JPS6330077A - Picture signal converter - Google Patents

Abstract

PURPOSE:To contrive to prevent the occurrence of a fogged picture or a duplicated picture in following to a mobileobject picture by retarding the result of dicriminating movement, confirming a moving field and selectlug an interpolation signal within the field or between fields accordingly. CONSTITUTION:An picture signal x1 is retarded by field memories 12, 14 by one frame and the result is fed to a selector 16 and a subtractor 18. Furthermore, a signal x2 delayed from the signal x1 by one field is fed to a line memory 20, an adder 22 and a time compression circuit 24. The adder 22 sums upper and lower lines of interpolation scanning lines, and the sum is fed to a 1/2 coefficient circuit 25, from which an in-field interpolation signal x5 is inputted to the selector 16. The subtractor 18 takes difference between the input x1 and a signal x3 before one frame, and the result is given to an absolute value circuit 26, from which an absolute value x6 is inputted to a comaprator circuit 28. The comaprator circuit 28 compares a frame difference absolute value x6 with a threshold value Th and gives an output to an interpolation selection circuit 30 as a movement signal S1. An interpolation selection signal S5 cancelling the movement signal being a cause to a fog is outputted to the selector 16, either signal x3 or the signal x5 is selected, the time compression circuit 24 compresses the time axis of the original signal x2 and an interpolation signal x7 by 1/2 and gives an output alternately and sequentially.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for converting incremental scanning of an image signal such as a television signal to non-incremental scanning.

[Conventional technology]

As a method for obtaining high-definition images from current inklace system video signals such as NTSC, a non-interlace system has been proposed in which the number of scanning lines in the field is doubled, for example.

To double the number of scanning lines, the problem is how to generate an interpolation signal between scanning lines. For example, intrafield interpolation uses the average value of two adjacent lines in the same field as the interpolation signal, and Interfield interpolation uses the corresponding signal of the field as an interpolation signal as it is,
A method of switching according to the movement of the image has been proposed.

In this method, the accuracy of motion detection in the object image is an important factor that affects the image quality, but in -S, the presence or absence of motion is determined based on whether there is a significant difference in the difference signal (frame difference) between the front and rear fields. are doing. However, in the current field, there may be no significant difference in the difference signals between the preceding and following fields even in a motion area, and in such cases, this type of determination method may cause significant image quality deterioration such as double images. .

This image quality deterioration will be explained with reference to FIGS. 6 and 7.

(1) to (6) in FIG. 6 correspond to (1) to (6) in FIG. 7. In FIGS. 6 and 7, the shaded area indicates the selection between the inner sleeves of the field. Now, in field i-1 (2)
The object image shown by the thick line, which was stationary at the position, moves from ■ to ■ in field i, and changes to (4) in field i+1.
). At this time, if motion detection is performed using the difference signal between the front and rear fields, in the areas shown by ■, ■ of field i in FIG.
Since there is a significant difference in the frame difference in ■, the intra-field field is selected, but since there is no significant difference in the frame difference in ■, the inter-field interpolation signal is selected even though it is a motion area. In the area marked ■ in FIG. 6, a signal corresponding to the background image of the previous field is interpolated, causing double image interference.

As a countermeasure against this problem, a method has been proposed in which, as shown in FIG. 8, a motion is determined when a significant difference occurs in any of the frame difference signals of adjacent fields. That is, if there is a significant difference in either ■ or ■° in FIG. 9, it is determined that there is movement. In the illustrated example, since there is a significant difference in the frame difference of ■°, the area marked ■ in FIG. 8 is determined to be motion,
The inner field spacing is selected to eliminate double image disturbances.

Note that in FIGS. 8 and 9, the shaded area indicates the selection between the inner sleeves of the field.

[Problem that the invention seeks to solve]

However, in this method, as shown in FIG. 8, intra-field interpolation signals are selected over a wide range even though fields i-1 and i+2 are stationary. Visually, this appears on the screen as a low-resolution image (so-called blurred image) that follows the moving object image before and after, causing unnaturalness in the moving image. In particular, the blurred image that follows the moving object image has two i+l, i+2
Since it spans a field, it is easy to see. Furthermore, the higher the resolution of the foreground image, the more significant the deterioration.

Therefore, it is an object of the present invention to provide an image conversion device that removes the blurred image that follows this moving object image.6 [Means for Solving the Problems] The image signal conversion device according to the present invention has the following features: A first interpolation signal forming means for forming an interpolation signal from a signal of another field, a second interpolation signal forming means for forming an interpolation signal from within the same field, and detecting motion between frames and generating a motion signal. It comprises an inter-frame motion detection means and a holding means for holding a motion detection signal of at least one field or more earlier, and the first and second motion detection signals are detected from the current inter-frame motion signal and the motion signal by the holding means. The interpolation signal of the interpolation signal forming means is selected.

[Effect]

By means of the above means, the present invention delays the result of motion determination, confirms a field with motion and selects an interpolation signal within the field and between fields accordingly, and blurred or double images that follow a moving object image. can be accurately prevented from occurring.

〔Example〕

Hereinafter, the present invention will be described using one embodiment of the present invention with reference to the drawings.

FIG. 1 is a block diagram of a first embodiment of the present invention. The image signal X inputted to the input terminal 10 is delayed by one frame by the field memory 12.14 and is supplied to the selector 16 and the subtracter 18. Further, the signal x2 delayed by one field in the field memory 12 is supplied to the line memory 20, the adder 22 and the time compression circuit 24.

Line memory 20 delays the input signal by one line and supplies it to adder 22 . The adder 22 takes the sum of the upper and lower lines of the interpolated scanning line, and the sum is converted to 1/2 by the 1/2 coefficient circuit 25.
The signal is doubled and becomes an intra-field interpolation signal X, which is input to the selector 16.

The subtracter 18 takes the difference between the input signal X and the signal X one frame before, and the difference signal is converted to the absolute value
&, and is input to the comparison circuit 28. The comparison circuit 28 compares the frame difference absolute value x6 with the darkness value Th, and outputs wHm when x>Th, and "L" when x6≦Th as a motion signal S to the interpolation selection circuit 30. The interpolation selection circuit 30 cancels motion signals that cause double image interference and blur following a moving object, and outputs an interpolation selection signal S that does not cause these to the selector 16. The selector 16 selects either the interfield interpolation signal x3 or the intrafield interpolation signal X according to the interpolation selection signal S, and outputs it to the time compression circuit 24. Time compression circuit 24
The time axes of the original signal x2 and the interpolated signal x7 are set to 1
/2 and sequentially and alternately supplied to the output terminal 32.

FIG. 2 shows an example of a specific circuit configuration of the interpolation selection circuit 30. The motion signal S1 is delayed by one field by one field delay circuits 34 and 36, respectively. The AND circuit 38 receives the motion signal S1 and the delay circuit 34.
and 2 fields (i.e. 1 frame) using the same 36
The OR circuit 40 performs a logical product with the delayed signal S3, and
The signal S2 delayed by one field by the delay circuit 34 is logically summed with the output of the AND circuit 38, and an interpolation selection signal S is outputted to the terminal 42. The blurred image preceding the moving object image (the shaded area in field i-1 in FIG. 8) is
The D circuit 38 removes the double image disturbance (region ▪ in field i in FIG. 6), and the OR circuit 40 removes the double image disturbance.

Next, an AND circuit 3 for the blurred image preceding the moving object image.
8 will be explained with reference to FIG. As shown in Fig. 3, the signals corresponding to the same positions on the screen of fields i-3゜i-1, i+l are respectively A, A, and
Let the corresponding signals of fields i-4゜i-'l and i be , , and , respectively. When motion is detected only from frame differences, a significant difference will appear in the frame differences regardless of whether motion occurs in A or A. For example, if A is stationary and A is moving, A should be used as the interpolation signal for field i, but intra-field interpolation is selected due to the movement of I, and the blurred image in front of the moving object image is Become.

Therefore, in the circuit shown in FIG. 2, the presence or absence of movement of A is confirmed using the frame difference a. For example, A and B are both stationary,
5, where only one is motion, no significant difference appears in the frame difference a, and only a significant difference occurs in the frame difference a.

On the other hand, when A is motion, a significant difference occurs in both frame differences a and b.

