KR20160054713A - Crosstalk reduction method and device, and multi-view autostereoscopic image display using the same - Google Patents

Abstract

The present invention relates to a crosstalk reduction method of a multi-view image, an apparatus thereof, and a multi-view autostereoscopic three-dimensional image display apparatus using the same. The crosstalk reduction method of the present invention comprises a step of determining a crosstalk region by analyzing original multi-view image data based on at least one among a depth distribution property, a brightness distribution property, and image complexity. Additionally, the crosstalk reduction method of the present invention modulates the original multi-view image data to be written in pixels of the crosstalk region. The crosstalk reduction method of the present invention can prevent reduction in motion parallax and reduce afterimages appeared in the boundaries of an object.

Description

Technical Field [0001] The present invention relates to a method and apparatus for reducing a crosstalk of a multi-view image, and a multi-view spectacle display method and apparatus using the same,

The present invention relates to a method and apparatus for reducing crosstalk of a multi-view image, and a multi-view spectacles stereoscopic image display apparatus using the same.

A stereoscopic image reproducing technique is applied to a display device such as a television or a monitor. The stereoscopic image display device can be divided into a spectacle method and a non-spectacle method. The spectacle method realizes a stereoscopic image by using polarizing glasses or liquid crystal shutter glasses to display the right and left parallax images in a direct view type display device or a projector by changing the polarization directions of the parallax images in a time division manner. In the non-eyeglass system, an optical component such as a parallax barrier (hereinafter referred to as a "barrier") or a lenticular lens (hereinafter referred to as a "lens") for separating the optical axis of left and right parallax images, The stereoscopic image is implemented by installing it in the front or rear.

The non-eyeglass stereoscopic image display device displays a multi-view image so that the stereoscopic image can be viewed when the viewer moves left and right in an optimal viewing distance (OVD) at which the stereoscopic image can be viewed normally. The multi-view spectacles stereoscopic image display apparatus disperses the paths of light output by pixels through a barrier or a lens, thereby displaying different views to viewers depending on the positions of viewers, thereby allowing viewers to feel a stereoscopic effect due to binocular disparity.

The multi-view spectacles stereoscopic image display device has a large crosstalk when the viewer moves as compared with the spectacles. The viewer can see a stereoscopic image without crosstalk when viewing only the left eye image with the left eye and only the right eye image with the right eye. However, when two paths are displayed in a monocular (left or right eye) view according to a viewer's position when a light path is separated by a barrier or a lens, crosstalk appears as a superimposed image of different view images or an image quality deteriorates artifacts.

As a method for reducing the crosstalk of a multi-view image, a method of adjusting the sharpness between views can be used. For example, Xiaofang Li, Qionghua Wang, Yuhong Tao, Dai Li, and Aihong Wang, "Crosstalk reduction in multi-view autostereoscopic three-dimensional display based on lenticular sheet, February 10, 2011 / Quot; CHINESE OPTICS LETTERS "discloses a crosstalk reduction method of a multi-view image. A crosstalk reduction method of a multi-view image is a method of subtracting pixel values of neighboring views from pixel values of n (n is a positive integer) view as shown in Equation 1 below, The pixel value of the pixel is increased.

Here, Vn is pixel data of the n-th view image. K, a is an arbitrary constant value.

However, the crosstalk reduction method of the multi-view image causes the following problems.

First, the motion parallax is reduced, and the image becomes discontinuous when the viewer moves. Applying the sharpness improvement method between neighboring view images reduces crosstalk because it reduces the influence of the neighboring view and increases the influence of the current view at the position where the current view image is to be displayed. However, when the influence on the current view increases The motion parallax that a viewer feels when moving their head or moving their position decreases. Motion parallax is one of the indicators of stereoscopic effect, and it shows the phenomenon that when the viewer watches the stereoscopic image as moving, various sections of the object are smoothly connected to each other.

Second, if crosstalk is improved by adding and subtracting pixel data between neighboring views, an afterimage phenomenon occurs at the edge of the object in the view image.

The present invention relates to a method and apparatus for reducing crosstalk of a multi-view image capable of improving motion parallax reduction caused by application of a crosstalk reduction method and improving a residual image displayed at a boundary of an object, and a multi- Device.

The crosstalk reduction method of the present invention includes a step of determining a crosstalk region by analyzing original multi view image data based on at least one of a depth distribution characteristic, a brightness distribution characteristic, and an image complexity. The method of claim 1, further comprising: modulating data of the original multi-view image to be written into pixels of the crosstalk region; writing multi-view image data modulated only in pixels in the crosstalk region; And writing the original multi-view image data to pixels other than the torque area.

A crosstalk canceling apparatus of the present invention is a crosstalk canceling apparatus comprising a judging unit for analyzing original multi view image data based on at least one of a depth distribution characteristic, a brightness distribution characteristic and an image complexity to judge a crosstalk region, A modulator for modulating data of the original multi-view image to be written, and a multi-view image data modulated only by pixels in the crosstalk area, and writing the multi-view image data to pixels other than the crosstalk area And a display panel driver for writing data.

A multi-view non-eyeglass stereoscopic image display apparatus of the present invention includes a display panel for displaying multi-view image data, a display panel driver for writing the multi-view image data, a 3D optical element for separating the optical axis of the multi- A determination unit configured to determine a crosstalk region by analyzing the multi-view image data based on at least one of distribution characteristics, brightness distribution characteristics, and image complexity of the multi-view image data, And a modulator for modulating the modulated signal.

The present invention improves the reduction of the motion parallax caused when the crosstalk reduction method is applied by predicting a crosstalk region having a high probability of occurrence of crosstalk in a multi-view image and modulating the data with a crosstalk reduction algorithm only in the crosstalk region It is possible to improve the afterimage displayed at the boundary of the object.

1 is a block diagram illustrating a multi-view spectacles stereoscopic image display apparatus according to an exemplary embodiment of the present invention.
2 is a sectional view showing a lens of a multi-view spectacles stereoscopic image display device.
3 is a cross-sectional view showing a barrier of the multi-view spectacles stereoscopic image display apparatus.
4 is a diagram showing an example of multi-view image data written in the pixel array.
5 is a view showing viewing zones in which a viewing area of a multi-view image is divided in a multi-view spectacles stereoscopic image display apparatus.
6 is an image showing an example of an image having a large depth difference between the background and the object.
7 is a diagram showing an example of a depth histogram in a window region.
8 is an image showing an example in which the crosstalk reduction technique is selectively applied based on the average brightness (APL) and the average depth value in the window region.
9 is an image showing an input / output image of the Sobel filter.
10 is a flowchart illustrating a crosstalk reduction method of a multi-view image according to an embodiment of the present invention.
11 is a detailed view of the crosstalk canceling module.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Like reference numerals throughout the specification denote substantially identical components. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

The inventors of the present invention analyzed the portion where crosstalk is seen when displaying a multi-view image through an image quality evaluation experiment of a 3D image. As a result, the crosstalk can be seen well in the portion where the depth difference is large in the multi-view image, the crosstalk is better in the peripheral views affecting the current view, and the portion where the complexity of the image is high, I confirmed that it is well visible. The present invention predicts a portion where crosstalk can be seen based on the crosstalk evaluation result and applies the crosstalk reduction method only to that portion to modulate the pixel data of the multi view image only in that portion. On the other hand, the present invention can improve the motion parallax and the afterimage problem due to the application of the crosstalk reduction technique because the crosstalk reduction method is not applied to an image portion where crosstalk is not recognized.

Before describing the embodiments, some terms used in the embodiments will be defined as follows.

The multi-view spectacles stereoscopic image display apparatus of the present invention can be applied to a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), an organic light emitting diode display An organic light emitting display (OLED), and an electrophoresis (EPD) display device. The stereoscopic image display device displays 2D image data in 2D mode and 3D image data in 3D mode. A 3D optical element may be disposed in front of or behind the display panel of the stereoscopic image display apparatus.

The 3D optical element is an optical component that separates subpixels viewed through the viewer's left eye and subpixels viewed through the right eye. The 3D optical element may be an optical component such as a barrier or a lens. The barrier and the lens may be implemented as switchable barriers or switchable lenses that are electrically controlled using a liquid crystal panel. The applicant of the present application has proposed a switchable barrier and a switchable lens through US Application No. 13/077565, US Application No. 13/325272, Application No. 10-2010-0030531, and Application No. 10-2010-0130547, etc.

1 to 3, the multi-view spectacles stereoscopic image display apparatus of the present invention includes a display panel 100, a display panel driving unit, a 3D optical element 200, a 3D optical element driving unit 210, a crosstalk reduction module A display unit 120, a 3D formatter 130, a timing controller 101, and the like.

The display panel 100 includes a pixel array in which a 3D image of a 2D image or a multi-view format is displayed. In the pixel array, the data lines 105 and the gate lines (or scan lines) 106 are crossed. In the pixel array, the pixels PIX are arranged in a matrix form.

The display panel driving unit includes a data driving circuit 102 for supplying a data voltage of a 2D / 3D image to the data lines 105 of the display panel 100, And a gate drive circuit 103 for sequentially supplying gate pulses (or scan pulses) synchronized with the voltage. The display panel driving units 102 and 103 disperse data of the multi-view image in the 3D mode into predetermined pixels PIX and write them.

The data driving circuit 102 converts the digital video data input from the timing controller 101 into an analog gamma voltage to generate a data voltage and supplies the data voltage to the data lines 105 of the display panel 100. The gate drive circuit 103 supplies a gate pulse synchronized with the data voltage supplied to the data lines 105 to the gate lines 106 under the control of the timing controller 101 and sequentially shifts the gate pulse .

The 3D optical element 200 may be realized by a lens (LENS) or a barrier (BAR) as shown in FIGS. The 3D optical element 200 is joined to the front or back of the display panel 100 or embedded in the display panel 100 to separate the left eye image data of the 3D image data and the optical axis of the right eye image data. The switchable barrier (BAR) or the switchable lens (LENS) includes a birefringent medium such as liquid crystal, an electrode, and the like, and is electrically driven by the 3D optical element driving unit 210 to separate the optical axis of light of the left eye image and the right eye image .

The 3D optical element driving unit 210 drives the switchable barrier (BAR) or the switchable lens (LENTI) in synchronization with the pixel data written in the pixel array of the display panel 100 in the 3D mode under the control of the timing controller 101 do. When the 3D optical element 200 is implemented as an optical element that is not electrically controlled, the 3D optical element driving part 210 is not required.

The crosstalk abatement module 120 estimates the crosstalk that can be perceived by the viewer when the multi view image is reproduced and applies the crosstalk reduction method only in a crosstalk region where crosstalk can occur, And modulates the pixel data. The operation of the crosstalk abatement module 120 can be expressed by Equation (2).

Here, V (x, y) is data of the n-th view image to be written to the pixel at (x, y) position. V _{n _ new} is the n-th view image data modulated only in the crosstalk region.

The crosstalk canceling module 120 modulates only the pixel data of the multi view image to be written in the pixels in the crosstalk region by the crosstalk reducing method and writes the pixel data in pixels other than the crosstalk region It does not modulate the pixel data to be processed.

The 3D formatter 130 receives the multi-view image data (V1 to V9) from the crosstalk reduction module 120 and generates multi-view image data (V1 to V9) as shown in FIG. 4 based on the multi- Rearranged in accordance with the pixel arrangement of the display panel 100, and transmitted to the timing controller 101.

The timing controller 101 transmits the digital video data RGB of the 2D / 3D input image input from the host system 110 to the data driving circuit 102. The timing controller 101 receives timing signals such as a vertical synchronization signal, a horizontal synchronization signal, a data enable signal, and a main clock synchronized with the digital video data RGB of the 2D / 3D input image. The timing controller 101 generates timing control signals for controlling the operation timings of the display panel driving units 102 and 103 and the 3D optical element driving unit 210 based on the received timing signals. The timing control signals include a source timing control signal DDC for controlling the operation timing of the data driving circuit 102, a gate timing control signal GDC for controlling the operation timing of the gate driving circuit 103, An element control signal 3DC, and the like.

The timing controller 101 increases the frame rate to the frequency of the frame rate × N (N is a positive integer of 2 or more) Hz of the input image and sets the operating frequency of the display panel driving units 102 and 103 and the 3D optical element driving unit 210 to It is possible to control the frame rate to be multiplied by N times. The frame rate of the input image is 60 Hz in the National Television Standards Committee (NTSC) method and 50 Hz in the PAL (Phase-Alternating Line) method.

The host system 110 may be implemented as any one of a TV system, a set top box, a navigation system, a DVD player, a Blu-ray player, a personal computer (PC), a home theater system, and a phone system. The host system 110 converts the digital video data of the 2D / 3D input image into a format suitable for the resolution of the display panel (PNL) 100 using a scaler, and transmits a timing signal to the timing controller 101 together with the data. Lt; / RTI >

The host system 110 supplies the 2D image to the timing controller 101 in the 2D mode while supplying the multi-view 3D image to the crosstalk abatement module 120 in the 3D mode.

