JPS5917580B2 - Television signal noise suppression device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a television signal noise suppression device.

When playing images on a TV, if the image is moving5, the degradation of image quality due to noise is not a visual problem, but if the image is a still image or has little movement, the degradation of image quality due to noise cannot be ignored. Become something you want.

In order to prevent deterioration of image quality due to such noise, a means as shown in FIG. 1 is used.

That is, the television signal A applied from the input terminal 1 and the output B of the frame memory 2, which will be described later, are input to the arithmetic circuit 5.
, 6, and the calculation output (in one part) A+KB. 15
The output of the arithmetic circuit T is outputted from the output terminal 3 as an output signal, and a portion thereof is stored in the frame memory 2.

Here, is a variable coefficient, and in the motion detection circuit 4, the difference between the signals A and B is obtained, and when this absolute value is large, the television signal is considered to correspond to a moving part, and = 0 so that the input signal A is taken out as is.

On the other hand, when the difference between signals A and B is small, it is assumed that it corresponds to a stationary part, for example, it is set to 0.5, that is, from the above formula, it becomes 1 (A + B), and the average of A and B is taken out as the output signal. .

As a result, noise components are suppressed. However, the structure of the arithmetic circuit or variable control circuit is complicated and there are problems in terms of circuit technology, such as the need to provide the motion detection circuit 4 separately from the arithmetic circuit 5 and 3θ 6.

Therefore, an object of the present invention is to suppress random noise in the stationary portion of a television signal by using a simple circuit configuration 35 in a television signal noise suppression device as described above, and to produce a high quality television image. The objective is to realize a device that obtains the following.

In order to achieve the above object, the present invention provides a difference signal (A-
B), and within a small range of the absolute value A-BI of this difference signal, the value −K(A -B) is read from the memory in which fixed values are recorded, and this is added to the above-mentioned input television signal to extract the noise-suppressed output television signal A-K (A-B), that is, (1-K)A+KB. It is configured as follows.

That is, in the present invention, the predetermined calculation output (1-K)A+
To obtain KB, use the difference signal as an address to read K from memory.
By using a simple circuit configuration that reads out (A-B) and adding it to the input television signal, the stationary portion and the moving portion of the television signal are given different transfer characteristics. This is designed to suppress random noise added to the image. The present invention will be explained in detail below with reference to the drawings.

FIG. 2 shows the configuration of an embodiment of a television signal noise suppression device according to the present invention. In the same figure, 1
1 is a television signal input terminal, 13 is an output terminal of a noise suppression device, 12 is a frame memory, 14 is a subtraction circuit, 1
5 is an adder circuit, 16 is a fixed storage device (memory), A, B
, D, Z, and Y all represent signals. The television signal A applied to the input terminal 11 is applied together with the output signal B of the frame memory 12 to a subtraction circuit 14, which outputs a difference signal D=A-B.

This difference signal D is applied to a fixed storage device (memory) 16 as an address signal. The address signal requires positive addresses and negative addresses depending on the polarity of the difference signal D, but it is also possible to shift a certain value so that all addresses are positive addresses, or
It is clear that complementary representation is also possible.
Various values are recorded at each address in the fixed storage device 16, and the absolute value of the difference signal D is a certain number D. O for larger addresses
is recorded. In addition, in terms of the device configuration, it is possible to simply configure the output to be O without providing a memory where D is large. When the value of the difference signal D is given to the storage device 16, the value corresponding to that address is obtained as the output z, and this output Z is added to the adder circuit 15, and the addition result A+Z
is taken out from the output terminal as an output signal Y. Difference signal D
When is large, Z=0, so the output of the adder 15 becomes Y=A. That is, input signal A is directly output for the moving image portion. On the other hand, the difference signal D is close to zero (
If the difference signal D is positive, i.e. A>B, then the negative (Z<O)
The stored contents of are read out and added to the adder circuit 15.

Therefore, since the value of the output signal Y acts to reduce the absolute value of Z from A, it does not respond immediately. Also, when the difference signal is negative, that is, D<O, the above-mentioned reverse operation works to suppress the immediate response. As a result, random noise is suppressed. At this time, it is stored so that Z<D. The simplest example is IZI-1DI/2.
As explained in the embodiment described above, the device of the present invention can be constructed simply from a generally well-known memory and an addition/subtraction circuit, and the relationship between the difference signal D and the output z is different from that of a fixed storage device. You can set it freely just by memorizing the value. In this way, the present invention does not require any special arithmetic circuit and provides an extremely effective means in practice. Note that it is clear that the present invention is not limited to the above embodiments,
It goes without saying that various circuit configurations, such as those described below, are possible within the scope of the claims according to the required accuracy cost and configuration requirements.

(1) When a so-called PLA (programmable logic array) is used as the fixed storage device 16.

(2) Further D.

It is also possible to make it variable. For example, if the surrounding pixels are determined to be moving pixels, D. In the opposite case, make it smaller, and vice versa. For this purpose, a plurality of fixed storage devices may be prepared and one of them may be selected depending on the situation of surrounding pixels. (3)
When the entire device is operated by signals that have been converted from analog to digital in advance, or when it is partially operated by analog signals.

(4) Regarding addition and subtraction, the adder 15 is used as a subtracter to invert the stored contents of the storage device 16.

etc., are included within the scope of the present invention. Furthermore, in the case of color television signals, it is possible to implement the apparatus of the present invention by providing a color signal component inversion circuit before or after the frame memory.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a conventional noise suppression device, and FIG. 2 is a diagram showing the configuration of an embodiment of the noise suppression device according to the present invention. 11...Input terminal, 12...Frame memory, 13...Output terminal, 14...
Subtraction circuit, 15... Addition circuit, 16...
- Fixed storage device.

Claims (1)

[Claims] 1. Input television signal A and frame memory output B
a first means for obtaining a difference signal A-B; a fixed storage device for reading out a fixed value proportional to A-B using the difference signal as an address; A noise suppression device for a television signal, comprising: second means for adding; and third means for inputting a part of the output of the second means to the frame memory. 2. In the television signal noise suppression device according to item 1, when the fixed storage device adds the difference signal A-B as an address signal, the fixed storage device stores the difference signal A as the fixed value.
−When the absolute value of B |A−B| is smaller than a specific value D, −
A noise suppression device for a television signal, characterized in that it is configured to read out K(A-B) (K is a coefficient whose absolute value is less than 1) and read out zero when it is larger than a specific value D.