JP2002135622A - Video noise reduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video noise reduction device capable of properly reducing noise by detecting noise quantity correctly. SOLUTION: A character data broadcasting detection circuit 4 detects an additional signal, such as the signal, etc., of character data broadcasting. A control part 6 specifies a horizontal period, which has no insertion of additional signal to which the additional signal is not inserted in a horizontal period, to which the additional signal can be inserted. A noise detection circuit 3 detects noise quantity in the horizontal period, without the insertion of the additional signal. The part 6 varies the noise reduction quantity of a noise reduction circuit 5, according to the noise quantity and the circuit 5 reduces a noise from a television signal by the noise reduction quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video noise reduction device for reducing the noise of a television signal.

[0002]

2. Description of the Related Art As an example of a television signal, in a PAL system which is an interlace system having 625 scanning lines, first to fifth horizontal periods are defined as vertical blanking periods.
The period after the sixth horizontal period is used as the transmission period of the broadcast program. Since the sixth to twenty-third horizontal periods generally do not appear on the screen due to so-called overscanning, they are used for transmitting data signals such as teletext. The horizontal period in which these signals are inserted is not necessarily uniform depending on the broadcasting station, and data signals such as teletext and a wide screen identification signal (WSS) are inserted in all or a part of the horizontal period. Generally, after the 24th horizontal period, the video signal is actually displayed on the screen.

[0003]

As a conventional video noise reduction device, there is a device for detecting and reducing noise during a vertical blanking period. In this conventional example, when retransmission by a relay station or video recording / reproduction by a video tape recorder or the like is performed, the synchronization signal portion may be reinserted, and the noise amount may not be detected correctly. As another conventional video noise reduction device, there is a device that detects and reduces noise during a video signal period. In this conventional example, since an actual video signal exists, it is difficult to distinguish between the noise and the video signal, and the noise amount may not be detected correctly.

As described above, the conventional video noise reduction apparatus has a problem that it is difficult to correctly detect the amount of noise generated by the transmission path, and it is difficult to accurately reduce the noise.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a video noise reduction device capable of correctly detecting a noise amount and accurately reducing noise. .

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention relates to a video noise reduction apparatus for reducing the noise of a television signal. An additional signal non-insertion horizontal period detecting means (4, 6) for detecting an additional signal non-insertion horizontal period in which no additional signal is inserted in a horizontal period in which an additional signal can be inserted; A noise amount detecting means (3) for detecting a noise amount of the television signal in a horizontal period; and a noise reduction amount variable according to the noise amount detected by the noise amount detecting means, thereby extracting noise from the television signal. A video noise reduction device characterized by comprising a noise reduction means (5) for reducing noise.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a video noise reduction apparatus according to the present invention. FIG. 1 is a block diagram showing one embodiment of the image noise reduction device of the present invention.

In FIG. 1, a composite video signal is input to a video signal processing circuit 1 and separated into a luminance signal Y and two color difference signals RY and BY. The composite video signal is also input to the sync separation count circuit 2, which separates the sync signal and counts the number of horizontal lines. The noise detection circuit 3 detects the amount of noise in the horizontal period specified by the control unit 6 including a microcomputer. The luminance signal Y from the video signal processing circuit 1 is input to the text data broadcast detection circuit 4 to detect a text data broadcast signal (teletext signal).

The count value of the sync separation count circuit 2 is input to a noise detection circuit 3 and a character data broadcast detection circuit 4. The character data broadcast detection circuit 4 detects in which horizontal period the signal of the character data broadcast is inserted, and inputs the detection result to the control unit 6. Here, it is assumed that a character data broadcast signal is detected, but an additional signal such as a WSS signal is also detected. The control unit 6 specifies not the vertical blanking period (so-called equalizing pulse period), but the horizontal period in which the additional signal such as the character data broadcast signal or the WSS signal is not inserted in the sixth to 22nd horizontal periods. , Is input to the noise detection circuit 3.

The noise detection circuit 3 detects the amount of noise in the horizontal period specified by the control unit 6, and inputs the detection result to the control unit 6. The luminance signal Y from the video signal processing circuit 1 is input to the noise reduction circuit 5. The noise reduction circuit 5 is a circuit that can vary the amount of noise reduction. The control unit 6 determines the amount of noise reduction in the noise reduction circuit 5 according to the amount of noise detected by the noise detection circuit 3. The noise reduction circuit 5 includes a control unit 6
The noise is reduced from the luminance signal Y by the noise reduction amount controlled by.

[0011]

As described above in detail, the video noise reduction apparatus of the present invention inserts an additional signal in a horizontal period in which an additional signal can be inserted in a period other than the vertical blanking period of a television signal. An additional signal non-insertion horizontal period detecting means for detecting a non-insertion signal non-insertion horizontal period, a noise amount detecting means for detecting a television signal noise amount in the additional signal non-insertion horizontal period, and a noise amount detection means Noise reduction means for reducing the noise from the television signal by varying the noise reduction amount in accordance with the noise amount obtained, so that a different noise amount can be correctly detected for each transmission path such as a broadcast station or a channel. Therefore, noise can be accurately reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Video signal processing circuit 2 Synchronization separation count circuit 3 Noise detection circuit (noise amount detection means) 4 Character data broadcast detection circuit (horizontal period detection means without additional signal) 5 Noise reduction circuit (noise reduction means) 6 Control unit (addition) Signal non-insertion horizontal period detection means)

Claims (1)

[Claims] 1. A video noise reduction apparatus for reducing noise of a television signal, wherein the additional signal is inserted in a horizontal period in which an additional signal can be inserted, other than a vertical blanking period of the television signal. An additional signal non-insertion horizontal period detecting means for detecting no additional signal non-insertion horizontal period; a noise amount detecting means for detecting a noise amount of the television signal in the additional signal non-insertion horizontal period; and the noise amount detecting means. A video noise reduction device comprising: a noise reduction unit configured to vary a noise reduction amount according to a detected noise amount and reduce noise from the television signal.