FIG. 5 shows an example of viewing zones at an optimum viewing distance where a viewer can normally view stereoscopic images when multi-view image data is displayed on a pixel array. In FIG. 5, the rhombic area means a viewing zone. The example of FIG. 5 exemplifies a multi-view image system displaying 4-view image data, but is not limited thereto. For example, the multi-view spectacles stereoscopic image display apparatus of the present invention can display N (N is a positive integer equal to or larger than 3) view image data.

The crosstalk estimation method applied in the crosstalk abatement module 120 predicts a portion where crosstalk occurs in a multi view image based on at least one of a depth distribution characteristic, a brightness distribution characteristic, and an image complexity.

Hereinafter, each of the crosstalk prediction methods will be described in detail.

(1) A method of predicting crosstalk based on depth distribution characteristics

Crosstalk is better seen on images with large depth differences. In other words, crosstalk is more clearly seen in images where the disparity difference between the view images is large due to the difference in depth between the view images viewed by the viewer and the images without depth difference. For example. As in the red box of FIG. 6, when there is a small depth difference between the views in the background and there is an object with a large depth value in front of the background, crosstalk is good.

In the method of measuring the depth distribution in an image, a depth map is first generated using a known depth map generating method. A depth map is image data in which three-dimensional spatial information of an object or an object is expressed in gradation according to the distance from the screen. The depth value defines the degree of shift of the pixel data, that is, the disparity. In the depth map, an object protruding forward from the screen is represented by data of high gradation (or white gradation), and an object moving away from the screen is represented by low gradation (or black gradation).

In the method of measuring the depth distribution in an image, a depth histogram is calculated in a window region of a predetermined size, depth values having a large cumulative number of pixels are extracted from the depth histogram, and a difference between the depth values is calculated . The size of the window region may be set to a size of 60x60 pixels, but is not limited thereto.

The crosstalk abatement module 120 compares the deepest values with the largest cumulative number of pixels in the window area and determines the window area having a difference larger than a predetermined threshold value as the crosstalk area. On the other hand, it is possible to compare two depth values having the largest cumulative number of pixels in the window area, but in order to more accurately predict the depth difference between the background and the object, the present invention compares the three depth values having the largest accumulated pixel number in the window area . 7 is a diagram illustrating an example of a depth histogram of a window area.

7, the x-axis is the depth value of the depth map, and the y-axis is the number of pixels. D1 is the Depth value with the largest number of accumulated pixels. D2 is the depth value of the second largest cumulative number of pixels. D3 is the depth value of the third largest cumulative number of pixels.

The crosstalk abatement module 120 sets the larger value of Diff ₁₂ and Diff ₂₃ (max (Diff ₁₂ , Diff ₂₃ )) as Diff ₁₂ = D 1 - D 2 and Diff ₂₃ = D 2 - Diff _final ), and judges the window area in which the _final depth hetthar value (Diff _final ) is larger than a predetermined threshold value as the crosstalk area. The crosstalk abatement module 120 applies the crosstalk reduction technique only in the crosstalk region.

If Diff _final > threshold

Application of crosstalk abatement technology

Else

No crosstalk reduction technology

(2) Method of predicting crosstalk based on brightness distribution characteristics

Crosstalk becomes larger as the surrounding view image, which affects the current view image viewed by the viewer, becomes brighter. Therefore, the crosstalk region can be predicted based on the brightness distribution of the window region, but the crosstalk region can be more accurately predicted by taking the depth size together.

The brightness distribution characteristic of the window region can be known by an average brightness, for example, an average picture level (called "APL "). APL is a value obtained by dividing the sum of the luminance values (Y) of all the pixel data in the window area by the number of pixels (n) in the window area as shown in Equation (3). The depth size in the window area can be calculated by the average depth value in the window area (Equation 4, Depth APL).

Here, Y _n is the luminance value of the n-th pixel data.

Here, D _n is the depth value of the n-th pixel data.

The crosstalk abatement module 120 sets the window area where the APL is larger than the predetermined first threshold value Y_TH and the average depth value APL is larger than the predetermined second threshold value D_TH as the crosstalk area . The crosstalk abatement module 120 applies the crosstalk reduction technique only in the crosstalk region. 8 is an image showing an example in which the crosstalk reduction technique is selectively applied based on the average brightness (APL) and the average depth value in the window region. In Fig. 8, the human foot portion is determined to be the crosstalk region because the average luminance and the average depth value are high.

