JP2738189B2 - Coordinate conversion method and coordinate conversion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for developing a graphic represented in a logical coordinate system into a bitmap image in a physical coordinate system, and in particular, to reduce errors in the length and position of the graphic developed in a bitmap image. The present invention relates to a coordinate conversion method and a coordinate conversion device.

2. Description of the Related Art In a printer or a display device, an outline font (character representing an outer shape by a line connecting coordinates) represented by a logical coordinate system is developed into a bitmap font represented by a physical coordinate system and then printed. Or display.

When an outline font is developed into a bitmap font, a coordinate value represented by a real number is obtained from the outline font. However, in a bitmap font in which a pixel is a minimum unit, the coordinate value represented by the real number is obtained. Needs to be expressed as an integer value in order to make the pixel unit.

Therefore, when developing a bitmap font, the decimal part of the coordinate value of the real number expression is rounded up, truncated,
Alternatively, rounding processing such as rounding is performed. However, due to this rounding processing, an error corresponding to a decimal part occurs in the coordinate values of the bitmap font. However, errors in the length and position of the figure change the impression of the character, and it is necessary to minimize the errors.

[0005]

2. Description of the Related Art Conventionally, when a logical coordinate value represented by a real number such as a graphic or an outline font is developed into a bitmap image represented by an integer, the logical coordinate value can be represented in a pixel unit of a printer device or a display device. Thus, the decimal part is rounded.

[0006] The most common rounding process is rounding so that a logical coordinate value is represented by the nearest pixel. FIG. 5 is a diagram illustrating an example of a conventional technique.

When the physical coordinate values 0 to 6 are plotted on the horizontal axis, FIG.
As shown in (A), for example, when the logical coordinate value of a figure is represented from 2.5 to 4.2, the logical coordinate value of 2.5 becomes 3 of the physical coordinate value by rounding off and rounding. The logical coordinate value of 4.2 is the physical coordinate value of 4.

Accordingly, as shown in FIG. 5A, the figure is a bitmap image having a width of one pixel. However, the width of the figure specified by the logical coordinate value is 4.2-2.5.
= 1.7, and the error is smaller with a width of 2 pixels instead of 1 pixel.

In a bitmap font developed from an outline font, this error in width changes the impression of a character, so it should be as small as possible. For this purpose, a method as shown in FIG. 5B is employed. That is, first, the logical coordinate value 2.5 of one of the figures is rounded off to obtain the physical coordinate value of 3. Next, the other logical coordinate value of 4.2 is rounded off, but as shown in FIG. 5, an error of 0.5 when one logical coordinate value of 2.5 is rounded off is added to 4.7 and then rounded off. . As a result, the physical coordinate value becomes 5, and the width of the figure becomes 2 pixels as shown in FIG.

[0010] However, although the position of the original figure is closer to the physical coordinate value of 2, it has been moved to the physical coordinate value of 5 by this operation.

[0011]

As described above, according to the conventional method, as shown in FIG. 5A, when each logical coordinate value of a figure is independently rounded, a large error occurs in the length of the figure. As a result, as shown in FIG. 5B, when an operation for reducing the error in the width of the figure is performed, there is a disadvantage that a large error occurs in the position of the figure.

Thus, the conventional disadvantage is that the length of the figure is not preserved or the position of the figure is not preserved. FIG. 6 is a diagram for explaining an error amount according to the related art.

FIG. 6A shows a case where the length of a figure is not stored, and FIG. 6B shows a case where the position of the figure is not stored. When the physical coordinate values 0 to 6 are taken on the horizontal axis, the logical coordinates a represented by the real numbers of the figure shown in FIG. 6A are rounded off and converted to physical coordinates represented by integers. The error is ± 0.5 as shown in FIG.
Similarly, when the logical coordinates b represented by the real numbers of the figure shown in FIG. 6A are rounded off and converted to physical coordinates represented by integers, the rounding error due to the rounding becomes as shown in FIG. As shown in (A), it is ± 0.5 pixel.

That is, in the range shown in FIG. 6A, the logical coordinate a is converted into the physical coordinate 2, and in the range shown in FIG. Is shown. The range shown in FIG. 6A shows the case where the length error is the longest, and the range shown in FIG. 6A shows the case where the length error is the shortest. Since every logical coordinate has the same error, the length of the figure is-=
An error of ± 1.0 pixel occurs.

When the logical coordinates a represented by the real numbers of the figure shown in FIG. 6B are rounded off and converted into physical coordinates represented by integers, the rounding error at this time is as shown in FIG. 6A. Similarly, it is ± 0.5 pixel as shown in the range shown in FIG.

