JPS6239988A - System conversion device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application) The present invention relates to a television format conversion method for converting the number of frames and the number of scanning lines of a television image signal.
In particular, it is possible to reduce image quality deterioration such as moth-eaten malfunctions that occur in a moving image portion due to frame number conversion of an image signal that includes a plurality of moving portions.

(Prior art) Conventionally, when performing method conversion, linear interpolation methods such as linear interpolation, position interpolation methods using motion vectors, and methods combining these have been proposed.
No. 712), when selecting a compensated interpolated image signal based on an optimal motion vector from among a plurality of motion compensated interpolated image signals based on a plurality of detected motion vectors, a malfunction may occur depending on the picture. , there was a moth-eaten □ image quality deterioration in the converted image.

FIG. 2 shows a block diagram outlining the configuration of an embodiment of the system converter described in the specification of Japanese Patent Application No. 1988-712 "System Conversion Apparatus". In order to convert an M line/2N field (interlaced scanning) television signal to a single television signal of a different type of Niin/2L field (interlaced scanning), first, as shown in Figure 8, The M line/2N field signal is converted into line/N frame scanning line number conversion and sequential scanning conversion, and then line/L frame signal is converted into line/N frame.
・Convert the number of frames to frames and perform interlaced scanning conversion.

Both the patent application and the present invention are mainly concerned with the frame number conversion part, for example, converting an input television signal of N=80 frames/second into an output television signal of L=25 frames/second. In the case of 10, the conversion cycle is to convert the first to sixth frames of the input signal into five frames aNe of the output signal, as shown in FIG.

In such frame number conversion, the simplest method is to use a weighted average of the input image signals of the previous and succeeding frames to form the output image signal of a new frame located in the middle of the input image signals of two consecutive frames. There is a linear interpolation method that calculates the amount of image, but it has a 2'' drawback in that when there is movement in the image, blurring and jerkiness occur at the edges of the moving parts of the output image, resulting in a significant deterioration in image quality.

As a method for eliminating the above-mentioned drawbacks, in Japanese Patent Application No. 59-244688 "Television System Conversion System" by the inventors of the present application, the inventors of the present invention have proposed a method for determining the motion of an image, motion vectors (representative motions, motion vectors, etc.). ) and synthesized the image position with a linear interpolation signal controlled by a motion vector, which greatly improved the above-mentioned drawbacks of normal images. It is true that many of the images have simple movements such as panning and tilting of a specific subject, and although a considerable effect was obtained with this method 1-1, there were relatively few attention-grabbing movements in the same image. Some images include a plurality of image parts that move easily and differently, and in such cases, a sufficient effect of improving image quality cannot be obtained.

The invention of the present application which further overcomes and improves the above-mentioned drawbacks is the patent application 1980-712 R system conversion device by the same applicant, and the outline of this device is explained below with reference to FIG. 2. do.

In the apparatus shown in Fig. 2, when converting the number of frames of the television system, consecutive N and one□...N+1
From the original image signal of the frame, a linearly interpolated image signal of a new frame is formed by linear interpolation (42,
48, 44, 45), dividing the original image into multiple regions,
A plurality of N and N+1 frames are obtained by moving the entire original image signals of N and N+1 frames, respectively, according to these vectors. forming a motion compensated image signal of (46, 47) and forming a motion compensated interpolation image signal of a plurality of new frames 1° (48);
, the absolute value (50) of the inter-frame difference between the original image signal of N and N+1 frames and the motion compensated image signal of multiple N and N+1 frames, and the straight line (51) corresponding to the minimum value of these absolute values. Interpolated image signal (45
), or one or more motion compensated interpolated image signals (48)
(52).

Problems to be Solved by the Invention) According to the device equipped with the means described above, even if there are a plurality of image parts 2... that are easily recognizable and move differently in the comparison song, it is possible to convert the number of frames. It was possible to considerably reduce image quality deterioration such as blurring and jabbiness that occurs along with this.

However, even with the above-mentioned apparatus, malfunctions have occurred when selecting five minimum values from among the plurality of absolute values of the inter-frame differences for certain types of images.

Figure 5 shows a situation in which a black point a moves on a white background, but for this moving point, the interpolation frame point based on the motion vector v0 becomes a black point, so it is correct, but it is correct due to the vector V. If the value is 10, it becomes a white dot, which is an error. Here, vector V and vector v2 are motion vectors detected from the image area where the black point will move and from other image areas, respectively.

Here, motion compensation at one point in the interpolation frame l) The interpolation image signal is selected as follows. In other words, the motion-compensated image signals of N and N+1 frames based on the motion vector V□ are the black point a on the N frame, the a1 signal just above the double signal that has moved to the right, and the black point a0 signal on the N+1 frame to the left. This is the a11 signal directly below the point that moved to 2.... Furthermore, the motion compensated image signals of N and N+1 frames by vector V21 are similarly divided into b signal and b1.
1 signal (both are not added). Here, in order to select the interpolated image signal with the correct motion vector, the signal a1 and the signal a
11 and the absolute value of the difference between signal b1 and signal b11, that is, comparing the absolute value of the difference between signal a and signal a0 and the absolute value of the difference between signal a and signal b1. In this case, both values become zero, and the optimal value for selection cannot be determined. This occurred because it was assumed that the sunspots 1...a were moving on a white background, but such a situation is quite possible in reality.

In this case, the minimum value label detection circuit 5 cannot make a precise decision, and it is not certain which one of the motion compensated interpolation image signals based on the vector V□ and the vector v2 to be selected.

In this example, we have taken the case of two vectors, but since the same situation will occur even if there are many motion vectors, a white point and a black point will be randomly selected as the motion compensation interpolation image signal of a black moving object, and thus It becomes a moth-eaten state where black and white alternate.

(Means for Solving the Problems) An object of the present invention is to eliminate the above-mentioned device malfunction, and to convert the number of frames of a television image signal, even in the case of a special image such as a black point moving on a white background. This aims to achieve high-quality frame number conversion by removing blur, jaquiness, and moth-eaten conditions in the moving image portion of the image.

In other words, the system conversion device of the present invention includes a means for detecting a motion vector corresponding to the moving direction and distance of the area image of the upper part of the screen, and a continuous N
and means for forming a plurality of motion compensated image signals of N and N+1 frames by respectively shifting the original image signal of N+1 frames to form motion compensated interpolated image signals of a plurality of new interpolation frames. In the frame number conversion television system conversion device, the plurality of motion compensated image signals are pattern matched using the plurality of detected motion vectors, the optimum motion vector is detected, and the optimum motion vector is detected. The present invention is characterized by comprising means for determining one image part number for compensation interpolation and obtaining a frame interpolation signal.

(Embodiment) A new algorithm and the configuration of the device for implementing the system conversion device of the present invention will be explained in detail below with reference to the drawings.

Figures 6 and 7 are vector diagrams for explaining the new algorithm, and Figure 1 is a block diagram of only the main parts of the device configuration related to the present invention. 1b Examples of Figures 6 and 7 Although the number of motion vectors detected by the motion vector detection circuit 49 in FIG. 2 is four, it goes without saying that this number can be expanded to any number. In this case the image is the fifth
Assume a scene in which a sunspot a moves on a white background as shown in the figure, and consider obtaining a motion-compensated interpolated image signal for the scene. In FIG. 6, interpolation point 1 in the interpolation frame is signal a. The black point can be correctly obtained by interpolating motion-compensated image signals obtained from vector v0 and a□. Since the vectors v2 to V are vectors detected from the moving image area of the other party, they are imposed vectors for the interpolation point i. The reason is that for the interpolation point i, the signals on the corresponding N frames by these vectors. l CQ tdo has a white background, so use vectors v2 to v4.

Therefore, when motion-compensated interpolation is performed, the interpolation point i becomes a white point, causing moth-eaten spots.

Now, from the interpolation point i, the interpolation candidates for 1 are the signals a, b, c, and d at four points corresponding to vectors v0 to ■,
. , bo, co, and do, however, as described above, an error will occur if the motion vector label is simply detected as the minimum value of the absolute value of the frame difference between the motion compensated image signals of N and N+1 frames. In this example, vector V□ must be selected as a label among the interpolation candidates for interpolation point 1. As soon as the frame is converted, one point of the interpolated frame is N frames, N+1 as shown in Figure 7.
1. To the signal on the frame. 2 (2=1 to k1+) and 2 vectors (2v1 to vector, v to vector) are used to perform motion compensation and generate two motion compensated image signals whose pixel positions □... are corrected. Synthesize and get 1.

Therefore, the present invention selects the optimal motion compensation interpolation image signal using the procedure described below.

First, as shown in FIG. 6, vector is calculated for interpolation point 1.

Pixel a on N frames corresponding to torque v0 to V. .

Set bo, co, and do. Next a. Regarding the point, signal a due to vl. and ax, the signal a due to the vector V. and a8, signal a by vector v8. and a8, vector V, a. and a, motion compensated image signal)...
The frame difference between N and N+1 frames for each vector is calculated (vector test unit 20 in FIG. 1). The frame difference is signal a. Those from and ao are zero, and everything else is not zero. This is signal a. is the black level, whereas 1 signal a, t a, ,
This is because a is the white level.

Do the same thing with other candidate signals. , co, and do (vector test units 21 and 22 in FIG. 1).

28). In FIG. 6, the signal is , co, do by the vectors v, , Va, V, N+1
Hu Lam's signal b11? Other than '8 t d4 are omitted to avoid complication of the figure.

The above operation is nothing but an operation of performing pattern matching using four vectors on each interpolation candidate signal. In this example, the above combinations are 16-sets in total, and the signal a. and a
If the absolute value of the frame difference related to o is written as θ, -□, then the absolute value of the frame difference related to the movement of point a is θ1-1=
01θ1-2~0. The absolute value of the frame difference related to the movement of c and d, which points from θ1-8 to 0・θ, -4 in the same way as O, is: θ, -1=θ2-2=θ, -8=θQ-4=Oθ8 -1
=08-2=θ8-8:θ8-4 ””θ, -□workθ,
-8: θ, -8: θ4-4 "". If we rearrange the above combinations in terms of vectors, we get PectA/v0
The pair involved is °θ1-1=θs-z ”θ8-1=0
4-1 = 0 similar vector Vs s Va t 'V
The groups related to 4 each have θ ~ 0. θ, -2=θ8
-3 engineering θ, -, erotic 1-ri θ ~0. θ8-8work θ8-8work θ, -8work 0θ
To O20,-1=θ8-1 θ,-, it becomes erotic.

Here, the sum of the absolute value of the frame difference related to the vector v0 and the absolute value of the frame difference related to the vectors V, , V, , V is calculated (adder 24 * in Fig. 1).
2 r1* 26 s 27 ), respectively 1□, i, , 18. i, the minimum value is 1
□, and the vector giving 11 becomes the correct movement vector (here, V□) of the moving object (minimum value detection unit 28 in FIG. 1).

Similarly, when V is correct, the output 1 of the adder 25 becomes the minimum, and an accurate vector label is detected for Va t V4 using the same algorithm.

A motion compensated interpolation image signal whose position has been correctly corrected is selected using the control signal 0 corresponding to the accurate vector determined by the minimum value vector label detection unit 28.

(Effects of the Invention) By using the device of the present invention, in a motion-compensated frame number conversion device, accurate motion vector label detection and corresponding selection can be achieved in selecting a motion-compensated interpolated image signal for each frame. Therefore, there is an advantage that a good format conversion can be performed without causing a bug-like image quality deterioration in the output image after the frame number conversion.

Furthermore, since the device of this invention can be applied to converting the number of frames of any television signal, it can also be applied to a system conversion device between current standard television systems, ``high-definition television system and standard 1/semi-television system. be able to.

[Brief explanation of the drawing]

Fig. 1 is a block diagram for explaining the main parts of the configuration of the device of the present invention, Fig. 2 is a block diagram of the configuration of the conventional device, Fig. 8 is a diagram showing the flow of the system conversion device, and Fig. 4 is Figures 5 and 6 are diagrams showing an example of the conversion cycle of frame number conversion, respectively, and show conventional vector selection. FIG. 7 is a diagram illustrating the relationship between interpolation frames and vector operations. 1... Frame memory (F) 2.13, 6, 7.8... Buffer memory (BFI4
, 卜...Coefficient multiplier (kx + k239, 10,
11, 24, 25, 26, 27... Adder (+) 12, 18, 14, 15... Subtractor (-
)16, 17, 18, 19... Absolute value circuit (A
BS) '20, 21, 22, 28...1st. Second. 8th degree Fourth block configuration circuit 28...Minimum vector label detection unit 41...Frame order circuit 42...Frame memory 48, 44...Coefficient multiplier (k, , k2) 45
, 48... Adder (+) 46, 47... Buffer memory 49... Motion vector detection circuit BO... Absolute value circuit (ABS) 51... Minimum value label detection circuit 52... Signal Selection circuit 53...Scanning line number/progressive scanning conversion 54...Frame number conversion

Claims (1)

[Claims] 1. Means for detecting motion vectors according to the moving direction and distance of a plurality of area images on the same screen, and a plurality of N and N+1 frames in which continuous N and N+1 frames of original image signals are respectively moved according to these vectors. and forming a motion-compensated interpolated image signal of a plurality of frames to form a motion-compensated interpolated image signal of a plurality of new interpolated frames, wherein the plurality of motion-compensated image signals and means for performing pattern matching using the plurality of detected motion vectors, detecting the optimum motion vector, determining the optimum motion compensation interpolation image signal, and obtaining a frame interpolation signal. A method conversion device characterized by: