EP2366253A1

EP2366253A1 - Stereoscopic display system, method and 3d glasses with an adjustment operational phase for adjusting display parameters

Info

Publication number: EP2366253A1
Application number: EP09737473A
Authority: EP
Inventors: Dániel RATAI
Original assignee: 3D For All Szamitastechnikai Fejleszto Kft
Current assignee: 3D For All Szamitastechnikai Fejleszto Kft
Priority date: 2008-08-07
Filing date: 2009-07-31
Publication date: 2011-09-21
Also published as: HU0800501D0; WO2010015867A1; HUP0800501A2; WO2010015868A1

Abstract

The present invention partly relates to an apparatus for generating a three- dimensional view, the apparatus comprising - an image-forming device (10) for displaying visual information corresponding to a first perspective and visual information corresponding to a second perspective, and - a perspective-separating device (11) comprising a first part (11a) separating the visual information corresponding to a first perspective for a first eye and a second part (11a) separating the visual information corresponding to a second perspective for a second eye, wherein the perspective-separating device (11) separates the visual information by means of different light transmitting behaviors of the two parts (11a, 11 b). The apparatus comprises a perspective-separating device (11), which also has an operational phase for adjusting at least one display parameter, said operational phase exhibiting identical light transmission behaviors in the two parts (11a, 11 b) of the perspective-separating device (11). Furthermore, the invention also relates to a method and 3D-glasses for the apparatus.

Description

APPARATUS, METHOD AND 3D-GLASSES FOR ADJUSTING DISPLAY PARAMETERS OF A THREE-DIMENSIONAL VIEW

TECHNICAL FIELD The present invention relates to an apparatus, a method and 3D-glasses for adjusting display parameters of a three-dimensional view. By way of example, such display parameter may be the synchronicity of the operation or the rate of ghost image filtering.

BACKGROUND ART

The object of 3D visual presentation is to enable the users to sense spatial shapes as a reality. Three-dimensional effect may be achieved by conveying separate images to the left and right eyes, in the same way, as the eyes perceive the spatial shapes from their respective different positions. For generating and sensing this double-image (so-called stereo image) several technologies have so far been developed. In the simplest case, the image is displayed on a conventional monitor for the two eyes simultaneously and the three-dimensional effect can be sensed by means of special glasses. There are, however, sophisticated and extremely expensive monitors as well, which do not require the use of the aforementioned glasses or any other auxiliary device, since the monitor itself provides the three-dimensional view.

One of the simplest and most widely used solutions is provided by the systems based on the separation of images appearing in the same place. These systems are based on the theory that the images for both the right and the left eyes are displayed on one display simultaneously, which two images are then separated by special, so-called 3D-glasses, in a way that through the left lens only the image displayed for the left eye and through the right lens only the image displayed for the right eye is allowed to pass.

It is the essence of all known 3D visualizations which are based on color- separation theory, that images of different color are generated for the left and the right eyes respectively, and the two different color images are separated by colored lenses. For this purpose, red and blue (or cyan, which is the mixture of blue and green) lenses are generally used. Through the red lens only the red light, while through the blue lens only the blue light can pass (anaglyph glasses). It is the advantage of color-separation-type systems, that they are extremely inexpensive, their disadvantage being, however, that 10-15 minute use thereof may already be harmful to the eyes, moreover, that three-dimensional view is not provided thereby without color limitation. Light-polarization-type systems are essentially based on generating images of different polarity for the left and the right eyes, and the two images of different polarity are separated by polarizing lenses. Contrary to the color separation-type systems, light-polarizing-type systems are capable of reproducing entirely realistic color images. Although the manufacturing costs of such glasses are relatively low, the monitor generating the two-directionally polarized stereo images is relatively expensive, and therefore this solution is primarily used in 3D movie theatres.

The systems using so-called shutter-glasses operate in a manner that the respective images for the left and the right eyes are displayed alternatingly, and the shutter-glasses alternatingly block one eye after the other, synchronously with the alternating images. Shutter-glasses have lenses adapted to switch between a blocked state and a transparent state at a high frequency. Similar to light- polarizing-type system, a shutter-type system is also capable to reproduce entirely realistic color images. Such a system is advantageous due to its relatively low price and to the fact that - unlike in light-polarizing-type systems - a conventional tube monitor is sufficient enough for use as display therein. It is a disadvantage of the shutter-glasses that the left and right eyes are blocked alternatingly, thereby causing flicker of the image seen through the glasses.

There are other known solutions as well, wherein the two states of the glasses are not a full block and a full transparency, but of two colors that are used by anaglyph glasses as well. The given perspectives are separated for the eyes by means of polarization. By way of example, such solutions are disclosed in patent documents US 4,641 ,178, US 4,995,718, US 5,564,810 and US 5,742,333. These solutions are generally referred to as polarized color multiplexing solutions.

Tuning of the various display parameters is of extraordinary importance in systems generating three-dimensional view in order to achieve a sufficient stereo effect. By way of example, such parameter may be synchronicity - which, if adjusted inappropriately, may cause the two eyes to see reverse images as well - or precise rate and position of the switching of the lenses of the glasses in order to gain the most correct spatial illusion, or tuning of the rate of ghost image filtering. A frequent problem with active glasses is that the eyes become ..reversed", that is, the left eye sees the image intended for the right eye and the right eye sees the image intended for the left eye. This is exactly what happens, if - for any reason - the control signal of the lenses of the glasses is offset by one period. The display itself often offsets one image frame, thereby making it even more unpredictable which period would be appropriate for a 3D display.

For creating products of this field, it is essential to enable the user - who most of the time is getting to know the system based on instructions - to tune the display parameters necessary for gaining adequate image in a most simple, clear, definite and reliable way.

In the prior art solutions, these parameters can be tuned upon one's own instincts while watching the three-dimensional images, or by pre-setting and continuous testing of the parameters. In order to achieve the best results, it is essential to provide the user with unambiguous tasks, that are executable in a straightforward way.

DESCRIPTION OF THE INVENTION

The object of the invention is to provide an apparatus, a method and 3D- glasses that enable adjusting the display parameters of the three-dimensional view in a simple, clear, definite and reliable way.

The object of the invention has been achieved by means of the apparatus according to claim 1 , the 3D-glasses according to claim 6 and the method according to claim 7. Preferred embodiments are defined in the independent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary preferred embodiments of the present invention are described hereunder on the basis of drawings, where

Fig. 1 is a schematic view of an apparatus according to the invention,

Fig. 2 is a schematic view of another apparatus according to invention, Fig. 3 is a time and impact diagram of a total block phase, Fig. 4 is a view of a parameter-adjustment according to the invention, Fig. 5 is a view of another parameter-adjustment according to the invention, Fig. 6 is a block diagram of a ghost image filter according to the invention, and

Fig. 7 is a block diagram of a ghost image filter according to another embodiment of the invention.

MODES FOR CARRYING OUT THE INVENTION

The solution according to the present invention provides an operational phase, wherein the twofold image and visual information presented on the image forming device is not separated for the two eyes but the same image component is displayed so as to tune the display parameters.

The present invention may advantageously be implemented with active 3D- glasses; so that in the phase according to the present invention both lenses receive the same control signal. The invention, however, is not only operational with 3D-glasses. By way of example, in case of passive polarization glasses, the glasses are used in the inventive phase with both lenses polarized in a parallel direction. Similarly, glasses containing, by way of example, two red lenses are also operational for tuning anaglyph stereo systems. The present invention will be primarily described with reference to active 3D-glasses.

Visual information corresponding to a first perspective and visual information corresponding to a second perspective is displayed by means of the image-forming device 10, advantageously an LCD monitor, as seen in Fig. 1 , in a way known per se.

According to the invention, a perspective-separating device 11 is used, which comprises a first part 11a separating visual information corresponding to a first perspective for a first eye and a second part 11b separating visual information corresponding to a second perspective for a second eye. Separation of the visual information is obtained by means of different light transmitting behaviors of the two parts 11a, 11b, which can be e.g. constant or periodic blocking of the light admittance in the entire spectrum or with regard to a spectral component. Blocking may be achieved by means of total block, color filter, or polarization. Accordingly, the perspective-separating device 11 may be active or passive 3D-glasses, e.g. shutter-glasses, polarizing glasses, anaglyph glasses or polarizing color- multiplexing glasses. By way of example, a polarization-rotating device 12 is positioned in a way as shown in Fig. 2, in front of a projector 13 and the image is projected onto a polarization maintaining screen 14. In this case, the two parts 11a, 11b of the perspective-separating device 11 are arranged in the form of 3D-glasses. In the solutions of the field of technology, the so-called total-block phase is preferably inserted in the operating sequence in between the image frame transitions when the two images are seen together for a while in the course of image refresh. By way of example, in the case of LCD monitors, refresh is made per image dots, that is, the image dots of the previous image are transposed by the new image dots. Therefore, in LCD monitors some image is always visible on the screen of the display.

As a result of this, by using conventional shutter-glasses and synchronicity- control together with an LCD monitor, it will cause good image in the upper part of the monitor, i.e. the left eye will see the image intended for the left eye and the right eye will see the image intended for the right eye, while the lower part of the monitor will gradually become transposed, hence sufficient stereo image is seen in the uppermost few lines of the monitor only. In this case it is advantageous to insert the total block phase when both two eyes are being blocked. While the monitor refreshes the display, or most parts of it, the control of the 3D-glasses turns on the total block, thereby the area in which the user does not see a stereo image may be reduced to a few lines of the display. By advantageously offsetting the synchronization pace, these few lines may be distributed along top and bottom of the display.

In the first row of Fig. 3 - in a color-multiplexing application - a cycle is depicted, wherein the left eye sees red (R)₁ and the right eye sees cyan (C). The perspective-separating device , i.e. the 3D-glasses, is in a phase between the two monitor representations in an R+C state, then the next image starts to be drawn in the essential mid-range part of the monitor, and the 3D-glasses switch to total block phase. This way, the view as seen in the right-hand side of the figure is provided for the user, wherein stereo image is visible in the essential part of the image, and only in the less frequently used top and bottom parts is reverse stereo image displayed. The last row of the figure demonstrates the results of the next cycle and block. The total block phase is applicable not only in the case of color-multiplexing systems, but also in systems comprising other similar problems, e.g. with simple shutter-glasses or with shutter-glasses without front polarizing filter as already described. According to the present invention, a dynamic total block phase control may also be implemented. By increasing the total block phase, the area having good stereo image quality will increase, however, the perceived illumination power will decrease. Together with the reduced perceived illumination power, flicker will also decrease. There is indeed always an optimal total block rate. It is, therefore, advisable to apply a software control relative to this rate. By way of example, if an image lighter on the whole a is presented on the display, which would cause more flicker, but would be visible if darker as well, then e.g. the rate of total block could be increased in order to find an optimal solution compromising the new situation. As the illumination power of the monitor cannot be controlled by software or in a very complex way only, the above dynamic control may provide an efficient solution to this problem as well. Another adjustment option may be that of the position of the total block phase. In a basic case, blocking is performed during the refresh of the mid-range image lines of the LCD screen. Blocking may also be performed in dependence of the displayed visual information, wherein predetermined image lines on the LCD screen are being refreshed. In this case, if - for any reason - it is more important to have good three-dimensional view in the upmost part of the display than in the bottom, the total block phase can be offset towards the top of the monitor.

As it can be clearly seen from the above, adjustment of synchronicity of the perspective-separating device 11, as well as of synchronicity and duration (determining the position and rate) of the phase that blocks display for both eyes, i.e. as display parameters, are required to have accurate adjustment in consideration of the given circumstances.

According to the present invention, it is possible, therefore, to control the two lenses of the glasses simultaneously, that is, to see the same with both eyes. On the image-forming device 10, e.g. monitor, two buttons may be displayed as seen in Fig. 4, so that one of them is covered by the glasses. Depending on which of the buttons is covered by the glasses, it can be determined which image is intended for the right eye and which is intended for the left eye during the stereo display. Synchron-adjustment can be advantageously achieved by the user clicking on the button seen by himself and by detecting the clicks by means of an appropriate computer program will implement the necessary adjustment step. Synchron-setting may indeed be implemented not only by means of button- representation but advisably in any other way via an unambiguous question asked from the user based on what is visible on the monitor.

