JP4137924B2 - Image processing apparatus and image processing program - Google Patents

Description

  The present invention relates to an image processing apparatus and an image processing program for preventing the occurrence of moire for a specific print pattern.

  Among the patterns defined in the print data transmitted from the host computer, some planes in the four planes (CMYK) may not be output at all due to interference with the halftone pattern of the object to which the pattern is applied, There is a moiré phenomenon that appears as an unintended striped pattern, and the color reproducibility is significantly lowered. For example, there is a checkered pattern (a pattern in which dot validity / invalidity is a checkered pattern) used for translucent processing of a specific application. In such a case, there is a problem that moiré or a phenomenon in which the colors are extremely different occurs.

In order to solve such a problem, it is determined whether or not the foreground image and the background image are to be translucent processed by a logical operation, and if it is determined to be translucent processed by a logical operation, There has been known an image processing apparatus that calculates an average value of corresponding pixels of a foreground image and a background image to obtain translucent image data (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2002-225381

  However, in the apparatus shown in Patent Document 1, it is determined whether or not to perform translucent processing, and translucent processing is performed. There is a problem that the moire phenomenon cannot be avoided.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an image processing apparatus and an image processing program capable of preventing the occurrence of moire for a specific print pattern.

The present invention relates to a data input means for inputting pattern data indicating validity or invalidity of a pixel, a pattern conversion table storage means for storing a pattern conversion table in which the order of validating pixels is defined on a processing target matrix, and an input the number of consecutive and at least one of the effective pixels in the width direction or a height direction of the pattern data is equal to or less than a predetermined number, the pattern period of the pattern data is equal to or smaller than a predetermined threshold value A determination means for determining whether or not there is a density value of the input pattern data by counting the number of effective pixels of the processing target matrix of the input pattern data when the pattern period is equal to or less than a predetermined threshold value; a density value calculation means for calculating, as the density value after the conversion is equal to the density value of the input pattern data, the pattern In the order to enable the pixels stored in the conversion table, a pattern conversion means for converting the processed matrix converted pattern data by setting an effective pixel of the same number as the density value calculated by the density calculating means It is provided with.

The present invention relates to an image processing program that operates on an image processing apparatus including a pattern conversion table storage unit that stores a pattern conversion table in which a pixel activation order is defined on a processing target matrix. or a data input process of inputting pattern data indicating the invalid number of consecutive and at least one of the effective pixels in the width direction or a height direction of the pattern data entered by or less than a predetermined number A determination process for determining whether or not the pattern period of the pattern data is equal to or less than a predetermined threshold value, and if the pattern period is equal to or less than the predetermined threshold value, the processing target matrix of the input pattern data is valid a density value calculation process for calculating a density value of the input pattern data by counting the number of pixels, the density value after the conversion is the As will become equal to the density value of the force pattern data, in the order to enable the pixels stored in the pattern conversion table, by setting the effective pixels of the same number as the density value calculated by the density calculating means A pattern conversion process for converting the processing object matrix into conversion pattern data is performed by a computer.

  According to the present invention, a pattern conversion table in which the order of enabling pixels is defined on a processing target matrix is stored, a pattern period of input pattern data is obtained, and the obtained pattern period is a predetermined threshold value. In the following cases, the pattern conversion table is referred to convert the converted density value into the conversion pattern data that is the same as the density value of the input pattern data, so that the moire phenomenon in the drawing object when the pattern is applied It is possible to avoid the occurrence of the color and to improve the color reproducibility.

