WO2009090735A1

WO2009090735A1 - Motion vector detection method and device, plasma display panel driving method, and plasma display device

Info

Publication number: WO2009090735A1
Application number: PCT/JP2008/050421
Authority: WO
Inventors: Yasunobu Hashimoto
Original assignee: Hitachi, Ltd.
Priority date: 2008-01-16
Filing date: 2008-01-16
Publication date: 2009-07-23

Abstract

A method for detecting a motion vector (ξ,ψ)1n between previous and next frames (SF) of a moving picture which is displayed on a screen (10) having pixels (11) that are arranged in matrix. The method is characterized in that the detection area for detecting the motion vector is arranged in a plurality of layers on the screen so that a low order detection area is included in the high order detection area; with respect to each of the detection areas in the plurality of layers, Fourier transform of the previous frame Fmn(u,v) and that of the next frame F'mn(u,v) are obtained and motion vector information ψmn(k,1) is calculated; and the motion vector in the lowest order detection area is decided from the lowest order detection area and the average of the motion vector information detected in the plurality of high order detection areas including the lowest order detection area among the detection areas in the plurality of layers.

Description

Motion vector detection method and apparatus, and plasma display panel driving method and plasma display apparatus

The present invention relates to a motion vector detection method and apparatus, and a plasma display panel driving method and plasma display apparatus.

Conventionally, in the field of image signal processing, particularly in video signal processing, motion direction and magnitude of each object in the image, that is, a motion vector is detected, and the motion from the reference frame image is detected using the motion vector A technique for expressing video and video data is known.

As such a motion vector detection method, a motion vector detection method using Fourier transform is known (see Patent Document 1). This will be described below.

First, let the number of the two-dimensional array of pixels be (k, l). If the region for detecting the motion vector is N × N pixels (N is a natural number), the pixel number is within the range of the expression (1).

Assuming that the image data in this region is f (k, l), the Fourier transform F (u, v) of this image data can be obtained from equation (2).

Here, (u, v) is an address in the frequency space and satisfies the expression (3).

Next, it is assumed that the original image has moved ξ in the x direction and ψ in the y direction. The new image f ′ (k, l) is expressed as in equation (4).

Here, when the Fourier transform F ′ (u, v) of f ′ (k, l) is obtained, the following equation (5) is obtained.

Next, the inverse Fourier transform φ (k, l) of the ratio of F ′ (u, v) and F (u, v) is obtained as shown in equation (6).

Here, δ is the Kronecker delta and takes a value as shown in equation (7).

Here, as can be seen from the equation (6), φ (k, l) has a peak at (ξ, ψ), whereby a motion vector can be detected. That is, the value of (k, l) that gives the peak of φ (k, l) is the motion vector. In this way, the motion vector (k, l) can be obtained.
JP-A-6-350997

However, in the motion vector detection method described in Patent Document 1 described above, a motion vector can be accurately detected when the entire screen moves uniformly, but when there are regions with different motions on the screen, There was a problem of not knowing which area was moving to which.

FIG. 8 is a diagram showing an example in which there are a plurality of regions having different motion vector directions in the same detection region. As shown in FIG. 8, when there is a detection region C having 0 to (N−1) pixel regions in the x and y directions, the region A moves in the x positive direction and the y positive direction. B moves in the x negative direction and the y negative direction, and the directions of the motion vectors are different. In such a case, there is a problem that it is not possible to detect in which direction the detection area C is moving as a whole, and it is also impossible to detect the movements of the areas A and B.

In order to prevent this, if the motion vector is detected by dividing the screen finely, if there is a repetitive pattern occupying a large area, the motion vector cannot be detected when the divided screen is smaller than the area. Another problem will arise.

FIG. 9 is a diagram showing a case where a large repetitive pattern area D exists in the screen and is larger than the area C where the motion vector is detected. In such a case, since there are many points that satisfy the pattern matching in the motion vector detection region C, the amount of motion cannot be determined. In such a case, an example of how the inverse Fourier transform φ (k, l) of F ′ (u, v) and F (u, v) for detecting a motion vector will be shown as follows. become that way.

First, if N is a multiple of 4, N can be expressed as in equation (8).

Further, if the display pattern is a vertical stripe with a period of 4 pixels, the image data f (k, l) can be expressed as in equation (9).

At this time, the Fourier transform F (u, v) of f (k, l) can be expressed as in equation (10).

As shown in the equation (10), F (u, v) can be zero, so in the calculation for obtaining φ (k, l), a term of F (u, v) that does not become zero is calculated. This corresponds to calculating only the spatial frequency component included in the display image.

Next, if the image of f (k, l) moves 4 pixels in the x direction in one frame, it overlaps with the original image, so its Fourier transform is the same as F (u, v), (11) It becomes like the formula.

Therefore, φ (k, l) in this case is as shown in equation (12).

That is, as can be seen from the equation (12), φ (k, l) has a peak at a 4-pixel cycle on the x-axis, and a motion vector cannot be determined.

As described above, in the conventional technique, since the Fourier transform is performed in a fixed area for detecting a motion vector in a certain area, the detection area to be calculated may be too narrow or the detection area may be too wide. In such a case, there is a problem that the motion vector cannot be determined.

Accordingly, the present invention provides a motion vector detection method and apparatus capable of appropriately detecting motion vectors having different orientations and sizes in the same image, and a plasma display panel. An object of the present invention is to provide a driving method and a plasma display device.

To achieve the above object, a motion vector detection method according to a first invention is a method for detecting a motion vector between frames before and after a moving image to be displayed on a screen having pixels arranged in a matrix.
A plurality of detection areas for detecting motion vectors are set on the screen such that a low-order detection area is included in a high-order detection area.
For each of the detection areas of the plurality of layers, obtain a Fourier transform of each of the preceding and following frames, calculate a motion vector,
A motion vector in the lowest order detection area is obtained from an average of motion vectors detected in the lowest order detection area and a plurality of higher order detection areas including the lowest order detection area among the detection areas of the plurality of hierarchies. It is characterized by determining.

This makes it difficult to determine a motion vector because multiple motion vectors that require a large detection area for detection and small motion vectors that have different directions in the large detection area are detected, such as an image that includes a repetitive pattern. Even if it exists, the suitable motion vector according to an area | region can be detected.

A second invention is the motion vector detection method according to the first invention,
The detection region is set so that a boundary of the higher-order detection region matches a boundary of the lower-order detection region.

This makes it easy to determine motion vectors.

A third invention is a motion vector detection method according to the second invention, wherein
The m-th detection area is set as an area of 2 ^m × 2 ^m pixels,
The lowest order detection area is set as a 2 × 2 pixel area.

Accordingly, it is possible to set a hierarchy having an inclusive relationship such that the boundary of the detection area of the m-th motion vector matches the boundary of the detection area of the (m−1) -th motion vector. The calculation can be facilitated, and a small pixel unit is set as the lowest detection area, so that a final motion vector can be determined with sufficient consideration from a small motion vector to a large motion vector.

The driving method of the plasma display panel according to the fourth invention is as follows:
A motion vector is detected by the motion vector detection method according to any one of the first to third aspects;
By using the motion vector, the lighting pattern of the subframe is controlled corresponding to the movement of the image.

This makes it possible to turn on the subframe with a lighting pattern along the direction of movement of the line of sight, and it is possible to cause the plasma display panel to perform a smooth moving image display that does not give a sense of incongruity to human eyes.

A motion vector detection device according to a fifth invention is a motion vector detection device that detects a motion vector between frames before and after a moving image displayed on a screen in which pixels are arranged in a matrix.
A detection area setting means for setting a plurality of hierarchies on the screen such that a detection area for detecting the motion vector is included in a high-order detection area;
For each of the motion vector detection regions of the plurality of layers, motion vector calculation means for performing a Fourier transform on each of the preceding and following frames, and calculating a motion vector between the preceding and following frames based on these.
A motion vector in the lowest order detection area is obtained from an average of motion vectors detected in the lowest order detection area and a plurality of higher order detection areas including the lowest order detection area among the detection areas of the plurality of hierarchies. Motion vector determining means for determining.

As a result, motion vectors between frames of moving images displayed on the screen can be detected in an appropriately sized inspection area including motion vectors, and large repetitive patterns and motion vectors with different orientations are in the same frame. Even if it exists in the image, it is possible to appropriately detect the motion vector based on each.

6th invention is the motion vector detection apparatus which concerns on 5th invention,
The detection area setting means sets the detection area so that a boundary of the higher-order detection area matches a boundary of the lower-order detection area.

This makes it easy to perform arithmetic processing for motion vector detection.

A seventh invention is the motion vector detection device according to the sixth invention, wherein
The detection area setting means sets the plurality of hierarchies to an m-th order detection area as an area of 2 ^m × 2 ^m pixels and to set the lowest order detection area as an area of 2 × 2 pixels. To do.

Accordingly, the boundary of the m-th detection region can be a hierarchical relationship that matches the boundary of the (m−1) -th detection region, and the arithmetic processing for determining the motion vector can be facilitated. .

A plasma display device according to an eighth invention is a plasma display device having a plasma display panel driven by a subframe driving method,
A motion vector detection device according to any one of claims 5 to 7,
Subframe control means for controlling the lighting pattern of the subframe based on the motion vector detected by the motion vector detection device;
And a plasma display panel driving circuit for driving the plasma display panel based on the lighting pattern.

This makes it possible to display a moving image with no blur and smooth movement on the plasma display panel using the motion vector.

According to the present invention, motion vector detection errors can be reduced, blurring of moving images displayed on the screen can be reduced, and image quality can be improved.

It is the figure which showed the hierarchical relationship of the motion vector detection area | region of the motion vector detection method etc. which concern on Example 1. FIG. It is the figure shown about the example of detection of a motion vector. FIG. 6 is a diagram illustrating an example in which a motion vector is displayed on a screen 10. FIG. 6 is an overall configuration diagram of a plasma display device according to a third embodiment. It is a figure which shows the structural example of 1 frame FR of an image. It is a figure showing an example of control of the lighting pattern of subframes SF1 to SF3. FIG. 10 is an operation flowchart of the plasma display device according to the third embodiment. It is the figure which showed the example which has an area | region where a motion vector differs in the same detection area. It is the figure which showed the example in which the big repeating pattern area | region D exists in a screen.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Screen 11 Pixel 15 Plasma display panel 16 Address electrode 17 Scan electrode 18 Sustain electrode 20 Plasma display panel drive circuit 21 Address driver 22 Y scan driver 23 Y scan circuit 24 X sustain circuit 30 Sub-frame control means 40 Motion vector detection apparatus 41 Detection Region setting means 42 Motion vector information calculating means 43 Motion vector determining means

In order to describe the present invention in more detail, the best mode for carrying out the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram illustrating a hierarchical relationship of a motion vector detection method and apparatus according to a first embodiment to which the present invention is applied, a plasma display panel driving method, and a motion vector detection region of the plasma display apparatus.

First, a detection area for obtaining motion vector information by Fourier transform is defined. The size of the detection area is a 2 ^m × 2 ^m pixel area, and the minimum area is a 2 × 2 pixel area so that FFT (Fast Fourier Transform) is performed at high speed. Here, the screen of the plasma display device as an object of the embodiment will be described by taking a screen of 1920 × 1080 pixels as an example, but the maximum size of the repeated pattern region that can appear is the entire screen. Here, for convenience of calculation, the screen area is expanded to 2048 × 2048 pixels, and the pixel data of the area outside the original screen of 1902 × 1080 pixels is set to 0.

FIG. 1 shows a motion vector detection region having 2 ^m × 2 ^m pixels. In FIG. 1, a detection area of 2 ^m × 2 ^m is referred to as an m-th detection area. Then, the (m−1) th order detection area becomes a pixel area of 2 ^m−1 × 2 ^m−1 , and the mth order detection area is twice as long as the (m−1) th order detection area. Each has twice as many pixel regions. Therefore, the m-th detection area has a detection area (number of pixels) that is 2 × 2 = 4 times the (m−1) -th detection area. Further, the boundary of the m-th detection region coincides with the boundary of the (m−1) -th detection region.

Here, when the above-described conditions are applied, the minimum area is the primary detection area and the maximum area is the 11th detection area. If a number is assigned in the set of m-th detection areas and this is expressed as the n-th, the m-th detection area can be expressed as Ω _mn . In the motion vector detection method and apparatus according to the present embodiment, the motion vector of the moving image between the preceding and following frames is detected by setting a plurality of layers having different detection areas on the screen. .

Next, a description will be given of a method for determining a motion vector on a screen in which such a detection area having a plurality of hierarchies is set.

First, motion vector candidates are obtained in each detection region. As the first step, Fourier transform is obtained in the detection area Ω _mn of the frame of interest and the next frame. The pixel data in the frame of interest is set to f _mn (k, l), and the pixel data in the next frame is set to f ′ _mn (k, l). Here, the pixel data is the Y value (luminance value) of the pixel, but another amount may be used.

Here, the address (coordinates) of the pixel is (k, l), but it is assumed that the address (k, l) is assigned to each target detection area. Therefore, the range of k and l is expressed as in equation (13) if it is an inspection region of the mth order hierarchy.

First, the Fourier transform F _mn (u, v) of the image data f _mn (k, l) of the frame of interest is obtained by the equation (14).

Next, the Fourier transform F ′ _mn (u, v) of the image data f ′ _mn (k, l) of the frame next to the frame of _{interest is} obtained by the equation (15).

Next, an inverse Fourier transform φ _mn (k, l) that gives motion vector information is obtained by equation (16).

Note that very small F _mn (u, v) means that there is little image information of the frequency component, and therefore hardly affects the motion vector information φ _mn (k, l). Accordingly, in the calculation for calculating the actual motion vector, in order to ensure the stability of the calculation, (u, v) that gives a very small F _mn (u, v) is included in the sum of the equations (16). Preferably not.

Here, the inverse Fourier transform φ _mn (k, l) is expressed by the following equation (17), and the entire detection region Ω _mn is expressed by (ξ, ψ) as described in the conventional equation (7). ) Will be Kronecker delta when moving in parallel.

Therefore, the inverse Fourier transform φ _mn (k, l) represents the movement of the detection region Ω _mn . Using this inverse Fourier transform φ _mn (k, l), the motion vector (ξ, ψ) _1n of the detection region Ω _1n can be determined by the equation (18).

Here, M is the order of the detection area of the highest hierarchy (11 in this example), and Λ (m, n) is a set of m-th order detection area numbers including the detection area Ω _1n .

Equation (18) means the average of motion vectors detected in the detection region including the detection region Ω _1n . Since an accurate motion vector can be detected in a small detection area included in the repeated pattern area, a value close to the accurate motion vector can be obtained by taking the average of the equation (18).

Also, if there are multiple areas on the screen that move differently, an accurate motion vector cannot be detected in a large detection area that contains them, but a single movement is detected in a sufficiently small detection area. By taking the average of equation (18), a value close to an accurate motion vector can be obtained.

In this way, for the image data of the moving image of the preceding and following frames, the motion vector detection area is set by dividing the screen, but the detection area is set in a plurality of layers with different sizes, and the preceding and following frames are set for each layer. By calculating the motion vector between them, and finally calculating the average of these to determine the motion vector, important vectors in the individual layers are detected, and by taking their average, Since important motion vectors are prominent, it is possible to appropriately detect motion vectors between the previous and next frames.

In the second embodiment, the motion vector detection method according to the present embodiment, which is theoretically explained using the equations (13) to (18) in the first embodiment, will be described with reference to FIGS. A specific example will be described.

FIG. 2 is a diagram illustrating an example of motion vector detection. FIG. 2 shows an example in which the motion vector (2, 2) is detected by the inverse Fourier transform φ _mn (k, l) giving the motion vector information. At this time, as described in the expression (17) of the first embodiment and the expression (7) of the prior art, the motion vector (2, 2) takes a value of 1 and the other motion vectors take a value of 0. Means. In the second embodiment, it is assumed that the motion vector itself is detected for each detection region, not the motion vector information φ _mn (k, l).

FIG. 3 is a diagram illustrating an example in which the motion vector described in FIG. 2 is displayed on the screen 10 having the pixels 11 arranged in a matrix. The screen 10 has 2048 × 2048 pixels 11 as in the first embodiment. Only a part of the screen 10 is shown, and m = 4 of the detection area from m = first order lowest detection area to m = third order of the detection area represented by 2 ^m × 2 ^m , All of the next detection areas in the x-axis direction and half the area in the y-axis direction are shown. In other words, one square indicating the lowest detection area of m = 1st order includes a pixel area for four pixels. For each of the m-th layer, for the n-th detection area, the left end of the top row of the screen 10 is set to the first, moved to the right, 2, 3, etc., and when that row ends, the next 2 Let us move to the first column at the left end of the line and sequentially number the right. Accordingly, it is assumed that the screen 10 has 1024 × 1024 inspection areas of the lowest order m = 1.

In FIG. 3, (1,1) motion vectors are detected in the n = 1st detection area for the inspection area of the m = 1st order hierarchy. This can be detected in the primary inspection area because all the motion vectors are included in the inspection area of the primary hierarchy. Similarly, a motion vector (1, 1) in the positive direction is also detected in the n = 5th inspection region in the m = 1st layer. On the other hand, the movement of n = 1030th inspection area (the 6th column of the 2nd row) and the n = 2051th inspection area (the 3rd column of the 3rd row) of m = 1st order are oppositely moved. A vector (-1, -1) has been detected. These are all motion vectors that are properly detected in the lowest order m = first order inspection region.

On the other hand, the motion vector (3, 3) is included halfway in the n = 1026th inspection area of the m = 1st order hierarchy. In this inspection area, all of the motion vectors (3, 3) are included. Is not included in the primary hierarchy, it cannot be accurately detected. In this case, even if the hierarchy of the inspection area is increased to m = 2 order, the motion vector (3, 3) protrudes from the n = 1st inspection area, and this motion vector (3, 3) is accurately set. It cannot be detected. Next, when the hierarchy of the inspection area is raised to m = 3rd order, the motion vector (3, 3) fits in the n = 1st inspection area of the 3rd hierarchy, so in the m = 3rd order hierarchy, The motion vector (3, 3) can be accurately detected.

Here, in addition, motion vectors (1, 1) and (−1, −1) are also detected in the n = 1 inspection region of the m = 3rd layer. These are motion vectors that are appropriately detected in a single direction in each inspection area in the m = 1st order hierarchy, but in the inspection area in the m = 3rd order hierarchy, the motion vector (3, 3). 3) is detected as a larger and more important motion vector, and is detected as a motion vector having a lower importance.

Further, in the n = 2nd inspection region of the m = 3rd layer, motion vectors (1, 1) and (-1, -1) having the same magnitude in the opposite direction are detected in the upper left part. In the inspection area of the m = 1st order hierarchy, each is detected in a single direction and has an important size, but in the inspection area of the m = 3rd order hierarchy, the importance is reduced. Will do. For example, if another larger motion vector exists in the same inspection area, the motion vector becomes more prominent. On the other hand, these motion vectors (1, 1) and (−1, −1) are both included in the n = 3rd inspection area of the m = 2 order hierarchy, and are also detected in this inspection area. In this case, the motion vector is detected as a motion vector having a higher degree of importance than that detected in the n = 2nd inspection region of the m = 3rd layer, but the directions of both are opposite, so that they cancel each other as a whole. It is detected as a motion vector and is detected with a lower importance than in the case of m = 1.

As described above, motion vectors having various sizes and directions are redundantly included in the inspection areas of a plurality of layers having different inspection areas. In other layers, it is detected as a small vector value or too large to be detected. Therefore, if the motion vector information of the moving image of the preceding and following frames is detected in each inspection region in different layers of the plurality of inspection regions, and all of these are added and averaged, the most in all layers A prominent motion vector is detected so as to emerge from the noise. Since the finally calculated motion vector is calculated from the average, it is expressed by the lowest-order motion vector.

Next, a method for detecting the motion vector of the repetitive pattern D shown in FIG. 3 will be described. In FIG. 3, for example, when the motion vector of the repetitive pattern D is to be detected in the m = 1 order hierarchy or the m = 2 order hierarchy, the peak value of the motion vector stands periodically. It becomes difficult to determine a motion vector in the inspection area. In such a case, for example, when a motion vector is detected in the m = third order hierarchy, the entire repetitive pattern D can be included in the n = 2nd inspection region. It is possible to calculate a motion vector between the entire previous and subsequent frames.

As described above, according to the motion vector detection method according to the second embodiment, it is not always possible to detect an accurate motion vector for each pixel, but it is possible to always calculate an appropriate motion vector between frames before and after. . In other words, for any moving image, it is possible to avoid a situation where a motion vector cannot be calculated or an obvious erroneous vector is calculated. It is possible to calculate a highly reliable motion vector without error in a large direction.

In the second embodiment, the setting of detection areas in a plurality of layers has a relationship of 2 ^m × 2 ^m , and an area obtained by dividing the m-th detection area vertically and horizontally is the (m−1) -th detection area. For example, there are various relationships such as a 3 ^m × 3 ^m relationship, and an area obtained by dividing the m-th detection area into three vertical and horizontal becomes the (m−1) -th detection area. Can be set.

In the second embodiment, the hierarchy is set so that the boundary of the m-th detection region matches the boundary of the (m−1) -th detection region. The detection area only needs to be larger than the (m−1) th detection area. For example, a detection area having a 2 × 2 pixel area is a detection area having a 3 × 3 pixel area. There may be. For example, in the first embodiment and the second embodiment, for the sake of easy understanding, the example in which the number of pixels on the screen 10 is 2048 × 2048 is described as an example, but the actual arrangement of the pixels 11 on the screen 10 is as follows. Since various formats are conceivable, the setting of the detection area may be variously changed according to the application, or the detection area may be set to a rectangle instead of the same number of pixels in the vertical and horizontal directions. However, in such a case, the boundaries of the layers may not match, so that instead of calculating the motion vector in the lowest detection region, the motion vector may be detected for each pixel.

In addition, the setting of detection areas of a plurality of hierarchies may be set in advance for the screen 10 or may be configured to be selectable. In the case of enabling selection, for example, it may be possible to change by an operation of a user or the like, or an automatic control for grasping a rough movement state of an image and setting an appropriate detection region based on the situation. May be.

Note that the arithmetic processing of the motion detection method described in the first and second embodiments may be realized by arithmetic processing means such as various electronic circuits, MPU (Micro Processing Unit), and ASIC (Application Specific Specific Integrated Circuit). By using these, it is possible to configure a motion vector detection device that implements the motion vector detection method according to the present embodiment as a device.

In the third embodiment, an example in which the motion vector detection method and apparatus described in the first or second embodiment is applied to a plasma display panel driving method and a plasma display apparatus will be described.

FIG. 4 is a functional block diagram showing the overall configuration of the plasma display apparatus according to the third embodiment to which the present invention is applied. In FIG. 4, the plasma display device according to the third embodiment includes a plasma display panel 15, a plasma display panel drive circuit 20, a subframe control unit 30, and a motion vector detection device 40. In FIG. 4, components for receiving a frame image signal and performing necessary signal processing are omitted, and only components necessary for screen display are shown. Therefore, the plasma display apparatus according to the present embodiment may include other elements necessary as a plasma display apparatus such as a signal processing γ correction circuit and a white balance adjustment circuit as necessary.

The plasma display panel 15 is a self-luminous display device that utilizes light emission associated with gas discharge, and a screen 10 is formed on the display surface. The plasma display panel 15 includes a plurality of address electrodes 16, a plurality of scan electrodes (scan electrodes) 17, and a plurality of sustain electrodes (sustain electrodes) 18. The plurality of address electrodes 16 are arranged in the vertical direction of the screen 10, and the plurality of scan electrodes 17 and the plurality of sustain electrodes 18 are arranged in the horizontal direction of the screen 10. The plurality of sustain electrodes 18 are connected in common. A display cell is formed at each intersection of the address electrode 16, the scan electrode 17, and the sustain electrode 18, and each display cell constitutes a pixel 11 on the screen.

The plasma display panel drive circuit 20 includes an address driver 21, a Y scan driver 22, a Y sustain circuit 23, and an X sustain circuit 24. The address driver 21 is connected to the plurality of address electrodes 16 of the plasma display panel 15. The Y scan driver 22 includes a drive circuit (driver IC) provided in each scan electrode 17, and each drive circuit is connected to the corresponding scan electrode 17 of the plasma display panel 15. The X sustain circuit is connected to the plurality of sustain electrodes 18 of the plasma display panel 15.

The address driver 21 applies an address pulse to the corresponding address electrode 16 of the plasma display panel 15 according to the image data in the address period in accordance with the control signal of the subframe control means 30.

The Y scan driver 22 sequentially applies the address pulse to the plurality of scan electrodes 17 of the plasma display panel 15 while shifting the shift pulse in the vertical scanning direction in the address period according to the control signal of the sub-frame control means 30. Thereby, address discharge is performed in the display cell of the corresponding pixel 11.

The Y sustain circuit 23 applies a periodic sustain pulse to the plurality of scan electrodes 17 of the plasma display panel 15 via the Y scan driver 22 in the sustain period in accordance with the control signal given from the subframe control means 30.

In accordance with the control signal supplied from the sub-frame control means 30, the X sustain circuit 24 causes the plurality of sustain electrodes 18 of the plasma display panel 15 to have a sustain phase shifted by 180 ° with respect to the sustain pulse of the scan electrode 17 in the sustain period. Apply pulses simultaneously. Thereby, a sustain discharge is performed in the display cell of the corresponding pixel 11.

The sub-frame control means 30 generates a sub-frame signal from the image data signal of one frame, and for the address driver 21, Y scan driver 22, Y sustain circuit 23 and X sustain circuit 24 of the plasma display panel drive circuit 20. Control means for sending subframe signals to drive these drive circuits. In the plasma display device according to the present embodiment, the subframe control means 30 generates a subframe signal using the motion vector detected by the motion vector detection device 40.

FIG. 5 is a diagram illustrating a configuration example of one frame FR of an image. The image is formed at 60 frames / second, for example. One frame FR is formed by a first subframe SF1, a second subframe SF2,..., An nth subframe SFn. This n is, for example, 10, and corresponds to the number of gradation bits. Each of the subframes SF1, SF2, etc., or their generic name is hereinafter referred to as a subframe SF.

Each subframe SF includes a reset period Tr, an address period Ta, and a sustain (sustain discharge) period Ts. In the reset period Tr, the display cell is initialized. In the address period Ta, light emission or non-light emission of each display cell can be selected by address discharge between the address electrode Aj and the Y electrode Yi. In the sustain period Ts, a sustain discharge is performed between the X electrode Xi and the Y electrode Yi of the selected display cell to emit light. In each SF, the number of times of light emission (the length of the sustain period Ts) by the sustain pulse between the X electrode Xi and the Y electrode Yi is different. Thereby, the gradation value can be determined.

The sub-frame control means 30 determines the gradation value in this way, but in the plasma display device according to the present embodiment, the motion vector between the previous and next frames is detected for the frame FR shown in FIG. Is used to control the gradation value.

FIG. 6 is a diagram showing a control example of the lighting pattern of the subframes SF1 to SF3. For example, as shown in FIG. 6, when the motion vector (1, 2) is detected by the motion vector detection device 40, a subframe that emits light corresponding to the motion vector from the first half to the second half of the subframe SF. To line up. In FIG. 6, the subframes SF1 to SF3 are sequentially turned on in accordance with the direction of movement of the motion vector. That is, since the user watching the plasma display panel 15 generally moves the line of sight following the moving subject on the screen, the movement position of the user's line of sight is predicted by detecting the motion vector of the subject. Can do. By using this and arranging the sub-frames that emit light on the moving line of sight, the moving images can be smoothly connected in the first half and the second half of the sub-frame SF, and the blur of the moving images can be reduced. it can. In FIG. 3, in the case of image data in which the position indicated by SF1 is emitted in the frame FR, the sub-frame is not continuously emitted at this position, but the decomposed sub-frame is adjusted to the direction of the motion vector. It controls to become the lighting pattern of a frame. Such control is performed by the subframe control means 30 according to the present embodiment.

The subframe control means 30 performs arithmetic processing for generating and controlling such subframes, and is realized by an electronic circuit having an arithmetic processing function, MPU (Micro Processing Unit), ASIC (Application Specific Specific Integrated Circuit), or the like. May be.

Referring back to FIG. 4, the other components will be described. The motion vector detection device 40 is means for detecting a motion vector of a moving image displayed on the screen 10 of the plasma display panel 15 and executes the motion vector detection method described in the first and second embodiments. The motion vector detection device 40 includes a detection area setting unit 41, a motion vector information calculation unit 42, and a motion vector determination unit 43.

The detection area setting means 41 is a means for setting a plurality of hierarchies of detection areas for detecting motion vectors. As described in the first and second embodiments, the detection areas of a plurality of hierarchies for detecting a motion vector have different sizes depending on the hierarchies, and there is a relationship in which a lower detection area is included in a higher detection area. And set on the screen 10 of the plasma display panel 15.

When the setting of the detection areas of a plurality of hierarchies is made in advance and fixed, the detection area setting unit 41 is configured to store storage means such as a memory for storing the set detection areas, or set detection areas. It may be an arithmetic processing means for detecting a motion vector.

In addition, if the setting of the detection area can be adjusted by the user's selection, such a selection function may be provided, or a function that can automatically set the detection area according to the motion of the moving image. May be provided with a function of performing calculation for setting the detection area.

Note that the contents of the detection area setting performed by the detection area setting means correspond to the contents that define the range of the size of k and l in the m-th layer in the contents described in the first and second embodiments.

The motion vector information calculation unit 42 is a unit that calculates and calculates motion vector information of a moving image between the previous and next frames for each detection region set by the detection region setting unit. The calculation of equations (13) to (17) in the first embodiment is performed to calculate motion vector information φ _mn (k, l) between the _previous and next frames for each of a plurality of layers.

The motion vector determination unit 43 is a unit for determining and detecting a final motion vector from the motion vector information in a plurality of layers calculated by the motion vector information calculation unit 42. Specifically, an average value of motion vector information φ _mn (k, l) of a plurality of layers is calculated using the equation (18) described in the first embodiment, and this is used as a final motion in the lowest layer. The vector (ξ, ψ) is determined as _1n . The detected motion vector (ξ, ψ) _1n is output from the motion vector detection device 40 to the subframe control means 30, and the motion detected by the subframe control means 30 in generating the subframe signal as described above. A vector is used, and a smooth moving image with less blur can be displayed on the screen 10 of the plasma display panel 15.

Note that the motion vector information calculation means 42 and the motion vector determination means 43 execute such arithmetic processing, and may be realized by arithmetic processing means such as an electronic circuit, MPU, or ASIC.

As described above, by applying the motion vector detection device according to the present embodiment to the plasma display device, the motion vector of the moving image displayed on the screen 10 of the plasma display panel 15 is appropriately detected, and the motion vector is used. The plasma display panel 15 can be driven by the method described above, and a plasma display device that can display a smooth moving image with less blur can be obtained.

Next, the processing flow of the motion vector detection method and the plasma display panel 15 driving method executed by the motion vector detection device and the plasma display device according to the third embodiment will be described with reference to FIG. FIG. 7 is an operation flowchart of the plasma display apparatus according to the third embodiment.

In step 100, it is determined whether or not a motion vector detection region is set by the detection region setting means 41. If detection areas of a plurality of hierarchies are set in advance on the screen 10, the process automatically proceeds to step 110, but if detection area setting change or setting control is performed, has the detection area setting been completed? It is determined whether or not. If the setting is not completed, step 100 is repeated until the setting is completed.

In step 110, the motion vector information calculation means 42 calculates the Fourier transform in the detection region between the frame of interest and the next frame, that is, the preceding and following frames. Specifically, the arithmetic processing of the equations (13) to (15) described in the first embodiment is executed, and Fourier transforms F _mn (u, v) and F ′ _mn (u, v) are obtained.

In step 120, the motion vector information calculation means 42 calculates motion vector information between the previous and subsequent frames in each detection region of the plurality of layers. Specifically, the calculations of equations (16) and (17) described in the first embodiment are performed, and each motion vector information φ _mn (k, l) of the detection region Ω _mn is calculated by inverse Fourier transform.

In step 130, the motion vector is determined by the motion vector determination means 43. Specifically, the calculation process of the equation (18) described in the first embodiment is executed, and all the motion vector information φ _mn (k, l) calculated by the motion vector information calculation unit 42 is summed, and the lowest The next average value is calculated and determined as the motion vector (ξ, ψ) _1n .

