JPH04373082A - Character generator - Google Patents

Abstract

PURPOSE:To process characters with high quality at high speed by executing both the processing of executing curve transformation after affine transformation and the processing of executing the affine transformation after the curve transformation. CONSTITUTION:Input font data 14 are processed by an affine transformation block 2 or a curve interpolation block 3. In that case, when outputting characters in a small size in comparison with a source outline font data size, the character quality is improved by executing the affine transformation after executing the curve interpolation. Reversely when outputting large characters, processing time can be considerably shortened by executing the curve interpolation after executing the affine transformation.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a character generation device that performs coordinate transformation calculations on character outline data expressed in vector format by affine transformation or curve interpolation, and then converts the data into raster format data and outputs the data. Regarding.

0002

[Prior Art] As a method for outputting characters of multiple character sizes, rotated characters, italic characters, etc., coordinates on the outline of character data are stored in a ROM or external storage device as a character font, and affine transformation is performed according to the specified output size. There is a method that performs coordinate transformation calculations and outputs them. In addition, in order to output the curved lines of characters beautifully, there are some that use curved interpolation to convert the coordinates to coordinates on the curved line and output them.

FIG. 9 is a block diagram of a conventional character generation device, in which a character generation LSI, OFP (outline font processor). Although not particularly limited, each circuit block surrounded by a solid line in the figure is formed on one semiconductor chip using well-known semiconductor integrated circuit technology. Here, the OFP 27 connects the host interface 28, the font input FiFo 29 inside the host interface, and the affine transformation block 3.
0, FiFo31, curve interpolation block 32, FiFo3
3, a line generation block 34, a dot memory 35, a fill-in BitBLT block 36, and a page memory interface 37. From the host interface 28, an address bus connected to the system bus,
Data bus and control signal group are output. Internal data bus 38 is connected to the system data bus. Also,
From the page memory interface 37, an address bus, a data bus, and a data bus are connected to the page memory controller.
A control signal group is output. In OFP, after a coordinate transformation operation by affine transformation, a coordinate transformation operation is performed on coordinates on a curve by curve interpolation.

[0004] It should be noted that the patent application No. 2-1 filed earlier by the present applicant
No. 19052, "Character Generator" 32900004 describes a character generator having a coordinate conversion function using affine transformation and curve interpolation.

[0005]

In the conventional character generating device described above, as shown in FIG. 9, after a coordinate transformation operation by affine transformation, a coordinate transformation operation is performed for coordinates on a curved line by curve interpolation. FIG. 8 shows how curve coordinate data of input outline font data is converted to coordinate data on a curve. The curve is a cubic Bezier curve,
The curve coordinate data representing one curve is the starting point (x1, y1),
Control point (x2, y2), control point (x3, y3), end point (
x4, y4). A curve is defined from the positional relationship of these four coordinate points, and coordinate data on the curve is newly generated.

First, let us consider the case where curve interpolation is performed after affine transformation as in the past. FIG. 8(a) is
This is a curve 23 shown by the original outline font data.

When outputting small characters, the curve coordinate data is (x1', y1'), (
x2', y2'), (x3', y3'), (x4', y
4') is affine transformed. At this time, since the coordinates are transformed from the mesh size where the original font was created to a smaller mesh size, the shape of the curve 25 is distorted with respect to the original curve 23 due to quantization error, which is caused by curve interpolation. The coordinate data 25p on the curve 25 is
Decrease character quality.

When outputting large characters, the curve coordinate data is (x1', y1'), (
x2', y2'), (x3', y3'), (x4', y
4') is affine transformed. At this time, the coordinates are transformed from the mesh size where the original font was created to a larger mesh size, so the quantization error can be ignored.
The shape of the curve 26 is not distorted with respect to the original curve 23, but on the contrary, unless a large number of coordinate data on the curve 26 are generated, character quality will deteriorate.

Next, consider the case where affine transformation is performed after curve interpolation.

When outputting small characters, as shown in FIG. 8(a), curved coordinate data (x1, y
1), (x2, y2), (x3, y3), (x4, y4
) to generate coordinate data 23p on the curve 23. These are on the curve in the original font data, so
Coordinate data 24p on the curve 24 after affine transformation
Even if it is converted to , the character quality will not be significantly degraded.

When outputting large characters, similarly, a large amount of coordinate data on the curve 23 is generated by curve interpolation, and converted to coordinate data 26p on the curve 26 by affine transformation. At this time, since affine transformation is performed on all coordinate data generated by curve interpolation, processing time is longer than when affine transformation is performed only on curve coordinate data.

That is, in order to improve character quality and processing speed, when outputting small characters, perform curve interpolation and then perform affine transformation, and when outputting large characters, perform affine transformation. After that, it is necessary to perform curve interpolation.

An object of the present invention is to provide a character generation method and apparatus suitable for LSI.

Another object of the present invention is to provide a character generation method and apparatus capable of switching the processing order of affine transformation and curve interpolation with a small circuit scale that can be implemented in LSI.

[0015]

[Means for Solving the Problems] In order to achieve the above object, a character generating device according to the present invention has an affine transformation block that performs affine transformation and a curve interpolation block that performs curve interpolation. Interpolation processing and affine transformation processing after curve interpolation are executed by switching buses without changing the contents of each block.

In the character generator, a signal for switching whether to perform affine transformation and then curve interpolation, or curve interpolation and then affine transformation, has one bit in the switching register. It is intended to make it possible to

In a character generator, a signal for switching between performing affine transformation followed by curve interpolation or curve interpolation followed by affine transformation can be easily generated according to the input information. This is generated by a control circuit.

[0018]

[Operation] According to the above-mentioned means, original outline font data can be restored by switching between two processes: affine transformation followed by curve interpolation and curve interpolation followed by affine transformation. When outputting characters that are small compared to the size, an improvement in character quality can be expected because affine transformation is performed after curve interpolation. Furthermore, when outputting large characters, curve interpolation is performed after affine transformation, so processing time can be significantly shortened. That is, it is possible to output high-quality characters at high speed according to the output character size. Furthermore, by switching the bus without changing the contents of the affine transformation block and the curve interpolation block, the scale of the entire character generator is not increased, making it suitable for LSI implementation.

Furthermore, the signal for switching between the two processes is
By providing one bit in the switching register, the user can set the switching between the two processes according to the character output size.

[0020] Furthermore, the signal for switching between the two processes is based on preset input information, such as output character size and affine matrix data in affine transformation.

[0021]

[Math. 1] x'= ax+by+e

(Affine transformation formula) y
'= cx+dy+f
......(1) Here, a
, b, c, d, e, f: are generated from affine matrix data using a simple control circuit, so that switching can be performed automatically without the user having to set a switching signal again.

[0022]

EXAMPLES Examples of the present invention will be described in detail below.

FIG. 1 shows a block diagram of affine transformation and curve interpolation of a character generator to which the present invention is applied. In addition,
The present device is not limited to this, and may be a single element integrated into an LSI as a microcomputer peripheral device, or a systemized device.

Reference numeral 1 denotes a block that switches and executes the process of performing affine transformation followed by curve interpolation and the process of performing affine transformation after curve interpolation according to the present invention. As elements constituting this, 2 is an affine transformation block that performs affine transformation, and 3 is a curve interpolation block that performs curve interpolation. 4 and 5 are FiFos that store coordinate data and flag data that have been coordinate transformed into an affine transformation block or a curve interpolation block.
It is. 6, 7, 8, and 9 are selectors for switching data buses, and a select signal 10 is connected as a switching signal. Each component is
They are connected by a data bus. The control signals output from the FiFos 4 and 5 to the affine transformation block and the curve interpolation block are write permission or read permission signals to the FiFos. Write or read enable signals from each block to the FiFo are omitted here.

FIG. 2 shows the selection signal 10 in FIG.
This is an example for generating . 11 is a register, one bit of which is assigned to the select signal 10; This register 11 is, for example, a command register, and is set by the user according to the output character size of the outline font data.

FIG. 3 is an example of generating the select signal 10. Reference numeral 13 indicates input information set in advance, such as output character size and affine matrix data for affine transformation. From these input information, a select signal 10 is generated using a simple control circuit 12, for example a decoder. Therefore, as shown in FIG. 2, automatic switching is possible without the user having to set the select signal 10 again.

Next, a description will be given of how outline font data is actually coordinate transformed by affine transformation and curve interpolation.

FIG. 4 is a structural diagram of outline font data. 14 is outline font data, which is roughly divided into flag data and coordinate data. 8001h is area start flag data, 8008h is curve start flag data, and 8004
h is character end flag data. (x0, y0) ~
(xn, yn) is coordinate data, which includes linear coordinate data and curved coordinate data.

FIG. 5 is a flowchart for explaining the operation of the affine transformation block 2. 15 reads the outline font data 14 word by word. In the case of end flag data 8004h, output 17 and end. Flag data other than end flag data, area start flag data 8001h or curve start flag data 8
If 008h, output 17. For coordinate data, (
x, y), executes the affine transformation 16 shown in equation (1), and outputs the coordinate data (x', y') 17.