On the contrary, if the two eyes received different images for the purposes of adjustment, for most users it would pose a problem to interpret whatever is seen in the picture or how to follow the instructions. A general deficiency of the known 3D-glasses is related to the fact that separation of the two images for the two eyes is imperfect, that is, the image intended for the right eye can be seen to a certain degree by the left eye and vica versa (ghost image). As a result thereof, beginner users often do not sense the 3D effect, and even with advance users the distance, in which virtual objects emerge from the plane of the monitor, in a way that it is perceived by the user in space, decreases. The more ghosting there is in the image, the worse of a quality the view becomes, and the less likely the brain will be "deceivable", that is, the more likely it will see the shape in the plane of the display. The ghost image filter according to the present invention hinders the image intended for the right eye to migrate into the left eye, or the contrary, thereby 3D effect is more easily created and more definite three-dimensional contrast may be perceived.

The rate of ghosting depends on the quality of 3D display system and the operating theory thereof. By means of decreasing or eliminating ghosting will not only provide better image quality but also will enable the use of less expensive, lower quality 3D display for a given task.

Accurate adjustment of the on-off switching position of the lenses of the glasses may greatly improve the three-dimensionallly displayed image quality. It is a frequently encountered problem, that if the switching of eyes starts on the image synchron signal promptly, then ghosting may be caused on account of the offsets which are present in the system.

In order to eliminate this problem, if the two eyes are simultaneously controlled, as depicted in Fig. 5 an icon representing a good image can be superimposed on one of the images to be separated, while on the other image an icon representing bad image can be superimposed on the other image. In this case, the user can accurately tell how much of the icon representing the good image he sees and how intensely he sees it, and how much of the icon representing the bad image he sees. At this point the user may, in any suitable way, separately tune the on-off switch positions of the lenses relative to the image synchron. The user may carry on the tuning until the image he sees becomes optimal, that is, the icon representing good image will greatly dominate. At this point the parameters may be tuned so that total block phase is reached, which is important in displays gradually switching the state of the pixels e.g. line by line. In this case, total block phase will prevent uninterpretable monitor image to reach the eyes in an in-between state of monitor-refresh.

The ghost image filter according to the present invention may for example operate in such a way that it combines the image generated for one eye with a reduced intensity negative (inverse) of the image generated for the other eye, displaying it as such. Accordingly, to the images intended for one eye a reduced intensity copy of the inverse image of the other eye is added. The intensity of the inverse image component shall be set so as to completely compensate the appearing ghost image. In this case ghost image can be totally eliminated and compensated, however, it requires appropriate adjustment of the parameters. Therefore, an icon representing the good image is superimposed on one of the images to be separated by the 3D-glasses, and an icon representing the bad image is superimposed on the other image. The two eyes are controlled simultaneously so that both eyes see the icon representing the good image. Ghost image filtering can be tuned by adjusting the rate of ghost image filtering as long as the icon representing the bad image does not disappear. It is a benefit of the present invention, that it enables more accurate detection of ghosting in the different parts of the monitor and, if necessary, various ghosting rates can also be applied relative to the various parts of the monitor. Ghost image filtering can be further tuned in accordance with the angle the 3D- glasses are positioned in. In case of polarizing-separation, the least ghosting generally occur in a horizontal position, and by turning the head it increases. If the turning angle of the glasses is detected, e.g. by applying head tracking, head- tracking adjustment of ghost image filter parameters may greatly increase the quality of stereo effect. By detecting the spatial placement (position, orientation) of the perspective-separating device 11 and by means of sufficiently dynamic adjustment of display parameters remarkable improvement of 3D image may be achieved.

According to the present invention, therefore, the two lenses of the glasses are controlled so that the two simultaneously block or admit light synchronously with the display frequency, and two images are produced in a way that they clearly indicate for the user which image is to be seen and which is not. The two images are presented on the display alternatingly in synchron with the display frequency and the glasses. By default, the user sees in the glasses only one image, i.e. the one representing the good image, but to a certain degree the icon representing the bad image may also be seen. In this case, a comfortably visible, clear and identical image is seen with the two eyes therefore adjustment of the appropriate parameters can be completed by the user. The parameters for stereo display is advantageously tuned so that the icon representing the good image is visible is the best possible image quality and the icon representing the bad image is seen in the worst image quality.

With this solution, it can be clearly managed if the optimum adjustment- values vary according to the different parts of the monitor. It also enables better detection of any changes of the optimum value of the adjustable parameters, if for any other reason they may change (e.g. head is not hold in horizontal position may change the optimum value of the adjustable parameters).

Fig. 6 demonstrates a block diagram of the exemplary ghost image filter 20 for interleaved 3D. The ghost image filter 20 is arranged so as to be interposed between the computer and the monitor, nevertheless the ghost image filter function may be arranged on e.g. the video card as well, moreover, such images may be generated by a software itself.

The received and transmitted vertical synchron signals are indicated by VSi_N and VSOUT signals, while the horizontal synchron signals are indicted by HSIN and HSOUT signals. The RGB signals arriving at the ghost image filter 20 will reach the monitor via a switch unit 21. The incoming RIN, GIN and BIN signals will also be led into an inverter unit 22 generating the inverse of the RGB - by an intensity adjustable by potentiometers 23 - which will be led to the switch unit 21 as well.

The ghost image filter 20 is advantageously operational in an interleaved display mode, wherein even and odd lines are controllable separately. In this case, the visual information corresponding to one perspective will preferably be displayed in the even lines, while the visual information corresponding to the other perspective will be displayed in the odd lines by means of the image-forming device 10, and with the help of the ghost image filter 20 the reduced intensity inverse image of the other perspective will be displayed in the image lines of the other perspective simultaneously with the display of the one perspective. Such display of the lines is implemented by the switch unit 21 , which is controlled by horizontal synchron signals.

The active 3D-glasses 25 are preferably controlled by the glasses-control- unit 24 comprising a part of the ghost image filter 20, issuing the CS_L control signal relative to the left eye as well as the CSR control signal relative to the right eye on the basis of the horizontal synchron signal. The glasses-control unit 24 may also derive the control from the horizontal synchron signal, which option is indicated by an intermittent line.

The intensity of ghost image filtering is controlled by potentiometers 23. By fine overtuning of the filter, extra three-dimensional effect can be obtained. In the case of LCD monitors, the degree of ghost image filtering is advisably set higher in the top and bottom areas of the display.

Fig. 7 is a block diagram of another preferred embodiment of the ghost image filter. This embodiment is advantageous relative to the already-described color multiplexing 3D-glasses. The additional potentiometers 26 comprised by the embodiment are optional; thereby any possible color distortions of the color 3D- glasses can be compensated. In case of color multiplexing solutions, color blocking may possibly affect the various colors differently in the course of color blocking. In case of DLP projectors, color distortion may comprise a problem as well. Theoretically, color correction may be achieved by tuning the various setting options of the image-forming device, however, it may also affect the ghost-filtered image, as well as both the eyes. It is advisable, therefore, to arrange a modulating option on the control electronics.

In a given case, the characteristics of the ghost image filter may also be tuned. In ghost image filtering, in a basic case, the inverse image is generated linearly; certain cases however may require - instead of generating a linear inverse of the original image - that certain pixels of the inverse image be given some weight in view of illumination power. The relevant characteristic curve mainly depends on the parameters of the given display. In the various areas of the display (depending upon the total block phase), the ideal curve may also vary. The desired characteristics may also differ with regard to the various colors; moreover, in an extreme case it may also be possible that e.g. more intense ghosting occurs in the left eye than in the right eye, in which case the respective ideal curves may differ relative to the two eyes. The curve may be tuned by means of software or hardware, as well.

The ghost image filter can be advantageously calibrated according to the present invention so that both eyes are connected to the same control (e.g. the left lens receives the signal of the right lens as well), then tuning of the ghost image filter is completed in regard to a test image as long as the image does not disappear.

