JP2001054143A - Crosstalk reduction method and apparatus in stereoscopic image display by time division method - Google Patents

Abstract

(57) [Summary] A stereoscopic image display device that displays a stereoscopic image by displaying a left-eye image and a right-eye image in a time-sharing display method with a left eye and a right eye, respectively, is used as a display device. Due to the persistence characteristics of the phosphor, a part of the image for the right eye leaks into the left eye and a part of the image for the left eye leaks into the right eye, and an image that should not be displayed as a display image for both the left and right eyes is displayed. Therefore, there is a problem to be solved to reduce image quality disturbance (crosstalk disturbance) caused by the moving image and the still image. SOLUTION: Before displaying an image, a right-eye image is subtracted from a left-eye image and a left-eye image is subtracted from a right-eye image by a predetermined leakage amount, and then displayed. In reducing talk disturbance, before subtraction, the right-eye or left-eye signal is reduced by one depending on the order in which the left- and right-eye images are displayed in a time-division manner.
The field period is delayed before subtraction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stereoscopic image display method and apparatus for displaying a stereoscopic image by displaying a left-eye image and a right-eye image in a time-division display system. And a crosstalk reduction method and apparatus for removing or reducing crosstalk interference between left and right images.

[0002]

2. Description of the Related Art Conventionally, an image for a left eye and an image for a right eye are displayed in a time division manner using an image display device such as a cathode ray tube (CRT) or a gas discharge display panel (PDP). To display a stereoscopic image (for example, a “stereoscopic image display method and apparatus” according to the present applicant's application (Japanese Patent Application No. 10-205093).
issue)).

However, in the stereoscopic image display method of displaying a stereoscopic image in this kind of time-division system, for example, the right-view image is not used because of the characteristics of the display device itself, such as the persistence characteristics of phosphors of CRTs and PDPs. Is partly leaked into the left eye, part of the image for the left eye leaks into the right eye (hereinafter referred to as crosstalk), and an image that should not be displayed as a display image for both the left and right eyes is displayed. Image quality interference (hereinafter referred to as crosstalk interference) occurs.

On the other hand, in order to eliminate or reduce crosstalk interference, a method and apparatus for reducing crosstalk in displaying a stereoscopic image filed by the present applicant (Japanese Patent Application No. 10-3).
05270).

A method of reducing the crosstalk (Japanese Patent Application No. 10-305270) will be briefly described. FIG. 4 shows a principle configuration of a crosstalk reduction method (hereinafter, this is referred to as a conventional crosstalk reduction circuit). In FIG. 4, an image input signal L for the left eye and an image input signal R for the right eye are each branched into two, and one of the branched signals is supplied to one of coefficient circuits 3 and 4 (both of them).

[Outside 1] ), And the other of the branched signals is input to the minuend terminals of the subtraction circuits 5 and 6. The output signals of the coefficient circuits 3 and 4 are input to the subtraction terminals of the subtraction circuits 5 and 6, and the left and right image signals L 'and R' obtained by subtracting the crosstalk from the output terminals of the subtraction circuits 5 and 6. Are respectively output.

In the above description, the image signal for the left eye that has passed through the coefficient circuit 3 has a value close to the previously measured crosstalk amount (the amount of the left-eye image leaking into the right eye). The signal is subtracted from the image signal for the right eye by the subtraction circuit 6. The right-eye image signal passed through the coefficient circuit 4 has a value close to the crosstalk amount (the amount of the right-eye image leaking to the left eye) measured in advance. The signal is subtracted from the image signal for the left eye by the subtraction circuit 5. Here, the coefficient value α of the coefficient circuits 3 and 4 is determined in advance by measuring the amount of crosstalk.

[0007]

However, the method for reducing crosstalk according to Japanese Patent Application No. 10-305270 described above is particularly effective when the stereoscopic image display device is configured in a time-division manner. If the image is a still image, the crosstalk can be completely removed in principle, but it has been found that when the image to be displayed in a stereoscopic image is a moving image, the crosstalk remains depending on the magnitude of the motion.

The reason is described below. Now, when displaying a stereoscopic image on an image display device in a time-division manner, the output signals L 'and R' of the circuit shown in FIG.
Is converted from a simultaneous signal to a time-division signal to perform time-division display of the left-eye image and the right-eye image, and it is assumed that the time arrangement of the signals L 'and R' at this time is as shown in FIG. In addition,
The subscript at the lower right of each signal L ', R' indicates the order of photographing (field number) by the stereoscopic camera, and L ', R' having the same subscript are signals of the same field. Further, one field of each of the left and right images L ′ and R ′ shown in FIG. 5 is (1/120) s.
ec is that one ordinary field is (1/6)
This is because the stereoscopic camera output of 0) sec is compressed to a time width of ２, and both left and right images are accommodated in the original one field period ((1/60) sec).

As described above, since the crosstalk between the left and right images is caused by the afterglow characteristics of the phosphor of the CRT or PDP, in the time-division stereoscopic image display, the image one field before is always leaked. Become. Now, when a three-dimensional image is displayed by the n-th (see FIG. 5) images L _n ′ and R _n ′, the brightness of each of the actually displayed left and right images is represented by L _n ″ and R _n ″. And L _n ″, R _n ″
Is represented by one field leakage of the previous image (see FIG. 5) in consideration of the _{L n "= L n '+} αR n-1' (1) R n" = R n '+ αL n' (2) .

Equations (1) and (2) represent crosstalk models in the time-division display method for the left and right eye images. This means that in the stereoscopic image display device of the simultaneous display system for the left and right eye images, unexpected crosstalk remains. FIG. 6 shows this situation by an equivalent circuit.

Assuming that image outputs from the camera supplied to the conventional crosstalk reduction circuit (same as the circuit in FIG. 4) in FIG. 6 are L _n and R _n (left and right eye image signals, respectively).
The output L _n of the reduction circuit _{', R n' L n '} = L n -αR n (3) R n' between = R _n -αL _n (4) is satisfied.

[0012] (3) and equation and rearranging by substituting field number n n-1 and the formula (1) formula _{(4), L n "= L n -α} 2 L n-1 + α (R _n−1 −R _n ) (5) From equation (5), if R _n−1 = R _n (still image), the term α (R _n−1 −R _n ) becomes zero. becomes, without crosstalk occurs, when the R _n-1 ≠ R n (movie), the crosstalk in accordance with the motion amount is not canceled (i.e., cross-talk remains) can be seen.

Meanwhile, (3) and rearranging equation (4) (2) are substituted into _{equation, R n "= R n -α} 2 R n (6) , and the still image, regardless of the video, It can be seen that the crosstalk is canceled (that is, no crosstalk remains).

In the above description, when displaying a three-dimensional image in a time-division manner, as shown in FIG. 5, the left-eye image among the left-eye images having the same field number emits light first. If the right-eye image emits light first, it is natural that crosstalk corresponding to the amount of motion remains in the brightness R ″ of the right-eye image. .

An object of the present invention is to provide a method and an apparatus for reducing crosstalk of a stereoscopic image display apparatus for displaying a stereoscopic image in a time-division manner, the method comprising the steps of: It is an object of the present invention to provide a method and an apparatus for reducing crosstalk in which no residual remains.

[0016]

In order to achieve the above object, the present invention provides a method for reducing crosstalk in a stereoscopic image display by a time-division method, wherein a left-eye image is divided into a left eye and a right-eye image is divided into a right eye. When displaying a stereoscopic image by displaying each image according to the method, before displaying the image, the image for the right eye from the image for the left eye, and the image for the left eye from the image for the right eye, respectively, by a predetermined leakage amount In the crosstalk reduction method in which the left-eye image having the same field number is displayed after the left-eye image is displayed first, the right-eye image is subtracted from the left-eye image. When the image for the right eye among the images for the left and right eyes having the same field number is displayed first, the image for the left eye is subtracted from the image for the right eye. It is is characterized in that so as to one field period delay before the subtraction.

Further, the crosstalk reducing apparatus for displaying a three-dimensional image by the time-division method according to the present invention displays a three-dimensional image by displaying the image for the left eye in the left eye and the image for the right eye in the right eye in the time-division method. A device for reducing crosstalk of a display device, wherein a right-eye image is subtracted from a left-eye image and a left-eye image is subtracted from a right-eye image by a predetermined leakage amount before displaying an image. And at least a subtraction circuit that performs the same operation for the right-eye image subtracted from the left-eye image when the left-eye image is displayed first among the left- and right-eye images having the same field number. When the image for the right eye among the images for the left and right eyes having the field numbers is displayed first, the images for the left eye to be subtracted from the image for the right eye are respectively subjected to the subtraction before the subtraction. 1-field delay circuit for one field period delayed I in which is characterized in that it is arranged on the subtrahend terminal of the subtraction circuit.

