JPH11205680A - Device and method for processing multi-gradation character data, record medium and television set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent flicker from being conspicuous even when displaying characters on a display of an interlace system. SOLUTION: In this processing method, a background dot, whose gradation value is the value of background part of a character, is retrieved from multi- gradation character data (S204), the gradation difference between the retrieved background dot and a right upper and/or lower dot is obtained, and when any gradation difference is more than a prescribed threshold value (N) (S206; YES or S209: YES), the gradation value of that background dot is increased by a prescribed value (S207).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for generating multi-tone character data which reduce flicker when displaying multi-tone character images on an interlaced display device such as a home television. .

[0002]

2. Description of the Related Art Display devices such as computer displays and home televisions have a lower resolution than printing devices. For this reason, small-sized characters such as 16 × 16 dots are generally used. A non-interlaced computer display can display even about 16 × 16 dots without practical problems, but a screen flicker called flicker occurs on an interlaced home television, making it very difficult to read.

FIG. 3 shows the character “member” in 16 × 16 dots. FIG.
(B) is “0” for the background of (a), “1” for the character part,
It is the figure which each expressed. When the character “member” of FIG. 3 is displayed on an interlaced display, when “0” and “1” are adjacent in the vertical direction, a flicker occurs due to a large difference in luminance.

Japanese Patent Laid-Open Publication No. Hei 6-337662 discloses a technique for reducing flicker by using multi-tone expression. This is to generate multi-gradation character data from binary character data, and to generate multi-gradation character data by weighting the line data of the line of interest and the line data immediately above and below it. By doing so, the gradation difference in the vertical direction (= luminance difference) is moderated to reduce flicker.
FIG. 4 shows an example in which the binary data of the character “member” is multi-graded using the method disclosed in Japanese Patent Application Laid-Open No. 6-337662.

Japanese Unexamined Patent Publication No. 7-296146 discloses another technique for reducing flicker by making binary character data multi-gradation. This is a technique for multi-grading by adding and combining row data immediately above and immediately below a target row at a fixed ratio with the target row gradation. FIG.
An example in which the binary data of the character “member” is multi-grayed using the method of Japanese Patent Application Publication No.

Japanese Patent Application Laid-Open No. H05-40463 discloses a technique for generating multi-gradation character data from an outline font or the like. FIG. 6 shows an example in which four-gradation character data is generated from an outline font of the character "member" using the method disclosed in Japanese Patent Application Laid-Open No. 5-40463.

[0007]

Problems to be Solved by the Invention
In the technique disclosed in Japanese Patent Laid-Open No. 2000-214, in the case of a character in which lines of “0” and “1” are alternately present (eg, “member”), the entire character is crushed as shown in FIG. There is a problem that it disappears. Further, since processing is performed with reference to upper and lower rows, a memory for storing one row of unprocessed data is required. In the technology disclosed in Japanese Patent Application Laid-Open No. 7-296146,
Characters in which lines of "0" and "1" alternate (for example,
In the case of "member"), although the skeleton of the character remains as shown in FIG. 5, the background portion between the horizontal lines constituting the character is crushed, and the character becomes unclear. Further, since processing is performed with reference to upper and lower rows, a memory for storing one row of unprocessed data is required. JP-A-5-40
As shown in FIG. 6, the multi-tone character data generated by the technique disclosed in Japanese Patent Application Publication No. 463 has a problem that flicker occurs when displayed in the interlaced mode because there is a portion having a large difference in luminance.

An object of the present invention is to prevent flicker from being noticeable even when characters are displayed on an interlaced display device. It is another object of the present invention to enable processing even if there is no memory for storing one row of unprocessed data.

[0009]

According to a first aspect of the present invention, a background dot which is a background portion of a character is searched from multi-tone character data, and the searched background dot and the gradation of the dot immediately above and / or immediately below the background dot are searched. A multi-tone character data processing method is characterized in that a difference is obtained, and if any of the tone differences is equal to or more than a predetermined threshold (N), the tone value of the background dot is increased by a predetermined value.

A second aspect of the present invention is the multi-tone character data processing method according to the first aspect, wherein the background dot is searched in a column direction. The invention of claim 3 is the multi-tone character data processing method according to claim 1 or 2, wherein the threshold value (N) is 2. According to a fourth aspect of the present invention, there is provided a multi-tone character data processing method according to the first or second aspect, wherein the threshold value (N) is changed according to a characteristic and / or a state of the display device. It is. According to a fifth aspect of the present invention, in the first, second, or fourth aspect, the threshold value is determined based on color information of a background dot, color information of a character dot, and color information of a halftone dot. N) is changed.

According to a sixth aspect of the present invention, there is provided a multi-gradation character data processing apparatus for reducing a luminance difference by changing a gradation of multi-gradation character data. Searching means for searching the toned character data for a background dot having a tone value equal to the background portion of the character; tone difference calculating means for obtaining a tone difference between the searched background dot and a dot immediately above and / or immediately below; A multi-gradation character data processing device comprising: a gradation changing means for increasing a gradation value of the background dot by a predetermined value when any of the gradation differences is equal to or more than a predetermined threshold (N). It is.

The invention of claim 7 is the multi-tone character data processing device according to claim 6, wherein the search means searches the background dot in a column direction. The invention of claim 8 is the multi-tone character data processing apparatus according to claim 6 or 7, wherein the gradation changing means uses 2 as the value of the threshold (N). . According to a ninth aspect, in the sixth or seventh aspect, the gradation changing means changes the value of the threshold value (N) according to characteristics and / or a state of a display device. This is a multi-tone character data processing device that is a feature. The invention of claim 10 is
10. The image processing apparatus according to claim 6, wherein the gradation changing means sets the value of the threshold (N) to color information of a background dot, color information of a character dot, and a dot of an intermediate gradation. A multi-tone character data processing device characterized in that the character data is changed according to color information.

According to an eleventh aspect of the present invention, a program for causing a computer to function as the input means, the search means, the tone difference calculating means, and the tone difference changing means according to any one of claims 6 to 10 is recorded. Computer-readable recording medium.

According to a twelfth aspect of the present invention, there is provided a television apparatus for processing a received signal and displaying the received signal on an image receiver in an interlaced manner, comprising: extracting means for extracting a character code from the received signal; Claim the data
A tone processing means for processing using the multi-tone character data processing device according to claim 10, and means for displaying a character on an image receiver based on the character data processed by the tone processing means. A television device comprising:

According to a thirteenth aspect of the present invention, in addition to the twelfth aspect, there is further provided a line connecting means for inputting information from a communication line, wherein the extracting means comprises an information input through the line connecting means. A television device having a function of extracting a character code from the inside.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A is a block diagram showing a multi-tone character data generating apparatus, and FIGS. 1B and 2 are FIGS.
A flow chart showing the processing procedure in the CPU 102 of FIG.
It is.

This device has a CPU 102, an auxiliary storage device 101, a main storage device 103, and a display device 104. In the CPU 102, a process of adding a gradation to a character to be processed is executed according to a predetermined program.
The predetermined program is stored in the auxiliary storage device 101. Further, the generated multi-tone character data is stored. The auxiliary storage device 101 is, for example, a magnetic disk,
It is configured using a magneto-optical disk, a semiconductor memory, or the like.
The above-described predetermined program is temporarily stored in the main storage device 103 for execution of the processing by the CPU 102. Further, data for processing multi-tone character data is temporarily stored. The main storage device 103 is configured using a normal memory. The display device 104 is a device for displaying characters, and ordinary display means is used.

Hereinafter, a case where multi-gradation character data has four gradations will be described with reference to the flowcharts of FIGS. Each character has its origin at the upper left and its dot position is indicated using a coordinate system of horizontal Sx dots and vertical Sy dots. Further, the gradation value of the background portion is set to 0, the gradation value of the character portion is set to 3, and the gradation value of 2 is closer to the character portion than the gradation value of 1. Tones.

First, multi-tone character data is read (S201). Next, 0 is substituted for a variable x indicating the x coordinate (S202). That is, the first column (leftmost column) is designated as the dot column of interest.

Next, a process is performed on the column of interest (the first column) (S203 to S211). That is, it is determined whether or not the dot of interest in the column of interest is the background portion. If the dot of interest is the background portion, it is checked whether or not the tone difference between the dot immediately above and immediately below the dot is large enough to cause flicker. In this case, a process of adding 1 to the tone of the target dot to approach the tone value of the dot immediately above or below is performed. This processing will be described later with reference to FIG.

When the processing for all the dots in the column of interest is completed, the variable x is incremented by 1 (S21).
2). As a result, the processing shifts to the next column (the column on the right), and the next column is set as a new column of interest and is similarly processed. However, the condition is that the column for which processing has been completed immediately before is not the last column (rightmost column) (S213; YES). If the last processed row is the last row (rightmost row) (S213; NO), it means that the processing for the multi-tone character data has been completed. A process of displaying data on the display device 104 is performed (S21).
4). The multi-tone character data for which processing has been completed may be stored in a storage device as appropriate.

Next, the processing of the noted column (S203 to S203)
211) will be described. First, a variable y indicating the y coordinate
Is assigned to (S203). That is, the first dot (uppermost dot) in the column of interest is designated as the dot of interest.

Next, the gradation value of the target dot (x, y) is 0.
In other words, it is checked whether it is a background portion. As a result, if it is the background portion (S204; NO), the condition is that the target dot is not the top dot (S2).
05; YES), first, the tone value of the dot immediately above is checked. As a result, if the tone value of the dot immediately above is 2 or more, in other words, if the tone difference between the target dot and the dot immediately above it is large enough to cause flicker (S20).
6; YES), 1 is added to the tone value of the target dot (S207). As a result, the gradation difference between the target dot and the dot immediately above the target dot becomes sufficiently small, and flicker becomes less noticeable.

On the other hand, in step S206, when the tone value of the dot immediately above is 1 or less (S206; NO),
Assuming that the target dot is not the bottom dot (S208; YES), the tone value of the dot immediately below is checked. As a result, when the tone value of the dot immediately below is 2 or more, in other words, when the tone difference between the target dot and the dot immediately below it is large enough to cause flicker (S20).
9; YES), 1 is added to the tone value of the target dot (S207). As a result, the gradation difference between the target dot and the dot immediately below the target dot becomes sufficiently small, and flicker becomes inconspicuous.

When the process for the dot of interest is completed,
The variable y indicating the y coordinate is incremented by 1 (S21).
0). The case where the process is completed means that the process of adding 1 to the tone value of the target dot when the tone difference between the target dot and the dot immediately above or below is large, or that the target dot is a non-background portion (S204; NO). Due to the increment of the variable y, the processing shifts to the next dot (= the dot immediately below), and the next dot (= the dot immediately below) is set as a new dot of interest and processed similarly. However, the condition is that the dot for which processing has been completed immediately before is not the last dot (= lowest dot) in the column of interest (S211; YES). If the dot that has just been processed is the last dot in the column of interest (S211; N
O) Since this is the case where the process for the column of interest has been completed, the process proceeds to step S212 to proceed to the process for the next column.

This processing is performed as described above. FIG.
Shows a case where the above-described processing is performed on the multi-tone character data of FIG. As is clear from FIG. 7, the application of this processing makes it possible to eliminate a portion having a large difference in tone, thereby reducing flicker. 4 and 5 after this processing.
Since characters are not crushed as in, characters can be clearly recognized.

Next, an example of the configuration of an apparatus for executing the above-described processing will be described with reference to FIG. System clock 801
Supplies a system clock signal. The timing generation circuit 803 generates a timing signal for synchronizing with a clock signal. Gradation character memory 80
2 stores multi-tone character data to be processed. It also has an area for storing multi-tone character data after processing. The address generation circuit 804 generates a read address and a write address of the gradation character memory 802. That is, the address for reading the tone value data of the dots (dot of interest, dot directly above, dot immediately below) in the character data to be processed, and the tone of the dot of interest after processing (addition processing / non-addition processing) An address for writing the value data at a predetermined position in the multi-tone character data area to which the target dot belongs is generated. The read tone value data of the dots is sequentially stored in the dot register 80 immediately above.
6 to the dot register of interest 807, and from the dot register of interest 807 to the dot register immediately below 808, only the address of the dot immediately above is actually generated as the read address. Decoder 805
Then, a control signal for the system is generated.

The tone value data of the dot read out from the tone character memory 802 is stored in the dot register 80 immediately above.
6 and then sequentially moved to the dot register of interest 807 and the dot register immediately below 808. The work register 809 temporarily stores the gradation value data of the target dot. The comparator 810 compares the tone value of the dot of interest with the dot immediately above or below it. as a result,
When the tone difference is equal to or larger than a predetermined threshold ("2" in the above example)
Indicates that the tone value of the target dot is 1 in the incrementer 811.
Is added, and the gradation value data after the addition is stored in a multi-tone character data area (gradation character memory 8) to which the dot of interest belongs.
02 area) is written at a predetermined position. on the other hand,
If the tone difference is less than the predetermined threshold value, the original tone value data that is not added remains unchanged for the multi-tone character data area (area in the tone character memory 802) to which the dot of interest belongs.
Is written to a predetermined position in

In the above description, the case of comparing the tone difference between the target dot and the dot immediately above or below the target dot is described. However, as shown in FIG. To check the tone value immediately above or below according to the result, the tone value of the target dot and the tone value 0
May be compared by the comparator 810, and the comparator 810 may compare the tone value immediately above or below with the tone value 0 according to the result.

Also, in the above-described example described with reference to FIGS. 1A and 2 and the above-described example described with reference to FIG. ), The multi-gradation character data may be generated from a vector font (outline font, stroke font, etc.) that represents the shape of the character by coordinate values, It may be generated from a font. Further, when generating multi-tone character data from these fonts, the processing of the present invention may be executed together. The source of the multi-tone character data to be processed is not limited to a memory, but may be a communication line or a recording medium.

In the above example, the case of four gradations is shown. However, in the case of three gradations, five gradations, eight gradations, or the like,
The invention is equally applicable. Further, in the above-described example, when the tone value of the target dot is 0 and the tone value of the dot immediately above or immediately below it is 2 or more, in other words, the tone level of the target dot and the dot immediately above or immediately below it. Although the processing is performed so that 1 is added to the tone value of the target dot when the tone difference N is 2 or more, it is also possible to perform processing to add the tone value when the tone difference N is 3 or more.

It is also possible to change the threshold value relating to the gradation difference N according to the characteristics and state of the display device. For example, the threshold value for N may be increased when the brightness is adjusted in the direction of brightening the display, and the threshold value for N may be decreased when the brightness is adjusted in the direction of darkening the display. Further, the threshold value regarding N may be changed according to the display color of the background, the display color of the character, or the luminance difference of the intermediate gradation.

Next, the above-described device (the device illustrated in FIG. 8)
Will be described with reference to FIG. 9. The illustrated television processes data received from the Internet or the like via a modem, in addition to television broadcasting (or text multiplex broadcasting) received from an antenna,
It has a function to display.

The signal received from the antenna is converted into an intermediate frequency signal by a tuner, amplified by a video intermediate frequency amplifier, detected by a video detector, amplified by a video amplifier, and displayed on a receiver. At the same time, sound is output from the speaker via the sound output circuit. The synchronous deflection circuit generates a sawtooth wave for deflecting the electron beam.

If the signal received by the antenna contains a character code, it is extracted by a code extraction circuit and
Input to PU. In the CPU, the luminance difference in the vertical direction of the multi-gradation character data is reduced by the above-described processing, and the multi-gradation character data with the reduced luminance difference is sent to the D / A conversion circuit and converted into an analog signal. Then, it is superimposed on the output of the video detector described above. The timing of this superposition is given by detecting the synchronization of the video detector and inputting it to the CPU.

As described above, the television shown in FIG. 9 is provided with the function of reducing the luminance difference in the vertical direction of multi-gradation character data. Therefore, the television is displayed on the receiver despite the interlace method. The character image is a good image with reduced flicker. Note that, in the above, the case where a character is included in a signal received from an antenna is described, but the same applies to a case where a character is included in a signal received via a modem. Further, character code information such as a menu screen may be stored in advance in the ROM of the television main body, and may be read out and displayed as appropriate. The same applies to that case.

[0037]

According to the present invention, the background dot which is the background portion of the character is searched from the multi-tone character data,
Alternatively, the tone difference of the dot immediately below is obtained, and if any tone difference is equal to or more than a predetermined threshold value (N), the tone value of the background dot is increased by a predetermined value. Is displayed, flicker can be made inconspicuous. Also, in the invention in which background dot search is performed in the column direction, processing can be performed without a memory for storing one row of unprocessed data.

[Brief description of the drawings]

FIG. 1A is a block diagram illustrating a configuration of a multi-tone character data processing device according to an embodiment, and FIG.
2 is a flowchart (b) showing the procedure of multi-tone character data processing executed in step 2.

FIG. 2 is a flowchart showing details of “processing of a column of interest” executed in the flowchart of FIG.

FIG. 3 shows an example of a bitmap pattern (a) of binary character data and data (b) of the bitmap pattern.

FIG. 4 shows a bitmap pattern (a) when the character data of FIG. 3 is processed by the method disclosed in JP-A-6-337662, and gradation data (b) of the bitmap pattern.

FIG. 5 shows a bitmap pattern (a) when the character data of FIG. 3 is processed by the method disclosed in JP-A-7-296146, and gradation data (b) of the bitmap pattern.

FIG. 6 shows a bitmap pattern (a) showing an example of 4-gradation character data generated from an outline font;
The gradation data (b) of the bitmap pattern.

FIG. 7 shows a bitmap pattern (a) when the four-tone character data of FIG. 6 is processed by the method of the present invention, and tone data (b) of the bitmap pattern.

FIG. 8 is a block diagram showing an example of an apparatus for implementing the method of the present invention.

FIG. 9 is a block diagram of a television equipped with the embodiment device of the present invention.

[Explanation of symbols]

 Reference Signs List 101 auxiliary storage device 102 CPU 103 main storage device 104 display device

Claims (13)

[Claims] 1. A background dot which is a background portion of a character is searched from multi-tone character data, and a gradation difference between the searched background dot and a dot immediately above and / or immediately below the searched background dot is obtained. A multi-gradation character data processing method comprising: increasing the gradation value of the background dot by a predetermined value when the gradation value is equal to or more than a predetermined threshold (N). 2. The multi-tone character data processing method according to claim 1, wherein the background dot is searched in a column direction. 3. The multi-tone character data processing method according to claim 1, wherein the threshold value (N) is 2. 4. The display device according to claim 1, wherein the threshold value (N) is set according to characteristics and / or a state of the display device.
A multi-tone character data processing method. 5. The threshold value (N) according to claim 1, 2 or 4, wherein the threshold value (N) is determined according to background dot color information, character dot color information, and halftone dot color information. A multi-tone character data processing method. 6. A multi-gradation character data processing apparatus for reducing a luminance difference by changing a gradation of multi-gradation character data, comprising: a multi-gradation character data input unit; Searching means for searching for a background dot having a tone value equal to the background part of the character; tone difference calculating means for obtaining a tone difference between the searched background dot and a dot immediately above and / or immediately below; A multi-tone character data processing device, comprising: a tone changing unit that increases a tone value of the background dot by a predetermined value when the difference is equal to or more than a predetermined threshold value (N). 7. The multi-tone character data processing device according to claim 6, wherein said search means searches for said background dot in a column direction. 8. The multi-tone character data processing device according to claim 6, wherein the tone changing means uses 2 as the value of the threshold (N). 9. The method according to claim 6, wherein the gradation changing unit changes the value of the threshold value (N) according to a characteristic and / or a state of a display device. Multi-tone character data processing device. 10. The gradation changing means according to claim 6, wherein the gradation changing means sets the value of the threshold value (N) to a value between the background dot color information and the character dot color information. A multi-gradation character data processing device, wherein the multi-gradation character data processing device changes in accordance with color information of gradation dots. 11. The computer according to claim 6, further comprising:
A computer-readable recording medium in which a program for functioning as any one of input means, search means, gradation difference calculating means, and gradation difference changing means is recorded. 12. A television apparatus for processing a received signal and displaying it on an image receiver in an interlaced manner, comprising: extracting means for extracting a character code from a received signal; and character data generated from the character code. A gradation processing means for processing using the multi-gradation character data processing device according to any one of claims 10 to 10, a means for displaying a character on a receiver based on character data processed by the gradation processing means, A television device, comprising: 13. The system according to claim 12, further comprising a line connection unit for inputting information from a communication line, wherein said extraction unit converts a character code from information input via said line connection unit. A television device having a function of extracting.