JPH08149243A - Print image forming method - Google Patents

Abstract

PURPOSE: To improve the print quality by making original image data a binary image with resolution smaller than print resolution so as to convert binary data of each picture element into a multi-valued processing image corresponding to print resolution and converting the image into a print binary image. CONSTITUTION: Data from an original image data storage area 9 are formed into a binary image with the number of picture elements whose resolution is made mode finner than a print resolution of a laser beam printer 3 by program control by a CPU 10 and expanded in an original image expansion section 14. Then a multi-valued image forming section 15 integrates the binary image data for each matrix corresponding to the print resolution to convert it into a multi-valued image. The multi-valued processed image is converted into a binary image for printing with the same picture element number as that of the same resolution as the print resolution based on the position relation of each of the multi-valued image by a print binary image forming section 16. The image having dot lines at intervals of one picture element added to a line of one picture element by the image data is printed out by a thickness being nearly a multiple of 1.5 of the width of one picture element and very small unevenness is averaged and the print quality is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print image forming method suitable for printing an image of characters, illustrations, etc. output from a word processor or a computer by a printer.

[0002]

2. Description of the Related Art Generally, images such as characters and figures output from a word processor or a computer are printed on plain paper, OHP by various printers such as a thermal printer, an ink jet printer and a laser printer which are used as a kind of output device. It is printed on various recording media such as paper, cardboard, postcards, and Christmas cards.

When characters or figures output from a word processor or a computer are printed by a printer, for example, the printing resolution of the printer is 300 pixels vertically and horizontally.
Assuming DPI (300 pixels per inch), if it is a bitmap font, an image (binary image) consisting of binary data for 300 DPI is prepared in advance, and if it is an outline font, the size of the output character is set. Therefore, a binary image of 300 DPI is formed from the original image data,
If it is a figure, the drawing function can
Form a binary image of DPI. Then, the printer mechanism is controlled based on the binary image so that a print image of 300 DPI is printed on the recording medium.

When the contour of the printed image printed on the recording medium is not smooth and needs improvement, the binary data (black and white information) of the binary image is minute due to the relationship with neighboring pixels. By forming various pixels, a smoothing process for smoothing the contour of the printed image is performed. FIG. 17 shows an example of smoothing processing of a printed image by a conventional laser printer having a printing resolution of 300 DPI.

[0005]

In recent years, printers are required to have high-quality printed images that look more beautiful, and in order to meet such demands, the printing resolution of the printer is further subdivided. ing. That is, the print resolution is subdivided into, for example, the print resolution of 600D.
If it is increased to about PI, when the printed image is viewed with human eyes, the jagged edges of the printed characters and figures cannot be visually recognized, and there is no need to smooth the edges by smoothing processing. Come on.

However, when the printing resolution is increased and the printed characters and figures are of high quality as a whole, this time, the variation in the line width and the line spacing becomes relatively worrisome. This issue will be newly highlighted.

That is, by subdividing the printing resolution of the printer, a binarization error occurs when a binary image is formed, and when the current image shown in FIG. As shown in (a) and (b), or (c) and (d) in 18 (b), the line width and / or line spacing of the printed image cannot be the same, resulting in variations and high-quality printing. There was a problem that an image could not be obtained.

Further, the variation of the line width and / or the line interval of the printed image cannot be prevented in principle by the above-described conventional smoothing process, and more advanced improved process of the printed image is required. .

The present invention has been made in view of these points, and provides a print image forming method capable of preventing variations in line width and line spacing of a print image and improving print quality. The purpose is to

[0010]

In order to achieve the above-mentioned object, the print image forming method of the present invention according to claim 1 is a binary image having the number of pixels obtained by subdividing the original image data of the original image by the print resolution. Then, the binary data of each pixel of this binary image is converted into multivalued data for each matrix corresponding to each pixel of the print image to form a multivalued image, and then the multivalued image is converted into each multivalued image. It is characterized in that it is converted into a printing binary image having the same number of pixels as the printing resolution based on the positional relationship of the pixels.

According to a second aspect of the present invention, there is provided a printed image forming method according to the first aspect, wherein the printing binary image is a multi-valued image binarized by an error diffusion method or a pattern dither method. It has a feature.

According to a third aspect of the present invention, there is provided a print image forming method according to the second aspect, wherein the error diffusion method sets a threshold value for binarization according to a positional relationship of each pixel of a multi-valued image. It is characterized by being variable.

[0013]

According to the print image forming method of the present invention as set forth in claim 1, the original image data is subdivided by the print resolution.
It is developed into a value image, and the binary data of each pixel of this binary image is converted into a multivalued image by converting it into multivalued data for each matrix corresponding to the printing resolution. This multi-valued image is converted into a print binary image having the same number of pixels as the print resolution based on the positional relationship of each pixel of the multi-valued image. In the print image printed by the printer according to the binary image for printing thus formed, the image in which the dotted line of every other pixel is added to the line of one pixel is about 1.5 times the line width of one pixel. In addition to being expressed by the thickness, minute irregularities due to the dotted lines every other pixel are smoothed (averaged) by printing to have a smooth contour, and as a result, the line width and line spacing that exceed the print resolution are exceeded. It is possible to obtain high quality print quality.

According to the print image forming method of the present invention as set forth in claim 2, high quality print quality is obtained by converting a multi-valued image into a binary image for printing by an error diffusion method or a pattern dither method. You can

According to the print image forming method of the present invention described in claim 3, it is possible to obtain higher quality print quality by making the threshold variable.

[0016]

The present invention will be described below with reference to the embodiments shown in the drawings.

First, an embodiment of a system to which the print image forming method according to the present invention is applied will be described with reference to FIG.

FIG. 1 is a system block diagram showing a main part of an embodiment to which a print image forming method according to the present invention is applied.

As shown in FIG. 1, the system 1 of the present embodiment to which the print image forming method according to the present invention is applied has at least a main body 2 such as a word processor or a computer.
And a laser beam printer (LBP) 3 which is a printer as a printing means for recording (printing) graphic information such as characters and illustrations on a recording medium (not shown) such as plain paper, OHP paper and postcards. , Not shown display,
It is composed of various input / output devices such as a keyboard and a mouse.

The main body 2 has at least a CPU 4 and
A main storage device 5 formed of a ROM, a RAM, and other memory (not shown) having an appropriate capacity, an HDD for storing desired basic data, for example, a character font called an outline font, various application programs, and the like. An external storage device 6, a printer control board 7, etc. are arranged.

The main memory 5 is provided with at least a program storage area 8 for storing a control program, an original image data storage area 9 for storing image data of an original image output from the main body 2, and the like.

On the printer control board 7,
At least a CPU 10 and an image memory 11 formed by a ROM, a RAM, other memory, and the like are provided. The image memory 11 is provided with a print program storage area 12 for using at least the original image data formed by the main body 2 as print data, and a data storage area 13 for storing various data.

In the print program storage area 12, at least the original image data developing section 14 for converting the original image data formed in the main body 2 into a binary image having the number of pixels subdivided by the printing resolution, and the subdivision. The pixels of the binarized image are grouped in a matrix unit corresponding to each pixel of the print image so as to have the same number of pixels as the print resolution, and the binary data of each pixel of the above-mentioned binary image (black and white information ) Is converted into multi-valued data to form a multi-valued image, and a multi-valued image forming unit 15 is formed, and printing data having the same number of pixels as the print resolution based on the positional relationship of each pixel of the multi-valued image. And a printing binary image forming section 16 for converting into a printing binary image.

Further, in the data storage area 13, a binary image storage section 17 for storing a binary image having a number of pixels subdivided at least by the print resolution, a multivalued image storage section 18 for storing a multivalued image, A binary print image storage unit 19 for storing a binary print image is provided.

Next, regarding the print image forming method of this embodiment, an LBP of about 64 dots with a print resolution of 600 DPI is used.
An example of printing characters in step 3 will be described with reference to the flowchart shown in FIG.

