JP4362650B2 - Printing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printing apparatus that expresses gradation by screen processing.
[0002]
[Prior art]
A color printing apparatus normally uses a plurality of color toners such as yellow (Y), magenta (M), and cyan (C), and expresses the density (gradation) by area gradation of each color. In addition, in order to perform area gradation at high speed, a dither pattern having a predetermined size and a predetermined printing position for each density is prepared, and the pattern is applied to each pixel and connected to make high speed. Color printing is realized.
[0003]
The dither pattern needs to be matched to the characteristics of the hardware that uses it, and there are various styles. Conventionally, in a printing process in an OS (operation system) environment, color printing is performed by using different dither patterns for each of three objects: characters (text), figures (graphics), and photographic images.
[0004]
In such a color printing apparatus, so-called screen processing is performed on input print data to express gradation. A plurality of filters (dither patterns) having different numbers of lines are used while being switched. For example, a screen with a small number of lines (dither pattern) is used for small-size character data, and a line number for graphic data with a large coloring area or image data such as photographic images. The printing process is performed using a low (coarse) screen. That is, the filter is determined according to the attribute of the drawing object, and the printing process is performed.
[0005]
The reason for this is that a filter with a large number of lines causes horizontal lines (jitter) due to uneven conveyance of paper and a vertical line (streaks) due to uneven light quantity of the head, compared to a filter with few lines. Although the color uniformity of the whole printed matter is inferior, it is excellent in the expressive power of fine portions. On the other hand, a filter with a small number of lines is inferior in expressiveness of fine parts compared to a filter with a large number of lines, but it is resistant to the above-mentioned jitter and streaks, and is excellent in color uniformity of the entire printed matter. It is.
[0006]
Patent Document 1 discloses an invention for changing a screen pattern according to an instruction for enlarging or reducing an image, and the present invention includes a plurality of screen patterns prepared in advance according to an instruction for enlarging or reducing an image. An optimum screen corresponding to the magnification is selected and printing processing is performed.
[0007]
[Patent Document 1]
JP-A-11-220613
[0008]
[Problems to be solved by the invention]
However, in the conventional screen line number determination method (filter determination method), as described above, the number of screen lines is determined by the attribute of the drawing object. For this reason, in the case of unexpected data, the drawbacks of the screen used are emphasized.
[0009]
For example, when the print data to be actually processed is large-size character data, the rendering object attribute is “character data”, and therefore the jitter and streaks are noticeable using a filter with a large number of lines. . On the other hand, even if the print data that is actually processed is graphic data with a small coloring area or image data that represents a fine portion, the drawing object attribute is “graphic data” or “image data”, and the screen has a low number of lines. Is selected, and the expression of the fine portion is reduced.
[0010]
  Therefore, the present invention selects a screen (filter) based on information of print data within a unit area, prevents occurrence of jitter and streaks, and performs print processing substantially matching the attributes of the drawing object. A printing apparatus is provided.
[Means for Solving the Problems]
[0012]
  UpThe problem is claimed1According to the described invention, in the printing apparatus that mounts a plurality of screens having different numbers of lines, uses the screens while switching, and performs a printing process based on the drawing data, means for dividing the print data per unit area; Means for calculating the degree of color variation from the divided print data per unit area; means for selecting one of the plurality of screens having different numbers of lines according to the degree of color variation; This can be achieved by providing a printing apparatus having means for generating drawing data using the selected screen based on print data per unit area.
[0013]
  By configuring in this wayRIn addition to preventing the occurrence of jitter and streaks, printing processing that substantially matches the attributes of the drawing object can be performed..
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
<First Embodiment>
FIG. 1 is a system configuration diagram of a printing apparatus used in the present embodiment. In the figure, a print data receiving unit 1 analyzes print data transmitted from a host device 2 such as a personal computer (PC), and holds print data for one page in a print data holding buffer 3. In addition, when the print data receiving unit 1 completes holding the print data for one page, the print data receiving unit 1 notifies the print data drawing unit 4 of the completion of holding the print data.
