KR100311470B1 - Method for caption text processing - Google Patents

Abstract

The present invention relates to a digital caption text processing method in a digital TV. In particular, when generating bitmap font image data, two bits per dot are allocated to store the inside, outside, and outline of the caption text separately on the screen. The displayed caption text is well-regarded regardless of the change of the TV video screen, and the TV video screen is minimized by the caption, so that the maximum TV video screen can be viewed together with the caption. In addition, according to the method of displaying two kinds of outlines of the bitmap font, various decorative effects can be applied to the caption text, such as outline display, shadow display, protrusion display, and depression indicator.

Description

Caption text processing {Method for caption text processing}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to digital captions in digital TVs, and more particularly to a caption text processing method capable of processing caption text having outlines at high speed.

Recently, with the advent of digital broadcasting, digital TVs supporting digital caption functions for digital broadcasting as well as existing analog captions are being developed.

In the case of the existing analog caption, as shown in FIG. 1, a caption text has been applied to distinguish a TV video screen from the caption text, and in the case of a newly implemented digital caption, a caption window is included here. By introducing the concept of FIG. 2, a method of distinguishing a TV video screen from a caption text is used.

However, this method causes a problem that a large portion of the TV video screen is blocked by the background of the caption text and the caption window, and the viewer's dissatisfaction with the caption text is also required to be improved.

Of course, the background and the caption window of the caption text may be processed in transparent color to avoid the problem of covering the TV video screen, but in this case, the caption text may not be easily distinguished according to the change of the TV video screen. Will occur.

5 is an example of the conventional bitmap font data for such caption text, which is made by allocating 1 bit per dot.

FIG. 6 is a flowchart illustrating an example of reading bitmap font data as shown in FIG. 5 and displaying them on a screen. First, the width, height, and start address of the font image to be displayed are read (step 601). After reading one bit of the font image (step 602), it is determined whether the read bit is one (step 603).

If the read bit is 1, one pixel is displayed in the address as the color of the caption text (step 604), and the number of processed bits is increased by one (step 605). However, if the read bit is not 1, the process proceeds to step 605 where only the number of bits is increased by one.

Then, it is determined whether the read bit is the last bit of the line (step 606).

If it is determined in step 606 that it is the last bit of the line, the number of processed lines is increased by one (step 607), and then it is determined whether it is the last line of the font image (step 608). If it is determined in step 608 that it is the last line of the font image, the display of the caption text is finished. 5, for example, one line is composed of 13 dots and the entire line is 16, so that when the increased number of bits reaches 14, the display of one line is finished, and when the number of increased lines reaches 17, one caption data is used. Will be over.

If it is determined in step 606 that it is not the last bit of the line, or if it is determined in step 608 that it is not the last line of the font image, the process returns to step 602 and repeats the above-described steps.

However, since the caption text processing method as shown in FIG. 6 has a problem in that the TV video screen is not covered or the caption text and the TV video screen are not easily distinguished, the caption text is well distinguished from the TV video screen without covering the TV video screen. A method of marking is desired. As a countermeasure, there is a method in which the outline of the caption text is bordered with a color opposite to the color of the caption text as shown in FIG. 4.

FIG. 7 is a conventional flowchart illustrating a method of processing outline caption text. The caption data is overwritten on the background color of the caption data by moving one pixel from the original position left and right and up and down to the original position. When the caption data is overwritten with the color of the caption data, the caption text having the outline is displayed.

That is, referring to FIG. 7, according to the flowchart shown in FIG. 6 as the background color of the caption text at the position (X-1, Y) moved 1 pixel to the left from the original caption text display position (X, Y) as shown in FIG. The caption text is displayed (step 701). Then, as shown in FIG. 8B, the caption text shifted one pixel to the left from the original position is displayed.

Then, as shown in FIG. 8B, the caption text is displayed in the background color of the caption text at a position (X + 1, Y) moved 1 pixel to the right from the original caption text display position (X, Y) while the caption text is displayed, as shown in FIG. 8B. Overwrite the caption text (step 702). Then, as shown in FIG. 8C, caption data extended by one pixel from side to side is displayed.

Similarly, according to the flowchart shown in FIG. 6 as the background color of the text at the position (X, Y-1) shifted one pixel upward from the original caption text display position (X, Y) while the caption text is displayed as shown in FIG. 8C. Overwrite the caption text (step 703). Then, as shown in FIG. 8D, the caption data stretched by one pixel from side to side is stretched and displayed by one pixel upward.

Then, as shown in FIG. 8D, the flow chart shown in FIG. 6 is used as the background color of the text at a position (X, Y + 1) moved downward by 1 pixel from the original caption text display position (X, Y) while the caption text is displayed. The caption text is then displayed (step 704). Then, as shown in FIG. 8E, the caption data extended by one pixel from left to right and up and down is displayed as the caption data background color.

Therefore, if the caption text is overwritten according to the flowchart shown in Fig. 6 with the caption text color at the original caption text display position (X, Y) (step 705), the caption text with outline is displayed as shown in Fig. 8F.

As described above, in order to display the caption text having the outline using the bitmap font data as shown in FIG. 5, the process of processing the caption text without the outline shown in FIG. 6 must be repeated several times as shown in FIG. 7. do.

That is, in order to minimize the video screen covered by the caption text, only the caption text should be displayed without the window as the background of the caption text as well as the background of the caption text. However, when only the caption text is displayed, the caption text is not easily distinguished from the video screen, and the outline of the caption text must be drawn once again using a color almost complementary to the caption text. For example, the caption text is displayed in white, and when the outline of the caption text is surrounded by black, the caption text is clearly displayed regardless of whether the background image screen is light or dark.

However, in order to display the caption text and the contour image of the caption text in different colors using a bit map font, the contour image of the caption text must be extracted through a complicated software process as shown in FIG. 7. However, since this process takes a lot of time, a high-speed central processing unit (CPU) is required to implement a caption function that needs to be displayed in real time. If the CPU processing speed is low, such a function is difficult to implement. do.

Accordingly, there is a need for a method of quickly displaying outlined caption text when considering the characteristics of captions to be processed in real time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a caption data processing method for minimizing an image screen covered by a caption while caption text is well distinguished from a TV image.

Another object of the present invention is to provide a caption data processing method for processing caption text and a contour image of caption text at high speed.

1 shows a display example of a typical analog caption text with a caption text background.

2 shows a display example of general digital caption text with a caption window.

3 shows a display example of typical digital caption text with a transparent caption window.

4 shows an example of display of typical digital caption text outlined with a transparent caption window.

5 is a diagram showing an example of conventional bitmap font data.

6 is a flowchart illustrating a conventional caption text processing process without outlines;

7 is a flow chart showing a conventional outlined caption text processing process

8A to 8F illustrate examples of caption data displayed as each step of FIG. 7 is performed.

9 illustrates an example of bitmap font data according to the present invention.

FIG. 10 is a diagram illustrating an example of caption text display having no shadow effect on an outline using the bitmap font data of FIG. 9. FIG.

FIG. 11 is a diagram illustrating an example of displaying caption text having a shadow effect on an outline by using the bitmap font data of FIG. 9. FIG.

FIG. 12 illustrates an example of caption text display in which an outline has a protruding effect using the bitmap font data of FIG. 9. FIG.

FIG. 13 is a diagram illustrating an example of caption text display in which an outline has a depression effect using the bitmap font data of FIG. 9; FIG.

14 is a flowchart illustrating a caption text processing method according to the present invention.

15 is a block diagram of a digital TV for caption text processing according to the present invention;

Explanation of symbols for main parts of the drawings

101: digital TV tuner 102: VSB demodulator

103: analog TV tuner 104: external terminal

105: power supply unit 106: image processing unit

107: image memory 108: system memory

109: flash ROM 110: voice processing unit

Caption data processing method according to the present invention for achieving the above object, the step of dividing the text display area with n (n is 2) bit allocation per bit at the time of the production of bitmap font data, and storing in the memory And reading the caption text by n bits when reading data for the caption from the memory and displaying various types of caption text.

The storing step is characterized by allocating different values by dividing the area into the area corresponding to the inside of the text, the area corresponding to the outline of the text, and the area corresponding to the outside of the text.

The area corresponding to the outline of the text is divided into an area corresponding to the right shadow and an area not corresponding thereto, and have different values.

The displaying step may include displaying various types of outlines by controlling a color allocated to an area corresponding to a bit value read from a memory.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention stores bitmap font data by dividing the inside of the caption text, the caption text outline image, and the outside of the text by assigning 2 bits per dot, and reading the bitmap font data by 2 bits. By processing differently depending on the value, the caption text can be distinguished well from the TV image while real-time processing is possible.

To this end, first, bitmap font data must be created and stored, and the storage format of the bitmap font data is shown in FIG. 9.

That is, the part that corresponds to the inside of the text (eg, saved as 10B), the part that corresponds to the outline of the text (eg, saved as 11B, 01B), and the part that corresponds to the outside of the text (eg, saved as 00B) When the bitmap font data is produced, the data are classified in advance and stored to have different binary values (binary 00B, 01B, 10B, and 11B).

Here, the part corresponding to the outline of the text is divided into parts corresponding to the right drop shadow (e.g., stored as 01B) and parts not corresponding to (e.g., stored as 11B). When the right shading effect and the entire text outline are displayed, they are separated to produce various contour effects depending on the processing method.

That is, when the same outline color is assigned to the binary values 11B and 01B corresponding to the outline of the caption text, caption text having the outline having no shadow effect is displayed as shown in FIG. 10. Also, if only 01B is assigned a color corresponding to the outline and 11B and 00B are assigned the same color as the text background, caption text having a shadow effect as shown in FIG. 11 is displayed.

Meanwhile, when different contour colors are assigned to binary values 11B and 01B corresponding to the outline of the caption text, caption data of the contour having a raised or depressed effect can be created. As shown in FIG. 12. If a brighter color is assigned to the right shade than the left shade, a protruding mark is displayed. If a brighter color is assigned to the left shade than the right shade, as shown in FIG.

14 is a flowchart illustrating a caption text processing method according to the present invention, and shows a display example when there is no outline and when there is an outline.

That is, the width, height, and start address of the font image to be displayed are read (step 901). In addition, the display characteristics of the caption text to be displayed are read (step 902).

Then, it is determined whether the display characteristic of the read caption text is outline caption text (step 903).

If it is determined in step 903 that the normal caption text has no outline, it reads the font image 2 bits (step 904), and then determines whether the read bit is 10B (step 905).

If the bit read in step 905 is 10B, the text corresponds to the inside of the text, and thus, 1 pixel is displayed as the color of the caption text at the corresponding address (step 906), and the number of processed bits is increased by 2 (step 907). In this case, if the read bit is not 10B, the process proceeds to step 907 to increase the number of bits by only 2 because it is outside the caption text.

Then, it is determined whether the read bit is the last bit of the line (step 908).

If it is determined in step 908 that it is the last bit of the corresponding line, the number of processed lines is increased by one (step 909), and then it is determined whether it is the last line of the font image (step 910). If it is determined in step 910 that the last line of the font image, the display of the caption text is finished.

If it is determined in step 908 that it is not the last bit of the line, or in step 910 it is determined that it is not the last line of the font image, the process returns to step 904 and repeats the above-described steps.

On the other hand, if it is determined in step 903 that the display characteristic of the caption text is the contour caption text, two bits of the font image are read (step 911), and the bit value is checked (step 912).

If it is determined in step 912 that the bit value is 10B, 1 pixel is displayed as the color of the caption text at the corresponding address (step 913). If it is determined that the bit value is 11B, 1 pixel is displayed as the background color of the caption text at the corresponding address. If the bit value is determined to be 01B (step 914), 1 pixel is displayed as the caption text background color at the corresponding address (step 915). At this time, according to the colors assigned to the bit values 00B, 01B, 10B, and 11B, various types of outlines may be displayed as shown in FIGS. 10 to 13.

If any one of the steps 913 to 915 is performed, the number of processed bits is increased by two (step 916). In addition, if it is determined in step 912 that the bit value is 00B, the process proceeds to step 916 where only the number of bits is increased by two.

Then, it is determined whether the read bit is the last bit of the line (step 917).

If it is determined in step 917 that it is the last bit of the line, the number of processed lines is increased by one (step 918), and it is determined whether the font line is the last line (step 919). If it is determined in step 919 that it is the last line of the font image, the display of the corresponding caption text with outlines ends.

If it is determined in step 917 that it is not the last bit of the corresponding line, or if it is determined in step 919 that it is not the last line of the font image, the process returns to step 911 and repeats the above processes.

15 is a schematic structural block diagram of a digital TV to which a caption data processing method according to the present invention is applied.

Referring to FIG. 15, the digital TV tuner 101 receives a digital broadcast signal from an antenna and outputs the digital broadcast signal to a residual sideband (VSB) demodulator 102. The VSB demodulator 102 receives the digital TV tuner unit ( Residual sideband (VSB) demodulation is performed on the channel received through 101 to output to the image processor 106. The analog TV tuner unit 103 receives an analog broadcast signal from an antenna and outputs the analog broadcast signal to the image processing unit 106, and the external terminal 104 receives a video graphics array (VGA) signal from the outside and outputs it to the image processing unit 106. do. The image processor 106 processes the input image signal and outputs the image signal to a display device, that is, a TV screen. In addition, the audio processing unit 110 processes the audio signal separated by the image processing unit 106 and outputs it to the speaker. At this time, the CPU 100 controls all of these, and the power supply unit 105 supplies the power required for the respective units.

Meanwhile, digital TV caption data is input together with an image signal, and a program for interpreting and processing the same and bitmap font data as shown in FIG. 9 are stored in the flash ROM 109. Therefore, if there is a display request of caption text, the corresponding font image is read from the flash ROM 109 under the control of the CPU 100 and stored in the image memory 107 as shown in Figs. Display on. Here, reference numeral 108 denotes a system memory.

As described above, since the present invention already has information corresponding to whether the caption text is inside, outside, or outline of the bitmap font data itself, it is not necessary to repeatedly display the caption text having the outline as many times as in the conventional method. The ability to draw at one time has the advantage of quickly processing outlined caption data. The difference from the conventional method is that instead of just reading 1 bit and checking, it reads 2 bits to determine what color (such as caption text color or caption text background color) to display.

The present invention can be easily applied to printers and word processor software using bitmap fonts to implement various character decoration effects.

As described above, according to the caption text processing method according to the present invention, when generating bitmap font data, by allocating 2 bits per dot and displaying and storing the inside, outside, outline, etc. of the caption text, the caption text is a TV image. Regardless of the change of the screen, while being well-divided, since the TV video screen is obscured by the caption is minimized, it is possible to watch the maximum TV video screen with the caption.

In addition, according to the method of displaying two kinds of outlines of the bitmap font, various decorative effects can be applied to the caption text, such as outline display, shadow display, protrusion display, and depression indicator.

Claims (9)

When producing bitmap font data, each dot is divided into an area corresponding to the inside of the test, an area corresponding to the outline of the text, and an area corresponding to the outside of the text, and different values for each area to distinguish the respective areas. Allocating n bits for each dot and storing the same in bits; And And reading caption text of various forms by reading n bits at the time of reading data for captions from the memory. The display step Reading the width, height, and start address of the font image you want to display, determining the display characteristics of the caption text, In the step of reading the font image n bits from the memory according to the display characteristics of the caption text and checking the bit values; If the bit value is an area value corresponding to the inside of the text, indicating 1 pixel as the color of the caption text at the corresponding address and increasing the number of bits by n; If the bit value is an area value corresponding to the outline of the text, indicating 1 pixel as the background color of the caption text at the corresponding address and increasing the number of bits by n; Increasing the number of bits n if the bit value is an area value corresponding to the outside of the text; And repeating the steps until the last bit of the line and the last line of the font image. The method of claim 1, wherein the area corresponding to the outline of the text is Caption text processing method characterized in that it is divided into a region corresponding to the right shade and a region that is not, so that the assigned n-bit value has a different value. The method of claim 1, wherein the displaying step Caption text processing method, characterized in that for displaying the outline of the various forms by controlling the color assigned to the area corresponding to the bit value read from the memory. The method of claim 5, Caption text processing method characterized in that the caption text of the contour having no shadow effect is displayed by allocating the color of the region corresponding to the right shade and the region not to the right of the region corresponding to the outline of the text. The method of claim 5, The caption text of the contour having a shading effect is displayed by allocating the same color of the remaining areas except for the right shade of the area corresponding to the outline of the text and the areas of the inside and outside of the text. How to handle caption text. The method of claim 5, Caption text processing method characterized in that the caption text of the contour having a protruding effect by displaying the color of the area corresponding to the right shade of the area corresponding to the outline of the text darker than the color of the other area. The method of claim 5, Caption text processing method characterized in that the caption text of the contour having a protruding effect by displaying the color of the area corresponding to the right shade of the area corresponding to the outline of the text brighter than the color of the other area. The method of claim 5, Caption text processing method characterized in that the caption text without the contour is displayed by assigning the same color of the area corresponding to the outline of the text and the area corresponding to the outside of the text. The method of claim 1, And n is at least two or more caption text processing methods.