JPH1031669A - Font data processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfactorily reduce the quantity of data and to suppress the cost of a font data processor by deciding whether the font data read out of a font memory part are compressed or not and then defrosting the font data if compressed. SOLUTION: The compressed font data 5 and the non-compressed font data 6 are stored in a font memory part 1 and then read out when a character code 4 is inputted from an external device. Then a decision part 2 decides whether the data 5 or 6 is read out, and both data 5 and 6 are outputted on the different routes. The data 5 is defrosted at a defrosting part 3, and the data 6 is directly outputted as output 7. Thus, the quantity of data can be satisfactorily reduced and the cost of a font data processor can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a font data processing device for generating bitmap data from a memory storing font data such as an outline font.

[0002]

2. Description of the Related Art Document data processed by a computer or the like is composed of character codes. When outputting this to a printer or a display, a character code is input to a font memory to obtain bitmap data. Recently, outline fonts are used to improve the quality of output characters. In this outline font, the outline data of a character is represented by coordinate values of both end points for a straight line, and coordinate values of both end points and control points for a curve. With the diversification of user requirements for the fonts and character types of the characters to be printed, the storage capacity of storage devices for storing such font data is increasing.

[0003]

However, the above-mentioned conventional apparatus has the following problems to be solved.
For example, consider a Japanese outline font. Japanese characters are approximately 600 non-kanji characters such as hiragana, katakana, numbers, and symbols, and approximately 300 first-level kanji.
There are 0 characters and about 3400 second-level kanji characters, for a total of 70 characters.
There are also 00 characters, and the number of characters is so large that they cannot be compared with European characters. When such outline data is stored in a memory, a large-capacity memory is required.

[0004] In the case of a hard disk of a personal computer, a sufficient area for storing such font data can be secured. However, for example, when the outline data is to be mounted on a ROM (read only memory) on the printer side, the data amount must be sufficiently reduced and the cost must be suppressed.

[0005]

The present invention employs the following structure to solve the above problems. <Structure 1> A font memory unit storing a mixture of font data that has been subjected to compression processing and font data that has not been subjected to compression processing, and a determination unit that determines whether the font data read from the font memory unit has been compressed. And a decompression unit for decompressing the font data determined by the determination unit to have been subjected to the compression process.

<Structure 2> In structure 1, the determination unit previously stores an address of a boundary between an area in which the compressed font data is stored and an area in which the uncompressed font data is stored. A font data processing apparatus for determining whether or not compression processing has been performed by comparing the address with the address of data read from the font memory.

<Structure 3> In structure 1, the determination unit includes an identification flag indicating whether or not compression processing has been performed on a part of the font data, and recognizes the flag to determine whether or not the font data has been compressed. Characteristic font data processing device.

<Structure 4> In the structure 1, when a part of font data of the same font stored in the font memory unit is compressed, the font data to be compressed is used in comparison with the font data not to be compressed. A font data processing device characterized by being selected from infrequent characters.

<Structure 5> In the structure 1, when font data of different fonts are collectively stored in the font memory unit, font data to be subjected to compression processing is font data which is used less frequently than font data which is not subjected to compression processing. A font data processing device selected from the group consisting of:

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below using specific examples. FIG. 1 is a schematic block diagram of an apparatus according to the present invention. This device includes a font memory unit 1, a determination unit 2,
A decompression unit 3. The font memory unit 1 stores font data 5 that has been subjected to compression processing in advance and font data 6 that has not been subjected to compression processing. When characters 4 are input from an external device (not shown), the font data is read. These are stored so that they can be distinguished from each other when read out, as described later.
When the font data is read, the determination unit 2 determines whether the font data 5 has undergone compression processing or the font data 6 which has not been subjected to compression processing.
Is determined, and each is output through a separate route. The compressed font data 5 is decompressed in the decompression unit 3. Further, the font data 6 not subjected to the compression processing is output as it is and becomes an output 7.

With the above-described configuration, the apparatus of the present invention compresses a part of the font data in the font memory unit 1 and stores it, thereby reducing the size of the font memory unit 1. The determination as to whether or not to perform compression processing depends on, for example, the frequency of use. A specific description thereof will be given later, and a more specific configuration and operation of the device of the present invention will be described.