[0015]
When the print data drawing unit 4 receives a print data holding completion notification from the print data receiving unit 1, the print data drawing unit 4 sequentially analyzes the held print data. In this analysis process, a drawing process to the image memory 6 is performed for each drawing object using a screen pattern developed in a screen pattern data development buffer 5 described later. When the drawing of all the print data for one page is completed, the print data drawing unit 4 notifies the drawing data transfer unit 7 of the completion of the drawing process.
[0016]
The screen pattern selection / development unit 8 reads the corresponding screen (filter) from the screen pattern data storage unit 10 based on the size information recognized by the drawing object size recognition unit 9 and registers it in the screen pattern data development buffer 5. .
[0017]
The drawing object size recognizing unit 9 has a function of reading the corresponding size information from the unit area information of the print data, and recognizes the corresponding size information with reference to the drawing object size table 11.
FIG. 2 is a diagram showing an example of the data configuration registered in the drawing object size table 11. Along with the record number, size information is registered. The drawing object size recognition unit 9 uses the print data per unit area to refer to the drawing object size table 11 and reads the corresponding size information.
[0018]
The printer engine 12 shown in FIG. 1 has a function of performing printing processing on paper using drawing data sequentially read from the image memory 6 by the processing of the drawing data transfer unit 7, and includes a print head or the like. Has been.
Hereinafter, the process of this example is demonstrated concretely.
[0019]
The host device 2 transmits print data created according to the application program to the printing apparatus, and the print data receiving unit 1 performs print data holding processing according to the flowchart shown in FIG. That is, it is determined whether or not print data has been received from the host device 2 (step (hereinafter referred to as S) 1). When print data is received (S1 is YES), the print data is sequentially written in the print data holding buffer 3 ( S3). Thereafter, it is determined whether or not the holding of the print data for one page is completed (S3). When the holding of the print data for one page is completed (S3 is YES), the print data holding buffer 3 is sent to the print data drawing unit 4. Is notified that print data for one page has been held (S4).
[0020]
Upon receiving this notification, the print data drawing unit 4 performs processing according to the flowchart shown in FIG. That is, when there is a notification of the completion of the print data holding, this notification is determined (S5 is YES), one unit of drawing objects among the undrawn drawing objects is recognized (S6), and the attribute of the drawing object is set to the screen. The pattern selection development unit 8 is notified (S7).
[0021]
The screen pattern selection / development unit 8 performs processing according to the flowchart shown in FIG. 5 and receives the above notification from the print data drawing unit 4 (S8), further notifies the drawing object size recognition unit 9 of information relating to the print size (S9). ). This print size information is information on the print data (print density) included per unit, and this information is transmitted to the drawing object size recognition unit 9.
[0022]
The drawing object size recognizing unit 9 determines whether the information is supplied from the screen pattern selection / development unit 8 (S10). When this information is supplied (S10 is YES), print size calculation processing is performed (S11). . In this processing, for example, the print data amount is large when the density is high, and the print data amount is small when the density is low.
[0023]
Next, the drawing object size recognition unit 9 refers to the drawing object size table 11 and compares the calculation result with the information of the print size (S12). If the print size is larger (YES in S13), the selection of a screen pattern with a lower number of lines is notified (S14). On the other hand, if the print size is smaller (NO in S13), the selection of a screen pattern having a higher number of lines is notified (S15).
[0024]
For example, the print size stored in the drawing object size table 11 (hereinafter referred to as “in-table print size”) will be specifically described as 0.25 square inches shown in FIG. First, when the drawing object is character data of 24 points 5 CPI (Character Per Inch), the print size of this drawing object is 24/72 inches high × 1/5 inches wide = 0.07 square inches. The print size "is 0.25 square inches or less. Accordingly, in this case, the drawing object size recognition unit 9 notifies the screen pattern selection development unit 8 of selection of a screen having a high number of lines.
[0025]
On the other hand, if the drawing object is short graphic data with a height of 20 mm and a width of 30 mm, the print size of the drawing object is 20 / 25.4 inches high × 30 / 25.4 inches wide = 0.93 square inches. Exceeds 0.25 square inch of “print size”. Accordingly, in this case, the drawing object size recognition unit 9 notifies the screen pattern selection development unit 8 of selection of a screen having a low number of lines.
[0026]
Further, when the drawing object is 80 pixel high and 120 pixel wide image data, the print size of the drawing object is 80/72 inches high × 120/72 inches wide = 1.85 square inches, and is 0.25 of “print size in table”. Above square inches. For this reason, the drawing object size recognition unit 9 notifies the screen pattern selection development unit 8 of selection of a screen having a low number of lines.
[0027]
When the screen pattern selection expansion unit 8 receives the selection information of the screen (filter) (S16 is YES (see FIG. 5)), it selects the corresponding screen (filter) from the screen pattern data storage unit 10 based on the information. Then, it is registered in the screen pattern data development buffer 5 (S17). Then, the screen pattern selection / expansion unit 8 notifies the print data drawing unit 4 of the completion of expansion of the screen pattern data (S18).
[0028]
When the print data drawing unit 4 confirms the notification (S19 is YES (see FIG. 4)), the print data is developed in the image memory 6 based on the screen pattern developed in the screen pattern data development buffer 5 (S20). ).
Thereafter, it is determined whether there is an unimaged drawing object (S21). If there is an unimaged drawing object (S21: NO), the above processing is repeated to develop the drawing data in the image memory 6. When all the non-image drawing objects are processed (YES in S21), the drawing data transfer unit 7 is notified that the printing data drawing process is completed (S22).
[0029]
The drawing data transfer unit 7 determines the notification according to the flowchart shown in FIG. 7 (S23). When the notification is received (S23 is YES), the drawing data is read from the image memory 6 and transferred to the printer engine 12 (see FIG. 7). S24). Thereafter, the above processing is repeated, and the drawing data developed in the image memory 6 is sequentially printed.
[0030]
As described above, according to the present embodiment, the number of lines on the screen is changed according to the print size for each drawing object, and the screen (filter) having the optimum number of lines can be automatically selected to perform the printing process. Therefore, it is possible to perform an optimal printing process without causing streaks or jitter.
[0031]
In the above embodiment, the screen pattern selection process is performed on the printer device side. However, the screen driver may be configured to transfer the information to the printing device by a printer driver.
Further, the screen is not limited to two stages, that is, a screen with a high number of lines and a screen with a low number of lines.
[0032]
Furthermore, in the above embodiment, the number of lines of the screen pattern is determined only by the print size, but the shape of the drawing object may be taken into account. For example, even when the calculated print size exceeds the “print size in table”, such as a rectangle (2 mm × 200 mm) having an extremely short short side, a screen with a high number of lines may be selected. .
<Second Embodiment>
Next, a second embodiment of the present invention will be described.
[0033]
FIG. 8 is a system configuration diagram illustrating the printing apparatus according to the present embodiment. In the figure, a configuration different from the above-described embodiment is provided with a unit area drawing data buffer 13 instead of the drawing object size recognition unit 9 and a reference difference value table 14 instead of the drawing object size table 11. Furthermore, a unit area drawing data buffer 15 is provided. Other configurations such as the print data receiving unit 1, the print data holding buffer 3, the print data drawing unit 4, and the drawing data transfer unit 7 are the same as those in the above-described embodiment.
[0034]
As described above, the print data receiving unit 1 first holds the print data supplied from the host device 2 in the print data holding buffer 3 for one page. The print data drawing unit 4 sequentially reads out the print data held in the print data holding buffer 3, performs analysis processing, and develops it in the image memory 6.
[0035]
Thereafter, the print data drawing unit 4 performs print processing according to the flowchart shown in FIG. 10, and first determines whether or not there is a print data holding completion notification (step (hereinafter referred to as ST) 1). When there is a print data holding completion notification (YES in ST1), undrawn print data is written into the unit area drawing data buffer 15 for each unit area (ST2). Then, the writing of the unit area drawing data is notified to the screen pattern selection development unit 8 (ST3). Thereafter, the screen pattern selection / development unit 8 waits for a screen pattern data expansion completion notification (ST4).
[0036]
The screen pattern selection / expansion unit 8 performs processing in accordance with the flowchart shown in FIG. 11 and receives the above notification from the print data drawing unit 4 (YES in ST5), notifies the writing of unit area drawing data (ST6). The unit area drawing data write notification is transmitted to the unit area drawing data buffer 13.
[0037]
The unit area drawing data buffer 13 performs processing in accordance with the flowchart shown in FIG. 12, and first determines whether the notification is transmitted from the screen pattern selection / development unit 8 (ST7). A difference value is calculated (ST8). And it compares with the reference | standard difference value registered into the reference | standard difference value table 14 (ST9). As a result, when the maximum difference value is larger than the reference difference value (YES in ST10), it is determined that the variation of the unit area drawing data is large, and selection of a screen pattern having a high number of lines is notified (ST11). On the other hand, if the maximum difference value is smaller than the reference difference value (NO in ST10), it is determined that the unit area drawing data has a small color variation, and a selection of a screen pattern having a low number of lines is notified (ST12).
[0038]
For example, when the unit area drawing data is CMYK 8 bit, 128 pixel × 128 pixel image data, 16384 pixel 128 × 128) is analyzed, and the maximum value and the minimum value are calculated for each CMYK. The difference value is calculated by subtracting the minimum value from the maximum value every time. The largest difference value for each CMYK is set as the maximum difference value. For example, in the example shown in FIG. 13, the difference value 24 of M is the maximum difference value. In the example illustrated in FIG. 14, the Y difference value 17 is the maximum difference value.
[0039]
Here, when the reference difference value stored in the reference difference value table 14 is 20, since the maximum difference value 24 exceeds the reference difference value 20, the unit area drawing data analysis unit 13 uses the screen pattern selection development unit. 8 is notified of selection of a screen having a high number of lines. On the other hand, in the example shown in FIG. 14, the Y difference value 17 is the maximum difference value, the reference difference value stored in the reference difference value table 14 is 20, and the maximum difference value 17 is the reference difference value. Since it is 20 or less, the unit area drawing data analysis unit 13 notifies the screen pattern selection development unit 8 of selection of a screen having a low number of lines.
[0040]
Upon receiving the screen selection information (ST13 is YES (see FIG. 13)), the screen pattern selection / expansion unit 8 selects a corresponding screen from the screen pattern data storage unit 10 based on the information, and the above-described screen pattern. The data is expanded in the data expansion buffer 5 (ST14). Then, the print data drawing unit 4 is notified of the completion of the development of the screen pattern data (ST15).
[0041]
When the print data drawing unit 4 confirms the notification (YES in ST4), the print data is stored in the image memory 6 based on the unit area drawing data table using the screen pattern developed in the screen pattern data development buffer 5. Expand (ST16).
[0042]
Thereafter, it is determined whether or not undrawn print data exists (ST17). If undrawn print data exists (YES in ST17), the above processing is repeated and the drawn data is sequentially developed in the image memory 6. When all undrawn print data has been processed (YES in ST17), the drawing data transfer unit 7 is notified that print data drawing processing has been completed (ST18).
[0043]
The drawing data transfer unit 7 determines the notification according to the flowchart shown in FIG. 7 described above, reads the drawing data from the image memory 6, transfers it to the printer engine 12, and performs printing processing on paper.
