JPH04250496A - data conversion device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data conversion device for converting outline data into bitmap data.

0002

2. Description of the Related Art Conventional data conversion devices of this type read outline data corresponding to a character code input from a host from a storage device, and convert the read outline data into bitmap data of a font size specified by the host. There is something to convert to. The converted bitmap data is output to an output device such as a laser printer. The conversion process of the conventional data conversion device will be briefly explained below.

As is well known, outline data consists of line elements in which the outline of a character is divided into a plurality of sections. The data includes type data indicating whether each line element is a straight line or a curve, the coordinate values of the start and end points of the line element, and if the line element is curve data and a Bezier curve, the coordinate values of the control point in addition to the start and end points. , if the line element is curve data and an arc, there are coordinate values of the auxiliary point in addition to the start point and end point. In the conversion process, first, the coordinate system data of this outline data is modified to be enlarged or reduced according to the specified font size. Next, by expanding the modified outline data using a predetermined function, a plurality of internal points existing on the outline of the character of the specified font size are created. Bitmap data is then created according to a predetermined procedure based on vector data in which internal points are connected by straight lines.

0004

[Problems to be Solved by the Invention] The conventional data conversion device described above uses outline data to output characters in a specified font size beautifully, but the computational processing load of developing the curve data of the outline data into a Bezier curve, circular arc, etc. There was a problem that the conversion process was large and took a long time.

The data conversion device of the present invention aims to shorten the time required for conversion processing.

[0006]

Means and Effects for Solving the Problems As illustrated in FIG. 1, the data conversion device of the present invention converts character outline data into bitmap data of a predetermined font size. and a size determining means for determining the size relationship between the font size and a reference size, and when the size determining means determines that the font size is larger than the reference size, the outline data is expanded based on a predetermined function to determine the size of the font size. internal point creation means for calculating an internal point on the outline; and internal point simplification for determining the outline data as an internal point on the outline of the font size when the font size is determined to be less than a reference size by the size determining means. creating means, vector generating means for generating a vector connecting the internal points created by the internal point creating means or the internal point simple creating means, and bitmap data of the font size from the vector generated by the vector generating means. and bitmap data creation means for creating a bitmap data.

In the data conversion device having the above configuration, when the size determining means determines that the font size is larger than the reference size, the internal point creating means expands the outline data based on a predetermined function to create an outline of the font size. Calculate the interior points above. On the other hand, if the size determining means determines that the font size is less than the reference size, the internal point simple creation means sets the outline data as an internal point on the outline of the font size. The vector generating means generates a vector that connects the internal points created by the internal point generating means or the internal point simple generating means. Then, the bitmap creation means creates bitmap data from the generated vector. That is, if the font size is smaller than the reference size, the process of developing the outline data into Bezier curves, circular arcs, etc. is omitted, and the outline data is converted into bitmap data. As a result, the load on calculation processing is reduced when viewed from the overall usage state in which various font sizes are used, and the average conversion processing time is shortened.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A data conversion apparatus used in a laser printer will be described below as an embodiment of the data conversion apparatus of the present invention.

A block diagram of FIG. 2 shows a portion of the laser printer control circuit relating to data conversion. The microcomputer section 1, which constitutes the main body of the control circuit, includes a CPU 3,
It includes a character ROM 5, a program ROM 7, a text memory 9, a working memory 11, a short vector data memory 13, and a bitmap data memory 15. These CPUs 3 and the like are connected by a bus 17. An input device 19 and a printing unit 21 are connected to the bus 17 . The input device 19 inputs necessary data to the microcomputer section 1. The printing section 21 is the microcomputer section 1
Printing is performed using a laser printing method based on instructions from the printer. From a functional perspective, the CPU 3 realizes a conceptual configuration of a data reading unit 23, a function expansion unit 25 that performs function expansion of outline data, a data conversion unit 27 that converts outline data into bitmap data, etc., as shown in FIG. do. The text memory 9 stores character data consisting of code data input from the input device 19. Working memory 11 temporarily stores data required when executing a program. The short vector data memory 13 stores short vector data obtained by the function expansion section 25. The bitmap data memory 15 stores bitmap data obtained by the data converter 27. The character ROM 5 stores outline data of characters such as alphabets and other characters and symbols.

The data conversion process executed by the CPU 3 will be explained below with reference to the flowchart shown in FIG. C.P.
When U3 starts the data conversion processing routine shown in FIG. 4, first, outline data representing the outline of the character is read from the character ROM 5 in accordance with the character data stored in the text memory 9 (S100). Next, it is determined whether the font size specified by the input device 19 is larger than a reference value (S110). The reference value in the example is 12 points.

[0011] If it is determined that the font size is larger than the reference value (S110), expansion processing (S120) is performed. In the expansion process (S120), the outline data is corrected according to the font size, and a function that defines the curve of the corrected outline data is expanded using a known method.
Find the interior points between the start and end points of the curve. The expansion process (S120) will be briefly explained below.

As described above, the outline data is composed of straight and curved line elements. Straight line data is defined by the coordinate values of the start point and end point, and curves are defined by various values depending on the type of curve. Curves often used for outline data include Bezier curves and circular arcs. For example, the Bezier curve is shown in Figure 5 (A
), as shown in curve 1, a set of data consisting of a start point P1, end point P2, and control points Q1, Q2; as shown in curve 2, data of a set consisting of a start point P2, end point P3, and control points Q3, Q4. Defined by

[0013] An internal point between the starting point P1 and the ending point P2 (Fig.
The coordinate values of (indicated by a "+" mark in (B)) are determined by the following equation. Note that the coordinate values of internal points between the starting point P2 and the ending point P3 can also be determined using the same formula.

B(t)=(1-t)3P1+3(1-t)2tQ1+
3(1-t)t2Q2+t3P2 Also, the arc has a starting point P as shown in curve 1 in Figure 6(A).
1. End point P2 and auxiliary point A1 (point set on the arc)
As shown in curve 2, starting point P2,
It is defined by a set of data consisting of the end point P3 and the auxiliary point A2. An internal point between the starting point P1 and the ending point P2 (Fig. 6 (B
The coordinate values of ) (indicated by a "+" mark in ) can be obtained by determining the radii r1 and r2 of the circular arc from the following equation, as shown in FIG. Note that an internal point between the starting point P2 and the ending point P3 can also be found using the same formula.

r1=d/(sinθ1+α×sinθ2)r2=α×
r1 where d is the distance between P1 and P2.

[0016] Also, α=(1-cosθ1)/(1-c
osθ2). As explained above, if it is determined that the font size is larger than the reference value (S110), a development process (S120) is executed and internal points are determined based on the outline data. Then, Fig. 5(B), Fig. 6(
As shown in B), short vector data is generated by connecting the determined internal points with straight lines (S130).

On the other hand, if it is determined that the font size is less than the reference value (S110), the above-mentioned expansion process (S110) is performed.
120), short vector generation is executed as follows (S130). That is, when the curve is a Bezier curve as shown in FIG.
), the internal points are connected in order to generate short vector data. When the curve is an arc as shown in FIG. 6(C), the starting point P1, auxiliary point A1, and end point P2 are set as internal points, and the internal points are connected in order as shown in FIG. 6(D) to create a short vector. Generate data.

As described above, if the font size is larger than the standard value (S110), the expansion process (S120) is executed to generate short vector data (S130), and if the font size is less than the standard value (S110), the expansion process is executed. Short vector data is generated (S130) by omitting the process (S120).

Next, a bitmap data creation process (S140) is executed to create bitmap data from the short vector data using a known method. The concept of the bitmap data creation process (S140) will be briefly explained below. FIG. 8 shows a pixel screen assumed to correspond to the printing surface of printing paper. Note that FIG. 8 shows only one pixel screen for one character for convenience of explanation. The pixel screen is partitioned into a grid pattern by pixel partition lines p, defining pixels in a matrix pattern. The intersection of the X-direction defining line x and the Y-direction defining line y, which are set parallel to the X-axis direction and the Y-axis direction, passes through the center point of each pixel. Conceptually, bitmap data is created by superimposing the outline of a character converted into a short vector onto this pixel screen. Then, for example, the bit data of each pixel existing inside the character outline superimposed on the pixel screen is set to a value of 1 (indicating that a dot is formed on the printing surface). At the boundary of the character outline, a portion of the pixels are inside the character outline, but in this embodiment, all bit data of pixels whose center point is inside the character outline are set to the value 1. In this way, bitmap data is created in which each pixel of the pixel screen is set with whether the bit data has a value of 1 or not.

According to the data conversion apparatus described above, bitmap data is created by omitting development processing for font sizes below the standard value, so the time required for conversion processing of data with font sizes below the standard value is extremely reduced. This has the effect of shortening the time. Moreover, the standard value is 12 points, so the quality deterioration of bitmap data obtained by omitting expansion processing is not so noticeable, and since 12 points is a frequently used size, various font sizes can be used. When viewed from the overall usage status, the actual conversion processing time is significantly reduced.

Although the embodiments of the present invention have been described above,
The present invention is not limited to these embodiments in any way, and it goes without saying that the present invention can be implemented in various forms without departing from the scope of the present invention, such as being applied to various types of printers other than laser printers.

[0022]

Effects of the Invention As detailed above, according to the data conversion device of the present invention, bitmap data is created by omitting outline data expansion processing for font sizes smaller than the standard size, so that average data conversion processing is possible. This has the effect of shortening the time required.

[Brief explanation of the drawing]

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

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

FIG. 3 is an explanatory diagram conceptually showing the functions of a CPU.

FIG. 4 is a flowchart showing a data conversion processing routine executed by the CPU.

FIG. 5 is an explanatory diagram showing how internal points are determined when the curve is a Bezier curve.

FIG. 6 is an explanatory diagram showing how to find internal points when the curve is an arc.

FIG. 7 is an explanatory diagram showing how an arc is expanded.

FIG. 8 is an explanatory diagram showing how bitmap data is created.

[Explanation of symbols]

1... Microcomputer section 3... CPU P1, P2, P3... Curve starting point and ending point Q1, Q2,
Q3, Q4...Control points of Bezier curve A1, A2...Auxiliary points of circular arc

Claims (1)

[Claims] 1. A data conversion device for converting outline data of a character into bitmap data of a predetermined font size, comprising: size determining means for determining the size relationship between the font size and a reference size; If the size is determined to be larger than the reference size, internal point creation means calculates an internal point on the outline of the font size by expanding the outline data based on a predetermined function, and the size determination means determines the font size. is determined to be smaller than the reference size, an internal point simple creation means for making the outline data an internal point on the outline of the font size, and an internal point created by the internal point creation means or the internal point simple creation means. A data conversion device comprising: vector generation means for generating concatenated vectors; and bitmap data generation means for generating bitmap data of the font size from the vectors generated by the vector generation means.