When the logical coordinate b of the figure has a relative distance to the logical coordinate a, as described above, the logical coordinate b is rounded off after the movement amount of the reference logical coordinate a is added. Therefore, the error ± 0.5 pixel of the logical coordinate b has
The rounding error when the error of the reference logical coordinate a ± 0.5 pixel is added and converted into the physical coordinate is shown in FIG.
As shown in the range shown in FIG.

The range shown in FIG. 6B shows the case where the length error is the longest, and the range shown in FIG. 6B shows the case where the length error is the shortest. = ± 0.5 pixels, indicating a small width error.

As described above, in the case of FIG. 6A, there is a problem that an error of ± 1.0 pixel occurs in the length of the figure, and the length of the figure looks largely shifted. In the case of,
There is a problem that an error of ± 1.0 pixel occurs in the position of the figure, and the position of the figure appears to be greatly shifted.

The present invention has been made in view of the above-described problems, and has as its object to provide a coordinate conversion device that prevents a large error in the length and position of a figure.

[0020]

FIG. 1 is a block diagram for explaining the principle of the present invention. The expansion control means 16 calculates a distance L between two coordinates indicating both ends of a line segment forming a graphic read from the graphic storage means 10 on logical coordinates, and calculates the distance L as an integer. A second calculating means 12 for converting the logical coordinates of one of the two coordinates of the line segment into (LL ') / 2
To calculate a physical value of one coordinate of the line segment, and add the integer value L ′ to the calculated physical coordinate value of one coordinate. The line segment is developed on a bitmap memory (15) by using third calculating means (13) for calculating the physical coordinate value of the other coordinate of the line segment, and the calculated physical coordinate value of the two coordinates. (14).

[0021]

With the above arrangement, the length error (L-L ') can be distributed to both coordinates by 1/2, so that the error of one coordinate is ± 0.5 pixel. And an error ± 0.25 due to (LL ′) / 2 is added, resulting in ± 0.75 pixels. The other coordinate error is also ± 0.75 pixels because the length error is evenly distributed. The error in the figure length is ± 0.5 pixel due to the conversion of L into L ′.

Therefore, unlike the conventional method, the error in the length of the figure does not become ± 1.0 pixels, the error in the position does not become ± 1.0 pixels, and the error in the length of the figure does not occur. The error can be reduced by ± 0.25 pixels, and the position error can be reduced by ± 0.5 pixels, so that a coordinate conversion device with a small error in the length and position of the figure can be provided.

[0023]

FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention. Character codes are input to the reception control unit 17 from a higher-level device (not shown), and are sequentially stored in the reception buffer memory 18 under the control of the reception control unit 17. When the character codes for one page are stored, the expansion control unit 20 reads the character codes in the reception buffer memory 18 in accordance with the instruction of the reception control unit 17, and stores them in the outline font storage unit 19.
, An outline font corresponding to the character code is read, and one page of character data is developed on the bitmap memory 15.

That is, the expansion control unit 20 calculates the upper and lower margins on the sheet, the printing position, and the like corresponding to one page of the sheet, and makes the same state as the state printed on the one page of the sheet. The character data is developed on the bitmap memory 15.

At this time, the development control unit 20 determines the coordinates a and b based on the figures forming the character pattern of the outline font read from the outline font storage unit 19, that is, the logical coordinates of the coordinates a and b at both ends of the straight line. Distance L between
Ask for.

Then, an integer value L 'obtained by rounding off the decimal part of the distance L is calculated, (LL-L') / 2 is calculated, for example, added to the logical coordinate value of the coordinate a, and the decimal part is rounded. The obtained integer value is determined as the physical coordinate value of the coordinate a.

Then, an integer value L 'is added to the physical coordinate value of the coordinate a.
Is taken as the physical coordinate value of the coordinate b.
When one character pattern is formed by the set of straight lines obtained in this way, the development control unit 20 associates the physical coordinate values of each coordinate on the character pattern with the print position of the bitmap memory 15. The data is converted into physical coordinate values and developed on the bitmap memory 15.

When the character data for one page is developed on the bitmap memory 15 in this way, the development control unit 20 instructs the print control unit 21 to start printing, and the print control unit 21 15 and reads out the expanded one-page character data, and controls the printing mechanism 22 to perform printing.

FIG. 3 is a diagram for explaining the operation of FIG. As shown in FIG. 3A, for example, the coordinates of the both ends of a straight line are a and b, and the coordinates a
Has a logical coordinate value of 2.5, and the logical coordinate value of the coordinate b is 4.2.
In this case, the distance L between the coordinates a and b obtained by the development control unit 20 is 4.2-2.5 = 1.7.

Therefore, the integer value L 'becomes 2, and (L-
L ′) / 2 = (1.7−2) = − 0.15. Therefore, the physical coordinate value a ′ of the coordinate a is an integer value 2 obtained by rounding 2.5−0.15 = 2.35.

The physical coordinate value b 'of the coordinate b is a'
+ L '= 2 + 2 = 4, and as shown in FIG.
The straight line in FIG. 3A expressed on logical coordinates is expressed as a straight line on physical coordinates.

As a result, the two coordinates of 2.5 and 4.2 on the logical coordinates are converted into the physical coordinates of 2 and 4, and a figure with a small error in length and position can be obtained. FIG. 3B illustrates the error amount of the present embodiment. The rounding error of the coordinates a of the figure is set to ± 0.5 pixel as shown in FIG.
L ′) / 2 adds an error of ± 0.25, resulting in ± 0.75 pixels.

This is the same for the coordinates b.
As shown in the figure, the rounding error is ± 0.75 pixels. The length error is an error of ± 0.5 pixels due to the conversion of L into L ′.

That is, the range shown in the figure is a case where the length error is the longest, and the range shown is a case where the length error is the shortest. FIG. 4 is a flowchart illustrating the operation of FIG.

The expansion controller 20 calculates L = ba in step (1) to obtain the distance between the two coordinates a and b. Then, in step (2), a process L ′ = round (L) for converting a real number into an integer is executed.

Next, in step (3), a = a + (L−L ′) / 2 is calculated to calculate the physical coordinate value of the coordinate a.
Processing to convert real numbers to integers in (4) a '= round
Execute (a).

In step (5), b '= a' + L 'is calculated to calculate the physical coordinate value of the coordinate b.

[0038]

As described above, according to the present invention, since both the length and the position of a graphic represented by the logical coordinate system are converted to the physical coordinate system with a small error, the graphic on the logical coordinate can be accurately converted to the physical coordinate. You can obtain a bitmap image developed in.

Therefore, in the bitmap development of an outline font in which quality is regarded as important, the physical coordinate values at both ends of the straight line forming the character pattern have an error with respect to the position and length indicated by the logical coordinate value. To reduce
It is possible to develop a good character pattern with little disturbance of the outer shape on the bitmap memory. Therefore, there is a great effect.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating the principle of the present invention.

FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention.

FIG. 3 is a view for explaining the operation of FIG. 2;

FIG. 4 is a flowchart illustrating the operation of FIG. 2;

FIG. 5 is a diagram illustrating an example of a conventional technique.

FIG. 6 is a diagram illustrating an error amount according to the related art.

[Explanation of symbols]

 10 figure storage means 11 first calculation means 12 second calculation means 13 third calculation means 14 expansion means 15 bitmap memory 16 expansion control means 17 reception control section 18 reception buffer memory 19 outline font storage section 20 expansion control section 21 Print control section 22 Printing mechanism section

Claims (2)

(57) [Claims] 1. A logical coordinate value represented by a real value of a graphic is converted into a physical coordinate value represented by an integer by converting the logical coordinate value into an integer value, and the graphic is developed as a bitmap image on a bitmap memory (15). In a coordinate conversion device provided with expansion control means (16), the expansion control means (16) obtains a distance L of two coordinates in a figure on a logical coordinate, and converts the distance L into an integer value L ′. Is obtained, and an integer value obtained by adding (LL ′) / 2 to the logical coordinate value of one of the two coordinates into an integer is converted to the physical coordinate value of the one coordinate. And performing a process of setting an integer value obtained by adding the integer value L ′ to the physical coordinate value of the one coordinate as a physical coordinate value of the other coordinate of the two coordinates. Coordinate transformation method. 2. A first calculating means (11) for calculating a distance L on logical coordinates of two coordinates indicating both ends of a line segment forming a figure read from a figure storing means (10); A second calculating means (12) for converting L to an integer to calculate an integer value L ', and adding (LL') / 2 to a logical coordinate value of one of two coordinates of the line segment. A real value is calculated, the real value is converted to an integer to calculate a physical coordinate value of one coordinate of the line segment, and the integer value L ′ is added to the calculated physical coordinate value of the one coordinate to obtain the line. Third calculating means (13) for calculating the physical coordinate value of the other coordinate of the minute, and developing means for developing the line segment on the bitmap memory (15) by using the calculated physical coordinate value of the two coordinates. (14) A coordinate conversion device characterized by having: