JPH01202072A - Noise reducer circuit - Google Patents

Abstract

PURPOSE:To reduce the fog of a picture by finding out a moving part detecting signal based on a difference between an input video signal and an output of an input video signal unit delay element and controlling the factor of transmission characteristics based on the moving part signal. CONSTITUTION:An output from a frame memory 2 is inputted to a subtractor 3 and a difference value between the input and a current frame signal is calculated. The output of the subtractor 3 is outputted to an adder 4 and also outputted to a non-linear processing circuit 5 as a moving part detecting signal epsilon. The signal epsilon inputted to an adder 4 is added to an output of a frame memory 6 in circulating loop and the added sum epsilon' is outputted to the circuit 5. The circuit 5 multiplies the inputted epsilon' by a factor K (epsilon, epsilon') and outputs the multiplied result Kepsilon' to a subtractor 7 and the frame memory 6 in the circulating loop. The signal Kepsilon' inputted to the subtractor 7 is subtracted from an input video signal and the subtracted signal is outputted to an output terminal 8. Consequently, a noise reducer circuit removing a moving part detecting error and the fog can be obtained.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) This invention provides noise resolution 1-1 for suppressing noise in video signals.
Regarding the circuit.

(Prior Art) The principle of a noise reducer will be explained using FIG. The video signal is stored in N frame memories and %N frame memories are stored.
- If we calculate the average of the frames, the signal component will remain as it is if there is no change between frames, but the noise will be
Since there is no correlation between frames, the power is attenuated by '/Nl. However, in real video, there is movement in the signal, so if we add C as it is, the video part will be blurred in time.Furthermore, frame memory is expensive, so we have to use %N frame memories to cycle through. Instead of a type filter, it is possible to use a recursive groove formed by a single frame memory, and a typical configuration thereof is as shown in Fig. 6 (g).

The transfer characteristic of this circuit is as follows. Here, the coefficient K O<K<1 is g=XIZ)-
X lz) = X (z) -Y Iz) @Z-'
I! ! It is a number and has a % note as shown in Figure 7, and e is
@7 part [This is Kei Izunoshi.

Where the movement is large, K=0, and equation (1) becomes Y (
z) = X (Z), so the video part is not blurred.
1j71 elephants. In a place where the movement is small, the noise becomes -'yO, and the noise can be suppressed by (1-'/(1+K) times) in the power phase.However, the problem here is that
The recommended part detection signal is not the difference between the signal x (z) of the current frame and the signal X (Z)/Z-1 of the previous frame, but the frame of the output signal Y [z) of the previous frame This is the difference from the delayed signal Y (z)·2−+. For this reason, there is a high possibility that an error will occur in the recommended portion detection signal, resulting in a blurred image at edge portions and fine pattern portions.

(The problem to be solved by the invention) Conventionally, the moving part detection signal, the current frame image signal and the previous frame image were obtained from the frame delay signal of the No. 100 noise reducer circuit output video signal. There was a high possibility that errors would occur in component detection, resulting in blurred images.

This invention is designed to reduce the blurring of the image in such a way.
<t, f, knee noise reducer circuit.

[Structure of the invention]

(Means and actions for solving the problem) In order to accurately detect a moving part, the input video signal x (z) and the output of the unit delay element of the input video signal x (z) x z * Z-
A moving part detection signal is obtained from the difference between ' and the coefficients are controlled using this moving part signal.

(Example) Hereinafter, an example of the book@-1 will be described in detail with reference to the drawings.
In the figure, a video signal input manually from an input terminal 1 is input to subtracters 3 and 7, and is also input to a unit delay element, in this case frame memory No. 2.

The output of frame memory 2 is 7$, totaling 33i inputs.

A difference value from the current frame signal is calculated. The output of the subtracter 3 is outputted as the addition 1W4G, and a non-selected signal is outputted to the processing circuit 5 as the @-marked portion detection signal ε. MJJX
e inputted to a4 is vOjt with the output of the frame memory 6 of one loop, and the additional charge ε is outputted to the processing circuit 5. In the nonlinear processing circuit 5, the input ε
is multiplied by a coefficient K (ε, ε), and outputs ε to the multiplication result to the subtracter 7 and the frame memory 6 of the circulating loop.

Here, the coefficient conventionally has a characteristic as shown in FIG. 7 due to the relationship only with ε, but in this embodiment, for example, it has a characteristic determined by the accurate motion detection signal ε as shown in FIG. It is a coefficient. The value ε input to the subtracter 7 is subtracted from the input video signal and output to the output terminal 8.

The transmission time of this embodiment is equal to that of the conventional embodiment. Since the coefficients are controlled based on the accurate moving part detection signal ε, it is possible to realize a noise reducer circuit without errors in moving part detection and without blur.

FIG. 3 is an example of a control pond for coefficients.

In this embodiment, K is a function of ε as in the prior art, but the characteristics of this function are prepared in an NI way and used by switching according to the accurate motion part signal e. Figure 3 shows N
This is the case when =3. The method for changing the characteristics is as follows.

0<III<Tl　:41) Gender 1 use T1ku1εl<T2: Use characteristic 2 T2<Igl: Use characteristic 3 Here, 0<TI<T2.

In this way, even if an error occurs in C, the error can be suppressed by using the accurate motion portion signal ε.

FIG. 4 is an embodiment of claim 2.

In the embodiment of the present invention (Fig. 1), the signal of the circulating loop in the conventional embodiment (Fig. 5) is an image signal, but since it is only a noise component, the delay element ( This makes it possible to reduce the word length of the frame memory (frame memory).

In the case of an image signal of 8 bits (0 to 255), the output range of the nonlinear processing circuit 5 in FIG. 1 is 6 bits (-
32-31) is sufficient, and if the % property of is M2 diagram,
As shown in Figure 4, the word length of frame memory 6 is 6 b.
It becomes smaller than the Eiken signal s btt,
By doing this, the hardware scale can be made smaller.

〔Effect of the invention〕

By accurately performing motion detection, it is possible to realize a noise reducer circuit with less blur.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing one embodiment of the present invention, Fig. 2 is a diagram showing an embodiment of the 1WIJ ring on the coefficient, and Fig. 3 is a diagram showing another embodiment of the 1811 bell on the coefficient. , FIG. 4 is a diagram showing the output range of the non-warm type circuit 5, FIG. 5 is a diagram showing the principle of the noise reducer, FIG. 6 is a diagram showing a conventional embodiment, and FIG. 7 is a diagram showing the conventional example. It is a figure which shows control on a coefficient. 1...Input terminal, 2...Frame memory, 3...
・Subtractor, 4...VD calculator, 5...Nonlinear processing circuit, 6...Frame memory, 7...Subtractor, 8...
・Output terminal. Agent Patent Attorney Noriyuki Chika Yudo Mitsuyuki Matsuyama Figure 1 Figure 4 The body is in a hot seat Figure 6

Claims (1)

[Claims] (1) A first subtracter that calculates the difference value between the input video signal and the output of the unit delay element of the input video signal, and the output signal of the first subtractor and the output of the unit delay element of the circulating loop. an adder that calculates the sum; a processing circuit that performs nonlinear processing on the output of this adder using the output of the first subtracter; and an output of the processing circuit that is input to a unit delay element of a circulating loop and output and a second subtracter for calculating a difference value between the input video signal and the input video signal, the output of the second subtracter is used as the output video signal, and the nonlinear processing characteristic is controlled by the output of the first subtracter. A noise reducer circuit characterized by: