KR20050052194A - Image processing apparatus for display panel - Google Patents

Abstract

An image processing apparatus according to the present invention includes a first motion detection unit for detecting a motion region by inter-pixel comparison of an image of a current frame and an image of a previous frame, and outputting a detection result as first data; A second motion detector for detecting an edge of an image of a current frame and an edge of an image of a previous frame, detecting a movement of the edge, and outputting a detection result as second data; And a logical multiplication unit configured to logically multiply the first data and the second data and output the logical multiplication unit.

According to the image processing apparatus of the present invention, in determining a moving picture, inter frame motion detection and inter frame edge motion detection are simultaneously performed. Therefore, in the still image, it is determined that an area without actual movement, such as a local noise image change or a change in contrast only, is not a video. Therefore, the video can be discriminated more accurately. According to the present invention, it is possible to reduce distortion of an image generated in an image processing process performed based on a moving image area by not detecting a change in pixel data due to noise or a change in contrast only in a still image as a moving image. Can be.

Description

Image processing apparatus for display panel

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to image processing of a display panel (PDP), and more particularly to an image processing apparatus for reducing video pseudo contours.

1 is a view showing the structure of a conventional three-electrode surface discharge plasma display panel.

Referring to FIG. 1, between the front and rear glass substrates 100 and 106 of a conventional surface discharge plasma display panel 1, address electrode lines A ₁ , A ₂ ,..., A _m , Dielectric layers 102 and 110, Y electrode lines Y ₁ , ..., Y _n , X electrode lines X ₁ , ..., X _n , fluorescent layer 112, barrier rib 114, and As a protective layer, the magnesium monoxide (MgO) layer 104 is provided, for example.

The address electrode lines A ₁ , A ₂ ,..., A _m are formed in a predetermined pattern on the front side of the rear glass substrate 106. The lower dielectric layer 110 is applied in front of the address electrode lines A ₁ , A ₂ ,..., A _m . In front of the lower dielectric layer 110, barrier ribs 114 are formed in a direction parallel to the address electrode lines A ₁ , A ₂ ,..., A _m . The partition walls 114 function to partition the discharge area of each display cell and to prevent optical interference between the display cells. The fluorescent layer 112 is formed between the partition walls 114.

The X electrode lines X ₁ , ..., X _n and the Y electrode lines Y ₁ , ..., Y _n are address electrode lines A ₁ , A ₂ , ..., A _m . It is formed in a predetermined pattern on the back of the front glass substrate 100 to be orthogonal to the. Each intersection sets a corresponding display cell. Each X electrode line (X ₁ , ..., X _n ) and each Y electrode line (Y ₁ , ..., Y _n ) are transparent electrode lines (X _na ) made of a transparent conductive material such as indium tin oxide (ITO). , Y _na ) and metal electrode lines X _nb and Y _nb for increasing conductivity may be formed. The front dielectric layer 102 is formed by applying the entire surface to the rear of the X electrode lines (X ₁ ,..., X _n ) and the Y electrode lines (Y ₁ ,..., Y _n ). A protective layer 104 for protecting the panel 1 from a strong electric field, for example, a magnesium monoxide (MgO) layer, is formed by applying a front surface to the back of the front dielectric layer 102. The plasma forming gas is sealed in the discharge space 108.

A driving scheme generally applied to such a plasma display panel is a method in which initialization, address, and display holding steps are sequentially performed in a unit sub-field. In the initialization step, the charge states of the display cells to be driven are made uniform. In the address step, the charge state of display cells to be selected and the charge state of display cells not to be selected are set. In the display holding step, display discharge is performed in the display cells to be selected. At this time, a plasma is formed from the plasma forming gas of the display cells performing display discharge, and the fluorescent layer 112 of the display cells is excited by ultraviolet radiation from the plasma to generate light.

2 illustrates a general driving device of the plasma display panel of FIG. 1.

Referring to the drawings, a typical driving device of the plasma display panel 1 includes an image processor 200, a controller 202, an address driver 206, an X driver 208, and a Y driver 204. The image processing unit 200 converts an external analog image signal into a digital signal, and internal image signals, for example, 8-bit red (R), green (G) and blue (B) image data, clock signals, vertical and horizontal, respectively. Generate synchronization signals. The controller 202 generates the driving control signals SA, SY, and SX according to the internal image signal from the image processor 200. The address driver 206 processes the address signal SA among the drive control signals SA, SY, and SX from the controller 202 to generate a display data signal, and generates the display data signal through the address electrode lines. To apply. The X driver 208 processes the X driving control signal SX among the driving control signals SA, SY, and SX from the controller 202 and applies the X driving control signal SX to the X electrode lines. The Y driver 204 processes the Y driving control signal SY among the driving control signals SA, SY, and SX from the controller 202 and applies the Y driving control signal SY to the Y electrode lines.