That is, if we take the case where there is a significant difference in the frame difference as positive logic, the movement of the signal of the previous field used for interpolation M(
(with motion as positive logic) becomes M2a-b. Therefore, the interpolation selection signal S is logically summed with the frame difference d to prevent double scratches using the following formula % Formula % By switching the interpolation signal according to this selection signal, the blurred image preceding the moving object image can be removed. .

Furthermore, the blurred image that follows the moving object image (the shaded area in field i+2 in FIG. 8) can be removed by checking the movement of the force in FIG. For example, if the force and the force are both stationary and only the force is a movement, there will be no significant difference in the frame difference C, but if the force is a movement, a significant difference will occur in both the frame differences C2d. Therefore, the interpolation selection signal S' may be set as shown in the following equation.

S'=a-b+d-c FIG. 4 shows an interpolation selection circuit that realizes this.

In FIG. 4, the motion signal S, is sequentially delayed by one field by one-field delay circuits 50, 52, and 54, resulting in signals S, , St, respectively.

It becomes S4. These motion signals S, , S, , S3+S4
correspond to s, d, a, and c in FIG. 3, respectively. 56
is a NOT circuit, 58, 60 is an AND circuit, and 62 is an OR circuit.

FIG. 5 shows a second embodiment of the present invention in which the interfield interpolation signal is appropriately switched according to the motion signal S1. The same members as in FIG. 1 are given the same reference numerals.

Hereinafter, parts different from those in FIG. 1 will be explained.

The adder 70 sums the input signal x1 and the video signal x2 of one frame before, and the result is multiplied by 1/2 in the 1/2 coefficient circuit 72 and applied to the selector 74. selector 7
4, the motion signal S1 is “H” (frame difference X6>Th
), the signal X of the previous field is selected, and when the motion signal S1 is "L" (frame difference x6≦Th), the average value X of the previous and previous fields is selected. As a result, when A and T shown in Figure 3 are both stationary, their average value is selected as the interpolation signal, and when A is stationary and A is moving, the signal A is selected as the interpolation signal. Become. When using the average value of the previous and previous fields as an interpolation signal, the S/N
Since the ratio becomes five times, this adaptive processing has the effect of improving the S/N ratio of the image after scanning line conversion.

〔Effect of the invention〕

As explained above, according to the present invention, image conversion can remove double image interference and images with low vertical resolution (blurred images) that follow moving object images, and can obtain non-interlaced images without image quality deterioration. device can be presented.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the first embodiment of the present invention, FIG. 2 is a diagram showing a detailed circuit example of the interpolation selection circuit 30 of FIG. 1, and FIG. 3 is a diagram showing the movement of an object image in the present invention. FIG. 4 is a diagram showing another circuit example of the interpolation selection circuit 30, and FIG. 5 is a circuit diagram of a second embodiment of the present invention. be. Figure 6, Figure 7, Figure 8,
FIG. 9 is a diagram illustrating the effect of an interpolation signal by a conventional device. 10...--Input terminal 12.14--Field memory 16--Selector 18--Adder 20-
-・Delay device 22- Adder 24- Time compression circuit
25・-・1/2 coefficient circuit 26・−・Absolute value circuit 2
8--Comparison circuit 30--Interpolation selection circuit 32--Output terminal 34.36--Delay device 38--AND circuit 40--OR circuit 42-Output terminal 50, 52.
54...-Delay device 56-N O7 circuit 58, 6
0-A N D circuit 62-=OR circuit Fig. 2 Fig. 3 - Fig. 4 Fig. 5 Prisoner Fig. 7 1-2ii◆2------y E L) No. Figure 8

Claims (1)

[Claims] An image signal conversion device that forms a high-definition image signal by inserting an interpolation signal into an image signal, the device comprising: a first interpolation signal forming means that forms an interpolation signal from a signal of another field; and a first interpolation signal forming means that forms an interpolation signal from a signal of another field; interframe motion detection means for detecting interframe motion and generating a motion signal; and holding means for retaining a motion detection signal from at least one field before. . An image signal conversion device, characterized in that the interpolation signals of the first and second interpolation signal forming means are selected from the current interframe motion signal and the motion signal of the holding means.