JPH05244400A - Binarizing device - Google Patents

Abstract

PURPOSE:To extend plotting by means of a dither pattern at high speed by permitting the dither pattern to be the aggregation of plural submatrixes and permitting the screen angle to be different from the respective matrixes. CONSTITUTION:The dither pattern stored in a dither pattern ROM 5 is the 16X16 dither pattern of the 0 deg. screen angle. Its inside is constituted of 25 sub- matrixes with 14 deg. screen angle. Thus, plotting by the dither pattern is extended at high speed. The dither pattern is the 16X16 sub-matrix dither pattern where the 4X4 sub-matrixes are arranged in 4X 4. The paint-out order of dots inside the respective sub-matrixes is the fatten-type dither matrix. In the meantime, the paint-out order of the dots in the respective sub-matrixes is the bayer-type one. Thus, a binary output picture with high resolution and superior multilevel property is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binarizing device which binarizes multi-valued input data using a dither matrix pattern and outputs the binarized data.

[0002]

2. Description of the Related Art (1) It is generally known that a screen angle is improved in a dither matrix to improve image quality. Particularly, in a color image, Y (yellow) is 0 °, M (magenta) is 45 °, and C (cyan) is 105 °.
It is said that it is good to set the angle K and the black (black) to 15 °. For example, -14 is added to the fatten type dither matrix.
With a screen angle of °, the dither matrix is as shown in FIG.

On the other hand, it is generally known that an image excellent in resolution and gradation can be obtained by using a sub-matrix dither pattern as the dither matrix. FIG. 7 shows an example in which the dither pattern shown in FIG. 6 is changed to a sub-matrix dither pattern.

(2) Conventionally, the dither matrix pattern of this type of binarization device uses an 8 × 8 dither matrix, and the inside of the dither matrix pattern is called a fatten type and bulges in a circular shape from the center as shown in FIG. A dither matrix having an increasing number of dots and a dither matrix called a Bayer type in which dots are filled in a place having the smallest dot density as shown in FIG. 9 are used.

[0005]

However, in the above example (1), since these dither patterns are angled as a whole, it is difficult to calculate the pattern based on the position.

FIG. 10 is a view showing the arrangement of the dither matrisk pattern with the screen corners shown in FIG.

For example, paying attention to the position of the black circle of the dither pattern, the same pattern appears every 34 dots on the same y coordinate, and appears two dots to the left of the y coordinate with a shift of 8 dots.

Therefore, the expression (x + 4y)% 34 (where y is an even number) and (x + 4 (y-1))% 34
(However, y is an odd number) It is necessary to obtain the dither patterns for the black circles and the cross marks.

Further, in the example of (2) above, fatten
In the case of the mold, unless the resolution is sufficiently high, halftone dots forming a circle are conspicuous and only an image with low resolution can be obtained. On the other hand, B
In the case of the ayer type, the filled dot and the density are not in a linear relationship, and the low density part tends to appear darker.
The image will also be rough.

On the other hand, in the dither matrix method, in order to improve the gradation, it is necessary to increase the size of the matrix to increase the number of dots forming the matrix. However, there is a problem that the resolution of is reduced.

As a dither matrix for solving such a problem, a sub-matrix type dither matrix shown in FIG. 11 has been proposed. The system using this dither matrix is a system in which an 8 × 8 dither matrix is decomposed into (4 × 4 sub-matrix) × 4, and resolution is maintained in each sub-matrix and gradation is maintained in all the matrices.

An object of the present invention is to solve the above-mentioned problems, to speed up drawing development using a dither pattern, and to obtain a binary output image having high resolution and excellent gradation. The object of the present invention is to provide a binarization device capable of performing the above.

[0013]

In order to achieve such an object, the present invention provides a binarization device for binarizing multi-valued input data using a dither pattern, wherein the dither pattern has a plurality of sub-matrices. And the screen angle is different from that of the individual sub-matrices.

Further, according to the present invention, in a binarizing device for binarizing multivalued input data by using a dither pattern in which a plurality of matrices are aggregated, each matrix formed by a fatten type dither pattern is a Bayer type. It is characterized in that it is provided with a selection means for sequentially selecting according to a matrix.

[0015]

In the present invention, the dither pattern is a set of a plurality of sub-matrices, and the screen angle thereof is different from that of the individual sub-matrices. Therefore, the drawing development by the dither pattern can be speeded up.

Further, according to the present invention, the individual matrices formed by the fatten type dither pattern are sequentially selected in accordance with the Bayer type matrix, so that a binary output image having high resolution and excellent gradation can be obtained. be able to.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

First Embodiment FIG. 1 is a block diagram of a binarizing device according to a first embodiment of the present invention.

In FIG. 1, reference numeral 1 is a main body. 2 is CP
In U, the overall control is performed according to a program described later. An input buffer 3 temporarily stores input multi-valued data. 4 is a program ROM, CP
A series of control procedures (programs) executed by U2 are stored. 5 is a dither matrix pattern ROM,
A dither matrix pattern for binarization described later is stored. Reference numeral 6 denotes a RAM, which internally includes a bitmap memory 6a for one raster which stores the data binarized by the dither pattern 5 and an x, y address 6b which stores the current coordinate position of the input data. It is used as a work area when the CPU 2 executes a program. 7 is an output buffer, which is a binarized bitmap 6
Output data is temporarily stored when a is output.

As shown in FIG. 2, the dither pattern stored in the dither pattern ROM 5 is a 16 × 16 dither pattern, and the inside is composed of 25 sub-matrices with an angle of about 14 °. However, pattern a
And j, f and o, k and t, p and y, b and u, c and v, d and w, and e and x form one pattern together with the adjacent dither patterns. If excluded, it is composed of 17 sub-matrices.

Thus, in this sub-matrix dither pattern, each sub-matrix has a screen angle of about 14 °, but the overall 16 × 16 dither pattern has a screen angle of 0 °, and each dither pattern has a screen angle of 0 °. The sub-matrixes are constructed so that they are properly combined with the adjacent sub-matrix dithers.

FIG. 3 is a flow chart showing a control program stored in the program ROM 4 shown in FIG.

First, when power is supplied from a power supply (not shown), the x and y addresses 6b of the input data are initialized to 0 in step S1 and the data storage bitmap 6a is cleared to 0. Next, in step S2, the multivalued image data for one pixel is received via the input buffer 3, and in step S3, the x, y address 6 of the input data is received.
The threshold value of the dither pattern 5 corresponding to the position is obtained from b. Since the dither pattern of this embodiment is 16 × 16, it can be easily obtained by calculating x% 16 and y% 16. Next, in step S4, the threshold value thus obtained is compared with the pixel data acquired in step S2. If the comparison result shows that the pixel data is greater than or equal to the threshold value, the process proceeds to step S5. In step S5, x in the bitmap memory 6a for one raster
The bit at the address position is turned ON (1), and step S6
Move to.

On the other hand, if the pixel data is greater than or not equal to the threshold value, the process proceeds to step S6.

In step S6, 1 is added to the x address, and in step S7, the preset image width pixel number is compared with the x address. As a result of comparison, the image width pixel number is x
If it is equal to or larger than the address, step S8
The x address is initialized to 0 and the y address is incremented by 1. Then, the bitmap data 6a for one raster stored in step S9 is output via the output buffer 7, the bitmap memory 6a is cleared to 0, and the process returns to step S2. After that, these flows are repeated.

In this embodiment, the dither pattern is a 16 × 16 matrix having a sub-matrix of about 14 ° with respect to a dither pattern of 0 °, but any combination may be used as long as the angles are different. . However, considering the advantage of the processing speed, the dither pattern is preferably 0 °, and the size is also preferably 16 × 16 or 32 × 32.

Second Embodiment This embodiment is different from the first embodiment in that the dither pattern used and the threshold value calculation method for the dither pattern are different.

