JPH0632453B2 - Moving part detection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of application) The present invention accurately determines whether a television signal to be processed is a moving image or a still image, and accurately determines, for example, motion adaptive YC separation. The present invention relates to a moving part detection circuit that can be used for.

(Prior Art) In the NTSC system, which is a standard television system, a luminance signal and a chrominance signal are frequency-multiplexed. When the luminance signal and the chrominance signal are separated by the frequency separation or the comb filter in the image receiver, obstacles such as cross color and dot interference occur. Therefore, attention has been paid to the interframe inversion of the color subcarrier phase, and attention has been paid to the separation of the luminance / color signals using a frame memory.

In this separation method, the luminance signal YS is obtained by taking the sum between the frames in the still region of the image (hereinafter referred to as the still image), and conversely, the color signal CS is obtained by taking the difference. In addition, since it is impossible to apply the sum and difference between frames in the moving region of the image (hereinafter referred to as a moving image), the above-described frequency separation,
Alternatively, the comb-shaped filter obtains the luminance signal YM and the color signal CM. A method of separating the luminance / color signals according to the motion of the image in this way is called motion adaptive YC separation. In this motion adaptive YC separation, it is necessary to make an accurate determination for switching between moving images and still images.

In making the above determination, it is especially important to detect a moving image as a moving image. Even if a still image is determined to be a moving image and luminance / color signal separation is performed using a frequency separation or a comb filter, this separation is a method that has been used in the past and does not cause further image quality deterioration. However, if the moving image is judged as a still image and the inter-frame separation is applied, the luminance signal becomes 2
Double image failure and color signal leakage occur, and luminance signal leakage occurs in one of the color signals, resulting in a great deterioration in image quality. Therefore, the operation of the motion detection circuit that generates the determination signal is the key to whether or not the motion adaptive YC separation can be normally performed.

FIG. 3 shows an example of a conventional moving part detecting circuit. In the figure, digitized image data 2 is input to a terminal 1.
The subtracter 5 takes the difference between the input signal 2 and the signal 4 delayed by the 2-frame memory 3. The difference signal 6 is supplied to the absolute value circuit 7, and the obtained difference absolute value signal 8 is input to the comparator 10. The circuit compares the absolute value signal 8 with the set value 9 and outputs the comparison result as a comparison signal 11. The comparison signal 11 is a determination signal for moving images / still images,
When the value is "1", it is a moving image, and when it is "0", it is a still image.
The reason why the two-frame difference signal is used in this detection circuit is that the color signal CS is output as a difference in the case of a still image when the one-frame difference signal is used due to the frame inversion of the color subcarrier described above. is there.

(Problems to be Solved by the Invention) When a certain object moves (moves from right to left) as shown in FIGS. 4A to 4C on the screen, the conventional motion detection circuit Since the inter-frame difference signal (for example, two-frame difference signal) is used, the area determined to be a moving image is the hatched area in FIG. 4 (d). In the same figure, the area indicated by the broken line is an area that should be determined as a moving image, but is determined as a still image. Therefore, the YC separation between frames is applied in this region, and the double image failure described above and the leakage between the luminance signal and the color signal occur, resulting in a great deterioration in image quality.

It is an object of the present invention to provide a motion part detection circuit free from the motion detection erroneous determination mentioned in the above problem. [Configuration of the Invention] (Means for Solving the Problems) The moving part detection circuit delays a television signal in which a color difference signal is frequency-multiplexed with a luminance signal by a frame period, and obtains an interframe difference signal from the delayed signal and the television signal, and the interframe difference signal. Is delayed by one frame, and a means for synthesizing the output signal obtained by this means and the inter-frame difference signal is provided.

(Operation) With the above configuration, in the area one frame before, which was erroneously determined to be a still image despite being a moving image area, the determination is assisted by a signal obtained by delaying the interframe difference signal. , No erroneous judgment will occur.

(Example) An example of the present invention is shown in FIG. The configuration until obtaining the comparison signal 11 is the same as that of the conventional circuit shown in FIG.

In the present invention, the comparison signal 11 is branched and supplied to the OR circuit 14. At this time, one is directly guided to the OR circuit 14 and the other is guided to the OR circuit 14 via the frame memory 12. The OR circuit 14 has a function of selecting and outputting the comparison signal 11 or the delay signal 13 obtained by delaying the comparison signal 11 by one frame, whichever has the larger absolute value. The output signal of the OR circuit 14 becomes a motion detection signal for determining whether the image is a moving image or a still image.

Next, the operation of this motion detection circuit will be described with reference to FIG. The area determined to be a moving image by the output signal 11 of the comparator 10 is the shaded area A in FIG. On the other hand, frame memory 1
Since the delayed signal 13 output by 2 is a motion signal one frame before, n-1 frames (FIG. 4 (c)) and n-3
It is equal to the signal detected by the difference of the frame (Fig. 4 (a)). Therefore, the delay signal 13 determines the movement of the shaded area B in FIG. 2 (e). The OR circuit 14 performs logical addition of the shaded area A and the shaded area B. Therefore, the area of the broken line portion, which is conventionally determined to be a still image, is determined to be a moving image by the delay signal 13, and erroneous detection is eliminated. On the contrary, in FIG. 2 (e), the shaded portion B at the right end is a region to be determined as a still image, but in this region, frequency separation or luminance / color signal separation by a comb filter is performed.

In the embodiment shown in FIG. 1, the motion detection signal is set to 1 bit by the comparator 10, but RO is used instead of the comparator.
It is also possible to use M or the like and use a motion detection circuit in which the motion detection signal is n bits. In this case, the frame memory 12 may be replaced with n bits, and the OR circuit 14 may be replaced with a maximum value selection circuit.

Although the above description has been made assuming an example of the NTSC signal, the present invention is not limited to this. For example, 2 frame memory 3 into 4 frame memory, frame memory 1
By using 2 as a 2-frame memory, it is possible to support PAL signals.

[Effects of the Invention] According to the present invention described above, a moving image is not erroneously determined to be a still image, and when YC separation is performed according to the determination result, image quality is not deteriorated and a stable image is obtained. Can be revealed.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a moving part detection circuit according to the present invention, FIG. 2 is a schematic diagram for explaining the circuit operation of the present invention, and FIG. 3 is a circuit diagram of a conventional circuit. FIG. 4 is a schematic diagram for explaining the operation of the conventional circuit. 3 ... 2 frame memory, 5 ... subtractor, 10 ... comparator, 11 ... comparison signal, 12 ... frame memory, 13 ... delay signal, 14 ... OR circuit, 15 ... decision signal.

Claims (1)

[Claims] 1. A first delay means for delaying a television signal, in which a color difference signal is frequency-multiplexed with a luminance signal by a carrier wave whose polarity is inverted every n frames, for a period of 2n frames, the television signal and the first delay means. A difference means for obtaining a difference signal from the output of the delay means, a second delay means for delaying the difference signal by n frame periods, and a combining means for combining the output signals of the first and second delay means. A moving part detection circuit characterized by being provided.