First, a control command (print command) is issued from the CPU 4 of the main body on the basis of information from an input device (not shown) such as a keyboard and is stored in the program storage area 8 of the main storage device 5. By the control program, original image data such as documents and illustrations formed on a display (not shown) or original image data such as documents and illustrations stored in the external storage device 6 is retrieved from the external storage device 6. And is stored in the original image data storage area 9 of the main storage device 5.

Then, the original image data for printing, which is stored in the original image data storage area 9, is sent to the printer control board 7 by the control program, and the processing by the print image forming method of this embodiment is started.

When the processing by the print image forming method of this embodiment is started, first, in step ST11, the original image data sent to the printer control board 7 is
In response to a control command from the CPU 10 of the printer control board 7, the data is sent to the original image data expansion unit 14, and the original image data expansion unit 14 prints the print resolution (600DP).
In this embodiment, which is subdivided from I), the length and width are 240.
The data storage area 13 is developed (formed) as bitmap data of a binary image of 0 DPI (binary binary data of 0 (white) and 1 (black) of 2400 pixels per inch).
Are sequentially stored in the binary image storage unit 17.

In other words, in the present embodiment, 1 at the time of printing
Pixels are quadrupled in the vertical direction and quadrupled in the horizontal direction for a total of 16
It is subdivided into pixels, and these 16 pixels form a matrix corresponding to the printing resolution. The binary image set to 2400 DPI is shown in FIG.

In the binary image in this embodiment, the original image data is 2400 DP, which is four times as wide as the printing resolution.
Although it is subdivided by I, the subdivision magnification need not have the same aspect ratio, and the magnification may be a real number, and is not particularly limited to the magnification of this embodiment.

Next, in step ST12, the binary image subdivided into 2400 DPI stored in the binary image storage unit 17 is taken into the multi-valued image forming unit 15, and the matrix corresponding to the printing resolution In the embodiment, the density value is 1 when the pixels are divided into 16 pixels vertically and horizontally 4 × 4 in total.
By accumulating the number of pixels having the value of (black), multi-valued data having multi-level grayscale information is formed for each matrix.

In other words, in the present embodiment, 1 at the time of printing
Vertical and horizontal 4 × 4 of 2400 DPI binary image corresponding to pixels
2 with a density value of black (1) for every 16 pixels in total
The density value is 0 (2
Multivalued data composed of multi-level density values having gradations of all 16 pixels of the value image being white (0) to 16 (all 16 pixels of the binary image being black (1)) are formed.

Next, in step ST13, 240
Binary images, which are 0DPI bitmap data, are collected for each matrix corresponding to the above-described printing resolution, that is, for each 16 pixels of 4 × 4 in the present embodiment, and multivalued data is given to each matrix. Thus, a multi-valued image of 600 DPI having the same number of pixels as the printing resolution is formed. This multivalued image is stored in the multivalued image storage unit 18. In other words, in the present embodiment, the pixels decomposed into 2400 DPI are the pixels of 600 DPI which is the same as the printing resolution, and each pixel of 600 DPI has 0 to 16 pixels.
A multi-valued image of 600 DPI to which the multi-level density value of is given is formed. FIG. 4 shows this multi-valued image with 600 DPI.

Next, in step ST14, it is determined whether or not a multi-valued image for one page has been formed. If NO (no multi-valued image for one page has been formed), the process proceeds to step ST12. Return to step ST14 until the determination in step ST14 becomes YES (a multi-valued image for one page is formed).
12 and step ST13 are repeated to repeat the step ST
If the determination in 14 is YES (a multi-valued image for one page is formed), the process proceeds to the next step ST15.

Next, in step ST15, the multi-valued image for one page stored in the multi-valued image storage section 18 is taken into the binary image forming section for printing 16, and the position of each pixel of the multi-valued image is read. Based on the relationship, it is binarized by an error diffusion method or a pattern dither method, which will be described later, and converted into a print binary image as print data of 600 DPI having the same number of pixels as the print resolution, and the print binary image storage unit 19 Memorized in. 600 DPI binarized by this error diffusion method
FIG. 5 shows a binary image for printing of, and FIG. 6 shows a binary image for printing of 600 DPI binarized by the pattern dither method.
For comparison, FIG. 7 shows a printing binary image obtained by processing original image data with conventional 600 DPI.