FIG. 2 is a block diagram showing a specific example of the apparatus of the present invention. In this specific example, description will be made using outline data as font data. FIG. 2 shows an outline font 10. The outline font 10 includes a code address conversion table 11,
Outline data table 12 and boundary value register 1
3 is provided. The determination unit 2 and the decompression unit 3 for processing the output of the outline font 10 are the same as those shown in FIG. Further, a bitmap developing unit 14 for processing or outputting an input character code and performing output control of bitmap data is provided here.

In this specific example, the uncompressed font data is stored in the outline data table 12 from the start address to a predetermined boundary value address in the same manner as in the prior art. On the other hand, outline data is stored after the boundary value address by using various well-known compression methods.
This compression method may employ a method used for compressing and writing data to a hard disk in a general personal computer and expanding a storage area of the hard disk. The boundary value register 13 stores an address serving as the boundary value.

FIG. 3 is an explanatory diagram showing a more detailed configuration of the outline font. The code address conversion table 11 is a table for converting an input character code into an address on the outline data table 12. The outline data table 12 includes:
For example, below the boundary value address "1,260,398",
The compressed outline data is stored. The boundary value register 13 stores the address of the boundary value. Therefore, as shown in the figure, for example, when a character code is input to the code address conversion table 11, the corresponding address is read, and the outline data corresponding to the character code is read from the corresponding address in the outline data table 12. At this time, whether or not the outline data has been compressed is determined based on the boundary value address stored in the boundary value register 13.

The specific operation of the apparatus shown in FIG. 2 will be described with reference to FIG. First, in step S1 of FIG.
Receives character size from external device. The outline font generates bitmap data of an arbitrary size based on the read outline data. Therefore,
This character size is stored in the bitmap developing unit 14.
Next, in step S2, a character code is received from an external device. Use this character code as outline font 1
0 is input to the code address conversion table 11. Then, in a step S3, it is determined whether or not the drawing of all of the input characters has been completed. If the drawing has not been completed, the process proceeds to a step S4. In step S4, outline data of the corresponding character is obtained. Next, the process proceeds to step S5, where it is determined whether or not the outline data is compressed. For example, assume that the input character code is “4A38, 3D71”. This is a character code representing a character string “document”. Since the first character code is “4A38”, the addresses “624, 82” in the outline data table 12 are used as shown in FIG.
The determination unit 2 shown in FIG. 2 acquires the outline data included in “0”. Here, the determination unit 2 receives a boundary value address from the boundary value register 13 and receives an address for reading outline data from the code address conversion table 11. Then, the two are compared.

If the address is smaller than the boundary value address, it is determined that the outline data is not compressed. If the address is equal to or larger than the boundary value address, it is determined that the data is compressed. The address “624,820” of the outline data of “statement” is the boundary value address “1,26”.
0,398 ", it can be determined that the image is not compressed. Therefore, steps S5 to S7 in FIG.
The outline data is sent to the bitmap developing unit 14 shown in FIG. 2 to start the developing process. The character size received first is, for example, 80 dots × 80 dots. The bitmap developing unit 14 performs a developing process according to the instruction, and outputs bitmap data of a character “sentence”. The same applies to the processing of the next character "". Since this font data is not compressed, it is sent directly from the determination section 2 to the bitmap development section 14 to obtain bitmap data.

On the other hand, for example, it is assumed that a character code is input for the character "2" and this is read from the outline data table 12. In this case, it is determined that the data is compressed in step S5 in FIG. 4, and the read outline data is output from the determination unit 2 to the decompression unit 3 shown in FIG. The decompression unit 3 decompresses the outline data, restores the outline data before compression, and outputs the data to the bitmap decompression unit 14.

When the above processing is performed, the expansion processing of the outline data that has not been compressed into the bitmap data can be performed at the same speed as the conventional processing. On the other hand, the compressed outline data is temporarily restored to the original outline data in the decompression unit 3, so that the processing is slightly delayed by that amount. here,
The following describes what characters are compressed and what characters are stored in the memory without being subjected to the compression processing.

FIG. 5 shows the appearance rate of characters in a certain publication. This represents, for example, the character type appearance rate of “11,852,351” characters included in data for three months in a newspaper. That is, the appearance ratio of each character type with respect to the total number of appearance characters is expressed as a percentage as shown in the figure. This character type is half-width characters, JIS1,2,6,7,
The characters were classified into eight wards, such as letters, numbers, alphabets, hiragana, katakana, first-level kanji, and second-level kanji. The horizontal axis of this graph is the percentage. From this figure, it can be seen that 60% of the characters in the newspaper data are non-Kanji characters and 40% are first-level Kanji characters. Accordingly, it can be understood from such statistics that if a character having an extremely low appearance rate is compressed, no significant reduction in speed occurs during bitmap data expansion processing.