As a driving method of the plasma display panel 1 having the structure described above, an address-display separation driving method which is mainly used is disclosed in US Pat.

FIG. 3 illustrates a conventional address-display separation driving method for Y electrode lines of the plasma display panel of FIG. 1.

Referring to the drawings, a unit frame may be divided into a predetermined number, for example, eight subfields SF1, ..., SF8 to realize time division gray scale display. Each subfield SF1, ..., SF8 is divided into a reset section (not shown), an address section A1, ..., A8, and a sustain discharge section S1, ..., S8. do.

In each address section A1, ..., A8, a display data signal is applied to the address electrode lines AR1, AG1, ..., AGm, ABm in FIG. Scan pulses corresponding to..., Yn) are sequentially applied.

In each sustain discharge section S1, ..., S8, pulses for display discharge alternately in the Y electrode lines Y1, ..., Yn and the X electrode lines X1, ..., Xn. Is applied to cause display discharge in discharge cells in which wall charges are formed in the address periods A1, ..., A8.

The luminance of the plasma display panel is proportional to the number of sustain discharge pulses in the sustain discharge sections S1, ..., S8 occupied in the unit frame. When one frame forming one image is represented by eight subfields and 256 gray levels, each subfield is sequentially held at a ratio of 1, 2, 4, 8, 16, 32, 64, and 128 in order. The number of pulses can be assigned. In order to obtain luminance of 133 gray levels, cells may be addressed and sustained and discharged during the subfield 1 period, the subfield 3 period, and the subfield 8 period.

The number of sustain discharges allocated to each subfield may be variably determined according to the weights of the subfields according to the APC (Automatic Power Control) step. In addition, the number of sustain discharges allocated to each subfield is. Various modifications are possible in consideration of gamma characteristics or panel characteristics. For example, the gradation level assigned to subfield 4 may be lowered from 8 to 6, and the gradation level assigned to subfield 6 may be increased from 32 to 34. In addition, the number of subfields forming one frame can be variously modified according to design specifications.

Unlike the CRT (Cathode Ray Tube) which adjusts the brightness by adjusting the intensity of the electron beam, the PDP expresses the brightness through the pulse number control method in the sustain discharge section as described with reference to FIG. 3.

4 illustrates an example of generating a pseudo pseudo contour.

Pseudo contouring is caused by human visual characteristics when displaying an image by a combination of subfields as shown in FIG. 3. Referring to FIG. 4, when the image having the gradations 127 and 128 side by side moves at a speed of 1 to the right, the image is displayed as shown in FIG. 4 by the subfield arrangement of FIG. Gradation is recognized by. Therefore, a pseudo contour such as 255 occurs between the grayscales 127 and 128.

5 is a block diagram of a conventional video detection unit. The memory control unit 500 writes and reads the input image IN to the N-1 frame memory 502A and the N frame memory 502B in the frame memory 502, so that the N-1 frame image 504 and the N frame are read. Image 506 is output.

The interframe pixel comparison unit 508 detects a difference in gray level between pixels at the same position in the N-1 frame image 504 and the N frame image 506 to determine a video.

However, the conventional method of discriminating a video only by pixel comparison between frames is capable of erroneously detecting a change in pixel data due to noise, and erroneously detecting a video even when only contrast is changed in a still image. There is a problem.

An algorithm capable of reducing pseudo contours is applied to the area detected by the moving picture. In addition, an afterimage prevention algorithm is applied to an area other than the area detected by the moving picture. Therefore, if the pseudo contour reduction algorithm or the afterimage prevention algorithm is applied based on the erroneously detected video region, the image may be severely distorted.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide an image processing apparatus for detecting only a region having substantial motion as a moving image region.