Next, in step ST16, the printing binary image for one page stored in the printing binary image storage unit 19 is sequentially output to the LBP 3 page by page, and the printing resolution 60
The processing is completed when all characters are printed (recorded) on a recording medium (not shown) with about 64 dots by LBP3 of 0 DPI.

Next, the formation of a printing binary image by binarizing a multivalued image using the error diffusion method will be described in detail with reference to the flowchart shown in FIG.

2 for printing using the error diffusion method of this embodiment
When the process of forming the value image is started, the initial setting for the coordinates (integer coordinates) of the multivalued image is performed in step ST21, the initial setting of the density value D is performed in the next step ST22, and the next step Proceed to ST23.

The initial setting of the coordinates in step ST21 is to set the coordinates in the X direction (horizontal direction) of the multi-valued image to 0 (X =
0) and the coordinate in the Y direction (vertical direction) of the multi-valued image is 0 (Y
= 0). That is, the origin of XY coordinates (X = 0, Y = 0) is formed. The origin of this XY coordinate is the origin for printing.

In the initial setting of the density value D in step ST22, the white of the multivalued data is set to 0 and the black is set to 16
It is performed by setting the multi-stage density value D of ˜16 to 0 (D = 0 (white)).

Next, in step ST23, the density value D of the pixel to be processed in the multi-valued image is set to the initially set density value D.
(X, Y) (D (X, Y) = 0 to 16) is added to obtain a new density value D (D = D + D (X, Y)) for processing.

Next, in step ST24, it is determined whether or not the coordinate X of the pixel to be processed in the multi-valued image is an even number. If the determination in step ST24 is YES (X is an even number), the process proceeds to the next step ST25a. The process proceeds to determine whether the coordinate Y of the pixel to be processed in the multi-valued image is an even number, and step ST25a
If the determination is YES (Y is an even number), the process proceeds to the next step ST26a, and the determination in step ST25a is NO.
If (Y is an odd number), the process proceeds to the next step ST26b. That is, the coordinates (X,
If Y) is a combination of even and even or odd and odd, the process proceeds to step ST26a.

If the determination in step ST24 is NO (X is an odd number), the process proceeds to the next step ST25b,
It is determined whether or not the coordinates Y of the pixels to be processed in the multi-valued image are even, and if the determination in step ST25b is YES (Y is an even number), the process proceeds to the next step ST26b and step S26b.
If the determination in T25b is NO (Y is an odd number), the process proceeds to the next step ST26a. That is, when the coordinates (X, Y) of the pixels to be processed in the multi-valued image are combinations of even numbers and odd numbers or odd numbers and even numbers, the process proceeds to step ST26b.

Next, in step ST26a, the new density value D of the pixel to be processed in the multi-valued image is set to the threshold value 12
It is determined whether or not (D ≧ 12), and step ST26a
If the determination is YES (threshold value 12 or more), the process proceeds to the next step ST27a, in which printing is performed as an output pixel located at the coordinates corresponding to the coordinates (X, Y) of the pixel of the multivalued image. The binary data of the pixel of the binary image is black (1),
The process proceeds to the next step ST28, and the value obtained by subtracting 16 from the density value D is set as a new density value D, and the next step S
Proceed to T29.

If the determination in step ST26a is NO (less than the threshold value 12), the process proceeds to the next step ST27b, where the pixel is located at the coordinates corresponding to the pixel coordinates (X, Y) of the multivalued image. The binary data of the pixel of the binary image for printing as the output pixel is set to white (0), and the next step ST29
Proceed to.

