JP3241539B2 - Video signal processing circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display screen of a television receiver of the current NTSC system or the like (aspect ratio 4: 3).
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing circuit of a video reproducing apparatus having a display screen having a wider landscape aspect ratio (for example, 16 to 9), and particularly to a video signal processing circuit capable of automatically changing a screen size from an input video signal. About.

[0002]

2. Description of the Related Art Currently used television receivers having a display screen with a wide aspect ratio include a high-vision receiver, a simple high-vision receiver, and a MUSE.
A wide television receiver with an NTSC converter,
There is a wide television receiver without a MUSE-NTSC converter. Also, it has been determined that a second-generation EDTV receiver uses a display screen with a wide aspect ratio.

Conventionally, in television broadcasting or video software using a movie as a source, in order to display the original screen without trimming, the width of the screen of the movie is made to match the width of the screen having an aspect ratio of 4: 3. Displaying blank areas without video at the top and bottom of a screen has been performed.

When such an image called a cinemascope size or a Vista size is reproduced on a display screen having a wide aspect ratio, the image portion on the display screen is stretched at the same vertical / horizontal ratio and the length of the image in the vertical direction is increased. When the length and the vertical length of the display screen are matched, the video can be reproduced to fill the display screen, so that a powerful video can be enjoyed.

[0005] As a conventional technique for determining the aspect ratio of video content from an input video signal in order to expand the amplitude, there is, for example, JP-A-1-305786. FIG. 7 is a block diagram of this conventional publication. The counter circuit 31 counts the horizontal synchronizing signal for each field. The count value of the counter circuit 31 is decoded and the upper end of the screen in one field (1, 2H), Center part of screen, bottom part of screen (26
Gate pulse a1,
A decoding circuit 32 for creating a2 and a3, a video signal is sampled, the added value thereof is compared with a predetermined threshold value, and a signal presence / absence detection circuit 33 for detecting the presence / absence of a signal is output by a gate pulse. a gate circuit 34 for outputting each of the periods a1, a2 and a3;
An aspect ratio discriminating circuit 35 is provided to detect the presence or absence of a video signal by comparing the added value of the video signal within the period of 1, a2, and a3 with a predetermined threshold, and determine the aspect ratio of the video content from the detection result. .

In this configuration, if the input video signal is a standard size NTSC signal, as shown in FIG. 8 (a), the video signal is present in any of the upper, center and lower portions of the screen. The ratio is determined to be 4 to 3. Also,
If the input video signal is a cinemascope-sized NTSC signal, a video signal is detected at the center of the screen as shown in FIG. 8B, but no video signal is detected at the top and bottom of the screen. The ratio is determined to be 16: 9. FIG. 8C shows the output timing of the gate pulses a1, a2 and a3 as the output of the decode circuit 32, and FIG. 8D shows the output count value of the counter circuit 31.

[0007] In addition to the above, a method of discriminating a video portion from a blank portion includes sampling a video signal a plurality of times, comparing each sample value with a predetermined threshold, and determining whether the video signal is blank based on the number of sample values exceeding the threshold. There is a method of determining the unit.

[0008]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. Hei.
In the conventional aspect ratio discrimination method disclosed in Japanese Patent No. 05786, when the image range is shifted from the center of the screen,
Centering suitable for the image cannot be performed.
Further, even in the case of an image having an aspect ratio of 4: 3, an image having dark areas at the top and bottom as shown in FIG. 9 is input, or an image having almost dark areas at the top as shown in FIG. If it is input, the start line and the end line at the vertical position of the video are erroneously recognized, and there is a disadvantage that the screen size is changed to the wrong one.

SUMMARY OF THE INVENTION It is an object of the present invention to accurately determine a video area of an input video signal, switch a display screen size and a display position in accordance with the determined video area, and set a video mode which is optimal for video content. It is to provide a processing circuit.

[0010]

A video signal processing circuit according to a first aspect of the present invention is separated from an input video signal.
The level of the digitized luminance signal is
Each, 1 at each point in the line, a luminance level comparison circuit to a predetermined threshold level and compared, the output of the luminance level comparison circuit, port of every one line that satisfies the threshold value level
The number of points and the first criterion are compared, a line that satisfies the first criterion is determined as a video area, and the vertical position of the start and end of the video is detected based on all the determined video lines. the first video area determining circuit, the output luminance level comparison circuit, 1 Lai filled the threshold value level
The number of points for each application is compared with a second criterion different from the first criterion, a line that satisfies the second criterion is determined as a video area, and based on all the determined video lines , Second to detect vertical position of start and end of video
If the vertical positions of the start and end of the video of both video area determination circuits match from the outputs of the video area determination circuit and the first and second video area determination circuits, the start and end of the matched video A video area determination circuit that determines the vertical position of the video area as a video area, a calculation circuit that calculates the screen size to be displayed on the display screen from the video area determined by the video area determination circuit, and a screen that is displayed on the display screen from the output of the calculation circuit A screen size switching circuit for switching the size,
An image position control circuit for controlling a display position of an image displayed on the display screen from an output of the arithmetic circuit.

According to a second aspect of the present invention, there is provided a video signal processing circuit which is separated from an input video signal ,
The level of the brightness signal
Is separated at each point, and the first luminance level comparison circuit to a first threshold level and compared, from the input video signal
And the level of the digitized luminance signal is 1
For each line, at each point in the line, the first
A second luminance level comparison circuit for comparing the threshold level and different from the second threshold level, the output of the first luminance level comparison circuit, each line of which satisfies the first threshold level
The number of points is compared with the first criterion, a line that satisfies the first criterion is determined as a video area, and the vertical position of the start and end of the video is detected based on all the determined video lines. A first video area determination circuit that performs
Video from the output of the luminance level comparison circuit compares the second determination criterion which is different from the number of points and the first criterion of 1 per line filled the threshold value level, a line that satisfies the second criterion Area, and all video lines
A second video area determination circuit for detecting the vertical position of the start and end of the video based on the video signal, and the start and end of the video of both video area determination circuits based on the outputs of the first and second video area determination circuits. If the vertical positions of
A video area determination circuit for determining the start and end vertical positions of the matched video in a video area, an arithmetic circuit for calculating a screen size to be displayed on a display screen from the video area determined by the video area determination circuit, and an arithmetic circuit And a video position control circuit for controlling a display position of a video to be displayed on the display screen from an output of the arithmetic circuit. A video signal processing circuit according to a third aspect of the present invention includes a first luminance level comparison circuit that compares a luminance signal level of an input video signal with a first threshold level; A second luminance level comparing circuit for comparing the first and second threshold levels with each other, and a first image for detecting the start and end vertical positions of the image based on a first criterion from the output of the first luminance level comparing circuit. An area determination circuit, a second video area determination circuit that detects a vertical position of a video start and an end based on a second determination criterion from an output of the second luminance level comparison circuit, and a first and a second video. A video area determination circuit for determining a video area from the output of the area determination circuit, an arithmetic circuit for calculating a screen size to be displayed on the display screen from the video area determined by the video area determination circuit, and a table from the output of the arithmetic circuit Comprising a screen size switching circuit for switching the screen size to be displayed on the screen, and a video position control circuit for controlling the display position of the image to be displayed on the display screen from the output of the arithmetic circuit.

[0012]

In the video signal processing circuit according to the first and second aspects of the present invention, the luminance level comparison circuit is separated from the input video signal .
And the digitized luminance signal level, one line
Each time, each point in one line is compared with a predetermined threshold level, and the determination result is sent to the first and second video area determination circuits. The first and second video area determination circuits perform video determination in accordance with the specified determination parameters, respectively, and send the result to the video area determination circuit. The video area determination circuit determines the reliability of the video determination data by comparing the transmitted video determination data, and determines the video area based on the reliability and the determination data. The determined data is sent to the arithmetic circuit. The arithmetic circuit calculates data such as a video range from the video start data and the video end data, transfers the data to the screen size switching circuit to switch to the optimal screen size, and also transmits the video center data and the like to the video position control circuit. The display position of the image is controlled by sending.

A video signal processing circuit according to a third aspect of the present invention is provided with first and second luminance level comparing circuits having different threshold levels. For example, the threshold level of the first luminance level comparing circuit is set low. , The first determination circuit is set to determine the image area when there is much data exceeding the threshold, the threshold level of the second luminance level comparison circuit is set high, and the second determination circuit exceeds the threshold. By setting so that the data is determined to be at least a video area and performing a comprehensive determination, it is possible to determine a video with high accuracy.

Therefore, when a cinemascope-sized or Vista-sized video signal having no video area at the top and bottom of the screen is input to a wide television receiver having a horizontally long aspect ratio of the display screen, a blank portion of the video signal is generated. It is possible to accurately identify the image portion and the screen size can be automatically switched.

[0015]

FIG. 1 is a block diagram showing an embodiment of a video signal processing circuit according to the present invention. In this embodiment, a video signal input from an input terminal 1 is separated into a luminance signal and a chroma signal by a Y / C separation circuit 2, and the separated luminance signals are input to a luminance level comparison circuit 3 and a synchronization separation circuit 4. Is done. It is assumed that the separated luminance signal is digitized before or after the Y / C separation circuit 2.

The luminance level comparison circuit 3 compares the level of the luminance signal with a predetermined threshold level, and compares the result of the determination with the first threshold level.
And to the second video area determination circuits 5 and 6. Further, the synchronization separation circuit 4 separates the horizontal synchronization signal and the vertical synchronization signal from the luminance signal, and sends them to the gate generation circuit 7. The gate generation circuit 7 creates various gate pulses based on the sent horizontal and vertical synchronization signals, and sends them to the first video area determination circuit 5 and the second video area determination circuit 6 as timing pulses.

The video area determination circuits 5 and 6 make video determinations in accordance with the specified determination parameters, and send the results to the video area determination circuit 8. The video area determination circuit 8 compares the individually transmitted video determination data to determine the reliability of the video determination data, and determines the video area based on the reliability and the determination data. The determined data is sent to the arithmetic circuit 9 having a microcomputer configuration.

The arithmetic circuit 9 calculates data such as a video range from the video start data and the video end data, transfers the data to the screen size switching circuit 10 to switch the screen to an optimum screen size, and to the video position control circuit 11 The display position of the image is controlled by transmitting data of the center of the image and the like.

In this configuration, the first video area determination circuit 5 sets the determination parameter to a large value, and if there are not many points exceeding the threshold in one line, the first video area determination circuit 5 does not determine it as a video. In the second video area determination circuit 6, the determination parameter is set to a small value, and a setting is made such that even if the number of points exceeding the threshold in one line is small, it is determined to be a video area.

For example, when a mountain-shaped image as shown in FIG. 2 is input and an image in a dark region above the mountain is input, the determination line of the first image area determination circuit 5 is line Lb, Assuming that the determination line of the video area determination circuit 6 is line La, the first video area determination circuit 5 sets a large determination parameter on the line Lb, so that it is determined that there are few points exceeding the threshold, and the video is determined to be a video. Do not judge. However, for the line La, the second video area determination circuit 6 sets the determination parameter to be small, and therefore determines that the line is the video area even if the number of points exceeding the threshold is small.

Based on this result, the first video area determination circuit 5 and the second video area determination circuit 6 output data of different video areas. The video area determination circuit 8 having received this data determines that the reliability of the data is low because the two data are different, and cancels the data update.

When a video having dark areas at the upper and lower ends as shown in FIG. 3 is input, both the first video area determination circuit 5 and the second video area determination circuit 6 on the line c At the same time, the image area is determined. This data is sent to the video area determination circuit 8, and the determination circuit 8 determines that the reliability is high, and updates the video area data. As described above, since the image area can be determined in consideration of the reliability from the determination results of the two determination circuits 5 and 6, the image area can be determined more accurately.

Next, another embodiment of the present invention will be described. FIG. 4 is a block diagram showing another embodiment of the video signal processing circuit according to the present invention, and the same components as those in FIG.

In this embodiment, in the configuration shown in FIG. 1, a second luminance level comparing circuit 12 is provided in addition to the luminance level comparing circuit 3, and the output of the first luminance level comparing circuit 3 is the first luminance level comparing circuit 3. The output of the second luminance level comparison circuit 12 is supplied to the video area determination circuit 5.
And a first threshold setting circuit 1 for setting threshold data of the first luminance level comparison circuit 3
3. Except that a second threshold setting circuit 14 for setting threshold data of the second luminance level comparison circuit 12 is provided, it has the same configuration as the configuration shown in FIG.

In this configuration, the luminance signal separated by the Y / C separation circuit 2 is divided into a first luminance level comparison circuit 3 and a second
Are input to the luminance level comparison circuit 12 and the synchronization separation circuit 4, respectively. In the first luminance level comparison circuit 3, the first
And compares the threshold data from the threshold setting circuit 13 with the video data, and sends the determination result to the first video area determination circuit 5. Also, the second luminance level comparison circuit 12 compares the threshold data from the second threshold setting circuit 14 with the video data, and sends the determination result to the second video area determination circuit 6.

The first luminance level comparison circuit 3 sets the threshold level to a low level, and the first video area determination circuit 5 determines that the image area is a video area when there are many points exceeding the threshold. Set it. Also, the second luminance level comparison circuit 12 sets the threshold level to a high level, and the second video area determination circuit 6 determines that the image area is a video area even if there are few points exceeding the higher threshold value. To be set.

For example, as shown in FIG. 5, most of the levels are equal to the threshold level THb of the first luminance level comparing circuit 3.
When a video signal that temporarily exceeds the threshold level THa of the second luminance level comparison circuit 12 is input, the first determination circuit 5 does not determine an image because there are few points that exceed the threshold. However, the second determination circuit 6 determines that the image is an image area because the image is determined to be an image even if the number of points exceeding the threshold is small. At this time, the video area determination circuit 8 determines that the area is a video area.

As shown in FIG. 6, a video signal whose level is almost between the threshold level THb of the first luminance level comparator 3 and the threshold level THa of the second luminance level comparator 12 is input. Then, the first determination circuit 5 determines that the area is the image area because there are many points exceeding the threshold value. However, the second determination circuit 6 does not determine the image area because there is no point exceeding the threshold. At this time, the video area determination circuit 8 determines that the area is a video area.

[0029]

According to the present invention, when determining the video area of the input video signal, the reliability of the determination data can be taken into consideration by individually performing video determination using a plurality of determination parameters. More accurate determination of the video area can be realized depending on the video content.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a video signal processing circuit according to the present invention.

FIG. 2 is an image example for explaining the operation of the embodiment shown in FIG. 1;

FIG. 3 is a video example for explaining the operation of the embodiment shown in FIG. 1;

FIG. 4 is a block diagram showing another embodiment of the video signal processing circuit according to the present invention.

FIG. 5 is an example of a video signal for explaining the operation of the embodiment shown in FIG. 4;

FIG. 6 is a video signal example for explaining the operation of the embodiment shown in FIG.

FIG. 7 is a block diagram of a conventional technique.

FIG. 8 is a waveform chart for explaining the operation of the conventional technique.

FIG. 9 is an example of a malfunctioning video in the related art.

FIG. 10 is an example of a malfunctioning image in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input terminal 2 Y / C separation circuit 3, 12 Brightness level comparison circuit 4 Synchronization separation circuit 5, 6 Image area determination circuit 7 Gate generation circuit 8 Image area determination circuit 9 Operation circuit 10 Screen size switching circuit 11 Image position control circuit 13 , 14 threshold setting circuit

Claims (2)

(57) [Claims] 1. An image processing apparatus which is separated from an input video signal and has a
The level of the digitized luminance signal is changed line by line.
At each point in one line, a certain threshold level and
A luminance level comparison circuit to compare, from said output luminance level comparison circuit compares the previous SL points threshold level satisfying 1 each line and the first criterion was met first criterion determines the line and picture area, based on the total image line that is the determination, the first video area determination circuit for detecting the start and end of the vertical position of the video, from the output of the luminance level comparison circuit, before Symbol The number of points for each line that satisfies the threshold level is compared with a second criterion different from the first criterion, and a line that satisfies the second criterion is determined as an image area. A second video area determination circuit that detects a vertical position at the start and end of the video based on all video lines , and an output of the first and second video area determination circuits,
When the start and end vertical positions of the images of both image area determination circuits match, an image area determination circuit that determines the start and end vertical positions of the matched images in the image area; An arithmetic circuit for calculating the screen size to be displayed on the display screen from the determined video area; a screen size switching circuit for switching the screen size to be displayed on the display screen from the output of the arithmetic circuit; and a display from the output of the arithmetic circuit to the display screen And a video position control circuit for controlling a display position of the video to be displayed. 2. A digital video signal which is separated from an input video signal and
The level of the digitalized luminance signal is
At each point in the line, a first luminance level comparison circuit for comparing with a first threshold level , separated from the input video signal and digitized;
The level of the luminance signal is changed for each line.
In each point of the second luminance level comparison circuit for comparing the first threshold level and different from the second threshold level, the output of the first luminance level comparison circuit, before Symbol first threshold level comparing the number of points per line and the first criterion was met, the line that satisfies the first criterion is determined that the image area, based on the total image line that is the determination, the start of the video and a first image area determination circuit for detecting the end of the vertical position, from the output of the second luminance level comparison circuit, a pre-Symbol points to the first criterion of 1 per line satisfying the threshold level The second line is compared with a different second criterion, a line that satisfies the second criterion is determined as an image area, and a vertical position at which a video starts and ends is detected based on all the determined video lines . 2 image area A determination circuit, the outputs of the first and second video area determining circuit,
A video area determination circuit for determining the start and end vertical positions of the matched video in the video area when the video start and end vertical positions of both video area determination circuits match; A calculation circuit for calculating a screen size to be displayed on the display screen from the video area determined in the above, a screen size switching circuit for switching a screen size to be displayed on the display screen from an output of the calculation circuit, and a display screen from the output of the calculation circuit. A video signal processing circuit, comprising: a video position control circuit that controls a display position of a video to be displayed.