Steps 100 to 130 are a motion vector detection method executed by the motion vector detection device 40. The contents so far can be applied not only to a display device using the plasma display panel 15 but also to display devices having various screens 10. The motion vector detected by the motion vector detection device 40 is output to the subframe control means 30.

In step 140, the subframe control means 30 performs lighting control of the subframe using the motion vector. Specifically, the movement of the line of sight is predicted from the motion of the subject using the motion vector, and the subframe signal is generated with the lighting pattern of the subframe reflecting this. The generated subframe signal (control signal) is output to the plasma display panel drive circuit 20, thereby controlling the drive of the plasma display panel 15.

In step 150, the plasma display panel drive circuit 20 drives the plasma display panel 15 in accordance with the subframe signal (control signal) sent from the subframe control means 30, and ends the processing flow.

According to such a processing flow, the driving method of the plasma display panel 15 according to the present embodiment is executed, whereby a smooth moving image can be displayed with less blur.

According to the motion vector detection method and apparatus and the plasma display panel 15 driving method and plasma display apparatus according to the present embodiment, precise motion vector detection for each pixel is performed as in the motion vector detection method by pattern matching. Since this is not performed, the circuit scale for calculating the motion vector can be greatly reduced.

Also, with such a precise motion vector detection method by pattern matching, there is a risk of false detection when a matching pattern cannot be found. In particular, in an image including a repeated pattern, the probability is high. On the other hand, according to the motion vector detection method according to the present embodiment, accurate detection of the motion vector for each pixel is not necessarily performed. However, since the motion vector is detected by a large detection area, the motion vector of the repetitive pattern D is also erroneous. It can be detected without detection.

In the case of executing the driving method of the plasma display panel 15 that performs the lighting control of the subframe SF in accordance with the line of sight of the subject described in the present embodiment, rather than detecting a precise motion vector for each pixel, It is much more important that there is no major failure due to false detection. For such applications, the motion vector detection method and apparatus, and the plasma display panel driving method and plasma display apparatus according to the present embodiment can be suitably applied.

The present invention is applicable to all display devices that display a moving image on a screen using a motion vector. In particular, it can be suitably applied to a plasma display device using a plasma display panel as a screen.

Claims

A method for detecting a motion vector between frames before and after a moving image to be displayed on a screen having pixels arranged in a matrix,
A plurality of detection areas for detecting motion vectors are set on the screen such that a low-order detection area is included in a high-order detection area.
For each of the detection areas of the plurality of layers, obtain the Fourier transform of each of the preceding and following frames, calculate the motion vector information,
The motion in the lowest order detection area is calculated from the average of the motion vector information detected in the lowest order detection area and the plurality of higher order detection areas including the lowest order detection area among the detection areas of the plurality of hierarchies. A motion vector detection method characterized by determining a vector.
The motion vector detection method according to claim 1, wherein the detection area is set such that a boundary of the higher-order detection area matches a boundary of the lower-order detection area.
The m-th detection area is set as an area of 2 m × 2 m pixels,
The motion vector detection method according to claim 2, wherein the lowest detection area is set as a 2 × 2 pixel area.
A motion vector is detected by the motion vector detection method according to any one of claims 1 to 3,
A driving method of a plasma display panel, wherein a lighting pattern of a subframe is controlled in accordance with movement of an image using the motion vector.
A motion vector detection device for detecting a motion vector between frames before and after a moving image displayed on a screen in which pixels are arranged in a matrix,
A detection area setting means for setting a plurality of hierarchies on the screen such that a detection area for detecting the motion vector is included in a high-order detection area;
For each of the motion vector detection regions of the plurality of layers, a motion vector information calculating unit that performs Fourier transform on each of the preceding and following frames and calculates motion vector information between the preceding and following frames based on the Fourier transform.
The motion in the lowest order detection area is calculated from the average of the motion vector information detected in the lowest order detection area and the plurality of higher order detection areas including the lowest order detection area among the detection areas of the plurality of hierarchies. And a motion vector determination means for determining a vector.
6. The motion vector according to claim 5, wherein the detection area setting means sets the detection area such that a boundary of the higher-order detection area matches a boundary of the lower-order detection area. Detection device.
The detection area setting means sets an m-th order detection area to an area of 2 m × 2 m pixels, and sets the lowest order detection area to an area of 2 × 2 pixels. The motion vector detection device described.
A plasma display device having a plasma display panel driven by a subframe driving method,
The motion vector detection device according to any one of claims 5 to 7,
Subframe control means for controlling the lighting pattern of the subframe based on the motion vector detected by the motion vector detection device;
And a plasma display panel driving circuit for driving the plasma display panel based on the lighting pattern.