JP2609937B2 - High image quality TV signal / TV signal converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention suppresses flicker of a high-definition TV signal / TV signal converter, in particular, when displaying a high-quality TV screen with a wide aspect ratio on a TV screen. To a high quality TV signal / TV signal converter.

[Prior art] NTSC, the standard TV system currently used in Japan
The method was adopted in the United States in 1953, but the lack of resolution has come to be felt with recent enlargement of the screen.

On the other hand, recent advances in electronics have been remarkable, including semiconductor technology and satellite transmission technology.
In order to solve the above-mentioned lack of resolution, some new high-quality images have been proposed.

Such high-definition TVs include, for example, HDTV, MAC (Multiple Analog Component), EDTV (Extend
ed definition TV) has been proposed, especially for HDTV, the aspect ratio of the screen is 9:16.
It is wider than the NTSC system, and the number of scanning lines is 1125, which is about twice that of the 525 lines in the NTSC system.

However, these high-definition technologies such as HDTV
Receivers (decoders) and receivers dedicated to TVs are relatively expensive, and therefore there is a need for a converter that can receive these high-quality TV images even with current TV receivers. .

There are several types of such high-definition TV signal / TV signal converters, but the wide-mode method, in which a high-quality screen with a wide aspect ratio is displayed on a TV screen with an aspect ratio of 3: 4 as it is, is called program production. Since it has the advantage that the intended composition is sometimes preserved, its practical value is high. FIG. 3 shows an example in which a high-definition screen having an aspect ratio of 9:16 is displayed on a current TV screen having an aspect ratio of 3: 4 using such a high-quality TV signal / TV signal converter. Since the screen in the horizontal and vertical directions is compressed and fitted into a 3: 4 screen, no image exists on the upper and lower sides 1 and 2 of the screen, and this portion is usually set to a black background.

FIG. 4 shows a waveform of a signal converted by the converter to display such an image portion and a background portion. For example, in the case of HDTV, the image signal is MUSE (Multip
le Sub-Nyquist-Sampling Encoding), which is transmitted after being band-compressed. This MUSE signal can be received by the current NTSC TV receiver using a conversion processing unit having a vertical filter, time axis conversion circuit, etc. The signal is converted into an image partial signal and becomes an image partial signal.

On the other hand, the background portion signal is created separately from the image portion signal, and is added to a predetermined line on the screen. The fourth
In the figure, only the upper background portion 1 is shown, on the 1-n lines of the odd field, and on the even field.
An example is shown in which this black level background portion signal is added to lines 264 to n + 263.

[Problems to be Solved by the Invention] As described above, in the conventional high image quality TV signal / TV signal converter, the background part signal and the image part signal are distinguished in each of the odd field and the even field, and the signal processing is performed. When interlaced scanning is performed using such a signal, flicker occurs at the boundary between the background portion and the image portion, and there is a problem that it is extremely unsightly.

In other words, in interlaced scanning, scanning of odd fields is performed in 1/60 seconds, and scanning of even fields is performed in 1/60 seconds, but the boundary part goes up and down in this 1/30 second, Flicker will occur.
FIG. 5 (A) shows an image obtained by a conventional high quality TV signal / TV signal converter, and FIG. 5 (B) shows a partially enlarged view of a boundary between a background portion and an image portion. The boundary rises and falls at the 1/2 line portion 3 and flicker occurs.

The present invention has been made in view of the above conventional problems,
An object of the present invention is to provide a high quality TV signal / TV signal converter capable of suppressing flicker occurring at a boundary between a background portion and an image portion.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a conversion process for converting an image signal of a high-quality TV screen having a predetermined aspect ratio into an image signal receivable by a TV receiver. And a high-quality TV screen with an aspect ratio of 3: 4 based on the converted image signal.
In a high-quality TV signal / TV signal converter for displaying in a TV screen, an image memory for storing the converted image signal, and a line counter for counting the number of horizontal scanning lines of the TV receiver, A decoder for detecting a line of a background portion located near a boundary with an image portion based on a count value from the line counter and outputting a detection signal; and a background signal generator for generating a background signal having an arbitrary luminance level Circuit, and when the detection signal is output from the decoder, the image signal of the converted first line or the last line and the background signal are added by a mixer so that the mixing ratio gradually increases toward the image boundary. And an output control circuit that outputs the converted image signal when the detection signal is not output from the decoder. Comprising a boundary in a region near the image of the background portion of the TV screen and displaying an ambiguous background.

Further, the output control circuit, when the detection signal from the decoder is a detection signal of the background portion of the upper end of the image, gradually increases the mixture ratio of the image signal of the converted top line, the lower end of the image When the signal is a detection signal of a background portion, the mixing ratio of the image signal of the converted last line is gradually reduced.

[Operation] The high-definition TV signal / TV signal converter of the present invention has such a configuration, and the high-definition TV screen has an aspect ratio
When displaying on a 3: 4 TV screen, a background is displayed outside a predetermined range of the screen, that is, at the top and bottom of the screen, and the boundary between the background portion and the image portion is blurred.

That is, the image signal converted to be receivable by the TV receiver is first stored in the image memory. On the other hand, a background signal of, for example, a black level is output from the background signal generation circuit to form a background portion. When the count value of the line counter is within a predetermined range, the output control circuit adds the image signal of the first line from the image memory to the background signal from the background signal generation circuit so that the mixing ratio gradually changes. The difference between the background signal and the image signal is reduced to make the boundary ambiguous.

When the count value of the line counter is out of the range, the image signal that has undergone the conversion processing is output.

Then, when using this output signal to display a high-quality TV screen on a TV screen, the border between the background part and the image part at the top and bottom of the screen is blurred. And flicker can be suppressed.

In addition, as the aspect of the change of the mixing ratio in the output control circuit, when the number of lines is within the first range, that is, the number of lines corresponding to the upper part of the screen, the mixing ratio of the image signal of the first line is gradually increased, , Ie, when the number of lines corresponds to the lower part of the screen, the difference between the background signal and the image signal can be gradually reduced by gradually decreasing the mixing ratio of the image signal of the first line to make the boundary ambiguous. it can.

[Embodiment] Hereinafter, a high quality TV signal according to the present invention will be described with reference to the drawings.
A preferred embodiment of the / TV signal converter will be described by taking a high definition TV as an example of a high quality TV.

FIG. 1 is a configuration block diagram in the present embodiment. A high-definition image signal having an aspect ratio of 9:16 and the number of scanning lines of 1125 is transmitted after being band-compressed by the MUSE method and input to the conversion processing unit 4 similar to the conventional one. This conversion processing unit 4
It has an A / D converter, vertical filter, and NTSC encoder, and converts MUSE image signals into image signals receivable by NTSC TV receivers, such as converting the number of scanning lines from 1125 to 525. . That is, in order to display a screen having an aspect ratio of 9:16 on a screen having an aspect ratio of 3: 4, 1125 image signals are converted into 392 image signals.

The image signal converted into the NTSC format is input to the image memory 5 for each field in the order of odd field (196) and even field (196). The image memory 5 is a RAM having a storage capacity of about 16 Kbytes.
Can be used, and an image signal stored by a control signal from a decoder described later is output as appropriate.

On the other hand, the number of horizontal scanning lines of the 525 system is counted by the counter 6, and the count output is output to the decoder 10. That is, the counter 6 counts 525 horizontal synchronizing signals for one frame for one frame. The decoder 10 detects a line for displaying the background and a line for displaying the converted image signal based on the count value of the counter 6, and displays the background signal and the image signal, which are the features of the present invention, by mixing them. Line to be detected. For example, when displaying a background on lines 1 to n in an odd field, 1
-N (background part) detection, n + 1-n + 196 (odd field image part) detection, n + 197-n + 263 (end of odd field and first background part of even field) detection, n + 264-n + 459 (even field image) part)
, And n + 460 to 525 (the background portion at the end of the even field). Further, when the number of lines to be displayed by mixing the background signal and the image signal is, for example, five, the decoder 10 detects n−4 to n (odd field), and n + 197.
To n + 201 (odd field) detection, n + 259 to n + 26
Detection of 3 (even field) and detection of n + 460 to n + 464 (even field) are performed. The decoder 10 controls the reading of the image memory 5, the control of the mixing ratio of the image / background signal mixer 9, and the control of the switches SW1 and SW2 based on the detection result.

A background signal for displaying a background above and below the TV screen is output from a background signal generation circuit 7. In this embodiment, the background signal generation circuit 7 is set to output a luminance level corresponding to a black level.

What is characteristic in this embodiment is that the outputs from the background signal generation circuit 7 and the image memory 5 are decoded.
That is, an output control circuit 8 that is controlled based on the output of the control unit 10 is provided. The output control circuit 8 has an image / background signal mixer 9 for mixing the image signal from the image memory 5 and the background signal from the background signal generation circuit 7 at an appropriate ratio, and two switches SW1 and SW2. In addition, the mixing ratio of the image / background signal mixer 9 and the ON / OFF of SW1 and SW2 are controlled by the control signal of the decoder 10 based on the count value of the counter 6.

Now, a case will be described in which the background is displayed on lines 1 to n of the odd field and the background and the image are mixed on five lines as in the above-described example. When the number of lines counted by the line counter 6 is 1 to n-5, SW1 is turned on and SW2 is turned on by the control signal from the decoder 10. Then, the image signal stored in the image memory 5 is not output, only the black level background signal from the background signal generation circuit 7 is output, and a black background is displayed on the TV screen.

Then, while the count number is from n−4 to n, SW1 is turned on and SW2 is turned on by the control signal from the decoder 10. The decoder 10 sends a read signal to the image memory 5 and repeatedly reads the image signal of the first line stored in the image memory 5. Further, a control signal is sent to the image / background signal mixer 9, and the mixing ratio of the image signal and the background signal is set so that the ratio of the image signal increases as the number of lines increases. That is, weighting that gradually increases from 0 to 1 as the number of lines increases is applied to the image signal of the first line repeatedly read out for each line from n−4 to n and added to the background signal to mix the two signals. I do. Then, the image / background signal mixer 9 outputs, from the image / background signal mixer 9, an increase in the mixing ratio for each line (background signal + image signal).

When the count value of the line counter 6 becomes equal to or more than n + 1, the control signal from the decoder 10
1 turns on, and SW2 turns on. Then, the image signals read from the image memory 5 are sequentially output to the output terminal from the head line by the read signal from the decoder 10. FIG. 2 shows the waveform of the signal thus output to the output terminal. FIG. 2A is a signal waveform of an odd field in which image signals are mixed into lines of n lines or less as described above, and FIG. 2B is a signal waveform of an even field in which image signals are mixed in the same manner. It is. The image signal starts from the (n + 1) line ((n + 264) line in the even field) as described above, but the image signal of the first line is mixed with several lines of the background signal for displaying the black background. It can be seen that the boundary between the background portion and the image portion is blurred when compared with the waveform of the conventional image quality improving TV / TV signal converter shown in FIG.

Then, when interlaced scanning of the odd and even fields is performed and displayed on the TV set, the boundary between the background and the image is not clear, and the boundary may fluctuate for 1/30 second. And flicker can be suppressed.

The counting by the line counter 6 further proceeds, and n + 19
When it becomes 7 to n + 201, the decoder 10 switches SW1 to the side and SW2
To the side. The decoder 10 sends a read signal to the image memory 5, and repeatedly reads the image signal of the last line. Further, a control signal is sent to the image / background signal mixer 9, and the mixing ratio of the image signal and the background signal is set so that the ratio of the image signal decreases as the number of lines increases.
That is, weighting is gradually reduced from 1 to 0 as the number of lines increases to the image signal of the last line, and this is added to the background signal to mix both signals.

Then, the mixing ratio is reduced (background signal + image signal) for each line from the image / background signal mixer 9 to the output terminal, and the TV signal is output using this output signal.
When displayed on the receiver, the boundary between the image portion and the background portion is blurred as in the case described above, and it is possible to suppress flicker.

[Effect of the Invention] As described above, the high-quality TV signal / T according to the present invention is
According to the V signal converter, there is an effect that a boundary between a background portion and an image portion is blurred, flicker is suppressed, and a clear screen can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a high quality TV signal / TV signal converter according to the present invention, FIG. 2 is a signal waveform diagram in the first embodiment, and FIG. FIG. 4 is an explanatory diagram showing a display example by a TV signal converter, FIG. 4 is a signal waveform diagram by the conventional converter, and FIG. 5 is an explanatory diagram of flicker occurrence by the conventional converter. 4 ... Conversion processing unit 5 ... Image memory 6 ... Line counter 7 ... Background signal generation circuit 8 ... Output control circuit 9 ... Image / background signal mixer 10 ... Decoder

Claims (2)

(57) [Claims] An image processing apparatus for converting an image signal of a high-quality TV screen having a predetermined aspect ratio into an image signal receivable by a TV receiver, wherein a high-quality image is generated based on the converted image signal. A high-definition TV signal / TV signal converter for displaying a converted TV screen in a TV screen having an aspect ratio of 3: 4, comprising: an image memory for storing the converted image signal; and a horizontal scanning line of the TV receiver. A line counter that counts the number of lines, based on a count value from the line counter, detects a line of a background portion located near a boundary with the image portion,
A decoder that outputs the detection signal; a background signal generation circuit that generates a background signal having an arbitrary luminance level; and an image signal of the first or last line that has been converted when the detection signal is output from the decoder. And, the background signal is added as a background signal by adding a mixer so that the mixing ratio gradually increases toward the image boundary,
An output control circuit that outputs the converted image signal when the detection signal is not output from the decoder, wherein a background having an ambiguous boundary is displayed in an area near an image of a background portion of the TV screen. High quality TV signal / TV signal converter. 2. The image processing apparatus according to claim 1, wherein the output control circuit gradually increases a mixing ratio of the image signal of the converted first line when the detection signal from the decoder is a detection signal of a background portion at an upper end of the image. 2. The high quality TV signal / TV signal converter according to claim 1, wherein the mixing ratio of the image signal of the converted final line is gradually reduced when the detection signal is a detection signal of a background portion at a lower end. .