In this embodiment, the dither pattern stored in the dither pattern ROM 5 is 4 × as shown in FIG.
This is a 16 × 16 sub-matrix dither pattern in which 4 × 4 4 sub-matrices are arranged, and the filling order of dots in each sub-matrix is a fatten type dither matrix as shown in the upper left of FIG. On the other hand, the filling order of each sub-matrix is a Bayer type of 1-16. The numbers 1 to 16 indicating the order are shown in a circle in FIG. Therefore, the final 16 × 1
The 6-dither pattern is as shown in FIG.

Comparing the control program stored in the program ROM 4 in this embodiment with the control program stored in the program ROM 4 in the first embodiment, only step S3 shown in FIG. 3 is different.

That is, referring to FIG. 5, the threshold value equivalent to the x and y address positions is the value of the dither pattern position of (x% pattern width, y% pattern height), and x = 0, y = If 0, 193, x = 15, y = 3
In the case of 0, 15% 16 = 15, 30% 16 = 14 and (15,14) → 22. The threshold value thus obtained is compared with the pixel data acquired in step S2 in step S4.

In this embodiment, the example in which the dither pattern is a 16 × 16 submatrix type dither pattern having a 4 × 4 submatrix has been described, but the size of the submatrix or the size of the entire dither pattern is not limited. However, for an image of about 300 dpi, each sub-matrix is about 4 × 4, and the dither pattern size is 16 × 1.
By setting the matrix size to 6 or 32 × 32 2 ⁿ (n ≧ 1), the processing speed can be improved and the most preferable image can be output.

In the first and second embodiments, the binarizing device for image data of one color has been described, but it goes without saying that the binarizing device for image data of two or more colors may be used. In that case, the dither patterns of the respective colors may be the same or different.

Further, the binarizing device according to the first and second embodiments may be a single device or a device attached to a CRT, a printer or the like.

Furthermore, in the first and second embodiments, an example in which the binarization process is performed using software has been described, but it may be performed using hardware. In that case, the processing speed is improved.

[0035]

As described above, according to the present invention,
Since the dither pattern is composed of a set of a plurality of sub-matrices and the screen angles of the individual sub-matrices and the dither pattern are set to different angles, there is an effect of speeding up drawing development by the dither pattern.

Further, since the individual matrices formed by the fatten type dither pattern are sequentially selected according to the Bayer type matrix, it is possible to obtain a binary output image having high resolution and excellent gradation. effective.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of a dither matrix according to the first embodiment.

FIG. 3 is a flowchart showing an example of a control program stored in a program ROM 4 shown in FIG.

FIG. 4 is a diagram showing an example of a dither matrix according to a second embodiment.

5 is a diagram showing a final dither pattern of the dither pattern shown in FIG. 4;

FIG. 6 is a diagram showing a conventional example of a fatten type dither matrix with a screen angle of 14 °.

7 is a diagram showing an example in which the dither matrix shown in FIG. 6 is changed to a sub-matrix type dither matrix.

FIG. 8 is a diagram showing a conventional example of a fatten type dither matrix.

FIG. 9 is a diagram showing a conventional example of a Bayer type dither matrix.

FIG. 10 is a diagram showing an arrangement example of the fatten type dither matrix shown in FIG. 6;

FIG. 11 is a diagram showing a conventional example of a sub-matrix type dither matrix.

[Explanation of symbols]

 1 main body 2 CPU 3 input buffer 4 program ROM 5 dither pattern ROM 6 RAM 6a bitmap memory 6b x, y address 7 output buffer

Claims (3)

[Claims] 1. A binarization device for binarizing multi-valued input data using a dither pattern, wherein the dither pattern is a set of a plurality of sub-matrices, and a screen angle thereof is different from the individual sub-matrices. A binarization device characterized by: 2. The binarizing device according to claim 1, wherein the dither pattern itself has a screen angle of 0 °. 3. A binarizing device for binarizing multi-valued input data using a dither pattern in which a plurality of matrices are assembled, wherein individual matrices made of fatten type dither patterns are sequentially selected according to a Bayer type matrix. A binarizing device comprising: