JP4735212B2 - Image processing device - Google Patents

Description

  The present invention relates to an image processing apparatus that generates a bitmap image based on image description information described in a page description language or the like.

  In recent years, due to technological progress of multimedia and DTP hardware / software, the contents of various documents such as office documents have become complicated. Currently, there is a demand for an image forming apparatus capable of forming such a complex document at high speed and high image quality.

  In order to achieve this object, for example, when an image described in a page description language such as Postscript (registered trademark) is developed into bitmap data for image formation, each pixel in the bitmap data is processed. Some of them associate attribute information related to instructions in the page description language.

For example, each pixel is associated with different attribute information depending on whether it is drawn with information specifying a character in the page description language or with information specifying a picture, and the printer refers to the attribute information. However, for example, there is a technique of printing by applying a screen optimized for each pixel by switching the screen (for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-185024

  However, in the above conventional technique, when determining attribute information to be associated with each pixel, the determination criterion is not based on, for example, a page description language command, but may be a drawing order or the like. For example, when a processing engine of a page description language additionally draws a fine line such as a hairline on a design (graphics), it adds attribute information indicating that the pixel is a character for the fine line pixel There is. If processed as it is, a graphics screen and a text screen will be mixed, and even if the density value is the same, fine lines will appear like streak lines and an uncomfortable image will be formed. It will be.

  As described above, in the conventional image processing technique, there is a case where an uncomfortable image is sometimes formed due to an erroneous determination of attribute information.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image processing apparatus capable of reducing the uncomfortable feeling of an image to be formed.

  The present invention for solving the problems of the conventional example described above is an image processing device that generates bitmap image data and attribute information representing attributes for each pixel of the bitmap image data based on image description information. If the attribute information different from the attribute information related to at least one reference pixel selected from the predetermined area including the target pixel is attached with reference to the attribute information for each pixel, the target pixel The attribute information is corrected and set to the attribute information of the reference pixel, and is output.

  Here, the reference pixel may be another pixel having a density value within a predetermined range within the predetermined area.

  Furthermore, one aspect of the present invention is a control method for an image processing device that generates bitmap image data and attribute information representing an attribute for each pixel of the bitmap image data based on image description information, When attribute information different from attribute information related to at least one reference pixel selected from a predetermined region including the target pixel is attached with reference to the attribute information for each pixel, the attribute information of the target pixel is It is characterized in that the attribute information of the reference pixel is corrected and set and output.

  Another aspect of the present invention is a program for causing a computer to generate bitmap image data and attribute information representing an attribute for each pixel of the bitmap image data based on the image description information. , When attribute information different from attribute information related to at least one reference pixel selected from a predetermined area including the target pixel is attached with reference to the attribute information for each pixel, the attribute information of the target pixel Is corrected to the attribute information of the reference pixel, and functions as means for outputting.

Embodiments of the present invention will be described with reference to the drawings. The image processing apparatus according to the present embodiment is realized as a page description language processing apparatus built in an image forming apparatus such as a printer. That is, the image processing apparatus 1 of the present embodiment is connected to a printer control apparatus 2 and an image forming apparatus 3 as illustrated in FIG. The image processing apparatus 1 includes a control unit 11, a storage unit 12, an input interface (I / F) 13, and an output interface (I / F) 14.

  The control unit 11 is a CPU or the like, and operates according to a program stored in the storage unit 12. The control unit 11 receives the image description information input from the control device 2 via the input I / F 13 and stores the image description information in the storage unit 12. Based on the stored image description information, the bitmap image data and the bit Attribute information indicating the attribute for each pixel of the map image data is generated and output to the image forming apparatus 3 via the output I / F 14. More detailed contents of the processing of the control unit 11 will be described later.

  The storage unit 12 includes a computer-readable storage medium such as a RAM (Random Access Memory) or an EEPROM (electrically erasable ROM). A program executed by the control unit 11 is stored in the EEPROM of the storage unit 12. The RAM of the storage unit 12 operates as a work memory of the control unit 11.

  The control device 2 receives an image formation instruction from a personal computer serving as a host via a network. This image formation instruction includes image description information in which an image to be formed is described in a page description language, formation condition information such as designation of paper used for formation, and the like. The control device 2 outputs image description information to the image processing device 1 and outputs formation condition information and the like to the image forming device 3.

  The image forming apparatus 3 includes a printer engine. This image forming apparatus forms bitmap image data input from the image processing apparatus 1 on a sheet specified by formation condition information or the like. The image forming apparatus 3 also executes processing such as switching the screen to be applied to each pixel included in the bitmap image data with reference to the attribute information output by the image processing apparatus 1.

  Here, specific processing contents of the control unit 11 of the image processing apparatus 1 will be described. The control unit 11 is functionally configured to include a rasterizer 21 and an attribute information correction unit 22 as shown in FIG. Here, similarly to the conventional one, the rasterizer 21 is based on the image description information describing the image to be formed, and the attribute information indicating the attribute for each pixel of the bitmap image data. And output.

  The attribute information correction unit 22 scans each pixel of the bitmap image data from left to right, for example, one line at a time in order from the pixel at the upper left corner. When the scanning of the line ends, the next line (one lower line) is scanned. The pixel of interest is sequentially selected in the order of scanning from left to right (so-called scan line order).

  Then, a predetermined area including the selected target pixel is defined. Then, at least one pixel other than the target pixel is selected from the predetermined area as a reference pixel. Then, referring to the attribute information about the selected reference pixel, if the attribute information associated with the target pixel is different from the attribute information about the at least one reference pixel, the attribute information of the target pixel is Then, correction to match the attribute information of the reference pixel is performed.

  For example, the predetermined area is a 5 × 5 pixel block centered on the target pixel (FIG. 3). In this area, as shown in FIG. 4, the attribute information correction unit 22 first selects one target pixel in the scan line order (S1), and determines whether the selected target pixel is an edge (S2). . For example, the block in the 5 × 5 pixels is labeled according to the density value. This associates the same label value with pixels of the same density. Then, when there are a plurality of types of label values and the label values attached to the target pixel are not isolated (when there are adjacent pixels having the same label value), it is determined that the target pixel is an edge. If the target pixel is an edge in this process S1, a pixel other than the target pixel having the same density as the target pixel in the 5 × 5 region is selected as a reference pixel (S3). Here, it is determined whether or not at least one reference pixel is selected (S4). If at least one reference pixel is selected, a histogram of attribute information associated with the reference pixel is generated (S5), and the target pixel Are corrected and set to attribute information corresponding to the mode value of the histogram (S6). Then, it is checked whether or not there is a pixel that has not been selected as the target pixel (S7). If there is no unselected pixel in the process S7, the process ends and the corrected attribute information is output.

  If no reference pixel is selected in process S4 and if it is not an edge in process S2, the process directly proceeds to process S7.

  In the present embodiment, the processing is performed as described above, and the following operation is performed. In the following, for example, it is assumed that a relatively large color character is drawn as graphics (bitmap), the outline of the bitmap is corrected, and a hairline is additionally drawn.

  In this case, when the contour portion is enlarged and observed in the bitmap image data generated by the operation of the rasterizer in the control unit 11, as shown in FIG. 5, the color character inside and the additionally drawn hairline are pixels having the same density. (A). However, the additionally drawn hairline is determined to be a character, and as attribute information, the edge portion corresponding to the hairline is given a text attribute (referred to as “T” in FIG. 5), and the graphics portion is the graphics. An attribute (referred to as “G” in FIG. 5) is added (B). If the image is processed in the printer engine as it is, different screens are applied to different portions of the attribute information, resulting in a difference in density between the hairline portion and the graphics portion (C).

  In the present embodiment, the attribute information correction unit 22 corrects this attribute information. For example, as shown in FIG. 6, in a 5 × 5 region, for a pixel of interest in the edge portion, refer to a pixel having the same density as this pixel of interest (a pixel having the same density on the generated bitmap image data). Select as a pixel. When a histogram of the attribute information attached to the reference pixel is generated, the character attribute “T” is 8 pixels, the graphics attribute “G” is 11 pixels, and the mode value is the graphics attribute “G”. " Therefore, the attribute information about the target pixel is corrected to the graphics attribute “G”.

  Thereafter, as a result of the same processing, the attribute information about the hairline part is corrected and set to the graphics attribute ((D) of FIG. 5). As a result, even in the result of the forming process by the image forming apparatus 3, different screens are not applied to the hair alignment part and the graphics part, no density difference occurs, and the sense of incongruity of the formed image can be reduced. .

  In the above description, the case where the predetermined area is a 5 × 5 area has been described as an example. However, the predetermined area is not limited thereto, and the predetermined area may be an area less than 5 × 5 such as a 3 × 3 area. It may be an area wider than 5 × 5.

  In addition, although an example in which only the edge portion is processed has been described here, the processing is not limited to the edge portion. Furthermore, although an example in which a pixel having the same density as the target pixel is selected as a reference pixel has been described here, other pixels whose difference from the density value of the target pixel is a density value within a predetermined range within a predetermined area. May be selected as a reference pixel.

It is a block diagram showing the example of a structure of the image processing apparatus which concerns on embodiment of this invention. It is a functional block diagram showing the example of the image processing apparatus which concerns on embodiment of this invention. It is explanatory drawing showing the example of the area | region defined in the image processing apparatus which concerns on embodiment of this invention. It is a flowchart figure showing the process example of the image processing apparatus which concerns on embodiment of this invention. It is a schematic diagram showing the process example of the image processing apparatus which concerns on embodiment of this invention. It is explanatory drawing showing the example of the attribute information used as the process target in the image processing apparatus which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Image processing apparatus, 2 Control apparatus, 3 Image forming apparatus, 11 Control part, 12 Storage part, 13 Input interface, 14 Output interface, 21 Rasterizer, 22 Attribute information correction part

Claims (3)

Pixel-of- interest selection means for selecting a pixel of interest from image data obtained by performing additional drawing on a bitmap image having attributes for each pixel;
Reference pixel selection means for selecting, as a reference pixel, a pixel whose density value is within a predetermined range from a predetermined area including the target pixel selected by the target pixel selection means;
Attribute information extraction means for extracting the most attribute information among attribute information representing attributes for each of the reference pixels selected by the reference pixel selection means;
If the attribute information extracted by the attribute information extraction unit does not match the attribute information of the target pixel, the attribute information change for changing the attribute information of the target pixel to the attribute information extracted by the attribute information extraction unit Means,
An image processing apparatus comprising: Select the pixel of interest from the image data obtained by additionally drawing the bitmap image with attributes for each pixel,
A pixel having a density value within a predetermined range from a predetermined area including the selected target pixel is selected as a reference pixel.
Of the attribute information representing the attribute for each of the reference pixels selected by the reference pixel selection means, extract the most attribute information,
When the most attribute information among the attribute information attached to the reference pixel does not match the attribute information of the target pixel, the attribute information is changed to the most attribute information among the attribute information attached to the reference pixel. Image processing method. Computer
Pixel-of- interest selection means for selecting a pixel of interest from image data obtained by additionally drawing a bitmap image with attributes for each pixel;
Reference pixel selecting means for selecting, as a reference pixel, a pixel whose density value is within a predetermined range from a predetermined area including the target pixel selected by the target pixel selecting means;
Attribute information extracting means for extracting the most attribute information among attribute information representing attributes for each of the reference pixels selected by the reference pixel selecting means; and
If the attribute information extracted by the attribute information extraction unit does not match the attribute information of the target pixel, the attribute information change for changing the attribute information of the target pixel to the attribute information extracted by the attribute information extraction unit means,
Program to function as.

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