  Hereinafter, an image processing apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the embodiment. In this figure, reference numeral 1 denotes a drawing data analysis unit that reads the image data to be drawn and analyzes the image data. Reference numeral 2 denotes a drawing data processing unit that processes drawing data based on an analysis result in the drawing data analysis unit 1. Reference numeral 21 denotes a drawing environment management unit that manages setting information related to drawing such as an enlargement / reduction setting matrix and a currently effective screen. Reference numeral 22 denotes an image processing unit for processing image data. Reference numeral 23 denotes a vector processing unit for processing vector data. Reference numeral 24 denotes a character processing unit that processes character data. Reference numeral 25 denotes a clip processing unit that performs clipping processing. Reference numeral 26 denotes a pattern conversion table storage unit in which a pattern conversion table that is referred to when converting specific pattern data is stored in advance. Reference numeral 3 denotes a drawing unit that creates a bitmap in the VRAM from each data created by the drawing data processing unit 2. Reference numeral 4 denotes an output unit that actually performs printing on a recording medium (printing paper). Reference numeral 5 denotes a system control unit that manages common system information and controls the system.

  Next, the table structure of the pattern conversion table stored in the pattern conversion table storage unit 26 shown in FIG. 1 will be described with reference to FIG. The pattern conversion table is a table in which order numbers indicating the order in which pixels are validated are defined on the processing target matrix. FIG. 3 shows an example in the case of using a processing target matrix consisting of 16 pixels of 4 pixels × 4 pixels, and the order numbers 1 to 16 are defined from the upper left pixel to the lower right pixel of the matrix. Yes. The arrangement of the sequential numbers is not limited to the arrangement example shown in FIG. 3, and an arbitrary sequential number arrangement pattern is determined and defined in advance.

  Next, the operation of the image processing apparatus shown in FIG. 1 will be described with reference to FIG. First, the drawing data analysis unit 1 reads the drawing data to be drawn, analyzes the drawing data (step S1), outputs the analysis result to the system control unit 5, and draws the read drawing data. Output to the data processing unit 2. In response to this, the system control unit 5 determines whether the read drawing data is pattern data based on the input analysis result (step S2). If it is not pattern data, the system control unit 5 proceeds to step S7. To control the operation.

  On the other hand, if the read drawing data is pattern data, the system control unit 5 instructs the image processing unit 22 to execute pattern conversion processing of the drawing data output by the drawing data analysis unit 1. In response to this, the image processing unit 22 converts the drawing data input from the drawing data analysis unit 1 into a bitmap pattern when the drawing data is developed in the destination (step S3). FIG. 4A shows an example of bitmap data (referred to as input pattern data) obtained by converting input drawing data into a bitmap pattern. The pattern data in this example is checkered pattern data, where a “1” pixel is valid and a “0” pixel is invalid.

  Next, the image processing unit 22 obtains a pattern period in the width direction and the height direction of the input pattern data obtained by conversion, and determines whether or not the obtained pattern period is equal to or less than a predetermined threshold value. (Step S4). This determination is made when the number of consecutive effective pixels (pixels for which “1” is set) in the width direction or the height direction is equal to or less than a predetermined threshold value (for example, one pixel). This is done by assuming that it is below a predetermined threshold. If either one or both of the width direction and the height direction is equal to or less than the threshold value, the determination in step S4 is “true”. As a result of this determination, if the pattern period is not less than or equal to the threshold value, the system control unit 5 controls the operation so as to proceed to step S7.

  On the other hand, when the pattern period is equal to or less than the threshold value, the image processing unit 22 obtains the density value of the input pattern data (step S5). The density value of the pattern data is obtained by counting the number of “1” s in the processing target matrix. In the example shown in FIG. 4A, since the number of “1” is “8”, the density value is “8”.

  Next, the image processing unit 22 refers to the pattern conversion table stored in the pattern conversion table storage unit 26, and converts the input pattern data into another pattern having the same density value (step S6). In this conversion, the sequence numbers “1” to “8” defined on the matrix of the pattern conversion table so that the density value of the converted pattern data becomes the density value “8” obtained in step S5 ( (The maximum value of the sequence number corresponds to the density value) is read, “1” is set to validate the pixel corresponding to the read position on the matrix, and the remaining pixels are set to “ This is done by setting “0”. Thereby, the conversion pattern data shown in FIG. 4B is obtained. Then, the image processing unit 22 outputs the obtained converted pattern data to the drawing unit 3.

  Next, the system control unit 5 determines whether or not the processing for one page is completed (step S7), and repeatedly executes the processing operations of steps S1 to S6 until the processing for one page is completed. To control the operation. When the processing for one page is completed, the bitmap data of the image to be drawn is created in the drawing unit 3, and the drawing unit 3 outputs this bitmap data to the output unit 4. One page is drawn (step S8).

  As described above, a pattern conversion table in which the order of enabling pixels is defined on the processing target matrix is stored, the pattern period of the input pattern data is obtained, and the obtained pattern period is less than a predetermined threshold value. In some cases, the pattern conversion table is referenced to convert the converted density value to the same conversion pattern data as the input pattern data density value, so the moiré phenomenon occurs in the drawing object when the pattern is applied. Can be avoided, and color reproducibility can be improved.

  Note that a program for realizing the functions of the processing unit in FIG. 1 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed to control image processing. May be performed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, and a CD-ROM, and a storage device such as a hard disk built in the computer system. Further, the “computer-readable recording medium” refers to a volatile memory (RAM) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, those holding programs for a certain period of time are also included.

  The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

It is a block diagram which shows the structure of one Embodiment of this invention. It is a flowchart which shows operation | movement of the apparatus shown in FIG. It is explanatory drawing which shows the table structure of the pattern conversion table memorize | stored in the pattern conversion table memory | storage part 26 shown in FIG. It is explanatory drawing which shows an example of input pattern data (a) and conversion pattern data (b).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Drawing data analysis part, 2 ... Drawing data processing part, 21 ... Drawing environment management part, 22 ... Image processing part, 23 ... Vector processing part, 24 ... Character processing part 25 ... Clip processing unit, 26 ... Pattern conversion table storage unit, 3 ... Drawing unit, 4 ... Output unit, 5 ... System control unit

Claims (2)

Data input means for inputting pattern data indicating validity or invalidity of pixels;
Pattern conversion table storage means for storing a pattern conversion table in which the order of enabling pixels is defined on the processing target matrix;
By determining whether the number of consecutive and at least one of the effective pixels in the width direction or a height direction of the pattern data input is below the predetermined number, the pattern period of the pattern data is equal to or less than a predetermined threshold value Determining means for determining whether or not
A density value calculating means for calculating the density value of the input pattern data by counting the number of effective pixels of the processing target matrix of the input pattern data when the pattern period is equal to or less than a predetermined threshold;
The number of density values calculated by the density value calculating means is the same as the density value calculated by the density value calculating means according to the order of enabling the pixels stored in the pattern conversion table so that the converted density value is the same as the density value of the input pattern data . An image processing apparatus comprising: pattern conversion means for converting the processing object matrix into conversion pattern data by setting effective pixels . An image processing program that operates on an image processing apparatus that includes a pattern conversion table storage unit that stores a pattern conversion table in which the order of enabling pixels is defined on a processing target matrix,
A data input process for inputting pattern data indicating validity or invalidity of a pixel;
By determining whether the number of consecutive and at least one of the effective pixels in the width direction or a height direction of the pattern data inputted is equal to or less than the predetermined number, the pattern period of the pattern data is equal to or less than a predetermined threshold value A determination process for determining whether or not
A density value calculation process for calculating a density value of the input pattern data by counting the number of effective pixels of the processing target matrix of the input pattern data when the pattern period is equal to or less than a predetermined threshold;
The number of density values calculated by the density value calculating means is the same as the density value calculated by the density value calculating means according to the order of enabling the pixels stored in the pattern conversion table so that the converted density value is the same as the density value of the input pattern data . An image processing program for causing a computer to perform pattern conversion processing for converting the processing target matrix into conversion pattern data by setting effective pixels .

Images