If (APL > Y_TH) && (Depth APL > D_TH)

Application of crosstalk abatement technology

Else

No crosstalk reduction technology

(3) How to predict crosstalk based on image complexity

The larger the complexity of the image, the higher the probability of crosstalk. This was confirmed through qualitative experiments. The complexity of an image can be measured by extracting an edge on the image and counting the number of edge frequencies in the window area. As the complexity of the image increases, the crosstalk seen as a double image and the crosstalk seen as a blur appear better.

The complexity of the image can be found by a method of calculating the edge frequency in the window region using an edge filter, for example, a sobel filter, which extracts only edge components from the input image. 9 is an image showing an input / output image of the Sobel filter. In Fig. 9, the left image is the original image, and the right image is the image through which the edge component is detected through the Sobel filter.

The crosstalk abatement module 120 determines a window region where the number of edges E is larger than a predetermined threshold E_TH as a crosstalk region as follows. The crosstalk abatement module 120 applies the crosstalk reduction technique only in the crosstalk region.

If E> E_TH

Application of crosstalk abatement technology

Else

No crosstalk reduction technology

10 is a flowchart illustrating a crosstalk reduction method of a multi-view image according to an embodiment of the present invention. This crosstalk reduction method is executed by the crosstalk reduction module 120. [ 11 is a detailed view of the crosstalk canceling module.

10 and 11, the crosstalk canceling module 120 includes a crosstalk determining section 122 for analyzing original multi-view image data (V1 to Vn) to determine a crosstalk region, And a data modulator 124 for modulating multi-view image data with a torque reduction algorithm.

The crosstalk judging unit 122 receives the original multi view image data V1 to Vn and predicts the crosstalk area in the multi view image based on at least one of the depth distribution characteristic, the brightness distribution characteristic, and the image complexity S1 to S3).

The data modulating section 124 receives the multi-view image data (V1 to Vn) and the position information of the crosstalk region from the crosstalk determining section 122. [ The data modulator 124 modulates the data of the multi-view image to be written in the pixels of the crosstalk area with a preset crosstalk reduction algorithm (S4 to S6). The display panel driving units 102 and 103 display multi-view image data (V1 'to Vn') modulated only by pixels in the crosstalk area and display original multi-view image data V1 to Vn).

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

100: display panel 101: timing controller
102: Data driving circuit 103: Gate driving circuit
110: Host system 120: Crosstalk abatement module
122: Crosstalk judging unit 124: Data modulating unit
130: 3D data formatter 200: 3D optical element
210: 3D optical element driving part

Claims (6)

Determining a crosstalk region by analyzing original multi-view image data based on at least one of a depth distribution characteristic, a brightness distribution characteristic, and an image complexity;
Modulating data of the original multi-view image to be written into pixels of the crosstalk region; And
And writing the multi-view image data modulated only by pixels in the crosstalk area, and writing the original multi-view image data to pixels other than the crosstalk area. A determining unit for determining a crosstalk area by analyzing original multi view image data based on at least one of a depth distribution characteristic, a brightness distribution characteristic, and an image complexity;
A modulator for modulating data of the original multi-view image to be written to pixels of the crosstalk area; And
And a display panel driver for writing multi-view image data modulated only by pixels in the crosstalk area and writing the original multi-view image data to pixels other than the crosstalk area, . A display panel for displaying multi-view image data;
A display panel driver for writing the multi-view image data;
A 3D optical element for separating an optical axis of the multi-view image data;
A determination unit for determining the crosstalk region by analyzing the multi view image data based on at least one of a depth distribution characteristic, a brightness distribution characteristic, and an image complexity; And
And a modulator for modulating the data of the multi-view image to be written into the pixels of the crosstalk area,
Wherein the display panel driver writes multi-view image data modulated only by pixels in the crosstalk area, and writes the original multi-view image data to pixels other than the crosstalk area. The method of claim 3,
The judging unit judges,
Eye stereoscopic image display apparatus compares three depth-worth values having the largest cumulative number of pixels in a predetermined window area and judges the window area having a difference greater than a predetermined threshold value as the crosstalk area. The method of claim 3,
The judging unit judges,
Eye stereoscopic image display device, wherein the crosstalk area is determined as a window area in which an average brightness of an image in a predetermined window area is greater than a first threshold value and an average depth value of the image is greater than a second threshold value. The method of claim 3,
The judging unit judges,
Eye stereoscopic image display device for detecting an edge of an image within a predetermined window area and judging a window area where the number of edges of the window area is larger than a predetermined threshold value as a crosstalk area.

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