FIG. 6 is a flowchart for explaining the operation of the curve interpolation block 3. 18 reads the outline font data 14 word by word. In the case of end flag data 8004h, output 20 and end. In the case of area start flag data 8001h, output 20
. In the case of curve start flag data 8008h, the coordinate data read first (x1, y1) and the coordinate data read next (x2, y2), (x3, y3), (x4, y4
), execute curve interpolation 19, and obtain the coordinate data (
x1, y1), (xb1, yb1), (xb2, yb2
), (xb3, yb3), (x4, y4) 2
0 (however, three coordinate points on the curve occur). 8008h is not output. Further, coordinate data unrelated to the curve start flag data, that is, linear coordinate data, is output as is.

A case will be explained in which curve interpolation is performed after affine transformation. In FIG. 1, it is assumed that the select signal 10 is "0", that is, in an off state. Selector 6, selector 7, and selector 8 output s0 of input s0 and input s1. In addition, the selector 9 is
Due to the inversion of the select signal 10 being "1", that is, the select signal in the on state, s1 of the input s0 and input s1 is
Output. The input font data 14 shown in FIG. 4 passes only through the selector 6 and is input to the affine transformation block 2. The affine-transformed data is output, passes only through the selector 8, and is written to the FiFo4. Next, Fi
The data read from Fo4 passes through only the selector 7 and is input to the curve interpolation block 3. The curve interpolated data is output, passes only through the selector 9, and is sent to the FiFo5
is written to. Assuming that the number of coordinate points generated on the curve in the curve interpolation block is three, the input font data 14 is as follows.
The output data is converted into the output data shown in FIG. 7(a) and written to the FiFo5.

Conversely, a case will be explained in which affine transformation is performed after curve interpolation. In FIG. 1, it is assumed that the select signal 10 is "1", that is, in the on state. Selector 6, selector 7, and selector 8 output s1 of input s0 and input s1. Further, the selector 9 outputs the inverted “0” of the select signal 10, that is,
With the select signal in the off state, input s0 and input s1
Of these, s0 is output. The input font data 14 shown in FIG. 4 passes only through the selector 7 and is input to the curve interpolation block 3. The curve-interpolated data is output, passes only through the selector 8, and is written to the FiFo 4. Next, F
The data read from the iFo4 passes only through the selector 6 and is input to the affine transformation block 2. The affine transformed data is output and passes only through selector 9,
Scratched into FiFo5. Similarly, if the number of coordinate points occurring on the curve is three, the input font data 14 is
The output data is converted into the output data shown in FIG. 7(b) and written to the FiFo5.

That is, as shown in FIG. 7, the structure of the output data is the same when curve interpolation is performed after affine transformation and when affine transformation is performed after curve interpolation. Therefore, even if the order of performing affine transformation and curve interpolation is changed, only necessary data can be output in the same format to the next line generation block, for example.

[0034]

[Effects of the Invention] According to the present invention, in the past, curve interpolation was performed after performing affine transformation, which made it impossible to output characters of sufficient quality. Since it is possible to execute both the process of performing curve interpolation later and the process of performing affine transformation after performing curve interpolation, high-quality characters can be processed at high speed. Furthermore, since this was realized by switching buses, there is no need to change the contents of the affine transformation block and curve interpolation block, and LSI
It is possible to switch the processing order of affine transformation and curve interpolation with a small circuit scale suitable for

[Brief explanation of the drawing]

[Figure 1] Block diagram of affine transformation and curve interpolation,

[Figure 2] Explanatory diagram of select signal register,

[Figure 3] Block diagram of select signal control circuit,

[Figure 4] Illustration of outline font data,

[Figure 5] Flowchart of affine transformation block,

[Fig. 6] Flowchart of curve interpolation block,

[Fig. 7] Explanatory diagram of output data,

[Fig. 8] An explanatory diagram of occurrence coordinate data on a curve,

FIG. 9 is a block diagram of a conventional character generator.

[Explanation of symbols]

1... Affine transformation and curve interpolation block, 2... Affine transformation block, 3... Curve interpolation block, 4... FiFo
, 5...FiFo, 14...outline font data,
23... Cubic Bezier curve, 27... Outline font processor (OFP).

Claims (3)

[Claims] Claim 1: A character generating device that generates characters by converting character contour data expressed in vector format into character data expressed in raster format after performing coordinate transformation using affine transformation or curve interpolation. An affine transformation block that performs the affine transformation and a curve interpolation block that performs curve interpolation are provided, and a process of performing the curve interpolation after performing the affine transformation, or a process of performing the affine transformation after performing the curve interpolation. is executed by switching buses without changing the contents of each block. 2. In claim 1, the character generating device comprises:
As means for switching between performing the curve interpolation after performing the affine transformation, or performing the affine transformation after performing the curve interpolation, it is possible to switch by providing a register for switching with one bit. Character generator. 3. In claim 1, the character generating device comprises:
Characters that are automatically switched according to input information as means for switching between performing the affine transformation and then performing the curve interpolation, or performing the curve interpolation and then performing the affine transformation. Generator.