As described above, according to the present embodiment, the number of lines of the screen can be automatically changed according to the degree of variation in the color of the data drawn for each unit area. This is done automatically, and regardless of the drawing object, only the advantages of screens with different numbers of lines are reflected, and a printed matter with high image quality can be obtained.
[0044]
In this embodiment as well, as in the first embodiment, a screen pattern selection process may be performed by a printer driver, and the information may be transferred to a printing apparatus. Further, the screen is not limited to two stages, that is, a screen with a high number of lines and a screen with a low number of lines.
[0045]
Furthermore, in the description of the second embodiment, the level of the number of lines of the screen pattern is determined by the maximum difference value. For example, a histogram is calculated for the unit area drawing data, and the standard deviation is referred to. A configuration may be adopted in which the degree of color variation is determined by statistical processing.
[0046]
In addition, the drawing data is expanded in the image memory 6 for each unit area (for example, 128 pixels × 128 pixels). However, the drawing data may be expanded for each pixel. Further, data of a unit area centered on the pixel (for example, 127 pixels × 127 pixels) may be used.
<Third Embodiment>
Next, a third embodiment of the present invention will be described.
[0047]
FIG. 15 is a configuration diagram of a printing system including the printing apparatus according to the present embodiment. In FIG. 1, a personal computer (PC) 20 has functions of an operating system (OS) 21, a printing application 22, and a printer driver 23, and is connected to a printer device (printing device) 24.
[0048]
The print data created based on the application 22 is sent to the printer driver 23 through the operating system 21, and the print data is converted into an intermediate code in the command format by the printer driver 23.
Here, FIG. 16 shows a condition setting dialog for conversion processing by the printer driver 23. There are settings to select dithering for text, graphics, and images. Hereinafter, description will be given with reference to the flowchart shown in FIG.
[0049]
First, the print data created by the application 22 is sent to the printer driver 23 through the operating system 21 as described above. The printer driver 23 first determines a drawing attribute (step (hereinafter referred to as STP) 1). That is, the input print data is classified into three attributes of text, graphic, and image (photo). Note that image data is not subject to dither “automatic” in this embodiment.
[0050]
On the other hand, for graphic data, it is first determined whether or not the dithering setting shown in FIG. 16 is “automatic” (STP2). Here, if it is not “automatic”, the designated dithering process is performed in the same manner as the image (STP3). On the other hand, when “automatic” is set, the next size is determined (STP4). In the case of text data, the same processing as in the case of the graphic data is performed (STP2, STP4).
[0051]
Next, the size can be determined in various ways and distinctions, taking into account the characteristics of the printer hardware, the processing capability of the software, and the like. For example, the character is simply determined by the character size (expressed in points). In this case, when the character is smaller than the preset point, the dither pattern “resolution priority” suitable for expressing the small character is selected (STP5). On the other hand, when the character is larger than a preset point, a dither pattern “gradation priority” suitable for expressing gradation and a wide area with a stable color is selected (STP6).
[0052]
For graphic data, for example, a dither pattern “resolution priority” (STP5) suitable for expressing fine figures and thin lines due to the characteristics of hardware, or a stable hue when painting large figures or large areas. A dither pattern “tone priority” (STP6) suitable for expression is selected.
[0053]
After selecting the dither pattern as described above, printer command conversion processing is performed (STP7), and print data is transmitted to the printer device 24. The printer device 24 performs a printing process in accordance with the print data. At that time, the dither pattern selected by the above-described process is used, and the dithering process is performed by using the optimum dither pattern depending on the size of characters and figures. For example, small characters and figures are easy to see and visibility is high, and large letters and large figures can achieve color printing with excellent gradation and color reproducibility and stability.
[0054]
Note that the flowchart shown in FIG. 18 is a modification of the present embodiment, and the processing will be described below. In this case, text data and image data are not targeted.
