JPH09138677A - Character data storage device and character output device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a character data storage device and a character output device capable of obtaining a remarkable data compression effect for various kinds of characters. SOLUTION: The data storage 100 stores the image data of plural characters by the bit map data expressed by a set of on/off information of a pixel. At this time, plural conversion methods converting the bit map data of the character from the data for an image output to the data for data storage are set in answering to respective characters, and a data conversion means 5 converts the bit map data to the data for the data storage for at least a part of respective characters based on the answering conversion method. Then, the converted bit map data are compressed by a data compression means 5, and the compressed bit map data are stored in a data storage means 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data storage device for storing image data of a plurality of characters by bit map data representing character shapes by pixel on / off information, and a character output device using the same.

[0002]

2. Description of the Related Art Conventionally, when outputting characters such as characters, symbols and figures to an output device such as a printer or a display, bitmap data is often used as image data of the characters. This bitmap data represents the shape of each character by a set of ON / OFF information of pixels arranged in a matrix, and the storage method thereof is ON / OFF information of all the pixels forming the matrix. A method is known in which is stored for each character. However, this method has a problem that the amount of data becomes large when the number of characters to be stored is large. Therefore, in order to solve this, bitmap data is compressed by various methods and then stored.

[0003]

By the way, with respect to the above-described data compression method, the same compression method has been conventionally used uniformly for all characters. However, in this case, the adopted data compression method is not always effective for all characters, and the data compression effect may not be sufficiently obtained depending on the character shape. As a result, there is a problem that the storage capacity cannot be saved so much even if the data compression is performed.

An object of the present invention is to provide a character data storage device which can obtain a remarkable data compression effect for many kinds of characters, and thus can save storage capacity more effectively. Especially.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a data storage device for storing image data of a plurality of characters as bitmap data represented by a set of pixel on / off information, and has the above-mentioned problems. The following features are provided to solve the problem. That is, a plurality of conversion methods for converting character bit map data from image output data storage data storage data are set in association with each character. Then, the data converting means converts the bitmap data of at least a part of each character into the one for storing the data based on the corresponding conversion method. The converted bitmap data is compressed by the data compression means, and the compressed bitmap data (compressed bitmap data) is stored in the data storage means.

According to the above data storage device, the bitmap data of the character is compressed and stored after being converted from the one for image output to the one for data storage by a method which differs depending on the type of the character. . Therefore,
If the conversion method is set so that the optimum compression result can be obtained in consideration of the character shape, etc., a remarkable compression effect can be achieved for many types of characters, and as a result, data storage The capacity can be effectively saved.

Here, in the above conversion method, the conversion operation of the bitmap data may include an operation of rearranging (that is, rearranging) the matrix arrangement of the ON / OFF information of each pixel based on a predetermined method. .
In this case, the total number of pixels in the on state and the total number of pixels in the off state are stored before and after the conversion. On the other hand, an operation in which the total number of pixels in the ON state and the total number of pixels in the OFF state are not stored, for example, an operation of independently inverting the ON / OFF states of specific pixels may be included.

At least one of the plurality of conversion methods described above may be a method including the following steps. That is, with respect to at least a part of the area of the matrix array of the bitmap data, either the vertical or horizontal array direction is set as the reference direction. Next, in the bitmap data arranged along the reference direction, the data located on one end side and the other end are arranged in the order from the outside to the inside of the array or from the inside to the outside. The data located on the side of the copy is sequentially and alternately taken out. Then, the operation of rearranging the data in the order of extraction along the reference direction is performed for each column of the bitmap data along the reference direction.

According to the above method, particularly in the case of a character pattern having a shape that is substantially symmetrical with respect to an axis intersecting with the reference direction, the continuity of the ON state pixel and the OFF state pixel after the data conversion in the reference direction is determined. Each is improved and the data compression rate is increased.

On the other hand, at least one of the plurality of conversion methods described above may be a method including the following steps. That is, with respect to at least a part of the area of the matrix array of the bitmap data, either the vertical or horizontal array direction is set as the reference direction. Next, the bitmap data arranged along the reference direction is divided into partial data strings each including an equal number of data. Further, according to a predetermined order between the partial data strings, the extraction order of the data in each partial data string is from one end side to the other end side of the partial data strings. Data is sequentially taken out one by one from each partial data string. Then, the operation of rearranging the data in the order of extraction along the reference direction is performed for each column of the bitmap data along the reference direction.

In the above method, in the case of a character formed by repeating the same or similar image patterns along the reference direction, the number of partial data strings to be formed can be made to coincide with the number of times the image pattern is repeated. For example, the continuity of the ON state pixel and the OFF state pixel after the data conversion in the reference direction is improved, and the data compression rate is increased.

Next, for at least a part of the character, the matrix array for image output of the bitmap data can be divided into a plurality of blocks. In this case, the plurality of conversion methods described above are set in association with each of the divided blocks. Then, the data conversion means performs the conversion of the bitmap data for each of these blocks based on the corresponding conversion method.
According to this structure, each part of the character is divided into blocks, and the data can be compressed after the bitmap data is converted by the optimum conversion method for each block, so that the data compression rate is further increased. be able to.

The data compression means uses the bitmap data converted by the data conversion means as a reference direction in any of the vertical and horizontal arrangement directions in the matrix arrangement,
This may be compressed based on the continuous number of pixels in the ON state and the continuous number of pixels in the OFF state in the reference direction, or information related to the continuous number. That is, since the individual ON / OFF information of consecutive pixels is not stored but only the number of consecutive pixels (or information related thereto) is stored, the data can be effectively compressed. For example, in the configuration described in claims 6 to 7, a good data compression rate can be achieved by matching the reference direction set at the time of data conversion with the reference direction at the time of data compression. You can

The data storage device having the above structure (hereinafter,
A data storage device (hereinafter, referred to as a second device) having the following requirements can be configured in association with the first device). Data storage means: Among the conversion methods set in association with each of the plurality of characters, the bitmap data of each character converted from the one for image output to the one for data storage by the corresponding conversion method. , And stores compressed bitmap data obtained by further compression. Data expansion means: Decompresses the bitmap data for data storage stored in the data storage means to the state before compression. Data inverse conversion means: Based on the inverse conversion method set for each character corresponding to the conversion method, the restored bitmap data for data storage is inversely converted to the state before conversion, and the bits for image output are converted. Restore map data.

That is, when the bitmap data is supplied in a pre-compressed state, the compressed bitmap data can be restored to the image output bitmap data by the second device. . By adding the requirements of and of the second device to the requirements of the first device, a data storage device having both a compressed bitmap data creation function and a decompression function can be configured. it can. Further, a character output device is configured by providing the above-mentioned first device or second device with an image output device for outputting an image of a character based on the restored bitmap data for image output. be able to.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings and with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a data storage device of the present invention and a character output device using the same. That is, the character output device 1 includes a control unit 2 including an I / O port 4 and a CPU 5, a ROM 6, a RAM 7, etc. connected to the I / O port 4.
And a disk storage device 8 and the like connected to the control unit 2. The control unit 2 and the disk storage device 8 constitute a data storage device 100 which is an embodiment of the present invention. A printer 3 as an image output device is connected to the I / O port 4. Furthermore, an input unit 9 such as a keyboard and a display control unit 10 are connected to the I / O port 4, and a monitor 11 such as a CRT or a liquid crystal display is connected to the display control unit 10. The CPU 5 is the main component of the data conversion means and the data compression means, as well as the data decompression means and the data inverse conversion means.

The ROM 6 of the control unit 2 includes a data storage control program storage unit 6a and an output control program storage unit 6b.
A data storage control program for controlling the data storage processing described below in this embodiment, and an output control program for outputting a character image based on the stored data. Each is remembered. Further, the RAM 7 has a work memory 7
a, a text memory 7b, an image memory 7f, etc. are formed. The work memory 7a is used to temporarily store necessary data when the CPU 5 executes a program. Further, the text memory 7b has an input unit 9
It is for storing the code and size of the character input from, and the character modification information such as the rotation and italic of the character or superscript / subscript. The role of the image memory 7f will be described later.

On the other hand, the disk storage device 8 is composed of a hard disk device, a magneto-optical disk device or the like, and a character storage portion 8a is formed therein. In the character storage unit 8a, character data corresponding to a large number of characters such as characters and symbols of various typefaces in a one-to-one correspondence is stored so as to be randomly read in units of one character.
As shown in FIG. 2, the character storage unit 8a includes a character management information storage unit 8b and a compressed bitmap data storage unit 8c.

In the character management information storage section 8b, a code storage area A1 for storing the code of each character,
An index storage area A2 for storing an index (for example, formed by address information of a storage device) of bitmap data corresponding to the code and a conversion information storage area A3 are formed. On the other hand, in the compressed bitmap data storage unit 8c, for example, as shown in FIG. 6A, bitmap data representing each character 20 by a combination of on / off information of each pixel arranged in a matrix is stored. Compressed bitmap data obtained by compression by the method described below is stored in association with the character index.

FIG. 3 shows an example of the contents of the conversion information storage area A3, which is composed of a block division mode flag storage area A4 and a conversion mode flag storage area A5. First, the block division mode flag storage area A4 stores a block division mode flag for dividing the matrix 21 (see FIG. 8) of bitmap data of each character into predetermined blocks. Four types of block division mode flags are set, for example, 0 to 4 in FIG. 4, and 0: matrix 2 respectively.
1 is designated as a whole, 1: Matrix 2 is divided into upper and lower parts
1 designates the upper half of the matrix, 2: designates the lower half thereof, 3: designates the right half of the matrix 21 which is divided into the left and right half, and 4: designates the left half thereof.

On the other hand, the conversion mode flag storage area A5 stores a flag for specifying the conversion mode of the bitmap data for each block specified by the block division mode flag. FIG. 5 shows an example of the conversion mode flag. First, "0" means that no conversion is performed. Next, "1" corresponds to the conversion for rearranging the bitmap data by the following method. That is, the reference direction is set in the lateral direction (hereinafter, referred to as X direction) of the matrix arrangement of the bitmap data of the block, and the bitmap data arranged along the reference direction goes from the outside to the inside of the arrangement. In order (or in the order from the inner side to the outer side), the data located on the one end side and the data located on the other end side are sequentially and alternately taken out. Then, the operation of rearranging the data in the order of extraction along the reference direction is performed for each column in the X direction of the bitmap data. On the other hand, “2” corresponds to setting the reference direction in the vertical direction of the matrix array (hereinafter referred to as the Y direction) and performing the same conversion.

For example, the conversion designated by the above "1" is applied to a character (or a character portion defined by a block) having a large left-right symmetry, such as "V" shown in FIG. 6 (a). Then, as shown in FIG. 7B, the pixel 22 in the ON state after conversion (displayed by a black circle in the figure) and the pixel 23 in the OFF state (displayed by a matrix cell in which no black circle exists in the figure) in the X direction The continuity in the (reference direction) is improved, and the efficiency of data compression described later is increased. Therefore, it can be said that the conversion designated by "1" or "2" is preferably performed on a character or a character portion having high symmetry in left and right or up and down. As shown in FIG. 7, in the case of a character having a symmetry axis M1 eccentric from the center M0 of the matrix 21, a partial matrix area 25 centered on the symmetry axis M1 is set and the partial matrix area 25 is set.
However, it is also possible to separately set a flag for performing the same conversion as that described above.

