JPH06301363A - Encode method for graphic data - Google Patents

Abstract

PURPOSE:To provide the encode method for graphic data capable of encoding graphic data to composite video signals without dot jamming. CONSTITUTION:When encoding (11) the graphic data to composite video signals VIDEO based on primary color signals (R, G and B), color synchronizing signal (SC) and horizontal synchronizing signal (HSYNC), frequency division (5) of a reference signal is performed at a prescribed frequency (f) by a second frequency division value 910 so as to generate the horizontal synchronizing signal (HSYNC), the phase of that signal is adjusted (13, 15, 17 and 19) to the other approximate phase so as to off-set the phase of a color signal in the composite video signal little by little between two adjacent scanning lines of a monitor television to input the composite video signal, and the phase of the color signal in each scanning line is inverted between two preceding and following frames of the monitor television.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for encoding graphic data into a composite video signal which can be displayed on a monitor television.

[0002]

2. Description of the Related Art Generally, in a monitor television, 525 scanning lines are alternately divided into two fields of a first field and a second field, and the scanning lines of each field are interlaced (interlaced) scanned from the top. To form an image for one screen. For example, a CD-graphic (hereinafter abbreviated as CD-G) is provided on such a monitor TV.
When displaying an image reproduced from the computer, a computer graphic image created by a graphic computer, or the like, the graphic data of the image is encoded (encoded) into a composite video signal.

As shown in FIG. 4, the composite video signal VIDEO is a horizontal synchronizing signal HSYNC for synchronizing with a scanning line during interlaced scanning, a luminance signal Y for controlling the contrast of the display screen, and a display screen. It includes a color signal C that controls color, and the color signal C is added to the luminance signal Y and multiplexed. Since the luminance signal Y needs to be taken as much as possible in the band of the composite video signal VIDEO to increase the resolution, there is no room to put the color signal C in the band of the luminance signal Y in the usual method.

However, when the luminance signal Y is decomposed into a Fourier series, the energy of the luminance signal Y is the horizontal synchronizing signal HSYN.
Since the color signal C is distributed at intervals of the frequency f _H (= 15.734 KHz), the color signal C is fitted in the gap.
Therefore, the frequency of the carrier wave of the color signal C and the frequency f _SC of the color synchronization signal are set to an odd multiple of half the horizontal synchronization frequency f _H. Specifically, taking the band of the color signal C into consideration,
455/2 times the horizontal synchronization frequency f _H (= 227.5f _H =
3.58 MHz) is set.

FIG. 5 is a block diagram showing an example of a conventional encoding apparatus for encoding graphic data from the above-mentioned CD-G or graphic computer into a composite video signal VIDEO. In the conventional encoder shown in FIG. 5, graphic data from a CD-G or a graphic computer is converted into R (red), G (green), B by a decoder 3 of a graphic decoder IC1.
Decode into three (blue) primary color signals. With this,
In the 910 frequency divider 5 of the graphic decoder IC1, the frequency from the master clock 9 is 4f _SC (= 14.3).
1813 MHz) clock is divided by 910 to generate a horizontal synchronizing signal HSYN having a frequency f _H (= 15.734 KHz).
C is generated, and similarly, the clock from the master clock 9 is frequency-divided by 4 in the frequency divider 7 to obtain the frequency f _SC (= 3.
The color synchronization signal SC of 58 MHz) is generated.

Then, in the encoding circuit 11,
A luminance signal Y and two color difference signals are generated from the three primary color signals of R, G, and B, and the color synchronization signal SC is generated by these two color difference signals.
Of a carrier wave having a frequency equal to the frequency f _{SC of the above} , a color signal C is generated, the color signal C is multiplexed and added to a luminance signal Y, and a horizontal synchronizing signal HSYNC is added to add graphic data to the composite video signal VIDEO. To encode.

Now, the above-mentioned composite video signal V
A monitor television that displays an image by IDEO uses a composite video signal VI in order to give drive signals to three electron guns R, G, and B that scan the scanning lines of a cathode ray tube.
Signal processing for separating the luminance signal Y and the color signal C from DEO is performed. The method of separating the luminance signal Y and the color signal C depends on the dimension of processing the composite video signal VIDEO.
This signal processing greatly affects the image quality including the image resolution, so monitor TVs with large screens, high-quality monitor TVs, etc., use a comb filter to set the luminance signal Y and color. The signal C is separated two-dimensionally to improve the horizontal resolution of the display image. This comb filter separates the color signal C by subtraction of the composite video signal VIDEO and the delayed signal thereof in which the phases of the color signal C are inverse to each other, and the separated color signal C is separated from the composite video signal VIDEO. The luminance signal Y is separated by subtracting it.

[0008]

However, when the luminance signal Y and the color signal C are separated from the composite video signal VIDEO by using the comb filter, the composite video signal VIDEO is generated at the color boundary (vertical change).
And the delayed signal thereof, the color signals C are not in a relationship of being inverted with each other. In that case, when the luminance signal Y is separated from the composite video signal VIDEO, a color signal C component that is not directly related to the image remains in the luminance signal Y, and as a result, the color signal C component is displayed on the screen of the monitor television. There is a problem in that the dot-shaped pattern D as shown in FIG. 1 appears, which causes an interference called dot crawl (hereinafter, referred to as dot interference).

Further, the phase of the color signal C of the composite video signal VIDEO for each scanning line is the same as that of the color synchronization signal S.
As long as the frequency f _{SC of} C (the frequency f _S of the carrier of the color signal C) and the frequency f _H of the horizontal synchronizing signal HSYNC are the same as described above, they always match even if the frame changes.
If the dot interference described above occurs, the dot-shaped pattern D will remain on the screen as it is even when the scanning of the next frame starts, and the pattern D will be emphasized in the eyes of the person watching the monitor television. There was a problem.

The present invention has been made in view of the above problems, and provides a graphic data encoding method capable of encoding graphic data from a CD-G or a graphic computer into a composite video signal free from dot interference. This is an issue.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention decodes graphic data into R,
Three primary color signals of G and B are generated, a reference signal of a predetermined frequency is divided by a first frequency division value to generate a color synchronization signal, and the reference signal is divided by a second frequency division value and then horizontal. Generate a sync signal,
When the graphic data is encoded into a composite video signal based on the three primary color signals, the color synchronization signal, and the horizontal synchronization signal, the phase of the horizontal synchronization signal is adjusted to another phase that approximates the composite video signal. The phase of the color signal of the composite video signal is gradually offset between two adjacent scan lines of the monitor TV to which the video signal is input, and the phase of the color signal of each scan line is inverted between the two frames before and after the monitor TV. It is characterized by doing so.

[0012]

According to the graphic data encoding method of the present invention as described above, the phase of the horizontal synchronizing signal generated by dividing the reference signal of the predetermined frequency by the second frequency dividing value is changed to another phase close to it. By adjusting, the phase of the color signal of the composite video signal is offset little by little between the two adjacent scanning lines of the monitor TV to which the composite video signal is input, and the scanning line of each scanning line between the two frames before and after the monitor TV is offset. Since the phase of the chrominance signal is inverted, when the luminance signal is separated from the composite video signal using a comb filter on a monitor TV, even if the chrominance signal component at the color boundary remains in the luminance signal, Since the phase of the remaining chrominance signal component is reversed from that of the previous frame when scanning in the frame, the chrominance signal that remains in the luminance signal There are offset by scanning in the two frames before and after, called dot interference is eliminated place called dot-like pattern appears in the monitor TV screen.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are views showing an embodiment of a graphic data encoding method according to the present invention.
FIG. 1 is a block diagram showing a schematic configuration of a specific encoding apparatus for carrying out the method of the present invention. In FIG. 1, the same parts as those shown in FIG. 5 are designated by the same reference numerals as those shown in FIG.

The encoding apparatus of this embodiment shown in FIG.
An element surrounded by a broken line in FIG. 1 is added between the graphic decoder IC1 and the master clock 9 in the conventional encoder shown in FIG.
A phase-locked loop (PLL) circuit is configured as a whole except for 1. Explaining each part in this broken line, reference numeral 13 is a frequency divider, which generates a signal obtained by dividing a clock (corresponding to a reference signal) of frequency 4f _SC from the master clock 9 by 4. In the encoding device of the present embodiment, the signal generated by the divide-by-four frequency divider 13 is used as the color synchronization signal SC and output to the encoding circuit 11. Further, reference numeral 15 is a 909 frequency divider, which has a frequency of 4 from the master clock 9.
A signal obtained by dividing the f _SC clock by 909 is generated.

Reference numeral 17 is a phase comparator, which outputs the signal output from the 909 frequency divider 15 and the graphic decoder IC1.
Phase comparison with the horizontal synchronization signal HSYNC generated by the 910 frequency divider 5 of FIG. Further, reference numeral 19 is a voltage controlled oscillator (VCO) that oscillates at a frequency f _O (free running frequency) = 4f _SC , and the phase comparator 17 corresponds to the phase difference between the two signals phase-compared by the phase comparator 17. according to the error signal from the direction in which the error signal becomes smaller one which changes a frequency f _O, signals of the frequency f _O is supplied to the 910 frequency divider 5 and the 1/4 frequency divider 7 of the graphic decoder IC1 It

Therefore, in the graphic decoder IC1, the graphic data in the decoder 3 is R (red) and G.
(Green), is decoded to the three primary color signals B (blue), and in 910-frequency divider 5, is 910 divided by the frequency f _O of the signal from the voltage controlled oscillator 19 is performed. The signal from the voltage controlled oscillator 19 whose frequency is 910 divided by the 910 frequency divider 5 is used as the horizontal synchronizing signal HSYNC and is output to the encoding circuit 11 and also to the phase comparator 17 as described above. To be done. In the encoding apparatus of this embodiment, the voltage controlled oscillator 19 divided by 4 by the divider 4 is used.
The signal from is not used. Further, in the encoding apparatus of the present embodiment, the frequency division value “4” of the frequency dividers 4 and 7 corresponds to the first frequency division value, and the frequency division value of the 910 frequency divider 5 is “9”.
"10" corresponds to the second frequency division value.

In the encoding apparatus of this embodiment having the above-described structure, first, when the voltage controlled oscillator 19 oscillates at the free running frequency f _O = 4f _SC , the graphic decoder I
Horizontal sync signal HS output from the 910 frequency divider 5 of C1
The frequency of YNC is f _H = 4f _SC / 910. This horizontal synchronizing signal HSYNC is output to the phase comparator 17, where the frequency f ₁ = 4 output from the 909 frequency divider 15 is output.
A phase comparison is made with the f _SC / 909 signal.

Since there is a frequency difference of 4f _SC / (909 × 910) between the two signals which the phase comparator 17 compares in phase, a phase difference naturally occurs, so that an error signal corresponding to the phase difference is generated. because There is output to the voltage controlled oscillator 19, voltage controlled oscillator 19 in response to this, changing the frequency f _O in a direction in which the error signal is reduced, the frequency f _O 4
Change from f _SC to 910 × 4 f _SC / 909.
Then, at the time when there is no phase difference between the two signals to be compared in phase by the phase comparator 17, the frequency of the signal output from the voltage controlled oscillator 19 becomes f _O = 910 × 4f _SC / 909. 91 of IC1
The frequency of the horizontal synchronizing signal HSYNC output from the 0 frequency divider 5 becomes f _H = 4f _SC / 909. In this state, the phase lock is applied, and thereafter the voltage controlled oscillator 19
Operates so that the frequency f _{O of} the signal output by itself follows the frequency f ₁ of the signal output from the 909 frequency divider 15, and accordingly 910 of the graphic decoder IC1.
The frequency of the horizontal synchronizing signal HSYNC output from the frequency divider 5 is fixed at f _H = 4f _SC / 909.

Therefore, in the encoding circuit 11, 3 decoded by the decoder 3 of the graphic decoder IC1 is used.
A luminance signal Y and two color difference signals are generated from one primary color signal, and the frequency f _SC of the color synchronization signal SC is generated by these two color difference signals.
To generate a color signal C by modulating a carrier wave having a frequency equal to
This color signal C is multiplexed with the luminance signal Y and added,
Horizontal sync signal HS whose frequency is f _H = 4f _SC / 909
YNC is added to encode the graphic data into the composite video signal VIDEO. The composite video signal VIDEO encoded in this way
The ratio between the frequency f _SC of the frequency f _H and the color burst signal SC of the horizontal synchronization signal HSYNC is normal _{f H: f SC = 4:} 9
Instead of 10, f _H : f _SC = 4: 909.

FIG. 2 is an enlarged view showing a screen of a monitor television having 525 scanning lines. N, n + in Fig. 2
1, n + 2, n + 3 are scanning lines, and scanning lines n, n + 2
Is in the first field, and scan lines n + 1 and n + 3 are in the second field.
In the field. This composite video signal VID
When interlacing these scanning lines n, n + 1, n + 2, and n + 3 with EO, the phase of the color signal C of each composite video signal VIDEO is sequentially offset by one-third of a half cycle as shown in FIG. In the next frame, the phase of the color signal C of the composite video signal VIDEO is inverted in each of the scanning lines n, n + 1, n + 2 and n + 3.

Therefore, when the luminance signal Y is separated from the composite video signal VIDEO encoded by the encoding apparatus of the present embodiment using the comb filter on the monitor television side, the color signal C component at the color boundary portion is the luminance. Signal Y
Even if it remains inside, since the phase of the remaining color signal C component at the time of scanning in the next frame is inverted from that at the time of scanning in the previous frame, the color signal C component remaining in the luminance signal Y Scanning in the two frames before and after is offset, and dot interference is prevented. As described above, according to the encoding apparatus of the present embodiment, it is possible to prevent the dot interference from occurring in the encoded composite video signal VIDEO when being displayed on the monitor television.

In this embodiment, the graphic decoder I
Although the case where the C1 is provided with the 910 frequency divider 5 has been described, the method of the present invention uses a graphic decoder for frequency dividers other than the 910 frequency divider, such as the 908 frequency divider, the 911 frequency divider, and the 920 frequency divider. Needless to say, the present invention can be applied to the case where the IC is provided, and by configuring the phase-locked loop as in the present embodiment, it does not depend on the frequency division value of the frequency divider in the ready-made graphic decoder IC. The frequency f _H of the horizontal sync signal HSYNC can be set to 4/909 times the frequency f _SC of the color sync signal SC.

Further, in this embodiment, the horizontal synchronizing signal HSYN
The frequency f _H of C is set to 4/9 of the frequency f _SC of the color synchronization signal SC.
The case where the color signal phase is set to 09 times is explained, but if the phase of the color signal can be offset little by little so that the phase of the color signal of the composite video signal of each scanning line can be inverted between the two frames before and after the monitor television, Of course, other numerical values can be selected.

[0024]

As described above, according to the present invention, the phase of the horizontal synchronizing signal generated by dividing the reference signal of the predetermined frequency by the second frequency dividing value is adjusted to another phase which is close to it. As a result, the phase of the color signal of the composite video signal is gradually offset between the adjacent two scanning lines of the monitor TV to which the composite video signal is input, and the color signal of each scanning line between the two frames before and after the monitor TV is offset. Since the phase is reversed, when the luminance signal is separated from the composite video signal using a comb filter on a monitor TV, even if the chrominance signal component at the color boundary remains in the luminance signal, the next frame Since the phase of the remaining chrominance signal component is reversed during the scanning in, the chrominance signal component remaining in the luminance signal is the two preceding and following frames. Offset by scanning in which, called dot interference place called dot-like pattern appears is eliminated during monitoring TV screen. That is, according to the graphic data encoding method of the present invention, graphic data from a CD-G or a graphic computer can be encoded into a composite video signal in which dot interference does not occur.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a specific encoding apparatus for implementing a method of encoding graphic data according to the present invention.

FIG. 2 is an enlarged view showing a screen having 525 scanning lines of a monitor television to which a composite video signal is input.

FIG. 3 is a waveform diagram showing how the phases of the color signals of the composite video signal for each scanning line of the monitor television shown in FIG. 2 are gradually offset.

FIG. 4 is a waveform diagram showing an example of a composite video signal.

FIG. 5 is a block diagram showing an example of a conventional encoding device.

FIG. 6 is an explanatory diagram showing a state where dot interference has occurred on the screen of the monitor television.

[Explanation of symbols]

 1 Graphic Decoder IC 3 Decoder 5 910 Divider 7, 13 4 Divider 9 Master Clock 11 Encoding Circuit 15 909 Divider 17 Phase Comparator 19 Voltage Controlled Oscillator (VCO) HSYNC Horizontal Sync Signal SC Color Sync Signal R, G, B primary color signal VIDEO composite video signal

Claims (1)

[Claims] 1. The graphic data is decoded into R,
G, B three primary color signals are generated, a reference signal of a predetermined frequency is divided by a first frequency division value to generate a color synchronization signal, and the reference signal is divided by a second frequency division value and then horizontal. A sync signal is generated, and when the graphic data is encoded into a composite video signal based on the three primary color signals, the color sync signal, and the horizontal sync signal, another phase that approximates the phase of the horizontal sync signal is generated. By adjusting, the phase of the color signal of the composite video signal is offset little by little between the two adjacent scanning lines of the monitor TV to which the composite video signal is input, and the scanning line of each scanning line between the two frames before and after the monitor TV is offset. A method for encoding graphic data, characterized in that the phases of color signals are inverted.