The crosstalk reduction apparatus for displaying a three-dimensional image by the time-division method according to the present invention may further comprise a right-eye image and a left-eye image each of which is a predetermined amount of leakage. An inverse gamma correction circuit is provided on each of the input sides of the extraction branch points for extraction from the input.

The present invention also provides a crosstalk reducing apparatus for a three-dimensional image display by a time-division method, wherein a limiter circuit for limiting the level of the pixel to a black level for a pixel having a negative brightness by performing the subtraction. Are arranged on the output side of the subtraction circuit, respectively.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on embodiments of the present invention with reference to the accompanying drawings. The crosstalk reduction method and apparatus of the present invention are based on the idea that the term of α (R _n−1 −R _n ) in the above equation (5) should be zero regardless of a still image or a moving image. I have.

[0021] Therefore, in the present invention, as described above (3) is written as _{L n '= L n -αR n} -1 (7), αR supplied to the subtraction circuit 5 in FIG. 6
The _n delayed one field period is assumed to be [alpha] R _n-1.

More specifically, when the left-eye image is displayed first in the time-division display (time arrangement shown in FIG. 5), only the leakage amount given in advance from the left-eye image signal is used. Before subtracting the image signal for the right eye, the image signal for the right eye is delayed by one field. Conversely, when the image for the right eye is displayed first, the image signal for the left eye is reduced by 1 before subtracting the image signal for the left eye from the image signal for the right eye by a predetermined leakage amount. Field delay is assumed.

FIG. 1 shows a first embodiment of the crosstalk reducing device of the present invention. Here, the same components as those in the conventional crosstalk reduction circuit shown in FIG. 4 are denoted by the same reference numerals. In the figure

[Outside 2] Represents a one-field delay circuit, whereby f (α
R _n ) = αR _n-1 . This configuration crosstalk reducing _{device, L n "= L n -α} 2 L n-1 (8) R n" = R n -α 2 R n (9) , and this case, still images, videos Irrespective of the above, the crosstalk component can be completely removed.

The circuit configuration of FIG. 1 shows a configuration corresponding to the case of displaying the image for the left eye first in the time arrangement of FIG.

[Outside 3] Is inserted between the coefficient circuit 4 and the subtraction circuit 5, but when the right-eye image is displayed first, the one-field delay circuit

[Outside 4] May be inserted between the coefficient circuit 3 and the attenuation circuit 6. In this case, the equations (8) and (9) are respectively L ″ = L _n −α ² L _n (10) R ″ = R _n −α ² R _n−1 (11)

The video input signals L and R shown in FIG.
Indicates the input signals of the left and right eye images of any of the three primary color signals of green, blue, and red, and the signal processing according to the present invention is performed on the remaining two primary color signals by the same circuit configuration. .

The purpose of using the inverse gamma correction circuits 1 and 2 in FIG. 1 is as follows. That is, since a normal image signal such as a television image signal is premised on display on a CRT, gamma correction is performed on the image transmitting side to correct input / output characteristics of the CRT, so-called gamma characteristics. Since the gamma-corrected signal is not a signal whose value is linear with respect to the brightness of the light to be displayed, the addition / subtraction of the image signals is performed as it is (the subtraction circuits 5 and 6 in FIG. 1 correspond). Can not. Therefore, the inverse gamma correction circuit 1
2 to convert to a linear signal. The inverse gamma correction circuit has input / output characteristics opposite to those of the gamma correction circuit on the image transmission side.

After the gamma characteristics are solved by the inverse gamma correction circuits 1 and 2, the left-eye image signal passes through the coefficient unit 3 and the crosstalk amount (the amount by which the left-eye image leaks into the right eye) is measured in advance. ). The signal is subtracted by the subtraction circuit 6 from the right-eye image signal. The right-eye image signal passes through the coefficient unit 4 and has a value close to the crosstalk amount (the amount of the right-eye image leaking to the left eye) measured in advance. The signal is further supplied to a subtraction circuit 5 via a one-field delay circuit, and is subtracted from the left-eye image signal. The coefficient values α of the coefficient units 5 and 6 are
It is determined in advance by measuring the amount of crosstalk.

As described above, since the crosstalk reduction method and apparatus of the present invention include the subtraction circuits 5 and 6 in the structure thereof, inverse gamma correction is performed before all signal processing for crosstalk reduction is performed. I have. For this reason, in the crosstalk reduction method and apparatus of the present invention, the image signal basically obtained is converted into a signal whose level is linear with respect to the brightness of the light to be displayed by the inverse gamma correction circuit included in the apparatus. Has become. This means that the method and apparatus of the present invention can be used to realize a time-division stereoscopic image display device using an image display device having a linear signal-to-emission luminance (brightness) characteristic such as PDP or liquid crystal (LCD). It can be said that it is particularly suitable.

FIG. 2 shows an example of the configuration of a PDP stereoscopic image display device using the subfield method, which is configured using the crosstalk reduction device of the present invention. In FIG. 2, a left-eye video input signal L and a right-eye video input signal R are:
The signals are input to A / D conversion circuits 7 and 8 and converted into digital signals. Also in this example, the video input signals L, R
(Analog signals) are three primary color signals of green, blue and red, respectively, and the following processing is performed for each signal. Further, as shown in the figure, the left-eye video input signal L is also input to a synchronization detection circuit 9, where horizontal and vertical synchronization signals are detected.

The digital video signals (for the left eye and the right eye, respectively) output from the A / D conversion circuits 7 and 8 are the same crosstalk reduction apparatus A of the present invention as shown in FIG. Is input to Output signals of the device, that is, left-eye and right-eye digital video signals L ′ and R ′ with reduced crosstalk are respectively limited by limiters 10 and
11 is input. The role of the limiters 10 and 11 is that the crosstalk reduction device A includes a subtraction process between the video signals, and as a result of the subtraction, the brightness of the video signal output from the output side of the crosstalk reduction device A is negative. However, since the negative brightness cannot be expressed as a video signal, the signal having the negative brightness is limited to the minimum brightness value (black level) through the limiters 10 and 11. It is.

In FIG. 2, a subfield conversion circuit 1
The circuit configuration of the second and subsequent circuits is described in “Stereoscopic image display method and apparatus” (Japanese Patent Application Nos. 10-205093 and 10-28259) according to the present applicant's application using the subfield method.
No. 0) is described as an example of the configuration of the three-dimensional image display device (FIG. 2) in the specification and the drawings, and has the same circuit configuration as the subfield conversion circuit 4 and thereafter.

That is, the horizontal and vertical synchronizing signals from the synchronism detecting circuit 9 and the left and right digital video signals L 'and R whose crosstalk has been reduced by the crosstalk reducing device A are supplied to the subfield conversion circuit 12. Are supplied via limiters 10 and 11, respectively, and the digital video signals L 'and R' are decomposed into subfield signals based on the horizontal and vertical synchronizing signals and output.
A timing signal for driving the shutter No. 6 is also output. This subfield conversion circuit 12 uses a pseudo-diffusion method or a dither method to reduce the number of bits of a video signal to a gray level that can be actually displayed without significantly lowering the gray-scale display performance. May include.

A subfield signal, which is an output signal of the subfield conversion circuit 12, is supplied to a PDP panel 14 via a panel driving circuit 13, and an image is displayed on the panel 14. Further, the timing signal from the subfield conversion circuit 12 is supplied to the spectacles control circuit 15 to generate an L-side and R-side shutter opening / closing signal of the shutter spectacles 16 and supply the signals to the spectacles. The shutter opening / closing signal at this time can be supplied to the shutter glasses 16 wirelessly by using a conductive wire or by using infrared rays.

FIG. 3 shows a second embodiment in which the first embodiment of the crosstalk reducing apparatus of the present invention shown in FIG. 1 is further modified so as to be suitable for a time-division display type stereoscopic image display apparatus using a CRT. The form is shown. In FIG. 3, limiters 10 and 11 limit a signal having a negative brightness to a black level, and are the same as those described with reference to FIG. Since the crosstalk reduction device of the present invention performs subtraction between image signals, the video signals for the left and right eyes are converted into linear signals by the inverse gamma correction circuits 1 and 2.