Returning to FIG. 5, "3" corresponds to the conversion for rearranging the bitmap data by the following method. That is, the reference direction is set in the X direction of the matrix arrangement of the bitmap data of the block, and the bitmap data arranged along the reference direction is divided into two partial data strings 31 and 32 containing equal numbers of data. Divide. Next, in order that the data extraction order in each of the partial data strings 31 and 32 is from one end side of the partial data strings 31 and 32 to the other end side,
Data is sequentially taken out one by one from each of the partial data strings 31 and 32. Then, the operation of rearranging the data in the order of extraction along the reference direction is performed for each column of the bitmap data along the reference direction. On the other hand, “4” corresponds to setting the reference direction in the Y direction of the matrix array and performing the same conversion.

The conversion designated by the above "3" is shown in FIG.
When applied to a character (or a character portion) whose left and right shapes are similar, such as “W” shown in (a), as shown in FIG. The continuity of the pixels 23 in the state in the X direction (reference direction) is improved, and the efficiency of data compression is increased. Therefore, it can be said that the conversion designated by "3" to "4" is preferably performed on a character or a character portion having a shape in which the same or similar patterns are continuous in the left-right or up-down direction. It should be noted that, for characters or character portions in which three or more identical or similar patterns are consecutive, a similar conversion can be performed by setting partial data strings in a number corresponding to the consecutive number. In this case, between those partial data strings,
The order of data extraction can be preset.

Next, "5" corresponds to a conversion for inverting the on / off information of all the pixels forming the bitmap data. In addition to this, the on / off information of pixels having a specific positional relationship on the matrix is inverted from each other, or a specific one of the pixels satisfying the positional relationship is uniformly set to on or off. And so on
Various conversion modes can be set. Furthermore, it is possible to set a mode in which two or more conversions defined by the above flags are combined and executed.

Returning to FIG. 3, for example, the block division mode flag stored in the conversion information 2 is “0”, and FIG.
Alternatively, as shown in FIG. 8, the entire matrix 21 is 1
It will be set as one block. On the other hand, in the conversion information 1, as shown in FIG.
1 is divided into two upper and lower blocks 21a and 21b,
The block division mode flags also store two, "1" designating the upper half and "2" designating the lower half, and the conversion mode flags are stored corresponding to each. For example, in the case of the character 20 shown in FIG. 9, the portion corresponding to the upper half has a low symmetry, while the portion corresponding to the lower half has a shape having a high symmetry in the X direction. The conversion mode flag of "1" is stored. Therefore, in the case of the character 20, the upper half is not converted, and the lower half is "1".
As a result of performing the conversion designated by, the state as shown in FIG. Matrix 2
It is also possible to divide 1 into three or more blocks, and a division mode is designated for each of these blocks.

The block division mode and the conversion mode for each block are designated for each character by individually inputting each flag for each character from the input unit 9 of FIG. 1 and the like. It is stored in the conversion information storage area A3 (FIG. 2) corresponding to the character. The block division of the matrix designated by each flag and the data conversion process are performed based on the above-mentioned data storage control program.

Returning to FIG. 1, the printer 3 is provided with a print output unit 13 that prints out an image of a character based on the bitmap data. This printout unit 1
Reference numeral 3 is composed of, for example, an electrophotographic printing device using a laser light source, an inkjet printing device, or the like. A printer buffer memory 12 may be provided between the print output unit 13 and the I / O port 4 for temporarily storing image data sent from the control unit 2 side.

The flow of processing in the character output device 1 will be described below with reference to a flowchart. First, FIG. 10 shows a flow of a storage process of bitmap data. In S1, uncompressed / unconverted bitmap data of a character to be stored is input together with a character code. This input may be performed, for example, by reading bitmap data separately stored in a floppy disk or the like from the floppy disk drive 15 or the like in FIG. Then, in S2, the index of the bitmap data and the conversion information are input (that is, the character management information is input). The conversion information is input by designating the above-mentioned block division mode flag and conversion mode flag in consideration of the character shape and the like. When the conversion information is input, the bitmap data conversion processing is performed according to the contents (S
3).

Then, in S4, compression processing is executed on the converted bitmap data. As a compression method, for example, as shown in FIG. 13, when a matrix array of bitmap data is scanned in a predetermined direction (for example, X direction), the pixel 22 in the ON state (hereinafter,
“Black” and off-state pixel 23 (hereinafter, referred to as “black”)
A method (so-called run-length method) of compressing data by storing each continuous number of "white") in the scan order can be exemplified. When the data compressed by such a method is restored to the original bitmap data (hereinafter referred to as expansion), “white” regions and “black” regions are formed on the matrix 21 according to the continuous number of data. (In this embodiment, the scanned bitmap data string is “white”).
It is defined as starting from a region, and in the case of data starting from a "black" region, a code "0" indicating that there is no "white" region is placed at the beginning to discriminate this.

On the other hand, as shown in FIG. 14, the scanned data is divided into bit strings A to D etc. each having a predetermined number of bits (4 bits in this embodiment), and a combination of bit data for each of these columns (hereinafter, It is also possible to adopt a method of analyzing data (called a bit pattern) and performing data compression. For example, in the method shown in FIG. 7A, when the bit strings of the same bit pattern are continuous, the data of the first bit string is stored as it is, and the subsequent bit strings are stored with the repetition code (“0” in this embodiment). By replacing the data, the data is compressed. On the other hand, in the method shown in (b), the bit patterns are classified, and the same classification code is given to the bit strings having the same pattern to compress the data. In any of the methods (a) and (b),
It is based on the principle of reducing the amount of data by constructing the repetitive code or the classification code with data having a smaller number of bits than the bit string. Further, as shown in (c), the appearance frequency of each of the classified bit patterns is analyzed, and a classification code having a smaller number of bits is assigned to the higher frequency, so that the data compression rate can be further increased. it can.

The compressed bitmap data thus obtained is stored in the character storage section 8a in association with the above-mentioned character management information in S5. The data that has been converted / compressed in advance may be stored in the character storage unit 6c in the ROM 6.

Next, FIG. 11 shows a flow of a character image output process based on the compressed data. First, in S51, the input unit 9 is used to input character code data. The input code data is stored in the text memory 7b (FIG. 1) of the RAM 7 as a text file. It should be noted that the text file created in advance may be stored in the disk storage device 8 or the like, and may be read out and used as appropriate.

Next, in S52, the character code included in the text data is read, and in S53, the compressed bitmap data is sequentially read by the index corresponding to the code. Then, in S54,
The compressed bitmap data is expanded. Next, if conversion information is attached to the bitmap data, S56
Then, the process proceeds to step 9 to perform inverse conversion processing of bitmap data. The details are as shown in FIG. 12. First, in S101,
The pointer is initialized to the first one of the blocks that divide the matrix, and the flags of the block division mode and the conversion mode are read in S102 and S103, respectively. Then, in S104, the bitmap data at the specified block position is inversely converted according to the specified conversion mode to restore the original bit array. Then, after incrementing the pointer to the next block in S106, S1
Returning to 02, if the same processing is completed for all blocks, the inverse conversion processing is ended. The inversely converted bitmap data is temporarily stored in the image memory 7f in the RAM 7.

When the inverse conversion process of the bitmap data is completed in this way, the process proceeds to S57 in FIG. 11 and the image memory 7
An image of a character is output from the printer 3 based on the bitmap data stored in f.

The character image based on the image data can be displayed / output on the monitor 11, for example, in addition to being printed / output on the printer 3. In this case, character data different from that for printing may be used for monitor output.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration example of a data storage device and a character output device of the present invention.

FIG. 2 is an explanatory view showing an example of the contents of a character storage section thereof.

FIG. 3 is an explanatory diagram showing an example of contents of conversion information.

FIG. 4 is an explanatory diagram showing an example of a block division mode flag.

FIG. 5 is an explanatory diagram showing an example of a conversion mode flag.

FIG. 6 is an explanatory diagram showing a first example of data conversion.

FIG. 7 is an explanatory diagram showing a second example of the same.

FIG. 8 is an explanatory diagram similarly showing a third example.

FIG. 9 is an explanatory diagram showing a fourth example of the same.