Ghost image filtering is advisably implemented in a way that it is set for the various colors independently, and is tuned for the two eyes separately.

Ghost image filtering of the present invention is applicable not only in respect of polarizing color-multiplexing solutions, but also in respect of any other systems providing three-dimensional view. With regard to the apparatus and 3D- glasses comprising parts of the present invention, implementation of ghost image filtering is of extreme importance since rotation of the polarization may be incomplete, thereby ghost image is easily generated. The invention is not limited to the exemplary embodiments described herein, but shall also include any possible further variations within the scope of the claims. In the exemplary embodiments presented herein, the adjustable display parameters are

- the synchronicity of the perspective-separating device, and/or - duration and synchronicity of the phase blocking display for both eyes, and/or

- switch-off time within a period of blocking of the individual eyes, or the switch-on time within the period, and/or

- the rate of ghost image filtering. The invention is not limited to these parameters only, but also applies to any other display parameter that may require adjusting.

Claims

1. An apparatus for generating a three-dimensional view, comprising

- an image-forming device (10) for displaying visual information corresponding to a first perspective and visual information corresponding to a second perspective, and

- a perspective-separating device (11) comprising a first part (11a) separating the visual information corresponding to a first perspective for a first eye and a second part (11a) separating the visual information corresponding to a second perspective for a second eye, wherein the perspective-separating device (11) separates the visual information by means of different light transmitting behaviors of the two parts (11a, 11b), c h a r a c t e r i z e d in that its perspective-separating device (11) also has an operational phase for adjusting at least one display parameter, said operational phase exhibiting identical light transmission behaviors in the two parts (11a, 11b) of the perspective-separating device (11).

2. The apparatus according to claim 1, characterized in that the light transmission behavior is the periodic blocking of light admittance of the two parts (11a, 11b).

3. The apparatus according to claim 2, characterized in that the periodic blocking relates to one spectral component of light admittance only.

4. The apparatus according to claim 1, characterized in that light transmission behavior is the permanent blocking of one spectral component of light admittance of the parts (11a, 11b).

5. The apparatus according to claim 1 , characterized in that the at least one display parameter is - the synchronicity of the perspective-separating device (11 ), and/or

- the duration and synchronicity of a phase blocking the display for both eyes, and/or

- the switch-off time or the switch-on time of the eyes within the period, and/or

- the rate of ghost image filtering.

6. 3D-glasses for an apparatus generating a three-dimensional view, c h a r a c t e r i z e d in that it is a perspective-separating device (11) in an apparatus according to any of claims 1 to 5.

7. A method for generating a three-dimensional view, comprising the steps of displaying visual information corresponding to a first perspective and visual information corresponding to a second perspective, and the visual information corresponding to the first perspective is separated for a first eye by means of a first part (11a) of a perspective-separating device (11) and the visual information corresponding to the second perspective is separated for a second eye by means of a second part (11b) of the perspective-separating device (11), wherein separation of the visual information is carried out by means of different light transmission behaviors of the two parts (11a, 11b), c h a r a c t e r i z e d in that an operational phase is generated for adjusting at least one display parameter, the operational phase exhibiting identical light transmission behaviors in the two parts (11a, 11b) of the perspective-separating device (11).

8. The method according to claim 7, characterized in that the light transmission behavior is the periodic blocking of light admittance of the two parts (11a, 11b).

9. The method according to claim 8, characterized in that the periodic blocking relates to one spectral component of light admittance only.

10. The method according to claim 7, characterized in that light transmission behavior is the permanent blocking of one spectral component of light admittance of the parts (11a, 11b).

11. The method according to claim 7, characterized in that the at least one display parameter is

- the synchronicity of the perspective-separating device (11), and/or

- the switch-off time or the switch-on time of the eyes within the period, and/or - the rate of ghost image filtering.

12. The method according to claim 11, characterized in that at least one display parameter can be adjusted differently in various parts of an image displayed by the image-forming device (10).

13. The method according to claim 11 , characterized in that a spatial placement of the perspective-separating device (11) is detected and the display parameters are adjusted accordingly, in a dynamic way.