JPH0951490A - Vertical compression circuit for sub image video signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a natural sub screen video image in a dynamic image in the vertical direction by selecting an offset of plural fields depending on the difference of a field polarity between a master image and a sub image and selecting a proper circuit in plural offset generating circuits depending on the relation of field frequencies of the main and sub images so as to apply interpolation and compression to the image. SOLUTION: A main image field discrimination circuit 11 discriminates a field polarity of the main image based on a vertical pulse and a horizontal pulse of the main image. A sub image field discrimination circuit 12 discriminates a field polarity of the sub image based on a vertical pulse and a horizontal pulse of the sub image. An offset generating circuit 13 generates an offset in response to the main image field discrimination signal, the sub image field discrimination signal and a compression rate. An interpolation circuit 14 provides an output of a video interpolation signal to arrange the field polarity of the main image and the sub image based on the offset, the compression rate and the input sub image video signal. Thus, one or plural sub images are displayed in compression interlacing with a different synchronization timing on the same screen together with the main image of interlace display.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, when displaying a plurality of video signals with different synchronization on a video display device, vertically compresses a sub-screen that operates at a synchronization timing different from the synchronization timing of the main screen. The present invention relates to a video signal vertical compression circuit. In particular, the present invention relates to a sub-screen video signal vertical compression circuit for performing compressed interlaced display on the same screen simultaneously with the main screen for interlaced display, and one or more sub-screens different in synchronization timing of the main screen.

[0002]

2. Description of the Related Art In recent years, there has been an increasing need for simultaneously displaying a plurality of images and information. There is a need for a display device compatible with such multimedia. Figure 6
An example of the display device is shown in FIG. 6, and when the sub screen 2 is displayed in the main screen 1 as shown in FIG.
As shown in (b), the sub-screens 4, 5 have the same size as the main screen 3,
6 may be displayed at the same time. At this time, the main screen is a screen displaying a video signal used as a synchronization signal of the displayed screen.

As described above, when a plurality of video signals having different sync signal timings are simultaneously displayed on one video display device, a combining technique thereof becomes important.

By the way, since the main screen signal is synchronized with the video display device, video signal processing such as screen compression does not pose a problem in terms of timing, but the sub-screen signal is not synchronized with the display device. Consideration is required.

The present invention relates to a sub-screen video signal vertical compression circuit for vertically compressing the sub-screen video signal by vertical interpolation, and presupposes that the main screen signal and the sub-screen signal are interlaced signals.

A conventional sub-picture video signal vertical compression circuit will be described below with reference to the drawings. FIG. 4 is a block diagram of a conventional sub-screen video signal vertical compression circuit, and FIG. 5 is an operation waveform diagram for explaining the operation of the conventional sub-screen video signal vertical compression circuit. The signals shown in FIGS. 4 and 5 correspond to each other.

In FIG. 4, reference numeral 31 is used to determine whether the scanning starts from the first field (odd field) or the second field (even field) in the interlaced scanning from the vertical pulse and the horizontal pulse, that is, the so-called polarity is determined. It is a field discriminating circuit for discriminating a field to be operated. Reference numeral 32 is an offset generation circuit that generates an offset according to the compression ratio in the first field and the second field. Reference numeral 33 is an interpolation circuit which interpolates and compresses with a compression rate.

The operation of the sub-picture video signal vertical compression circuit configured as described above will be described below.

First, the field discriminating circuit 31 discriminates from the vertical pulse and the horizontal pulse whether it is the first field or the second field and outputs it.

Next, the offset generation circuit 32 sets the offset of the first field to 0, and the offset of the second field is obtained according to the compression rate of the sub-screen. In FIG. 5, since the signal of 5 lines of the input sub-screen video signal is compressed to the signal of 4 lines in the sub-screen, the compression rate is 4/5,
The interlace of 1/2 is subtracted from 1/2 of the reciprocal of the compression ratio (that is, 5/8), and 1/8 becomes the offset.

Next, the interpolation circuit 33 sets pixel values between scanning lines by interpolation, thins out the scanning lines, and outputs a compressed video signal. At this time, in the second field, the pixel value is interpolated at a position where the interpolation phase is delayed by the offset time.

[0012]

In the conventional configuration as described above, when the main screen and the sub-screen signals having different field polarities are simultaneously displayed, the phase of the signal of the second field of the compressed sub-screen is the first. There is a problem in that the vertical scanning order of the sub-screen signals is reversed in the first field and the second field without being displayed at 1/2 of the field phase, which causes an unnatural image in the vertical direction. .

In view of the above problems, the present invention judges whether the field polarities of the main screen and the sub screen are the same, and generates the offset of the first field and the second field according to the result, It is intended to provide a sub-screen video signal vertical compression circuit that corrects the phase of pixel value interpolation based on it and performs interpolation and compression so that the sub-screen does not become unnatural even when it moves in the vertical direction.

[0014]

In order to solve the above-mentioned problems, the sub-screen video signal vertical compression circuit according to claims 1 to 5 of the present invention starts field scanning of the main screen from a vertical pulse and a horizontal pulse of the main screen. Main screen field discriminating circuit for generating a field discriminating signal for discriminating the polarity indicating whether the field is the first field or the second field, and the vertical pulse of the sub-screen for compressing and displaying the input screen sub-screen video signal at a predetermined compression ratio. The sub-screen field discriminating circuit for generating a field discriminating signal for discriminating the field scanning start polarity of the sub-screen from the horizontal pulse and the horizontal pulse, and the main screen field discriminating signal, the sub-screen field discriminating signal and the compression ratio are inputted, and the first sub-screen is inputted. Offset generation circuit for generating an offset according to the compression ratio in the first field and the second field, and the offset, the compression ratio, and the input sub-screen Enter the image signal, and the amount corresponding shifting the input sub-picture video signal for the field scan start timing of the sub-screen corresponding to the offset from the output circuit for vertically compressed output.

According to a sixth aspect of the present invention, there is provided a sub-screen video signal vertical compression circuit which comprises a main-screen field discrimination circuit for generating a main-screen field discrimination signal from a vertical pulse and a horizontal pulse of the main screen, and a vertical pulse of the sub-screen. And a sub-screen field discriminating circuit for generating a sub-screen field discriminating signal from a horizontal pulse, and a main screen field discriminating signal, a sub-screen field discriminating signal and a compression ratio are inputted, and the compression ratio is set in the first and second fields of the sub-screen. 5. An offset generation circuit according to claim 4, which generates an offset according to the main screen field discrimination signal, the sub-screen field discrimination signal, and a compression ratio, and the offset corresponding to the compression ratio in the first field and the second field of the sub-screen. 6. An offset generation circuit according to claim 5 for generating a noise, an output signal of the offset generation circuit according to claim 4 and claim 5. An output signal of the offset generation circuit according to claim 4, wherein the output signal of the offset generation circuit, the main screen field frequency and the sub screen field frequency are input, and the difference between the main screen field frequency and the sub screen field frequency is detected and the frequency difference is used. The frequency difference detection circuit that selects and outputs any of the output signals of the offset generation circuit described in Item 5, the output signal of the frequency difference detection circuit, the compression ratio, and the input sub-screen video signal are input, and the input sub-screen video signal is input. It is composed of an interpolation circuit that interpolates and outputs.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, according to this structure, an appropriate offset is generated in the first field and the second field depending on whether the field polarities of the main screen and the sub screen are the same, and compression is performed. It is possible to prevent reversal of the vertical scanning order in the first field and the second field of the sub-screen signal after being combined with the main screen, and obtain a sub-screen image in which the sub-screen does not become unnatural even if it moves in the vertical direction. it can.

Further, according to the sixth aspect, by switching between the two offset circuits by using the main screen field frequency and the sub screen field frequency, it is improved to generate a more preferable offset.

(Embodiment 1) A sub-picture video signal vertical compression circuit showing an embodiment of the present invention will be described below with reference to the drawings. 1 is a block diagram showing an embodiment of claims 1 to 5 of the present invention, and FIG. 2 is a block diagram of a sub-picture video signal vertical compression circuit showing an embodiment of claim 6 of the present invention. FIG. 3 is an operation waveform diagram for explaining the operation of the sub-screen video signal vertical compression circuit showing an embodiment of claim 6 of the present invention. The signals shown in FIGS. 1 to 3 correspond to each other.

In FIG. 1, reference numeral 11 is a main screen field discriminating circuit for discriminating the field polarity of the main screen from vertical and horizontal pulses of a video signal having video information of the main screen. Reference numeral 12 is a sub-screen field discriminating circuit for discriminating the field polarity of the sub-screen from the vertical pulse and the horizontal pulse of the input sub-screen video signal having the video information of the sub-screen. Reference numeral 13 denotes an offset generation circuit that generates an offset according to the compression rate in the first field and the second field of the sub screen. Reference numeral 14 is an interpolation circuit that interpolates and outputs the input sub-screen video signal according to the offset and the compression rate.

The operation of the sub-picture video signal vertical compression circuit configured as described above will be described below.

First, the main screen field discriminating circuit 11 discriminates from the vertical and horizontal pulses of the main screen whether the field is the first field or the second field and outputs it.

Next, the sub-screen field discrimination circuit 12 discriminates from the vertical and horizontal pulses of the sub-screen whether the field is the first field or the second field, and outputs it.

Next, the offset generation circuit 13 calculates the offset. First, when the field polarities of the main screen and the sub screen are the same, the offset of the first field is set to 0, and the offset of the second field is obtained according to the compression rate. In FIG. 3, since the 5-line signal of the input sub-screen video signal is compressed into the 4-line signal on the sub-screen, the compression rate is 4/5, and 1/2 of the reciprocal of the compression rate is subtracted from 1/2. The offset is 1/8.

When the field polarities of the main screen and the sub screen are different, the offset of the first field is 1 which is the reciprocal of the compression rate.
Subtract 1/2 from / 2. The offset of the second field is -1.

Next, since it is necessary to arrange pixels in a portion where scanning lines do not exist due to thinning by compression in the interpolation circuit 14, it is possible to arrange pixels by interpolating between scanning lines. Compresses and outputs the sub-screen video signal. At this time, the interpolation phase is delayed by the offset in each of the first field and the second field.

Depending on the thinning-out method, it may be possible to perform the compression by using the pixels in which the scanning line is exactly present. Therefore, in this case, the interpolation work is not performed, and the compression by simply thinning out the scanning line is performed. Be seen.

That is, in FIG. 3, "when the offset circuit of claim 4 is used" corresponds to this, and when the field polarities of the main screen and the sub-screen are the same, the offset of the first field is 0, so that in the first field. Indicates that the input sub-screen video signal and the output sub-screen video signal (when the main and sub-field polarities are the same) have the same interpolation phase, and the offset of the second field is 1/8. It can be seen that the phase of the output sub-screen video signal is delayed by 1/8 (when the main and sub-field polarities are the same).

Further, when the field polarities of the main screen and the sub screen are different, the offset is 1 in the first field.
Since it is / 8, the output sub-screen video signal is 1/8 of the input sub-screen video signal (when the main sub-field polarity is different).
Since the phase is delayed by 1 and the offset is -1 in the second field, the phase of the output sub-screen video signal is advanced by 1 (when the polarities of the main and sub-fields are different) with respect to the input sub-screen video signal of the second field. I know that there is.

As described above, by switching the offsets generated in the first field and the second field according to whether the polarities of the main and sub fields are the same or different, the first and second sub-screen signals of the main screen and the combined sub-screen are combined. It is possible to prevent reversal of the scanning order in the vertical direction between the field and the second field, and obtain a sub screen image that is natural even if the sub screen moves in the vertical direction. Further, since the offsets of the first field and the second field are simply switched when the main and sub field polarities are the same or different, there is an advantage that the image quality of the sub screen after interpolation compression in the vertical direction can be maintained. .

(Embodiment 2) However, there is a drawback that the phase of the sub-screen after interpolation compression is shifted by 0.5 line in the vertical direction when the main and sub field polarities are the same and different.

In the fifth aspect, when the field polarities of the main screen and the sub-screen are the same, the offset of the first field is set to 0 and the offset of the second field is 1/2 of the reciprocal of the compression rate, as in the second aspect. Subtract 1/2 from. On the other hand, when the field polarities of the main screen and the sub screen are different, the offset of the first field is ½ of the reciprocal of the compression rate, and the offset of the second field is −1/2, so that The phase of the sub-screen after interpolation compression can be made to be the same in the vertical direction when the polarities are the same or different.

That is, in FIG. 3, "when the offset circuit of claim 5 is used" corresponds to this, and when the field polarities of the main screen and the sub-screen are the same, the offset of the first field is the same as in the case of claim 2. Is 0, the interpolating phases of the input sub-screen video signal and the output sub-screen video signal (when the main sub-field polarities are the same) are the same in the first field, and the offset of the second field is ⅛, so that It can be seen that the output sub-screen video signal (when the polarities of the main and sub-fields are the same) is delayed in phase by 1/8 with respect to the input sub-screen video signal.

When the field polarities of the main screen and the sub screen are different, the offset is 5 in the first field.
Since it is / 8, the interpolation phase of the output sub-screen video signal (when the main sub-field polarity is different) is 5 with respect to the input sub-screen video signal.
Since it is delayed by / 8 and the offset is -1/2 in the second field, the phase is advanced by 1/2 from the input sub-screen video signal in the second field (when the polarities of the main and sub-fields are different). You can see that you are out.

(Third Embodiment) However, since the offsets are given differently when the field polarities of the main and sub fields are the same and different, the image quality of the sub screen after interpolation compression in the vertical direction differs.

In the sixth aspect, the offset generating circuits of the fourth and fifth aspects are switched depending on the difference between the main screen field frequency and the sub-screen field frequency.

When the frequency difference is small, switching between the field polarities of the main and sub fields does not occur frequently, so
It is tolerable that the phase of the sub-screen after interpolation compression in the vertical direction is shifted by 0.5 line when the main and sub field polarities are the same and different, and the offset generating circuit according to claim 4 is selected with priority on image quality. Interpolation compression is performed by using the output signal of the offset generation circuit of claim 4 as an offset. When the frequency difference is large, switching between the field polarities of the main and sub fields frequently occurs, and it is not preferable that the phase of the sub screen shifts by 0.5 line. Therefore, the offset generating circuit of claim 5 is selected, and the vertical direction is selected. Make the phases of the sub-screens after interpolation compression the same.

[0037]

As described above, according to the present invention, the offset of the first field and the second field is switched depending on whether the field polarities of the main screen and the sub-screen are the same or different, and the field frequency of the main screen and the sub-screen is changed. Because of the relationship
By selecting a circuit that generates an appropriate offset from the two offset generation circuits and performing interpolation compression, it is possible to obtain a sub-screen image in which a vertical motion in a moving image is natural.

[Brief description of drawings]

FIG. 1 is a block diagram of a sub-screen video signal vertical compression circuit showing one embodiment of claims 1 to 5 of the present invention.

FIG. 2 is a block diagram of a sub-screen video signal vertical compression circuit showing an embodiment of claim 6 of the present invention.

FIG. 3 is an operation waveform diagram for explaining the operation of the circuit.

FIG. 4 is a block diagram of a conventional sub-screen video signal vertical compression circuit.

FIG. 5 is an operation waveform diagram for explaining the operation of the circuit.

FIG. 6A shows a first example in which a plurality of video signals with different sync signal timings are displayed on a single video display device. FIG. 6B shows a plurality of video signals with different sync signal timings as a single video. The figure which shows the 2nd example displayed on the display device.

[Explanation of symbols]

 1, 3 Main screen 2, 4, 5, 6 Sub screen 11 Main screen field discrimination circuit 12 Sub screen field discrimination circuit 13 Offset generation circuit 13a Offset generation circuit 13b Claim 5 Offset generation circuit 14 Interpolation circuit 15 Frequency difference detection circuit

Claims (6)

[Claims] 1. A sub-screen video signal vertical compression circuit for vertically compressing a sub-screen video signal, depending on whether the field polarities of the main screen and the sub-screen are the same or different and the field frequency of the main screen and the sub-screen. , A sub-screen video signal vertical compression circuit for performing interpolation compression by switching the generation method of the first field offset and the second field offset. 2. A main screen field discriminating circuit for generating a field discriminating signal for discriminating the polarity indicating whether the field scanning start of the main screen is the first field or the second field from the vertical pulse and the horizontal pulse of the main screen, and an input sub-circuit. A sub-screen field discriminating circuit for generating a field discriminating signal for discriminating a field scan start polarity of the sub-screen from vertical and horizontal pulses of the sub-screen for compressing and displaying the screen video signal at a predetermined compression ratio, and the main screen field An offset generation circuit for inputting a discrimination signal, the sub-screen field discrimination signal, and the compression rate, and generating an offset according to the compression rate in the first field and the second field of the sub-screen, the offset and the compression rate. Input the sub-screen video signal, and the field scan start timing of the sub-screen corresponds to the offset A sub-screen video signal vertical compression circuit provided with an output circuit for vertically compressing and outputting the input sub-screen video signal by shifting by the amount. 3. The sub-screen video signal vertical compression circuit according to claim 2, wherein the output circuit outputs a pixel value interpolated from a pixel value based on the input sub-screen video signal, and thins out scanning lines to perform vertical compression. 4. When the field polarities of the main screen and the sub screen are the same, the offset of the first field is set to 0, and the offset of the second field is 1/2 to 1/2 of the reciprocal of the compression rate.
Is subtracted, and when the field polarities of the main screen and the sub-screen are different, the offset of the first field is subtracted from 1/2 to 1/2 of the reciprocal of the compression ratio, and the offset of the second field is -1. The sub-screen video signal vertical compression circuit according to claim 2, further comprising an offset generation circuit. 5. When the field polarities of the main screen and the sub screen are the same, the offset of the first field is set to 0, and the offset of the second field is 1/2 to 1/2 of the reciprocal of the compression rate.
Is subtracted, and when the field polarities of the main screen and the sub screen are different, the offset of the first field is 1/2 of the reciprocal of the compression ratio, and the offset of the second field is -1.
3. The sub-screen video signal vertical compression circuit according to claim 2, further comprising an offset generation circuit that sets the frequency to 1/2. 6. The offset circuit sets the offset of the first field to 0 when the field polarities of the main screen and the sub screen are the same, and subtracts 1/2 to 1/2 of the reciprocal of the compression ratio for the offset of the second field. When the field polarities of the main screen and the sub screen are different, the offset of the first field is obtained by subtracting 1/2 from 1/2 of the reciprocal of the compression ratio,
The offset of the second field is -1. When the field polarity of the main screen and the sub screen is the same as that of the first offset generation circuit, the offset of the first field is set to 0, and the offset of the second field is the reciprocal of the compression rate. 1/2 is subtracted from 1/2, and when the field polarities of the main screen and the sub screen are different, the offset of the first field is 1 / the reciprocal of the compression rate.
2, the offset of the second field is set to −1/2, and the difference between the field frequency of the main screen and the field frequency of the sub-screen is detected, and the first difference is detected by the frequency difference. 3. The sub-screen video signal vertical compression circuit according to claim 2, further comprising: a frequency difference detection circuit that selects and outputs one of the output signal of the offset generation circuit and the output signal of the second offset generation circuit.