JP2609938B2 - 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 there is therefore a demand 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 blank 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 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.

That is, in the interlaced scanning, the scanning of the odd field is performed in 1/60 second, and the scanning of the even field is performed in 1/60 second, and thus, between the background partial signal and the image partial signal. If there is a large level difference,
The boundary part moves up and down in 1/30 second, causing flicker. 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 high quality TV signal.
A / TV signal converter includes a line counter that counts the number of horizontal scanning lines of the TV receiver, a background signal generation circuit that generates a background signal having a plurality of luminance levels, and the number of lines counted by the line counter. Is in the first range, a background signal whose luminance level increases gradually from the blank level to approximately 50% of the maximum luminance level according to the number of lines is selected from the background signal generation circuit and output. When the number is in the second range, a background signal whose luminance level sequentially decreases from approximately 50% of the maximum luminance level to a blank level according to the number of lines is selected from the background signal generating circuit and output. An output control circuit for outputting an image signal when the number is other than the above.

[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 a change in the luminance level at the boundary between the background portion and the image portion is reduced.

That is, a background signal having a plurality of brightness levels is generated from the background generation signal. When the count value of the line counter is within the first range, the output control circuit sequentially sets the brightness level to approximately 50% of the maximum brightness level. And outputs and displays the background signal which increases to the level of. When the count value of the line counter is in the second range, the output control circuit sequentially outputs a background signal whose luminance level decreases to approximately 50% of the maximum luminance level.

Then, at the boundary between the image part and the background part, there is no large change in the luminance level between the background signal and the image signal, and even when interlaced scanning is performed, the luminance change due to the fluctuation of the boundary is small, and flicker can be suppressed. 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 lines) and even field (196 lines).

Further, a background signal generating circuit 6 for generating a background signal for displaying a background at the top and bottom of the TV screen is provided.
A background signal having five luminance levels, that is, 2.5 levels, 25 levels, and 50 levels can be generated.

What is characteristic in this embodiment is that the output of the background signal generation circuit 6 and the image signal is output to the line counter 5.
The output control circuit 7 for controlling based on the count value is provided. The output control circuit 7 includes a five-terminal switch SW1 for switching a background signal having each luminance level from the background signal generation circuit 6, a two-terminal switch SW2 for switching between a signal from the SW1 and an image signal, and these switches. The decoder 8 controls the switching between SW1 and SW2 based on the count value from the line counter 5.

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
The number of 525 horizontal synchronization signals of the 525 system is counted 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 of the counter 6, and also changes the luminance level of the background signal, which is a feature of the present invention, for the line for displaying. Is detected. For example, when displaying a background on lines 1 to n in an odd field, 1
Ｎn (background portion) detection, n + 1１〜n + 196 (odd field image portion) detection, n + 197〜n + 263 (end of odd field and beginning background portion of even field)
, N + 264 to n + 459 (the image portion of the even field), 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 changing the luminance level of the background signal is, for example, four,
The decoder 10 detects n−3 to n (odd field),
Detection of n + 197 to n + 200 (odd field), n + 260
To n + 263 (even field), n + 460 to n + 46
3 (even field) is detected. This decoder 10
Controls the reading of the image memory 5 and the switches SW1 and SW2 based on the detection result.

Now, when the number of lines counted by the line counter 5 is 1 to n-4, SW1 is connected to the side by the control signal from the decoder 8, and SW2 is also connected to the side. Then, no image signal is output and only the background signal having a blank level from the background signal generation circuit 6 is output, and a black background is displayed on the TV screen.

When the count reaches n-3, SW1 is switched to the side by the control signal from the decoder 8. Then, a background signal having a 5.3 level is output from the background signal generation circuit 6, and a background having a slightly higher luminance than the blank level is displayed on the TV screen.

Then, every time the count number is counted up from n−3 to n, the decoder 8 sends a control signal and switches SW1 →→
Switch sequentially with →. Then, the background signal generation circuit 6
, A background signal whose luminance level increases in the order of 5.2 level → 12.5 level → 25 level → 50 level is output, and the luminance of the background portion of the TV screen sequentially increases.

When the count of the number of lines advances and becomes (n + 1) or more, the decoder 8 sends a control signal and switches SW2 to the side. Then, the background signal from the background signal generation circuit is not output, and only the image signal is output.

FIG. 2 shows the waveform of the signal thus output to the output terminal. FIG. 2A is a signal waveform of an odd field processed as described above, and FIG. 2B is a signal waveform of an even field processed in the same manner. The image signal starts from the (n + 1) line ((n + 264) line in the even field) as described above, but several lines of the background signal for displaying the background ((n-4) in the odd field)
Ｎn lines and (n + 259) ｎn + 263 of even fields
It can be seen that the luminance level of the line (line) gradually increases from 0, ie, the blank level, to 50% of the maximum luminance level, ie, 50 levels.

Then, when the odd field and the even field are interlaced and displayed on the TV receiver by performing interlaced scanning, there is no large difference in the brightness level even at the boundary between the background part and the image part. Even if the boundary fluctuates, the change in luminance is small and flicker can be suppressed.

The counting by the line counter 5 further proceeds, and n + 19
When it becomes 7 to n + 200, the decoder 8 depends on the number of lines.
Sends a control signal, switches SW1 in the order of →→→→, and switches SW2 to the side. Then, from the background signal generation circuit 6, 50 level → 25 level → 12.5 level →
A background signal in which the luminance level sequentially decreases from the 5.2 level to the blank level is output, and a background portion in which the luminance sequentially decreases is displayed on the TV screen.

Then, when interlaced scanning of the odd field and the even field is performed and displayed on the TV receiver as in the case described above, there is no large difference in the luminance level even at the boundary between the background part and the image part. Even if this boundary fluctuates for 30 seconds, the change in luminance is small and flicker can be suppressed.

[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 the background portion and the luminance level are changed stepwise to suppress flicker and obtain a clear screen.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of an embodiment of a high-definition TV signal / TV signal converter according to the present invention, FIG. 2 is a signal waveform diagram in the embodiment, and FIG. FIG. 4 is an explanatory diagram showing an example of display by a high quality image quality TV signal / 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 Line counter 6 Background signal generation circuit 7 Output control circuit 8 Decoder

Claims (1)

(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 an improved TV screen in a TV screen having an aspect ratio of 3: 4, a line counter for counting the number of horizontal scanning lines of the TV receiver, and a plurality of brightness levels. A background signal generation circuit for generating a background signal having the line counter;
When the number of lines is within the range, a background signal whose luminance level sequentially increases from a blank level to approximately 50% of the maximum luminance level according to the number of lines is selected from the background signal generation circuit and output. When it is in the range of 2, the luminance level is almost 50 of the maximum luminance level according to the number of lines.
An output control circuit for selecting and outputting a background signal sequentially decreasing from the% level to a blank level from the background signal generation circuit, and outputting an image signal when the number of lines is other than the above. A high-quality TV signal / TV signal converter characterized by displaying a background in which a luminance level changes stepwise in a first range and a second range other than the image portion.