On the other hand, in step ST26b, it is determined whether or not the new density value D of the pixel to be processed in the multi-valued image is equal to or greater than the threshold value 4 (D ≧ 4), and the determination in step ST26b is YES (threshold value). If the value is 4 or more), the process proceeds to the next step ST27a, and 2 of the pixels of the binary image for printing as the output pixel located at the coordinates corresponding to the coordinates (X, Y) of the pixel of the multivalued image. The value data is set to black (1), the process proceeds to the next step ST28, and the value obtained by subtracting 16 from the density value D is set as the new density value D, and the next step ST28.
Proceed to 29.

If the determination in step ST26b is NO (less than the threshold value 4), the process proceeds to the next step ST27b, where the pixel is located at the coordinates corresponding to the coordinates (X, Y) of the pixel of the multivalued image. The binary data of the pixel of the binary image for printing as the output pixel is set to white (0), and the process proceeds to the next step ST29.

Next, in step ST29, the coordinate X
Is added to 1 to set a new X coordinate (X = X + 1), the pixel to be processed next adjacent to the X coordinate of the processed pixel in the X direction is selected, and the process proceeds to the next step ST30.

Next, in step ST30, it is determined whether or not the new X coordinate exceeds the maximum X coordinate, and the determination in step ST30 is NO (the maximum X coordinate is not exceeded).
In this case, the process returns to step ST23, and steps ST23 to ST29 are repeated until the determination in step ST30 becomes YES (exceeds the maximum X coordinate).

If the determination in step ST30 is YES (exceeds the maximum X coordinate), the next step ST31
Then, the coordinate X is set to 0 (X = 0), the process proceeds to the next step ST32, 1 is added to the coordinate Y, and a new Y coordinate (Y
= Y + 1), and proceeds to the next step ST33.

Then, in step ST33, it is determined whether or not the new Y coordinate exceeds the maximum Y coordinate, and the determination in step ST33 is NO (the maximum Y coordinate is not exceeded).
In this case, the process returns to step ST23, and steps ST23 to ST32 are repeated until the determination in step ST33 becomes YES (exceeds the maximum Y coordinate).

If the determination in step ST33 is YES (exceeds the maximum Y coordinate), the process ends.

The threshold value (1
2, 4) may be determined by the design concept based on the number of pixels of the binary image to be subdivided, the size of multi-valued data (the number of sections), the print resolution, the target level of the print quality, and the like. The values are not limited to those in this embodiment.

Further, in the present embodiment, when converting a multi-valued image into a binary image for printing, the threshold value for binarization is made variable depending on the positional relationship of each pixel of the multi-valued image. Is being done. This threshold value is made variable by setting the threshold value to a constant value when the image for printing the figure to be drawn is positioned at the intermediate position of the print pixels as shown in FIG. 9A. , A case where a binary image for printing is shown in FIG. 9B depending on the size of the figure and the phase with the pixel.
(Bad example) and Case B shown in (c) of FIG. 9 (Good example)
One of the two forms will be taken. At this time, in the case B, the printed image printed on the recording medium is smoothed, so that there is no problem. However, in the case A, the printed image is printed on the recording medium. The image becomes a broken line, which is not preferable.

Therefore, in the present embodiment, when converting a multi-valued image into a binary image for printing, the position (coordinate) of each pixel of the multi-valued image is an even number with respect to the abscissa (X coordinate). In the table below, depending on the combination of even and odd numbers for the abscissa and ordinate, as shown in the table below, which is an odd number and which is an even number or an odd number for the ordinate (Y coordinate) The control is performed so that the case B is always performed by lowering the threshold value and raising the threshold value in the case of (a) in the table below.

[0056] In the error diffusion method, the control of the threshold value is as shown in FIG.
Step ST24 to Step S of the flowchart shown in
It is provided by T26.

Next, the formation of a binary image for printing by binarizing a multivalued image using the pattern dither method will be described with reference to FIG.
This will be described in detail with reference to the flowchart shown in FIG. In addition,
In the case of the pattern dither method, the size of the pixel matrix used is 4 pixels vertically and horizontally 2 × 2, 1 vertically and horizontally 4 × 4.
Although various types such as 6 pixels and 64 pixels of 8 × 8 in length and width can be considered, in the present embodiment, description will be made assuming that a pixel matrix of 2 × 2 in length and width is used.

When the process of forming the binary image for printing using the pattern dither method of this embodiment is started, step S
At T51, the initial setting for the coordinates (integer coordinates) of the multivalued image is performed, and the process proceeds to the next step ST52.

The initial setting of the coordinates in step ST51 is to set the coordinates in the X direction (horizontal direction) of the multi-valued image to 0 (X =
0) and the coordinate in the Y direction (vertical direction) of the multi-valued image is 0 (Y
= 0). That is, the origin of XY coordinates (X = 0, Y = 0) is formed. The origin of this XY coordinate is the origin for printing.

Next, in step ST52, it is determined whether or not the coordinate X of the pixel to be processed in the multi-valued image is an even number. If the determination in step ST52 is YES (X is an even number), the process proceeds to the next step ST53. Coordinate Y of the pixel to process and process
Is an even number, and the judgment in step ST53 is YES.
If (Y is an even number), the process proceeds to the next step ST54, the threshold value S is set to 3 (S = 3), and the next step S
Proceed to T59.

When the determination in step ST53 is NO (Y is an odd number), the process proceeds to the next step ST55, the threshold value S is set to 10 (S = 10), and the next step ST59
Proceed to.

On the other hand, the determination in step ST52 is NO.
If (X is an odd number), the process proceeds to the next step ST56, and it is determined whether or not the coordinate Y of the pixel to be processed is an even number. If the determination in step ST56 is YES (Y is an even number),
Next, in step ST57, the threshold value S is set to 14 (S
= 14), and proceeds to the next step ST59.

If the determination in step ST56 is NO (Y is an odd number), the process proceeds to the next step ST58, the threshold value S is set to 7 (S = 7), and the process proceeds to the next step ST59.

Next, at step ST59, whether the value of the density value D (X, Y) of the pixel (X, Y) to be processed in the multivalued image is greater than or equal to the threshold value S (D (X, Y) ≧ S). , More specifically, the combination of the coordinate X and the coordinate Y of the pixel to be processed is
When X and Y are even numbers, the threshold value S = 3 or more (D ≧
S = 3), if X is even and Y is odd, threshold S = 10 or more (D ≧ S = 10); if X is odd and Y is even, threshold S = 14 or more (D ≧ S =
14), if X and Y are odd, it is judged whether the threshold value S = 7 or more (D ≧ 7), and step ST
If the judgment in 59 is YES (greater than or equal to the threshold value), the process proceeds to the next step ST60a, in which printing is performed as an output pixel located at the coordinates corresponding to the coordinates (X, Y) of the pixel of the multivalued image. The binary data of the pixel of the binary image is set to black (1),
Then, the process proceeds to next step ST61.

If the determination in step ST59 is NO (less than the threshold value), the process proceeds to the next step ST60b, and the output located at the coordinates corresponding to the coordinates (X, Y) of the pixel of the multivalued image is output. The binary data of the pixel of the binary image for printing as a pixel is set to white (0), and the process proceeds to the next step ST61.

Next, in step ST61, the coordinate X
Is added to 1 as a new X coordinate (X = X + 1), and the next pixel to be processed next to the X coordinate of the processed pixel in the X direction is selected, and the process proceeds to the next step ST62.

Next, in step ST62, it is determined whether or not the new X coordinate exceeds the maximum X coordinate, and the determination in step ST62 is NO (the maximum X coordinate is not exceeded).
In the case of, the process returns to step ST52, and steps ST52 to ST62 are repeated until the determination in step ST62 becomes YES (exceeds the maximum X coordinate).

If the determination in step ST62 is YES (exceeds the maximum X coordinate), then step ST63
The coordinate X is set to 0 (X = 0), the process proceeds to the next step ST64, 1 is added to the coordinate Y to obtain a new Y coordinate (Y = Y + 1), and the process proceeds to the next step ST65.

Next, in step ST65, it is determined whether or not the new Y coordinate exceeds the maximum Y coordinate, and the determination in step ST65 is NO (the maximum Y coordinate is not exceeded).
In this case, the process returns to step ST52, and steps ST52 to ST65 are repeated until the determination in step ST65 becomes YES (exceeds the maximum Y coordinate).

If the determination in step ST65 is YES (exceeds the maximum Y coordinate), the process ends.

The value (3, 10, 14, 7) of the threshold value S in this embodiment is the number of pixels of the binary image to be subdivided, the size of multi-valued data (the number of sections), the printing resolution, It may be determined based on the design concept based on the target level of print quality, etc., and is not particularly limited to the value of this embodiment.

Further, in the present embodiment, the error diffusion method and the pattern dither method have been exemplified in the case of converting a multi-valued image into a binary image for printing. The error diffusion method is superior to the pattern dither method, and regarding the processing speed, the pattern dither method is superior to the error diffusion method, and which method to select is based on the target level of print quality, the processing speed, etc. , It may be decided according to the design concept.

As described above, according to the printing binary image using the print image forming method of this embodiment, the current image of the straight line is one straight line as shown in FIG. It is formed in any form of one straight line and a combination line in which dotted lines for every other pixel are combined. When this binary image for printing is printed by LBP3 having a printing resolution of 600 DPI, one line is formed for each pixel as shown in FIG. 11 (b).
A binary image for printing, which is composed of a combination line to which a dotted line for every pixel is added, is expressed with a thickness of about 1.5 times the line width of one pixel, and minute unevenness due to a dotted line for every pixel is printed. Smoothed (averaged), resulting in 600D
It is possible to obtain a print quality with a line width and / or line spacing corresponding to 1200 DPI, which exceeds the print resolution of PI. Even if such a smoothed print image is enlarged, a smooth contour is formed as shown in FIG. 11C, and a high-quality print image exceeding the print resolution can be surely obtained. be able to. That is, according to the present embodiment, it is possible to reliably obtain a high-quality printed image having a smooth contour and higher than the printing resolution without improving the printing resolution.

FIG. 12 (a) shows the case of using the error diffusion method in the print example of printing with the LBP3 having the print resolution of 600 DPI using the print image forming method of the present embodiment. An enlarged version of the character "Beauty" in the print example is shown in FIG. 13, a print example using the pattern dither method is shown in FIG. 12B, and a "Beauty" print example in the case of using the pattern dither method. FIG. 14 shows an enlarged version of the letters. For comparison, a print example of printing with a 600 DPI LBP (not shown) according to the conventional print image forming method is shown in FIG.
Print examples printed with 00DPI LBP (not shown) are shown in (d) of FIG. 12, and enlarged characters of “Beauty” in these print examples are shown in FIGS. 15 and 16.

In the present embodiment, the case of printing characters has been described. However, not only characters, but also illustrations and drawn figures, and binary figures subdivided by the scanning resolution by the scanner and captured. Can of course also be applied.

Further, although the present embodiment has been described by using the configuration in which the image data is processed by the printer control board 7, in the present invention, such a printer control board 7 is not used and a printing program is used. It is also possible to store the above in the main storage device 5 and to perform all processing of various image data by the CPU 4 of the main body 2.

Furthermore, in this embodiment, the LBP3 having a print resolution of 600 DPI is used as the printer, but the printer may be a thermal printer such as a thermal transfer printer. Normally, this thermal printer has been conventionally subjected to energization history correction in order to avoid the effect of heat accumulation in the thermal head. However, by adjusting the conditions of this energization history correction, the printed image The smoothness of the contour can be further enhanced.

Further, the smoothing of the contour of the printed image using the printed image forming method of the present embodiment is performed when the fine unevenness is averaged by the printing and the fine unevenness cannot be discriminated by the naked eye due to the printing. It becomes effective with print resolution exceeding either of them. The effective print resolution varies depending on the type of printer (printing method), but the print resolution is about 400 to 800 DPI or more in the laser beam printer and 600 D in the thermal transfer printer.
The print resolution is 400 DP or more, since it is about PI or more and bleeding occurs after printing in an inkjet printer.
It is about I or more.

The present invention is not limited to the above embodiment, but can be modified as necessary.

[0080]

As described above, according to the print image forming method of the present invention, it is possible to surely obtain a high-quality print image having a smooth contour and higher than the print resolution without improving the print resolution. That is an extremely excellent effect.

[Brief description of drawings]

FIG. 1 is a system block diagram showing a main part of an embodiment to which a print image forming method according to the present invention is applied.

FIG. 2 is a flowchart showing an embodiment of a print image forming method according to the present invention.

FIG. 3 is an explanatory diagram showing a binary image subdivided from the print resolution formed by the print image forming method according to the present invention.

FIG. 4 is an explanatory diagram showing a multi-valued image having the same resolution as the print resolution formed by the print image forming method according to the present invention.

FIG. 5 is an explanatory diagram showing a binary image for printing, which is binarized by the error diffusion method of the printed image forming method according to the present invention.

FIG. 6 is an explanatory view showing a binary image for printing, which is binarized by the pattern dither method of the printed image forming method according to the present invention.

FIG. 7 is an explanatory diagram showing a binary print image formed by a conventional print image forming method.

FIG. 8 is a flowchart showing an error diffusion method of a print image forming method according to the present invention.

9A to 9C are diagrams for explaining the reason why the threshold value for binarizing the print image forming method according to the present invention is variable, and FIG. 9A shows the image to be drawn. Explanatory diagram showing, (b) explanatory diagram showing a bad example, (c) explanatory diagram showing a good example

FIG. 10 is a flowchart showing a pattern dither method of a print image forming method according to the present invention.

11 (a) to 11 (c) show a printing binary image and a printing example by the printing image forming method according to the present invention, and FIG. 11 (a) shows the contents of printing two image data. FIG. 6B is an explanatory diagram showing an example of printing at 600 DPI,
(C) is an enlarged view of (b)

12A to 12D show examples of printing, FIG. 12A is an explanatory diagram showing an example of printing by an error diffusion method of a printed image forming method according to the present invention, and FIG. FIG. 6C is an explanatory view showing an example of printing by the pattern dither method of the print image forming method according to FIG.
Explanatory diagram showing a printing example of 00 DPI, (d) Explanatory diagram showing a printing example of 300 DPI by the conventional print image forming method

FIG. 13 is an enlarged view in which the character “Beauty” in the print example shown in FIG. 8A is enlarged.

FIG. 14 is an enlarged view in which the character “Beauty” in the print example shown in FIG. 8B is enlarged.

FIG. 15 is an enlarged view in which the character “Beauty” in the print example shown in FIG. 8C is enlarged.

FIG. 16 is an enlarged view in which the character “Beauty” in the print example shown in FIG. 8D is enlarged.

FIG. 17 is an explanatory diagram showing an example of smoothing processing of a print image by a conventional laser printer having a print resolution of 300 DPI.

18A and 18B are diagrams for explaining a binarization error by a conventional print image forming method, FIG. 18A is an explanatory diagram showing a current image, and FIG. 18B is a conventional print image forming method. Explanatory diagram showing the binarization error by the method

[Explanation of symbols]

 1 System 2 Main Body 3 Laser Beam Printer (LBP) 4 CPU 5 Main Storage Device 6 External Storage Device 7 Printer Control Board 10 CPU 11 Image Memory 12 Print Program Storage Area 13 Data Storage Area

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Claims (3)

[Claims] 1. An original image data of an original image is made into a binary image having a number of pixels subdivided from a printing resolution, and binary data of each pixel of this binary image is multi-valued for each matrix corresponding to each pixel of the printed image. A multi-valued image is formed by converting it into value data, and then the multi-valued image is converted into a printing binary image having the same number of pixels as the printing resolution based on the positional relationship of each pixel of the multi-valued image. A method for forming a printed image. 2. The printed image forming method according to claim 1, wherein the binary image for printing is binarized from a multi-valued image by an error diffusion method or a pattern dither method. 3. The print image forming method according to claim 2, wherein in the error diffusion method, a threshold value for binarization is variable depending on a positional relationship of each pixel of a multivalued image. .