According to an aspect of the present invention, there is provided a video processing apparatus including: a first motion detector configured to detect a motion region by inter-pixel comparison of an image of a current frame and an image of a previous frame, and output a detection result as first data; ; A second motion detector for detecting an edge of an image of a current frame and an edge of an image of a previous frame, detecting a movement of the edge, and outputting a detection result as second data; And a logical multiplication unit configured to logically multiply the first data and the second data and output the logical multiplication unit.

The second motion detector may include: a first edge detector configured to detect a first edge from a previous frame image; A second edge detector detecting a second edge in the current frame image; And an edge comparison unit configured to compare the first edge and the second edge to detect an edge movement and output the detection result as second data.

The edge comparator may detect the movement of the edge by detecting the variation of the first edge and the second edge for each line, and output the second data as a line flag when the movement is detected.

The first edge detector and the second edge detector, respectively, an edge filter for detecting the edge in the image; And a quantization unit configured to quantize the detected edge based on a threshold value.

Hereinafter, the configuration and operation of an image processing apparatus according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The basic concept of the present invention is to determine an area in which a motion is detected by the system of pixels between frames, and an area in which motion of an edge is detected as a moving picture area.

FIG. 6 is a block diagram illustrating an image processing apparatus according to an exemplary embodiment of the present invention, and includes a first motion detector 608, a second motion detector 610, and an AND logic unit 616.

The memory controller 600 shown in FIG. 6 writes and reads the input image IN into the N-1 frame memory 602A and the N frame memory 602B in the frame memory 602, and thus the current frame image 604. And the previous frame image 606 are output.

The first motion detector 608 detects the motion region by comparing the pixels between frames of the image 604 of the current frame and the image 606 of the previous frame. In other words, the case where even the system of the pixel of the same position is more than predetermined value is detected as a motion pixel. The detection result is output as the first data 612.

The second motion detector 610 detects the edge of the image 604 of the current frame and the edge of the image 606 of the previous frame, and detects the movement of the edge. The detection result is output as the second data 614. The edge corresponds to the contour of the object in the image and is a boundary where the gray level changes abruptly. Thus, moving an edge means that the object that outlines that edge moves.

The AND product 616 logically outputs the first data 612 and the second data 614. The output result of the logical product 616 becomes a moving picture detection area by the image processing apparatus of the present invention. The output of the logical product 616 is the result of excluding the region where the edge movement does not exist in the change region even in the system of co-located pixels between frames. Therefore, if only contrast is changed between the current frame and the previous frame in the still image, the movement of the edge is not detected, so this case is excluded from the moving picture area.

The conventional method of discriminating a moving picture has a problem that a change in pixel data due to noise can be detected incorrectly as a moving picture, and even when only the contrast is changed in a still picture, it can be detected as a moving picture. An algorithm capable of reducing pseudo contours is applied to the area detected by the moving picture. In addition, an afterimage prevention algorithm is applied to an area other than the area detected by the moving picture. Therefore, if the pseudo contour reduction algorithm or the afterimage prevention algorithm is applied based on the erroneously detected video region, the image may be severely distorted.

According to the present invention, the problem of the conventional video detection method described above is solved by not detecting the change of the pixel data due to noise or the case where only the contrast is changed in the still picture as a moving picture.

FIG. 7 is a block diagram illustrating an exemplary embodiment of the second motion detector 610 illustrated in FIG. 6, and includes a first edge detector 700, a second edge detector 702, and an edge comparator 708. It is provided.

The first edge detector 700 detects the first edge 704 from the previous frame image IN1. The second edge detector 702 detects the second edge 706 from the current frame image IN2.

The edge comparator 708 compares the first edge 704 and the second edge 706 to detect the movement of the edge. Here, the edge comparison unit 708 may detect the movement of the edge by comparing the positions of the first edge 704 and the second edge 706. The edge comparator 708 may determine that there is an edge movement when a variation of the edge is detected by a predetermined number or more.

In addition, the edge comparator 708 may detect the movement of the edge for each line, and may output the line flag OUT when the movement is detected. In this case, the line flag OUT output of FIG. 7 becomes second data 614 of FIG. 6.

At this time, the output of the logical product 616 determines only the pixels in which the interframe frame has exceeded a predetermined value in the line where the edge movement is detected as the moving picture area.

FIG. 8 is a block diagram illustrating an embodiment of the first edge detector 700 and the second edge detector 702 of FIG. 7, and includes an edge filter 800 and a quantizer 802.

The edge filter 800 detects edges in the image. The edge corresponds to the contour of the object in the image and is a boundary where the gray level changes abruptly.

The edge filter 800 may be most simply implemented by a subtraction operation. There are horizontal edges and vertical edges at the edges of the differential operation. The vertical edge can be detected, for example, by subtracting the original image from the image in which the image is moved a predetermined pixel to the left. The horizontal edge can be detected by moving the image up a predetermined pixel and subtracting from the initial image. The result of such a subtraction operation is then output. Although not shown in the drawing, the edge filter 800 may include an appropriate number of line memories according to the specification of the horizontal edge to be detected.

In addition to the above-described subtraction operation, the edge filter 800 may be a sobel filter, a predetermined filter, a Roberts filter, or the like using a well-known edge filter gradient operator.

The quantization unit 802 quantizes the edge detected by the edge filter 800 based on the threshold value. That is, the quantization unit 802 quantizes the system by giving a threshold to the output edge. The threshold may be an average signal level of the frame image.

The image processing apparatus according to the present invention is prepared by a schematic or ultra high-speed integrated circuit hardware description language (VHDL) or the like on a computer, and is connected to a computer and programmed by an integrated circuit, for example, a field programmable gate array (FPGA). It can be implemented as a circuit.

In addition, the image processing apparatus according to the present invention may be implemented by being included in, for example, the image processing unit 200 illustrated in FIG. 2 when applied to a plasma display panel.

The best embodiments have been disclosed in the drawings and specification above. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, according to the image processing apparatus of the present invention, interframe motion detection and interframe edge motion detection are simultaneously performed in determining a video. Therefore, in the still image, it is determined that an area without actual movement, such as a local noise image change or a change in contrast only, is not a video. Therefore, the video can be discriminated more accurately.

The conventional method of discriminating a moving picture has a problem that a change in pixel data due to noise can be detected incorrectly as a moving picture, and even when only the contrast is changed in a still picture, it can be detected as a moving picture. An algorithm capable of reducing pseudo contours is applied to the area detected by the moving picture. In addition, an afterimage prevention algorithm is applied to an area other than the area detected by the moving picture. Therefore, if the pseudo contour reduction algorithm or the afterimage prevention algorithm is applied based on the erroneously detected video region, the image may be severely distorted.

According to the present invention, it is possible to reduce distortion of an image generated in an image processing process performed based on a moving image area by not detecting a change in pixel data due to noise or a change in contrast only in a still image as a moving image. Can be.

The invention is not limited to the examples described above and represented in the drawings. Those skilled in the art taught by the above-described embodiments, many modifications to the above-described embodiments are possible by substitution, erasure, merging, etc. within the scope and object of the present invention described in the following claims.

1 is a view showing the structure of a conventional three-electrode surface discharge plasma display panel.

FIG. 2 shows a typical driving apparatus of the plasma display panel shown in FIG. 1.

FIG. 3 shows a conventional address-display separation driving method for Y electrode lines of the plasma display panel of FIG. 1.

4 illustrates an example of generating a pseudo pseudo contour.

5 is a block diagram of a conventional video detection unit.

6 is a block diagram illustrating an image processing apparatus according to an exemplary embodiment of the present invention.

FIG. 7 is a block diagram illustrating an exemplary embodiment of the second motion detector 610 illustrated in FIG. 6.

FIG. 8 is a block diagram illustrating an exemplary embodiment of the first edge detector 700 and the second edge detector 702 of FIG. 7.

Claims (4)

A first motion detector which detects a motion region by inter-pixel comparison of an image of a current frame and an image of a previous frame and outputs a detection result as first data; A second motion detector for detecting an edge of an image of a current frame and an edge of an image of a previous frame, detecting a movement of the edge, and outputting a detection result as second data; And And a logical product for performing an AND operation on the first data and the second data. The method of claim 1, wherein the second movement detection unit, A first edge detector detecting a first edge in a previous frame image; A second edge detector detecting a second edge in the current frame image; And And an edge comparator which detects movement of an edge by comparing the first edge and the second edge, and outputs a detection result as second data. The method of claim 2, wherein the edge comparison unit And detecting the movement of the edge by detecting the variation of the first and second edges for each line, and outputting the second data as a line flag when the movement is detected. The method of claim 2, wherein the first edge detector and the second edge detector, An edge filter detecting edges in the image; And And a quantization unit configured to quantize the detected edges based on a threshold value.