduced so as to function as a correction unit that decreases the gradation value of each pixel so as to be equal. The multi-valued image data subjected to the digitization process is transmitted to the image forming apparatus by the communication means, and the halftone object image and the other image data are reduced while reducing the amount of laser exposure when forming the extracted pixels. A halftone object image is formed on a recording sheet.

  The invention according to claim 18 is a storage medium in which the image output program according to claim 16 or claim 17 is stored so as to be readable by a computer.

  The present invention extracts pixels of the halftone object image that are in contact with the boundary between the halftone object image and the background image of the multivalued image data, and reduces the gradation value of the pixels of the extracted halftone object image. In addition to performing correction, multivalued image data including a halftone object image with a reduced gradation value and a background image is transmitted to the image forming apparatus to reduce the amount of laser exposure when forming the extracted pixels. Meanwhile, the halftone object image and the background image are formed on the recording paper.

  As a result, the pixel size of the halftone object image in contact with the boundary between the halftone object image and the background image is reduced, so that the boundary (edge) of the halftone object image in the image output using the electrophotographic method is smooth. Can be improved.

  Further, the present invention extracts and extracts pixels of the halftone object image in contact with the boundary between the halftone object image and the background image of the multivalued image data in response to the correction instruction made by the user interface. The halftone object image is corrected so as to reduce the gradation value of the pixel, and the multivalued image data including the halftone object image with the reduced gradation value and the background image is transmitted to the image forming apparatus. The halftone object image and the background image are formed on the recording paper while reducing the amount of laser exposure when forming the extracted pixels.

  As a result, for example, when high-quality images are required, such as when proofing is used or when the final product is output, an image with improved smoothness of the edge of the halftone object image can be obtained by operating the user interface. Since the image can be output, the smoothness of the edge of the halftone object image in the image output using the electrophotographic method can be improved, and the convenience can be improved.

  Further, the present invention extracts pixels of the halftone object image and the other halftone object image that are in contact with the boundary between the halftone object image of the multi-value image data and the other halftone object image, A halftone object image in which one or both of the tone object image and the other halftone object image are corrected so as to reduce the tone value of the extracted pixel, and one or both tone values are reduced, and Multi-level image data including other halftone object images is transmitted to the image forming apparatus, and the halftone object image and other halftone object images are reduced while reducing the laser exposure amount when forming the extracted pixels. It is configured to be formed on a recording sheet.

  As a result, the size of the pixels in contact with the boundary between the two halftone object images is reduced, so that it is possible to improve the smoothness of the boundary (edge) between the halftone object images in the image output using the electrophotographic method.

  The present invention also provides the halftone object image and the other that are in contact with the boundary between the halftone object image of the multivalued image data and the other halftone object image in response to the correction instruction made by the user interface. Each halftone object image is extracted and corrected so as to reduce the gradation value of the extracted pixel in one or both of the halftone object image and the other halftone object image, and Multi-level image data including halftone object images with reduced gradation values and other halftone object images are transmitted to the image forming apparatus to reduce the laser exposure when forming the extracted pixels. Meanwhile, the halftone object image and the other halftone object image are formed on the recording sheet.

  As a result, when a high-quality image is required, an image with improved edge smoothness can be output by manipulating the user interface, so image output using an electrophotographic method The smoothness of the edge of the halftone object image can be improved, and the convenience can also be improved.

  An example of a preferred embodiment of an image output system, an image output control apparatus, an image output method, an image output program, and a storage medium storing the program readable by a computer according to the present invention will be described in detail with reference to the drawings. To do.

<First Embodiment>
[System configuration]
FIG. 1 shows an example of a preferred embodiment of an image output system according to the present invention. An image output system 1 shown in FIG. 1 includes an image output control device 10, a color laser printer 20, and an editing terminal 30. Any number of editing terminals 30 can be installed. The image output control device 10, the color laser printer 20, and the editing terminal 30 are connected via an arbitrary network such as a LAN or a dedicated line.

[Configuration of editing terminal]
The editing terminal 30 is a computer equipped with DTP (Desk Top Publishing) software for performing editing work such as design and layout of printed matter. The image data created by the editing terminal 30 is data described in a page description language (PDL) such as PostScript (registered trademark), for example, data representing a halftone object image such as a figure, It includes data representing characters, as well as object position information. Such data will be referred to as PDL data.

  The editing terminal 30 includes a user interface including an operation device and a display device, like a normal computer. As the operation device, any device such as a keyboard, a mouse, a trackball, and a control panel is used. As a display device, an arbitrary display device such as an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube) is provided.

  A predetermined print setting screen is displayed on the display device. This print setting screen is a screen for performing various setting operations when printing out an image created on the editing terminal 30, and is conventionally provided in general DTP software, document creation software, spreadsheet software, and the like. The screen is similar to that shown.

  This print display screen is displayed as a pop-up on the display screen of the display device, for example, in response to a predetermined print instruction operation by the user. The user operates the operation device such as a mouse to input various settings in the printing process.

  Information that can be set on this print setting screen includes the size of the recording paper for outputting the image, the number of output sheets, the number of output copies, single-sided printing / double-sided printing, etc., whether or not punch processing is performed, and punch holes in punch processing. Forming number and position, whether or not stapling is executed, stapling position and number of staples in stapling, whether or not folding processing is performed, folding position and direction in folding processing, whether or not binding processing is performed, and binding processing There are general settings such as the binding mode (inner binding, outer binding), whether or not to perform the cutting process, and the cutting position of the recording paper in the cutting process.

  Further, the print setting screen can be provided with a correction instruction input unit including a soft key or the like for performing an image correction instruction as a setting content unique to the present embodiment. The operation of the system 1 (particularly the image output control device 10) corresponding to the operation of the correction instruction input unit will be described later.

  The setting information input on the print setting screen is converted into PDL data, added to the PDL data of the output image, and transmitted to the image output control apparatus 10.

[Configuration of color laser printer]
The color laser printer 20 is an electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multi-value image data for each of a plurality of recording colors (C, M, Y, K). It is. The color laser printer 20 is used not only for comp applications but also for proof applications and final finished printing applications. FIG. 2 shows an example of the configuration of the color laser printer 20.

  A color laser printer 20 shown in FIG. 2 is an image forming apparatus referred to as a so-called multi-function machine having a printer function, a scanner function, a copy function, and a FAX function. Although not shown, the color laser printer 20 includes a printer body and a post-processing device (finisher) 26 that are integrally provided.

  Note that a driver for the color laser printer 20 is installed in the image output control device 10 and the editing terminal 30 in advance. Further, the image forming apparatus according to the present invention need not be the above-described multifunction peripheral, and may be sufficient if it has at least a printer function.

  The printer main body is provided with an image reading unit 21, an image processing unit 22, a control unit 23, an operation unit 24, and a printer unit 25.

  The image reading unit 21 reads a document image when using a scanner function or a copy function. The image reading unit 21 includes a CCD image sensor 21A and a control unit 21B that drives the CCD image sensor 21A.

  The image processing unit 22 includes a control unit 22A that processes image data sent from the image output control device 10 and image data read by the image reading unit 21, an image memory 22C (for example, a DRAM) that stores image data, A DRAM control unit 22B that writes and reads image data to and from the image memory 22C and a LAN interface (IF) 22D that performs data communication with the image output control device 10 are provided.

  The operation unit 24 includes a touch panel liquid crystal display (LCD) 24A, and a control unit 24B that controls display processing by the LCD 24A and outputs an operation signal corresponding to the operation on the LCD 24A. The operation unit 24 may include hard keys such as various operation buttons such as a print start button.

  The printer unit 25 performs a process of forming an image on recording paper based on the image data. The printer unit 25 includes a semiconductor laser (LD) 25A, an automatic duplex unit (ADU) 25B for forming images on both sides of a recording sheet, and a control unit 25C for controlling the semiconductor laser 25A and the automatic duplex unit 25B. Is provided. The semiconductor laser 25A outputs a laser for each recording color. The control unit 25C changes the exposure amount of the laser based on the multi-value image data for each recording color.

  The control unit 23 controls operations of the image reading unit 21, the operation unit 24, and the printer unit 25. The control unit 23 mainly includes an image control unit 23A, a DRAM control unit 23B, an image memory 23D, a reading processing unit 23E, and a writing processing unit 23G. The nonvolatile memory 23C stores a program for controlling the operation of the color laser printer 20, setting information corresponding to various functions of the color laser printer 20, and the like.

  The image control unit 23A includes a microprocessor such as a CPU, and controls the control unit 21B of the image reading unit 21, the control unit 24B of the operation unit 24, the control unit 25C of the printer unit 25, and the DRAM control unit 23D. This control process is executed based on a program or setting information stored in the nonvolatile memory 23C.

  The DRAM control unit 23B corresponds to the instruction of the image control unit 23A, reads image data from the image memory 23D, and stores image data in the image memory 23D. The image memory 23D is configured by a DRAM, for example.

  The reading processing unit 23E processes the analog signal photoelectrically converted by the CCD image sensor 21A and outputs image data to the compression unit 23F. The compression unit 23F compresses the read image data and outputs the compressed image data to the DRAM control unit 23B.

  The decompression unit 23H receives the compressed image data from the DRAM control unit 23B, decompresses the image data, and outputs the decompressed image data to the write processing unit 23G. The writing processing unit 23G processes the decompressed image data for writing on a recording sheet and outputs the processed data to the printer unit 25.

  The post-processing device (finisher) 26 is provided with a folding unit 26A, a stapler 26B, a shift unit 26C, a punching unit 26D, a cutting unit 26E, and an FS control unit 26F, as in the prior art.

  The FS control unit 26F is connected to the control unit 25C of the printer unit 25. Based on a control signal sent from the image control unit 23A via the control unit 25C, the folding unit 26A, the stapler 26B, and the shift unit 26C. The operation control of each of the punching means 26D and the cutting means 26E is performed.

  The folding means 26A performs processing (folding processing) for folding the recording paper. The folding position and folding direction (inner folding, outer folding) are set in advance by the operation unit 24, the image output control device 10, the editing terminal 30, and the like.

  The stapler 26B performs a process (stapling process) of binding a bundle of recording sheets stacked on an intermediate stacker (not shown) with a binding needle. The setting of the number of bindings, the stapling position of the binding needle, the number of binding needles, and the like are set in advance by the operation unit 24, the image output control device 10, the editing terminal 30, and the like.

  The shift unit 26C is a processing unit that changes the discharge position of the recording paper in the conveyance width direction for each copy. The number of each unit is set in advance by the operation unit 24, the image output control device 10, the editing terminal 30, and the like.

  The punching means 26D performs a process (punch process) for forming a file punch hole on the recording paper. The formation positions and the number of punch holes (collectively referred to as punch positions) are preset by the operation unit 24, the image output control device 10, the editing terminal 30, and the like.

  The cutting unit 26E performs a process of cutting a part of the recording paper in order to adjust the size of the output material. The cutting position is set in advance by the operation unit 24, the image output control device 10, the editing terminal 30, and the like.

  Although not shown, the post-processing device 26 is provided with a fixed paper discharge tray, a lift paper discharge tray, and the like, as in the prior art. The recording paper on which the image has been output and the post-processing has been performed is discharged and accumulated in these discharge trays.

[Configuration of Image Output Control Device]
The image output control device 10 is constituted by a general-purpose computer on which the image output program of the present invention is mounted, for example. FIG. 3 shows an example of the functional configuration of the image output control apparatus 10, and FIG. 4 shows an example of the hardware configuration.

[Hardware configuration of image output control device]
First, the hardware configuration of the image output control apparatus 10 will be described with reference to FIG. The image output control device 10 has a hardware configuration similar to that of a conventional computer. Specifically, it includes a microprocessor 101, RAM 102, ROM 103, hard disk drive (HDD) 104, keyboard 105, mouse 106, display 107, and communication interface (I / F) 108. These units are connected via a bus 109.

  The microprocessor 101 is configured by an arbitrary microprocessor such as a CPU or MPU, and executes an operation characteristic of the present invention by developing an image output program 104a stored in advance in the hard disk drive 104 on the RAM 102. The image output program 104a corresponds to an example of the “image output program” of the present invention.

  Further, the microprocessor 101 develops a basic program such as BIOS (Basic Input / Output System) stored in advance in the ROM 103 on the RAM 102, and performs various controls relating to peripheral devices (keyboard 105, mouse 106, display 107, etc.). I do.

  Processing mainly executed by the microprocessor 101 includes operation control of the color laser printer 20, management of image data created by the editing terminal 30, operation control corresponding to operation signals from the keyboard 105 and mouse 106, and display 107. There are screen display control, transmission / reception processing control of various programs, data, signals, etc. by the communication interface 108.

  The hard disk drive 104 is a large-capacity nonvolatile storage device. The hard disk drive 104 stores various data such as image data created by the editing terminal 30 together with the image output program 104a. Note that the image data and the like can also be configured to be stored in an external database accessible by the image output control apparatus 10.

  The keyboard 105, the mouse 106, and the display 107 function as a user interface UI of the image output control device 10. The keyboard 105 is a device used for typing and inputting characters and numbers. The mouse 106 is a device for performing various input operations on the object displayed on the display screen of the display 107. The display 107 is an arbitrary display device such as an LCD or a CRT, and displays various operation screens and setting screens.

  The communication interface 108 includes a communication device such as a LAN card for performing local communication with the color laser printer 20 and the editing terminal 30. A communication device such as a modem for connecting to a wide area network such as the Internet may be provided.

[Functional configuration of image output control device]
Next, the functional configuration of the image output control apparatus 10 will be described with reference to FIG. The image output control device 10 includes a data storage unit 11, an image processing unit 12, an extraction processing unit 13, a correction processing unit 14, and a transmission processing unit 15.

(Data storage)
The data storage unit 11 stores various data such as PDL data transmitted from the editing terminal 30 and image data created based on the PDL data. The data storage unit 11 is configured by a writable storage device such as a hard disk drive 104, for example.

(Image processing unit)
The image processing unit 12 reads the PDL data from the data storage unit 11, rasterizes the PDL data by interpreting the page description language, and raster images for each recording color (C, M, Y, K). Image data of (bitmap image) is created, and setting information included in the PDL data is acquired. The raster image image data and setting information are stored in the data storage unit 11.

  Further, the image processing unit 12 performs a halftone processing (screening) on the image data of the raster image of each recording color, and performs processing for creating halftone image data having a predetermined screen line number and screen angle. . The halftone dot image data and setting information are stored in the data storage unit 11. A multi-value screen is used for this halftone processing. Therefore, the halftone dot image data to be created is multi-value image data for each recording color.

  The image processing unit 12 that executes the image processing as described above includes, for example, a microprocessor 101 and a RAM 102.

(Extraction processing unit)
The extraction processing unit 13 corresponds to an example of the “extraction unit” of the present invention, reads rasterized image data for each recording color created by the image processing unit 12 from the data storage unit 11, and performs the rasterized processing. It operates so as to extract pixels of the halftone object image in contact with the boundary between the halftone object image and the background image included in the image data. The extraction processing unit 13 includes a microprocessor 101 and a RAM 102, for example.

  The extraction processing unit 13 includes a boundary extraction unit 131 and a pixel extraction unit 132. The boundary extraction unit 131 reads rasterized image data (a type of multi-valued image data) from the image storage unit 11, and the rasterized image data includes a halftone object image and a background image as a background thereof. If included, the boundary between the halftone object image and the background image is extracted.

  As an extraction method, for example, a pixel whose gradation value exceeds a predetermined threshold is determined as a pixel of a halftone object image, and a pixel whose gradation value is equal to or less than the threshold is determined as a pixel of a background image. At the same time, the position at which the pixel of the halftone object image and the pixel of the background image obtained thereby are extracted as a position on the boundary between them. As a result, the boundary between the halftone object image and the background image is extracted.

  Note that the boundary extraction method is not limited to this, and a method for obtaining a boundary with a background image with reference to position information such as a figure of a halftone object image included in PDL data can be used. Alternatively, any method that can extract a target boundary, such as a method that uses a gradient of an image by filtering, or a method that uses pattern matching, can be applied. Also, instead of extracting the boundary between the halftone object and the background image based on the rasterized image data, the boundary is extracted by analyzing the screened halftone dot image data (a kind of multi-value image data). You can also

  The pixel extraction unit 132 extracts pixels of the halftone object image that are in contact with the boundary extracted by the boundary extraction unit 131. More specifically, for example, based on the extracted boundary position and the pixel position of the halftone object image, the pixel extraction unit 132 selects the pixels of the halftone object image that are adjacent to the boundary. Extract. This extraction process may be performed using other appropriate methods. Information on the pixels in contact with the boundary extracted by the pixel extraction unit 132 (pixel position information) is sent to the data storage unit 11 and stored therein.

  It should be noted that any method other than the above-described method using the extraction processing unit 13 can be used as appropriate for the process of extracting the pixels of the halftone object image in contact with the boundary between the halftone object image and the background image. .

(Correction processor)
The correction processing unit 14 corresponds to an example of the “correction unit” of the present invention, and reads halftone image data and pixel position information of the halftone object image obtained by the extraction processing unit 13 from the data storage unit 11. The tone value of the pixel of the halftone dot image data corresponding to the position information of the pixel is reduced. A pixel of halftone image data corresponding to the pixel position information obtained by the extraction processing unit 13 may be abbreviated as “extracted pixel” or the like. The correction processing unit 14 includes a gradation value changing unit 141 and a related information storage unit 142.

  The related information storage unit 142 corresponds to an example of the “storage unit” of the present invention, and stores in advance related information 142a that associates the gradation value of the pixel of the halftone object image with the amount of decrease in the gradation value. ing. The related information storage unit 142 includes a storage device such as the hard disk drive 104, for example.

  FIG. 5 shows an example of the related information 142a. The related information 142a includes gradation value reduction amounts Δa and Δb for each of the gradation value ranges A + 1 to B, B + 1 to C, C + 1 to D,..., Y + 1 to Z of the pixels of the halftone object image. , Δc,..., Δy are set. Each reduction amount is, for example, the size of a pixel formed by laser exposure by the color laser printer 20 as shown in FIG. 14 (the size is w 2 when the pixel width is w). ).

  Here, the gradation value A is, for example, the aforementioned threshold value, and the gradation value Z is “maximum gradation value−1” (for example, Z = 254 in the case of 256 gradations). This corresponds to the case where the gradation value of the extracted pixel is “maximum gradation value−1” and the gradation value of the background image is 0.

  In addition, A + 1 <B, B + 1 <C, C + 1 <D,..., Y + 1 <Z, and Δa <Δb <Δc <. That is, the larger the gradation value of the pixel, the larger the reduction amount is set. Note that Δa <A + 1, Δb <B + 1, Δc <C + 1,..., Δy <Y + 1 are set so that the corrected gradation value does not become a negative value.

  The gradation value changing unit 141 relates the reduction amount associated with the gradation value of the pixel of the halftone image data corresponding to the position information of the pixel of the halftone object image obtained by the extraction processing unit 13. While selecting from the information 142a, the gradation value of the pixel is decreased by the selected decrease amount. Note that the gradation value is not changed for other pixels. The gradation value changing unit 141 includes, for example, a microprocessor 101 and a RAM 102.

  An example of processing executed by the gradation value changing unit 141 will be described. First, the gradation value changing unit 141 determines which range in the related information 142a the extracted pixel gradation value x corresponds to. When the gradation value x of this pixel is determined to be, for example, B + 1 ≦ x ≦ C, the gradation value changing unit 141 selects a decrease amount Δb corresponding to B + 1 to C in the related information 142a. Then, the gradation value x of the pixel is decreased by Δb. Therefore, the corrected gradation value of the pixel is x−Δb. Since Δb <B + 1 is set, the corrected gradation value x−Δb> 0.

(Transmission processing part)
The transmission processing unit 15 transmits the halftone image data (multi-valued image data) for each recording color in which the pixel gradation value has been changed by the gradation value changing unit 141 to the color laser printer. The transmission processing unit 15 includes, for example, a microprocessor 101, a RAM 102, and a communication interface 108. The transmission processing unit 15 corresponds to an example of “communication means” of the present invention.

  The color laser printer 20 forms an image (including a halftone object image and a background image) based on the multi-value image data on a recording sheet. At this time, when forming the extracted pixels, that is, the pixels of the halftone object image in contact with the boundary between the halftone object image and the background image, the above reduction amounts (Δa, Δb, Δc,..., Δy) are set. The exposure amount is reduced by a corresponding amount.

  The editing terminal 30 is provided with a user interface 31 including the aforementioned operation device and display device.

[System Operation]
The operation of the image output system 1 of the present embodiment having the above configuration will be described. FIG. 6 shows an example of the operation of the image output system 1.

  First, the user creates PDL data of an output image using the editing terminal 30 (S1), performs a predetermined operation, and transmits this PDL data to the image output control apparatus 10. This PDL data is stored in the data storage unit 11. The PDL data includes a halftone object image such as a graphic and a background image thereof.

  Next, the image processing unit 12 reads the PDL data from the data storage unit 11 and creates raster image data for each recording color (C, M, Y, K) (S2).

  Subsequently, the boundary extraction unit 131 of the extraction processing unit 13 extracts the boundary between the halftone object image and the background image included in the image data of the raster image (S3), and the pixel extraction unit 132 further Pixels of the halftone object image in contact with the extracted boundary are extracted (S4). The extracted pixel position information is stored in the data storage unit 11.

  Next, the image processing unit 12 applies halftone processing to the image data of the raster image created in step S2 to create halftone image data for each recording color (S5).

  Subsequently, the gradation value changing unit 141 of the correction processing unit 14 refers to the related information 142a and selects a reduction amount of the gradation value associated with the gradation value of the pixel of the extracted halftone object image ( S6) The gradation value of the pixel is reduced by this reduction amount (S7). The transmission processing unit 15 transmits the halftone image data for each recording color in which the gradation value of the pixel of the halftone object image is corrected to the color laser printer 20 (S8).

  The color laser printer 20 forms an image on the recording paper based on the halftone dot image data provided from the image output control device 10 (S9). This completes the image output process by the image output system 1 of the present embodiment.

[Action / Effect]
FIG. 7 shows an aspect of an image output by the image output system 1 as described above. According to the image output system 1, since the gradation value when forming the pixel T in contact with the edge (boundary with the background image B) of the halftone object image O is reduced, these pixels T are converted into the color laser printer 20. This reduces the exposure amount when laser exposure is performed. As a result, the pixel T formed by laser exposure is substantially equal to the theoretical pixel size (w ^ 2) shown in FIG.

  Thereby, the edge E ″ of the halftone object image O according to the present embodiment is at a position substantially equal to the theoretical edge E of FIG. 14, that is, a position displaced to the halftone object image O side from the conventional edge E. Therefore, the depth d of the halftone dot P from the edge E ″ is shallower than the depth d ′ from the conventional edge E ′.

  7 is arranged so that pixels form a step near the boundary with the background image B. According to the present embodiment, the depth e of the step is equal to that of the conventional step. It becomes shallower than the depth e ′ of the step.

  As described above, according to the image output system 1 according to the present embodiment, the depth from the edge of the halftone dot of the halftone object image can be reduced to improve the smoothness of the edge. Therefore, even if the electrophotographic method is used, only the same degree of jaggies as offset printing occurs, and the printing quality is improved.

  In the present embodiment, the amount of decrease in gradation value is changed according to the gradation value of the pixel of the extracted halftone object image. That is, as shown in the related information 142a in FIG. 5, the reduction amount is set to increase as the gradation value of the extracted pixel increases. As the gradation value of the pixel in contact with the boundary is larger, the jaggies become more conspicuous. However, according to the present embodiment, the larger the original gradation value is, the larger the reduction amount due to the correction is, so that the jaggies are effectively eliminated. be able to.

[Other operation examples]
Another operation example of the image output system 1 according to this embodiment will be described. In this operation example, the gradation value is corrected only when the user gives a correction instruction. As a result, when correction is not required, for example, when outputting images for comps, the correction process can be omitted to shorten the output time. On the other hand, when outputting proofs and final products, etc. Can output a high-quality image on which correction processing has been performed. Such an operation example will be described with reference to the flowchart of FIG. In FIG. 8, steps similar to those in FIG. 7 are denoted by the same reference numerals.

  First, the user creates PDL data at the editing terminal 30 (S1). Further, the user instructs whether to execute gradation value correction at the boundary between the halftone object image and the background image (S10). When instructing the execution of correction, the user operates the user interface 31 to input an instruction to the correction instruction input unit of the print setting screen described above. When correction execution is instructed, setting information indicating that is transmitted to the image output control apparatus 10 together with the PDL data.

  The image processing unit 12 of the image output control device 10 creates raster image image data for each recording color from the PDL data (S2).

  Next, the microprocessor 101 of the image output control device 10 analyzes the received setting information according to the image output program 104a, and determines whether or not a correction instruction has been given (S11).

  When it is determined that the correction instruction has not been made (S11; N), the transmission processing unit 15 reads the halftone image data for each recording color created by the image processing unit 12 from the data storage unit 11, and the color laser printer. 20 (S12).

  The color laser printer 20 forms an image on the recording paper based on the halftone dot image data provided from the image output control device 10 (S9). This completes the processing in the case where no correction instruction has been given (in the case of a comp application or the like).

  On the other hand, when it is determined that a correction instruction has been given (S11; Y), the boundary extraction unit 131 extracts the boundary between the halftone object image and its background image (S3), and the pixel extraction unit 132 is located at this boundary. Pixels of the halftone object image that are in contact are extracted (S4). Further, the image processing unit 12 performs halftone dot processing on the image data of the raster image to create halftone dot image data for each recording color (S5). Further, the gradation value changing unit 141 of the correction processing unit 14 selects a reduction amount corresponding to the extracted pixel gradation value from the related information 142a (S6), and corrects the gradation value of the pixel (S7). ). The transmission processing unit 15 transmits the halftone image data for each recording color after the gradation value correction to the color laser printer 20 (S8).

  The color laser printer 20 forms an image on the recording paper based on the halftone dot image data provided from the image output control device 10 (S9). This completes the processing when a correction instruction is given (for proof use, final finished product use, etc.).

<Second Embodiment>
Another embodiment of the image output system according to the present invention will be described. This embodiment is intended to reduce jaggies occurring at the boundary between a halftone object image and another halftone object image. Hereinafter, the same components as those in the first embodiment will be described using the same reference numerals.

  Similar to the first embodiment, the image output system 1000 according to the present embodiment includes the image output control device 10, the color laser printer 20, and the editing terminal 30 (see FIG. 9). Further, the image output control apparatus 10 of the present embodiment has the same hardware configuration as that of the first embodiment (see FIG. 4).

[Functional configuration]
An example of a functional configuration of the image output control apparatus 10 in the present embodiment is shown in FIG. As in the first embodiment, the image output control apparatus 10 includes a data storage unit 11, an image processing unit 12, an extraction processing unit 13, a correction processing unit 14, and a transmission processing unit 15. The data storage unit 11, the image processing unit 12, and the transmission processing unit 15 have the same functions as those in the first embodiment. On the other hand, the extraction processing unit 13 and the correction processing unit 14 have functions different from those of the first embodiment. Hereinafter, the extraction processing unit 13 and the correction processing unit 14 according to the present embodiment will be described.

(Extraction processing unit)
The extraction processing unit 13 of the present embodiment corresponds to an example of the “extraction unit” of the present invention, reads halftone image data for each recording color created by the image processing unit 12 from the data storage unit 11, and The pixel touching the boundary between the halftone object image and the other halftone object image included in the point image data acts to extract from both object images.

  Here, the boundary between the halftone object images O1 and O2 arranged to overlap each other in the image G shown in FIG. 12 is an example of the boundary between the halftone object image and another halftone object image. A boundary is also formed when two halftone object images are arranged so as to contact each other.

  As in the first embodiment, the extraction processing unit 13 includes a boundary extraction unit 131 and a pixel extraction unit 132. The boundary extraction unit 131 reads halftone image data (multi-valued image data) from the image storage unit 11 and extracts a boundary between a halftone object image and another halftone object image from the halftone image data.

  As the extraction method, for example, the following method is used. First, with reference to the position information of each halftone object image of the PDL data stored in the data storage unit 11, it is determined whether or not there are a plurality of halftone object images arranged so as to have a boundary. . When such a plurality of halftone object images exist, the boundary between halftone object images in the halftone image data can be extracted based on the position information.

  Note that the boundary extraction method is not limited to this, and the method described in the first embodiment can be appropriately applied.

  The pixel extraction unit 132 extracts pixels that touch the boundary extracted by the boundary extraction unit 131 for each halftone object image. More specifically, the pixel extraction unit 132, for example, based on the extracted boundary position and the pixel position of the halftone object image, the pixel of the halftone object image at the position adjacent to the boundary. To extract. Such pixel extraction processing is performed for each of a plurality of halftone object images overlapping each other. This extraction process may be performed using other appropriate methods.

(Correction processor)
The correction processing unit 14 corresponds to an example of the “correction unit” of the present invention, and the gradation value of the pixel extracted by the extraction processing unit 13 is obtained for one or both of the halftone object image and the other halftone object image. Acts to correct. The correction processing unit 14 includes a gradation value changing unit 141, a related information storage unit 142, and a gradation value comparing unit 143.

  The gradation value comparison unit 143 corresponds to an example of the “comparison unit” of the present invention, and the gradation values of the pixels of the halftone object image extracted by the extraction processing unit 13 and the pixels of the other halftone object images. The gradation value is compared to determine the magnitude relationship between them. The gradation value comparison unit 143 includes, for example, a microprocessor 101 and a RAM 102.

  The related information storage unit 142 corresponds to an example of the “storage unit” of the present invention, and associates the gradation value of the pixel of the halftone object image with the amount of decrease in the gradation value, as in the first embodiment. Related information 142a (see FIG. 5) is stored in advance.

  The gradation value changing unit 141 reduces the gradation value of the pixels extracted from one or both of the halftone object image and the other halftone object image based on the comparison result by the gradation value comparison unit 143. More specifically, first, based on the magnitude relationship determined by the gradation value comparison unit 143, a reduction amount corresponding to the gradation value of the pixel having the larger gradation value is selected from the related information 142a, and then Thus, the gradation value of the pixel having the larger gradation value is corrected by the selected decrease value.

[System Operation]
The operation of the image output system 1000 of the present embodiment having the above configuration will be described. FIG. 10 shows an example of the operation of the image output system 1000.

  First, the user creates PDL data of an output image using the editing terminal 30 (S21), performs a predetermined operation, and transmits the PDL data to the image output control apparatus 10. This PDL data is stored in the data storage unit 11. The PDL data includes a plurality of halftone object images.

  Next, the image processing unit 12 creates raster image data for each recording color based on the PDL data (S22), and further, for each recording color based on the raster image image data. Halftone image data is created (S23).

  Subsequently, the boundary extraction unit 131 of the extraction processing unit 13 determines whether there are two (a plurality of) halftone object images arranged in an overlapping manner based on the position information of the halftone object image included in the PDL data. Is determined (S24).

  When such two halftone object images do not exist (S24; N), the transmission processing unit 15 reads the halftone image data for each recording color from the data storage unit 11 and transmits it to the color laser printer 20 ( S32).

  The color laser printer 20 forms an image on the recording paper based on the halftone dot image data provided from the image output control device 10 (S31). This is the end of the processing when there is no boundary between halftone object images.

  On the other hand, if there are two halftone object images having a boundary (S24; Y), the boundary extraction unit 131 uses the halftone object image in the halftone image data based on the position information of the halftone object image in the PDL data. The boundary between each other is extracted (S25). Subsequently, the pixel extraction unit 132 extracts pixels in contact with the extracted boundary from each of the two halftone object images (S26).

  Next, the gradation value comparison unit 143 of the correction processing unit 14 compares the pixels of the two halftone object images extracted in step S26 to determine the magnitude relationship (S27). Subsequently, the gradation value changing unit 141 selects a reduction amount corresponding to the gradation value of the pixel having the larger gradation value from the related information 142a (S28). Further, the gradation value changing unit 141 corrects the gradation value of the pixel having the larger gradation value by the selected decrease value (S29). The transmission processing unit 15 transmits the halftone image data for each recording color for which the gradation value has been corrected to the color laser printer 20 (S30).

  The color laser printer 20 forms an image on the recording paper based on the halftone dot image data provided from the image output control device 10 (S31). This completes the image output process by the image output system 1 of the present embodiment.

[Action / Effect]
According to the image output system 1 according to the present embodiment, since the gradation value when forming pixels in contact with the boundary between two halftone object images is reduced, these pixels are laser-exposed with the color laser printer 20. The amount of exposure decreases. As a result, the pixel is formed on the recording paper with a size substantially equal to the theoretical pixel size (w ^ 2) shown in FIG.

  Thereby, the depth of the halftone dot and the step of the halftone dot at the boundary between the two halftone object images are reduced (see FIG. 7), and the smoothness of the boundary is improved. Therefore, even if the electrophotographic method is used, only the same degree of jaggies as offset printing occurs, so that the printing quality is improved.

  In the present embodiment, the gradation values of the pixels of the two halftone object images having the boundary are compared, and the gradation value of the pixel having the larger gradation value is reduced based on the comparison result. It has become. Thereby, the smoothness of the boundary can be improved and jaggies can be reduced as compared with the case where the gradation value of the pixel having the smaller gradation value is corrected. Note that a configuration for correcting the gradation value of the pixel having the smaller gradation value may be applied, or a configuration for correcting the gradation value of both pixels may be applied.

  In the present embodiment, the amount of decrease in the gradation value is changed according to the gradation value of the pixel of the extracted halftone object image (see FIG. 5). Therefore, even when the gradation values of a plurality of pixels in contact with the boundary with the background image are different, the edge (boundary) of the halftone object image is formed.

  In addition, the larger the gradation value of the pixel in contact with the boundary, the more noticeable the jaggy becomes. In this case, the gradation value is greatly reduced, so that the jaggy can be effectively eliminated.

[Other operation examples]
Another operation example of the image output system 1 according to this embodiment will be described. In this operation example, the gradation value is corrected only when the user gives a correction instruction. Thereby, it is convenient that the presence or absence of correction can be properly used according to the use of the output. An example of this operation will be described with reference to the flowchart of FIG. In FIG. 11, steps similar to those in FIG. 10 are denoted by the same reference numerals.

  First, the user creates PDL data (S21). In addition, the user operates the user interface 31 to instruct whether or not to execute gradation value correction at the boundary (S40). When correction execution is instructed, setting information indicating that is transmitted to the image output control apparatus 10 together with the PDL data.

  Based on the PDL data, the image processing unit 12 of the image output control device 10 creates raster image data for each recording color (S22), and further creates halftone image data for each recording color. (S23).

  Next, the microprocessor 101 of the image output control apparatus 10 analyzes the received setting information according to the image output program 104a, and determines whether or not a correction instruction has been given (S41).

  If it is determined that no correction instruction has been given (S41; N), the transmission processing unit 15 reads the halftone image data for each recording color from the data storage unit 11 and transmits it to the color laser printer 20 (S32).

  The color laser printer 20 forms an image on the recording paper based on the halftone dot image data provided from the image output control device 10 (S31). This completes the processing in the case where no correction instruction has been given (in the case of a comp application or the like).

  On the other hand, when it is determined that a correction instruction has been issued (S41; Y), the boundary extraction unit 131 of the extraction processing unit 13 determines whether there is a halftone object image having a boundary (S24).

  If it does not exist (S24; N), halftone dot image data for each recording color is transmitted to the color laser printer 20 (S32), and an image is formed on the recording paper (S31). This is the end of the processing when a correction instruction is given and there is no boundary between halftone object images.

  On the other hand, when there are two halftone object images having a boundary (S24; Y), the boundary extraction unit 131 extracts the boundary between the two halftone object images (S25). The pixel extraction unit 132 extracts pixels that touch the extracted boundary from each halftone object image (S26).

  Next, the gradation value comparison unit 143 of the correction processing unit 14 compares the pixels extracted from the two halftone object images to determine the magnitude relationship (S27). The gradation value changing unit 141 selects a reduction amount corresponding to the gradation value of the pixel having the larger gradation value from the related information 142a (S28). The gradation value changing unit 141 corrects the gradation value of the pixel having the larger gradation value by the selected decrease value (S29). The corrected halftone image data for each recording color is transmitted to the color laser printer 20 (S30), and an image is formed on the recording paper (S31). This completes the processing when a correction instruction is given and there is a boundary between halftone object images.

[Image output control device]
Each of the image output control apparatuses 10 described in the first and second embodiments corresponds to an example of the “image output control apparatus” of the present invention. This image output control apparatus is an apparatus including a computer that operates based on the image output program of the present invention. Instead of applying a configuration in which the microprocessor operates by executing the image output program, a dedicated circuit that performs the same operation may be mounted.

[About storage media]
In each of the above embodiments, the image output program according to the present invention is stored in the hard disk drive. In addition, it can be stored in a storage medium that can be read by the image output control device (computer). For example, image output to any storage medium such as an optical disk, a magneto-optical disk (CD-ROM / DVD-RAM / DVD-ROM / MO, etc.), a magnetic storage medium (hard disk / floppy (registered trademark) disk / ZIP, etc.), etc. It is possible to memorize a program.

  The configuration described in detail above is merely an example for carrying out the present invention. Therefore, arbitrary modifications can be appropriately made within the scope of the gist of the present invention.

1 is a schematic diagram illustrating an example of the overall configuration of a first embodiment of an image output system according to the present invention. 1 is a schematic block diagram illustrating an example of an internal configuration of a color laser printer in a first embodiment of an image output system according to the present invention. It is a schematic block diagram showing an example of a functional composition of a 1st embodiment of an image output system concerning the present invention. It is a schematic block diagram showing an example of the hardware constitutions of the image output control apparatus in 1st Embodiment of the image output system which concerns on this invention. It is a figure showing an example of the relevant information in 1st Embodiment of the image output system which concerns on this invention. It is a flowchart showing an example of operation | movement of 1st Embodiment of the image output system which concerns on this invention. It is a schematic explanatory drawing for demonstrating the effect | action of 1st Embodiment of the image output system which concerns on this invention. It is a flowchart showing the other operation example by 1st Embodiment of the image output system which concerns on this invention. It is a schematic block diagram showing an example of a functional structure of 2nd Embodiment of the image output system which concerns on this invention. It is a flowchart showing an example of operation | movement of 2nd Embodiment of the image output system which concerns on this invention. It is a flowchart showing the other operation example by 2nd Embodiment of the image output system which concerns on this invention. It is the schematic showing an example of the image containing a halftone object image and a background image. It is the schematic showing the aspect of the halftone dot in the vicinity of the boundary of a halftone object image and a background image. It is a schematic explanatory drawing for demonstrating the smoothness (jaggy size) of the boundary of a halftone object image and a background image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1000 Image output system 10 Image output control apparatus 11 Data storage part 12 Image processing part 13 Extraction processing part 131 Boundary extraction part 132 Pixel extraction part 14 Correction processing part 141 Tone value change part 142 Related information storage part 142a Related information 143 Tone value comparison unit 15 Transmission processing unit 20 Color laser printer 30 Editing terminal 31 User interface 104a Image output program

Claims (18)

An electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multivalued image data for each of a plurality of recording colors;
An image output control device including a halftone object image and a background image, and transmitting halftone-processed multi-value image data to the image forming device via a network;
An image output system comprising:
The image output control device includes:
Extraction means for extracting pixels of the halftone object image in contact with the boundary between the halftone object image and the background image of the halftone image data subjected to the halftone processing;
Correction means for reducing the gradation value of each pixel so that the size of each pixel of the extracted halftone object image formed by laser exposure is equal to the theoretical pixel size ;
Comprising the halftone image including the halftone object image with the gradation value reduced and the background image, and transmitting the multivalued image data to the image forming apparatus.
The image forming apparatus records the halftone object image and the background image while reducing a laser exposure amount when forming the extracted pixels based on the multivalued image data subjected to the halftone processing. Form on paper,
An image output system characterized by that. An electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multi-value image data for each of a plurality of recording colors;
An image output control device including a halftone object image and a background image, and transmitting halftone-processed multi-value image data to the image forming device through a network;
An image output system comprising:
With user interface,
The image output control device includes:
Extraction means for extracting pixels of the halftone object image in contact with the boundary between the halftone object image and the background image of the multi-valued image data subjected to halftone processing in response to the correction instruction made by the user interface When,
Correction means for reducing the gradation value of each pixel so that the size of each pixel of the extracted halftone object image formed by laser exposure is equal to the theoretical pixel size ;
Comprising the halftone image including the halftone object image and the background image with the gradation value reduced, and transmitting the multivalued image data to the image forming apparatus.
The image forming apparatus records the halftone object image and the background image while reducing a laser exposure amount when forming the extracted pixels based on the multi-value image data subjected to the halftone processing. Forming on paper,
An image output system characterized by that. The correction unit changes a decrease amount of a gradation value according to a gradation value of a pixel of the halftone object image extracted by the extraction unit;
The image output system according to claim 1, wherein the image output system is an image output system. The correction means increases the decrease amount as the gradation value of the extracted pixel is larger.
The image output system according to claim 3. The correction means includes
Storage means for storing in advance relevant information associating a gradation value of a pixel of a halftone object image with a reduction amount of the gradation value;
A reduction amount associated with the gradation value of the pixel extracted by the extraction unit is selected from the related information, and the extracted gradation value of the pixel is decreased by the selected reduction amount;
The image output system according to claim 3, wherein the image output system is an image output system. An electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multivalued image data for each of a plurality of recording colors;
A halftone object image and another halftone object image formed at a position overlapping or in contact with the halftone object image, and the halftone image processed multi-valued image data is transferred to the image forming apparatus through the network. An image output control device for transmission;
An image output system comprising:
The image output control device includes:
Extraction means for extracting respective pixels of the halftone object image and the other halftone object image that are in contact with the boundary between the halftone object image and the other halftone object image of the half-tone image data subjected to the halftone processing When,
The level of each pixel is set so that the size of each of the extracted pixels formed by laser exposure in one or both of the halftone object image and the other halftone object image is equal to the theoretical pixel size. Correction means for reducing the key value;
And halftone image data including the halftone object image in which one or both of the gradation values are reduced and the other halftone object image are transmitted to the image forming apparatus,
The image forming apparatus reduces the laser exposure amount when forming the extracted pixels based on the halftoned multi-value image data, while reducing the halftone object image and the other halftone images. Forming an object image on recording paper,
An image output system characterized by that. An electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multivalued image data for each of a plurality of recording colors;
A halftone object image and another halftone object image formed at a position overlapping or in contact with the halftone object image, and the halftone image processed multi-valued image data is transferred to the image forming apparatus through the network. An image output control device for transmission;
An image output system comprising:
With user interface,
The image output control device includes:
Corresponding to the correction instruction made by the user interface, the halftone object image and the halftone object image that are in contact with the boundary between the halftone object image of the halftone image data subjected to the halftone processing and the other halftone object image and the halftone object image Extraction means for extracting each pixel of another halftone object image;
The level of each pixel is set so that the size of each of the extracted pixels formed by laser exposure in one or both of the halftone object image and the other halftone object image is equal to the theoretical pixel size. Correction means for reducing the key value;
And halftone image data including the halftone object image in which one or both of the gradation values are reduced and the other halftone object image are transmitted to the image forming apparatus,
The image forming apparatus reduces the halftone object image and the other halftone images while reducing the laser exposure amount when forming the extracted pixels based on the multi-valued image data subjected to the halftone processing. Forming an object image on recording paper,
An image output system characterized by that. The correction means includes
Comparing means for comparing a gradation value of a pixel of the halftone object image extracted by the extracting means with a gradation value of a pixel of the other halftone object image;
Based on the comparison result, the gradation value of the pixel having the larger gradation value is decreased.
8. The image output system according to claim 6, wherein the image output system is an image output system. The correction means may reduce the gradation value reduction amount according to the gradation value of the pixel of the halftone object image extracted by the extraction means and / or the gradation value of the pixel of the other halftone object image. change,
The image output system according to claim 6, wherein the image output system is an image output system. The correction means increases the decrease amount as the gradation value of the extracted pixel is larger.
The image output system according to claim 9. The correction means includes
Storage means for storing in advance relevant information associating a gradation value of a pixel of a halftone object image with a reduction amount of the gradation value;
Selecting a reduction amount associated with the gradation value of the pixel extracted by the extraction means from the related information, and correcting the extracted gradation value of the pixel by the selected reduction amount;
The image output system according to claim 9 or 10, characterized in that A halftone object image and a background image are connected via a network to an electrophotographic image forming apparatus that forms an image on recording paper while changing the laser exposure amount based on multi-value image data for each of a plurality of recording colors. An image output control device that transmits halftone-processed multi-valued image data to the image forming device through the network,
Extraction means for extracting pixels of the halftone object image in contact with the boundary between the halftone object image and the background image of the halftone image data subjected to the halftone processing;
Correction means for reducing the gradation value of each pixel so that the size of each pixel of the extracted halftone object image formed by laser exposure is equal to the theoretical pixel size ;
With
When the halftone image data including the halftone object image with the gradation value reduced and the background image are transmitted to the image forming apparatus to form the extracted pixels. Forming the halftone object image and the background image on a recording sheet while reducing a laser exposure amount;
An image output control apparatus characterized by that. A halftone object image is connected to an electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multi-value image data for each of a plurality of recording colors. An image output control device for transmitting halftone-processed multi-valued image data to the image forming apparatus through the network, including another halftone object image formed at a position overlapping or in contact with the halftone object image Because
Extraction means for extracting respective pixels of the halftone object image and the other halftone object image that are in contact with the boundary between the halftone object image and the other halftone object image of the half-tone image data subjected to the halftone processing When,
The level of each pixel is set so that the size of each of the extracted pixels formed by laser exposure in one or both of the halftone object image and the other halftone object image is equal to the theoretical pixel size. Correction means for reducing the key value;
With
The halftone image data including the halftone object image and the other halftone object image in which one or both of the gradation values are reduced is transmitted to the image forming apparatus and extracted. Forming the halftone object image and the other halftone object image on a recording sheet while reducing the amount of laser exposure when forming pixels.
An image output control apparatus characterized by that. An electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multivalued image data for each of a plurality of recording colors;
An image output control device including a halftone object image and a background image, and transmitting halftone-processed multi-value image data to the image forming device via a network;
An image output method executed by
The image output control device extracting pixels of the halftone object image in contact with the boundary between the halftone object image and the background image of the multi-valued image data subjected to the halftone processing;
The image output control device reduces the gradation value of each pixel so that the size of each pixel of the extracted halftone object image formed by laser exposure is equal to the theoretical pixel size. When,
The image output control device transmitting halftone-processed multi-valued image data including the halftone object image with the gradation value reduced and the background image to the image forming device;
The image forming apparatus records the halftone object image and the background image while reducing the laser exposure amount when forming the extracted pixels based on the multi-valued image data subjected to the halftone processing. Forming on paper,
An image output method comprising: An electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multivalued image data for each of a plurality of recording colors;
A halftone object image and another halftone object image formed at a position overlapping or in contact with the halftone object image, and the halftone image processed multi-valued image data is transferred to the image forming apparatus through the network. An image output control device for transmission;
An image output method executed by
Each of the halftone object image and the other halftone object image is in contact with the boundary between the halftone object image of the multi-valued image data subjected to the halftone processing and the other halftone object image. Extracting the pixels of
The image output control device makes the size of each extracted pixel formed by laser exposure of one or both of the halftone object image and the other halftone object image equal to a theoretical pixel size. And reducing the gradation value of each pixel ,
The image output control device outputs halftone image data including the halftone object image and the other halftone object image in which one or both of the gradation values are reduced to the image forming device. Sending, and
The image forming apparatus reduces the halftone object image and the other halftones while reducing the laser exposure amount when forming the extracted pixels based on the multivalued image data subjected to the halftone processing. Forming an object image on recording paper;
An image output method comprising: A halftone object image and a background image are connected via a network to an electrophotographic image forming apparatus that forms an image on recording paper while changing the laser exposure amount based on multi-value image data for each of a plurality of recording colors. An image output program for controlling a computer having communication means for transmitting halftone-processed multi-value image data to the image forming apparatus through the network,
Causing the computer to function as an extraction unit that extracts pixels of the halftone object image in contact with the boundary between the halftone object image and the background image of the multivalued image data subjected to the halftone processing;
The computer functions as correction means for reducing the gradation value of each pixel so that the size of each pixel of the extracted halftone object image formed by laser exposure is equal to the theoretical pixel size. Let
The extracted pixel is transmitted by the communication means to the image forming apparatus through the communication means including halftone image data including the halftone object image with the gradation value reduced and the background image. Forming the halftone object image and the background image on a recording sheet while reducing the amount of laser exposure when forming
An image output program characterized by that. A halftone object image is connected to an electrophotographic image forming apparatus that forms an image on a recording sheet while changing a laser exposure amount based on multi-value image data for each of a plurality of recording colors. Communication means for transmitting halftone-processed multi-value image data to the image forming apparatus through the network, including other halftone object images formed at positions overlapping or in contact with the halftone object images An image output program for controlling a computer,
Each pixel of the halftone object image and the other halftone object image that is in contact with the boundary between the halftone object image of the multi-valued image data subjected to halftone processing and the other halftone object image is displayed on the computer. Function as an extraction means to extract,
The computer is configured to make the size of each extracted pixel formed by laser exposure of one or both of the halftone object image and the other halftone object image equal to a theoretical pixel size. Function as a correction means to reduce the gradation value of each pixel ,
The halftone image data including the halftone object image and the other halftone object image in which one or both of the gradation values are reduced is transmitted to the image forming apparatus by the communication unit. The halftone object image and the other halftone object image are formed on a recording sheet while reducing the laser exposure amount when forming the extracted pixels.
An image output program characterized by that.   A storage medium storing the image output program according to claim 16 or 17 so as to be readable by a computer.

Images