As described above, the print data created by the application 22 is sent to the printer driver 23 through the operating system 21. The printer driver 23 determines the drawing attributes (STP1), and the input print data is converted into text, graphics, and images (photographs). Are classified into the following three attributes.
[0055]
Next, it is determined whether or not the graphic data is “automatic” (STP8). If the graphic data is not “automatic”, a designated dithering process is performed as in the case of the image (STP9). Next, the shape of the figure is determined (STP10). This determination is performed on, for example, a line angle (a graphic edge). In general, a dither pattern has an angle (screen angle), and the angle differs for each color or for each type of dither pattern depending on various factors such as hardware characteristics, color characteristics of a color material, and the purpose of color expression. That is, the angle of the line that you are good at depends on the angle of the dither pattern.
[0056]
Therefore, in determining the shape of a graphic, the angle of the edge of the graphic (for example, the angle at which a line is drawn) is determined, the dither pattern type for the angle is preset, and the optimum dither pattern is selected (STP11). , STP12).
The subsequent processing is the same as described above, and printer command conversion processing is performed (STP7), and print data is transmitted to the printer device 24. The printer device 24 performs a printing process according to the print data. At this time, the dither pattern selected by the above-described process is used, and the dithering process is performed using an optimum dither pattern depending on the size of characters and figures.
[0057]
Therefore, by performing the processing as described above, an optimal dither pattern can be selected and the edges of the figure can be expressed smoothly.
[0058]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to prevent the occurrence of jitter and streaks and to perform a printing process that substantially matches the attributes of the drawing object.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of a printing apparatus used in a first embodiment.
FIG. 2 is a diagram illustrating an example of a data configuration registered in a drawing object size table.
FIG. 3 is a flowchart illustrating processing of a print data receiving unit.
FIG. 4 is a flowchart illustrating processing of a print data drawing unit.
FIG. 5 is a flowchart for explaining processing of a screen pattern selection development unit.
FIG. 6 is a flowchart illustrating processing of a drawing object size recognition unit.
FIG. 7 is a flowchart illustrating processing of a drawing data transfer unit.
FIG. 8 is a system configuration diagram of a printing apparatus used in a second embodiment.
FIG. 9 is a diagram illustrating an example of a data configuration registered in a reference difference value table.
FIG. 10 is a flowchart illustrating processing of a print data drawing unit.
FIG. 11 is a flowchart for explaining processing of a screen pattern selection development unit.
FIG. 12 is a flowchart illustrating processing of a drawing object size recognition unit.
FIG. 13 is a diagram illustrating an example of a maximum difference value.
FIG. 14 is a diagram illustrating an example of a maximum difference value.
FIG. 15 is a configuration diagram of a printing system used in the third embodiment.
FIG. 16 is a diagram illustrating a condition setting dialog for conversion processing by a printer driver.
FIG. 17 is a flowchart illustrating a third embodiment.
FIG. 18 is a flowchart illustrating a modification of the third embodiment.
[Explanation of symbols]
1 Print data receiver
2 Host device
3 Print data holding buffer
4 Print data drawing section
5 Screen pattern data expansion buffer
6 Image memory
7 Drawing data transfer unit
8 Screen pattern selection development section
9 Drawing object size recognition part
10 Screen pattern data storage
11 Drawing object size table
12 Printer engine
13 Unit area drawing data buffer
14 Standard difference value table
15 Unit area drawing data buffer
20 Personal computer (PC)
21 Operating System (OS)
22 Printing applications
23 Printer Driver
24 Printer device

Claims (1)

In a printing apparatus that is equipped with a plurality of screens having different numbers of lines, is used while switching the screen, and performs a printing process based on drawing data,
Means for dividing the print data per unit area;
Means for calculating the degree of color variation from the divided print data per unit area;
Means for selecting one of a plurality of screens having different numbers of lines according to the degree of variation in the color;
Means for generating drawing data using the selected screen based on the divided print data per unit area;
A printing apparatus comprising:

Images