Further, although not shown in FIG. 5, characters which do not appear once in the newspaper data are 153 in the first-level kanji.
There are 2686 characters in characters and second-level kanji, for a total of 28
It turned out that 39 characters were not used for such newspaper data. From this fact, if characters that do not appear at all in newspaper data are compressed, efficient use of the memory can be achieved without adverse effects in the decompression process. For example, assume that the average value of the size of the outline data for one character is 200 bytes. If this can be reduced to 120 bytes by 60% compression, the size of outline data before compression is 7000 characters x 2
00 bytes means 1,367 MB (megabytes). On the other hand, when data of 2839 characters is compressed,
39 characters x 120 bytes + 4161 characters x 200 bytes, which is 1,145 MB. That is, the memory size can be reduced to 84%.

These characters are not always arranged in the order of the character codes. Therefore, if the method of FIG. 3 is used, outline data that has not been subjected to compression processing is stored in order from the top of the outline data table, and the compressed outline data is written in the latter half.
Then, the address of the boundary value is written to the boundary value register. If the correspondence between the character code and the address is set in this storage order, any character can be subjected to compression processing to become outline data. If this compression method is such that the original data can be completely restored, it is possible to maintain the quality of the outline font and reduce the processing speed of the font memory without deteriorating the processing speed when drawing relatively frequently used characters. The size can be reduced.

In addition to the above example, a method of uncompressing the first-level kanji and compressing all the second-level kanji can be considered. In this case, 3390 characters can be compressed. Further, in the case of a Japanese sentence, compression or non-compression is selected according to the character type as described above, but in the case of an English sentence, it can be selected by the font. For example, "Gothic",
There are various fonts such as "Dutch", "Arial", and "Century". Of these fonts,
The compression processing is performed on the font data of the font that is used infrequently and is stored. In this case, the determination unit determines the type of font data processing and selects the operation of the decompression unit.

FIG. 6 is a diagram illustrating a modification of the outline font. Here, another example of the outline font of the present invention will be described. Here, an identification flag is added to the first bit of each outline font. This identification flag indicates whether the font data is compressed or uncompressed. When the content is "1", the content is compressed, and when the content is "0", the content is uncompressed.
When the outline data is read from the outline font 10, it is input to the determination unit together with the identification flag. The determination unit determines the identification flag separately from the outline data, and selects compression or non-compression.

As described above, the outline data is data such as 200 bytes per character. However, even if an identification flag is added to the head of the outline data by about 1 bit, the data amount does not largely increase as a whole. As a result, there is an effect that the degree of freedom in the method of arbitrarily selecting the infrequently used font data and storing it in the outline data table is increased.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of the device of the present invention.

FIG. 2 is a block diagram of a specific example of the device of the present invention.

FIG. 3 is a detailed explanatory diagram of an outline font.

FIG. 4 is an operation flowchart of the apparatus of the present invention.

FIG. 5 is a diagram illustrating the appearance rate of characters in a certain publication.

FIG. 6 is a diagram illustrating a modification of an outline font.

[Description of Signs] 1 Font memory unit 2 Judgment unit 3 Decompression unit 5 Compressed font data 6 Font data not compressed

Claims (5)

[Claims] 1. A font memory unit that stores font data that has been subjected to compression processing and font data that has not been subjected to compression processing, and determines whether the font data read from the font memory unit is compressed. And a decompression unit for decompressing the font data determined by the determination unit to be compressed. 2. The method according to claim 1, wherein the determining unit stores, in advance, an address of a boundary between the area storing the compressed font data and the area storing the uncompressed font data, A font data processing device, which determines whether or not compression processing has been performed by comparing the address with the address of data read from a font memory. 3. The method according to claim 1, wherein the determination unit includes an identification flag indicating whether or not the compression processing has been performed on a part of the font data, and determines whether or not the compression processing has been performed by recognizing the flag. Characteristic font data processing device. 4. The font data according to claim 1, wherein, when a part of the font data of the same font stored in the font memory part is compressed, the font data to be compressed is used more frequently than font data which is not compressed. A font data processing device characterized in that the font data is selected from characters having a low character. 5. The font data to be compressed according to claim 1, wherein font data of different fonts are collectively stored in the font memory unit.
A font data processing apparatus characterized by selecting a font that is used less frequently than font data that is not subjected to compression processing.