FIG. 10 is a flowchart showing the flow of a bitmap data storage process.

FIG. 11 is a flowchart showing the flow of a character image output process.

FIG. 12 is a flowchart showing details of the data inverse conversion process.

FIG. 13 is a diagram conceptually showing an example of a data compression method.

FIG. 14 is a diagram conceptually showing another example of the data compression method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 character output device 2 control section 5 CPU (data conversion means, data compression means, data decompression means, data inverse conversion means) 8 disk storage device (data storage means) 20 character 21 matrix 22 pixel in ON state 23 pixel in OFF state 100 data storage device

Claims (8)

[Claims] 1. Image data of a plurality of characters,
A data storage device for storing bit map data represented by a set of pixel on / off information, wherein the conversion method for converting character bit map data from image output data storage data is Is set in association with at least a part of each character, and data conversion means for converting the bitmap data based on the corresponding conversion method, and the converted bitmap data. A character data storage device comprising: a data compression unit that compresses to create compressed bitmap data; and a data storage unit that stores the compressed bitmap data. 2. A data decompression means for decompressing bitmap data for data storage stored in said data storage means to a state before compression, and an inverse conversion method set for each character corresponding to said conversion method. 2. The data storage according to claim 1, further comprising: a data reverse conversion unit that reversely converts the restored bitmap data for data storage to a state before conversion to restore the bitmap data for image output. apparatus. 3. For at least a part of the character, the matrix array for image output of the bitmap data is divided into a plurality of blocks, and the conversion method is associated with each of the divided blocks. 3. A data storage device according to claim 1, wherein a plurality of data conversion units are set, and the data conversion unit converts the bitmap data for each of the blocks based on the corresponding conversion method. 4. The data compressing means uses the bitmap data converted by the data converting means as a reference direction in any of the vertical and horizontal arrangement directions in the matrix arrangement, and selects the pixel in the ON state in the reference direction. 4. The data storage device according to claim 1, wherein the number of consecutive pixels and the number of consecutive pixels in the off state or the information related to the consecutive numbers is used to compress the pixels. 5. A data storage device for storing image data of a plurality of characters by bitmap data represented by a set of pixel on / off information, wherein a plurality of conversions are set in association with each of the plurality of characters. Data storage means for storing compressed bitmap data obtained by further compressing the bitmap data of each character converted from the one for image output to the one for data storage by the corresponding conversion method among the methods. A data decompression means for decompressing the bitmap data for data storage stored in the data storage means to a state before compression, and an inverse conversion method set for each character corresponding to the conversion method, The restored bitmap data for data storage is converted back to the state before conversion, and the image output Data storage device of the character, characterized by comprising: a data inverse conversion means for restoring the Tsu sort map data. 6. At least one of the plurality of conversion methods is configured such that, for at least a part of an area of a matrix array of the bitmap data, a vertical or horizontal array direction is used as a reference direction, and the reference direction is set as a reference direction. Of the bitmap data arranged along the direction,
The data located on one end side and the data located on the other end side of the array are sequentially and alternately taken out in the order from the outside to the inside of the array or from the inside to the outside. 6. The method according to claim 1, further comprising a step of performing an operation of rearranging the data along the reference direction in a predetermined order for each column of the bitmap data along the reference direction. The data storage device described. 7. At least one of the plurality of conversion methods, wherein at least a part of the area of the matrix array of the bitmap data is defined as a reference direction in any of vertical and horizontal array directions, Bitmap data arranged along the reference direction,
It is divided into partial data strings each including an equal number of data, and the extraction order of the data in each partial data string is from one end side to the other end side of the partial data string. An operation of sequentially retrieving the data one by one from each of the partial data strings in accordance with a predetermined order between the partial data strings and rearranging the data in the order of extraction along the reference direction. 7. The data storage device according to claim 1, further comprising a step of performing each column of the bit map data along the reference direction. 8. A data storage device according to claim 2, and an image output device for outputting a character image based on the restored bitmap data for image output. Character output device characterized by.