However, when displaying an image on a CRT, it is necessary to match the relationship between the signal of the video signal and the light emission luminance (brightness) with the characteristics of the gamma correction circuit performed on the image transmitting side. Gamma correction circuits 17 and 18 having the same characteristics as the gamma correction on the image side are inserted into the signal paths of the left-eye video signal and the right-eye video signal, respectively.

[0036]

According to the present invention, in a three-dimensional image display for displaying a three-dimensional image by displaying an image for the left eye on the left eye and an image for the right eye on the right eye by the time-division display method, Due to the persistence characteristics of the body, part of the image for the right eye leaks into the left eye, part of the image for the left eye leaks into the right eye, and an image that should not be displayed as a display image for both the left and right eyes is displayed The image quality disturbance caused by the image can be reduced irrespective of a moving image or a still image.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a crosstalk reduction device of the present invention.

FIG. 2 shows a configuration example of a PDP stereoscopic image display device based on a subfield method configured using the crosstalk reduction device of the present invention.

FIG. 3 shows a second embodiment of the crosstalk reduction device of the present invention.

FIG. 4 shows a conventional crosstalk reduction circuit.

FIG. 5 shows a time arrangement of a left-eye image and a right-eye image displayed on the image display device.

FIG. 6 is an equivalent circuit showing that when signals for the left and right eyes are supplied to the image display device in a time-division manner, crosstalk remains even when a conventional crosstalk reduction circuit is used.

[Explanation of symbols]

 1,2 inverse gamma correction circuit 3,4 coefficient circuit 5,6 subtraction circuit 7,8 A / D conversion circuit 9 synchronization detection circuit 10,11 limiter 12 subfield conversion circuit 13 panel drive circuit 14 PDP panel 15 glasses control circuit 16 Shutter glasses 17, 18 Gamma correction circuit A Crosstalk reduction device

[Outside 5]

Claims (4)

[Claims] When displaying a stereoscopic image by displaying an image for the left eye in the left eye and an image for the right eye in the right eye in a time division manner, the image for the left eye is displayed before the image is displayed. In the crosstalk reduction method of subtracting the left-eye image from the right-eye image by a predetermined leakage amount from the right-eye image, and displaying the same, the left-eye image and the right-eye image having the same field number are displayed. When the image for the left eye is displayed first, the image for the right eye to be subtracted from the image for the left eye is displayed first, and the image for the right eye is displayed first among the images for the left and right eyes having the same field number. The time-division stereoscopic image display is characterized in that the left-eye image subtracted from the right-eye image is delayed by one field period prior to the subtraction. Cross-talk reduction how. 2. A device for reducing crosstalk of a display device for displaying a stereoscopic image by displaying a left-eye image in a left-eye image and a right-eye image in a right-eye image in a time-division manner. Before performing the processing, at least a subtraction circuit that subtracts the image for the right eye from the image for the left eye and the image for the left eye from the image for the right eye by a predetermined leakage amount is provided. When the image for the left eye among the images for the eye is displayed first, the image for the right eye to be subtracted from the image for the left eye is replaced with the image for the right eye among the images for the left and right having the same field number. Is displayed first, the one-field delay circuit for delaying the left-eye image subtracted from the right-eye image by one field period prior to the subtraction, respectively, is used. Crosstalk reduction apparatus in the stereoscopic image display by time division system, characterized in that the are located on the subtrahend terminal side. 3. The crosstalk reduction apparatus according to claim 2, wherein the right-eye image and the left-eye image corresponding to the predetermined amount of leakage are replaced with the right-eye image and the left-eye image, respectively. A crosstalk reducing apparatus for stereoscopic image display by a time-division method, wherein an inverse gamma correction circuit is arranged on each input side of an extraction branch point for extracting from an image for use. 4. A crosstalk reduction apparatus for displaying a three-dimensional image by a time-division method according to claim 2 or 3, wherein the level of the pixel having a negative brightness due to the subtraction is limited to a black level. A crosstalk reducing device for displaying a three-dimensional image by a time-division method, wherein limiters are provided on the output side of the subtraction circuit.