JPH0462234B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a motion detection circuit, and more particularly, to a motion detection circuit for an image of a television signal, and particularly to a motion detection circuit for detecting motion of a subject included in an interlace-scanned television signal. Concerning circuits for extracting information.

[Background of the invention]

In interlace-scanned television images, there are disturbances such as flickering in thin horizontal stripes such as characters. In order to improve this problem, there is a method of interpolating the scanning lines and displaying the scanning lines of two fields at the same time, thereby eliminating interlaced scanning and creating a progressive scanning television image. In this case, the signal of the interpolated scan line is interpolated from the signal of the previous field. In the case of a stationary subject, this allows you to display a high-quality image without flicker, but if the subject moves, the field image from 1/60 second ago will be overlaid with the current field image, so if the subject moves The edges in the exposed areas become comb-like, resulting in unsightly deterioration of image quality.

In order to avoid this disturbance of image quality, we extract the object motion information from the TV signal, and in the video part, instead of interpolating from the previous field, we create an interpolated scan line signal using the average value of adjacent scan lines of the current field image. methods are being tried.

Figure 1 shows television images (i-
2, i-1, i field) are shown. The number of scanning lines for one image is due to interlaced scanning.
525/2 lines, and in the figure, some of the scanning lines are shown by solid lines 1, 2, and 3. From this interlaced television image, each image is created by doubling the number of scanning lines.
Creates a progressively scanned television image consisting of 525 scanning lines. An interpolated scanning line 4 for this purpose is shown by a broken line in the figure. For a still image, the interpolated scanning line signal is interpolated from scanning line 3 at the same position in the vertical direction (V direction) of the previous field, and for a moving image, it is interpolated by the average value of upper and lower scanning lines 1 and 2 of the same field. and create it. FIG. 2 shows the state of this interpolation using a time axis t and a vertical axis V, where ◯ marks indicate interlaced scanning lines and ● marks indicate interpolated scanning lines. Numbers 1, 2, 3, and 4 represent the same scan lines shown in FIG.

To determine whether or not the subject is moving, compare the scanning lines at the same position two fields (one frame) ago, as shown by the double arrows in Figure 2, and if the difference is small, it is determined that the image is still. If it is large, it is determined that it is a moving image. Thereby, the signal of the interpolation scanning line 4 is switched to the average value of the scanning line 3 of the previous field or the scanning lines 1 and 2 of the same field.

Consider, for example, a case where an image as shown in FIG. 3, that is, a black image 5 consisting of three scanning lines, is moving upward in the above-described signal processing method. FIG. 4 shows this in terms of time t and vertical axis V, and the figure shows that it is moving upward at a rate of three lines per field period. In this case, since there is a difference from the scanning line one frame before in areas A and C, it is considered a moving image, and the interpolated scanning line is interpolated using the average value of the upper and lower scanning lines of the same field as shown in the figure. . On the other hand, in area B, the i field and
Since the values of the scanning lines of the i-2 field are equal, it is regarded as a still image, and interpolation is performed using the scanning lines of the i-1 field. Therefore, in region B, i
The black scan line of the i-1 field is interpolated onto the bright background of the field. As a result, as shown in FIG. 5, the progressive scan conversion image of the i-th field has a black image 7 of area A above it, and black images 8 and 9 appear every other line below it (area B). , resulting in an unsightly deterioration of image quality.

[Purpose of the invention]

An object of the present invention is to solve the above-mentioned problems and provide a motion information detection circuit for obtaining a scanning line interpolation signal that does not cause image quality deterioration even in moving images.

[Summary of the invention]

In order to achieve the above object of the present invention, in a circuit for extracting object movement information included in an interlaced television signal, frame difference signals of a plurality of scanning lines are used to extract object movement information. It is characterized by

Here, the "frame difference signal of a scanning line" refers to a difference signal between a certain scanning line and the corresponding scanning line one frame difference (two fields) before.

[Embodiments of the invention]

The principle of one embodiment of the present invention will be described below with reference to FIG. FIG. 6 shows the arrangement of four successive fields of scanning lines with the time axis t and the vertical axis V.
This shows a portion corresponding to area B in FIG. 4. The interpolation mode of interpolation scanning line 4 is based on these three frames, taking into consideration the magnitudes of the frame difference signals 11 and 12 of scanning lines 1 and 2, and the frame difference signal 13 of scanning line 3 at the same position in the previous field. Difference signal 11, 12, 1
3 are all small, it is determined that it is a still image, and the signal of interpolation scanning line 4 is interpolated from scanning line 3 of the previous field.Otherwise, it is determined that it is a moving image, and the signal of interpolation scanning line 4 is interpolated from scanning line 1 of the previous field. , 2 is interpolated. In the case of interpolated scanning line 4 in the figure, frame difference signals 11 and 12 are small, but signal 13 is large, so it is determined that it is a moving image, and interpolation is performed using the average value of scanning lines 1 and 2. As a result, image quality deterioration such as 8 and 9 shown in FIG. 5 does not occur.

In the embodiment of FIG. 6, the image signals of the i and i-1 fields are used to obtain the signal of the interpolated scanning line of the i field. On the other hand, i-1, i-
2, i-3 field signals are used. Therefore, there is a large time lag between the static/dynamic determination result and the interpolation process, and the static/dynamic adaptive process may not be performed correctly.

If the interpolation processing of the i-1th field is performed using the static/motion determination results of the i-3 to i fields,
The signals of the i-2 and i-1 fields are used for interpolation processing, and the signals of the i-3 and i fields before and after it are used for motion determination. There is little time lag with processing, and almost correct motion adaptive processing can be achieved. That is, the static/motion determination of the signal of the interpolated scanning line 20 of the i-1 field in FIG.
If the determination is made using the difference signals 15 and 19 and the difference signals 16 and 18, the maximum time interval will be two field periods, and the time difference between the interpolation calculation and the static/motion determination is small.

FIG. 8 shows the signals of the interpolated scanning line 20 and the scanning line 14,
17 and the mixture ratio of the average values of scanning lines 15 and 16 using the motion coefficient k obtained from the static/motion determination results.
An example of a circuit configuration in which calculation is performed by varying (0k1) is shown. In the figure, field memories 21, 23, 24 and line memories 22, 25
When connected continuously as shown in the figure, the time/space positional relationship of the input/output signals is as shown in the scanning lines 14 to 14 in FIG.
19 signal. The signal (20) of the interpolation scanning line 20 is sent to the adder circuits 26, 28, 32 and the coefficient circuits 27, 2.
9 and multiplication circuits 30 and 31, it is calculated as shown in the following equation.

(20)=k・(14)+(17)/2+(1−k)・(15)+(16)
/2 However, (0k1) Here, the motion coefficient k approaches 1 in the still image portion and approaches 0 in the moving image portion. The motion detection circuit is composed of subtraction circuits 33, 35, 37, absolute value conversion circuits 34, 36, 38, addition circuit 39, and coefficient conversion circuit 40, and generates three frame difference signals [(14)-(17) ], [(15)−(19)], [(16)−(18)]
If the signal obtained by adding the absolute values of is small, k is set to 1, and as the signal increases, k approaches 0. A motion coefficient k is obtained as the output of the coefficient conversion circuit 40.

〔Effect of the invention〕

As described above, according to the present invention, the motion information of an interlaced image is extracted from the frame difference signal of two successive fields. Unsightly image quality deterioration can be avoided, and scanning line interpolation processing that does not cause image quality deterioration can be realized. As a result, it is possible to realize a high-definition television receiver that can display general television images in extremely high quality.

[Brief explanation of drawings]

Figure 1 is a three-dimensional model of a television image, Figure 2 is an explanatory diagram of conventional motion adaptive scanning line interpolation processing, and Figure 3 is an explanatory diagram of conventional motion adaptive scanning line interpolation processing.
The figure is an example of a moving image, FIGS. 4 and 5 are examples of images with degraded image quality obtained by conventional scanning line interpolation processing, and FIGS. 6 and 7 are operation explanatory diagrams of the motion determination processing of the present invention. FIG. 8 shows a block diagram of an embodiment of the present invention. 21, 23, 24...field memory, 22,
25...Line memory, 26, 28, 32, 33,
35, 37, 39...addition (subtraction) circuit, 27, 29
...Coefficient circuit, 30, 31...Multiplication circuit, 40...Motion coefficient conversion circuit.

Claims (1)

[Claims] 1. In a circuit that detects the movement of a subject included in an interlace-scanned television signal, a frame difference signal of a scanning line immediately above a scanning line to be interpolated in a certain field, and the scanning line to be interpolated. means for respectively obtaining a frame difference signal of a scanning line immediately below the field, and a frame difference signal between scanning lines at the same position as the scanning line to be interpolated in both fields immediately before and after the field; A motion detection circuit comprising: means for determining a motion coefficient indicating the degree of motion of the subject according to the magnitude of the signal.