HUP0800501A2 - Device, methods and 3d spectacles for producing stereoscopic sight - Google Patents

Description

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6507R

PUBLICATION COPY

P080050 1

Apparatus for producing 3D vision, and methods and 3D glasses therefor

The invention relates to a device for producing a three-dimensional view, as well as methods therefor and 3D glasses, which are based on the color separation principle for producing a stereo image, but still enable the production of a three-dimensional view without color limitations.

The goal of 3D imaging is to be able to make spatial forms appear real to the user. The spatial effect can be achieved by delivering separate images to the left and right eyes, in accordance with the way the eyes themselves perceive spatial forms from separate positions. Various technologies have been developed to produce and perceive this double image (so-called stereo image). In the simplest case, the image is displayed simultaneously to both eyes on a conventional monitor and the spatial effect can be perceived with the help of special glasses. However, there are also complex and extremely expensive screens that do not require the aforementioned glasses or other aids, but the screen itself provides the spatial view.

One of the simplest and most common solutions is a system based on the separation of images displayed in one place. Such systems are based on the principle that the image intended for the right and left eyes is displayed simultaneously on a display, and these two images are separated by special so-called 3D glasses in such a way that only the image intended for the left eye is transmitted through the left lens, and only the image intended for the right eye is transmitted through the right lens.

The essence of the known 3D displays based on color separation is that a different color image is produced for the left and right eyes, and the two different color images are separated by colored lenses. For this purpose, red and blue (or cyan, which is a mixture of blue and green) lenses are usually used. Only red light passes through the red lens, and only blue light passes through the blue lens (anaglyph glasses). The advantage of the color separation system is that it is extremely cheap, but the disadvantage is that it is harmful after 10-15 minutes of use.

-2 can be on the eye, and it cannot provide a 3D view without color restrictions.

The essence of systems based on light polarization is that they produce differently polarized images for the left and right eyes, and the two images with different polarities are separated by polarizing lenses. In contrast to systems based on color separation, systems based on light polarization are able to reproduce a colorful, completely realistic image. Although the production cost of such glasses is relatively low, the screen that produces a stereo image polarized in two directions is relatively expensive, so this solution has spread mainly in 3D cinemas.

Systems based on the use of so-called shutter glasses work by displaying the image alternately for the left and right eyes, and the shutter glasses alternately cover one or the other eye in sync with the image change. Shutter glasses have lenses that can darken and let light through at high frequencies. Like the system based on light polarization, the shutter glasses system is also capable of reproducing a colorful, completely realistic image. Its advantage is that it is relatively inexpensive, and - unlike the system based on light polarization - a conventional cathode ray tube monitor can be used as a screen. However, the disadvantage of shutter glasses is that they alternately cover the left and right eyes, which causes the image seen through the glasses to flicker.

The vibration depends to a large extent on the difference in brightness between the individual states. If black and white states alternate, the vibration is much stronger than if two tones of similar brightness alternate. For this reason, solutions have been created in which the two states of the glasses are not complete coverage and complete light transmission, but two colors that are also used by anaglyph glasses. The given perspectives are separated for the eyes by polarization. In this case, the two above-mentioned disadvantages of anaglyph glasses do not occur, that the illusion obtained is limited in colors, and the user perceives the image in different colors with both eyes, which is harmful to health if used for a long time. The image will not be limited in colors, because the two states of the glasses' lens are complementary colors to each other, so the colors that do not pass through in one period pass through in the next. The two eyes

-3 sees the images in the same color. The resulting vibration is also dramatically reduced, since the image is never completely obscured at any moment, and the brightness contrast between the vibration states is minimized. Such solutions are described, for example, 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 polarization color multiplexing solutions.

The disadvantage of the known solutions is that they require the use of extremely complex imaging devices and are not suitable for providing 3D display even with simple, everyday displays. Another problem is that the known solutions do not provide the possibility to filter ghost images that occur during color transitions, or they cannot be applied to displays that refresh the image pixel by pixel. Another known shortcoming is that 3D solutions are less applicable to LCD or similar refresh rate displays, or they result in a very high degree of flicker.

The aim of the invention is to create a device and method for producing a three-dimensional view, and to create 3D glasses associated therewith, which are free from the disadvantages of the prior art solutions and can be implemented with relatively simple elements and at low cost. A further aim of the invention is to create a device, method and 3D glasses that can be implemented at low cost and which also enable ghosting, result in less flickering, and are suitable for use in pixel-by-pixel refresh displays, e.g. LCD (e.g. TFT) monitors.

The objects of the invention are achieved by the device according to claim 1, the 3D glasses according to claims 15, 23 and 25, and the methods according to claims 27, 35 and 41. Preferred embodiments are defined in the subclaims.

Preferred embodiments of the invention are described hereinafter with reference to the drawings, in which:

Figure 1 is a diagram of an apparatus according to the invention,

Figure 2 is a control time diagram of the elements of the equipment according to Figure 1,

Figure 3 is a diagram of another device according to the invention, the

Figure 4 is a control time diagram of the elements of the equipment according to Figure 3,

Figure 5 is a diagram of a third device according to the invention,

Figure 6 is a control time diagram of the elements of the equipment according to Figure 5,

Figure 7 is a schematic diagram of a third device according to the invention, comprising passive 3D glasses,

Figure 8 is a diagram of the time course and effect of the full masking phase,

Figure 9 is a block diagram of a ghost filter according to the invention, and

Figure 10 is a block diagram of a ghost filter according to another embodiment of the invention.

Monitors produce the displayed image from three colors. These are red, green, and blue. Anaglyph, or color separation glasses, can use any color combination where the two lenses do not contain the same color. The most common anaglyph glasses are red-cyan. The red lens lets the light from the monitor's red pixels through, and the cyan lens lets the light from the monitor's green and blue pixels through. This has three advantages. The first is that it reaches the eyes, so all three primary colors can be perceived. The second is that the two colors are located at opposite ends of the light spectrum, so it is easier and better to separate the images than if we were to choose green and the complementary color of green. The third is that the difference in light intensity that the human eye perceives between the two eyes is smaller than if we were to choose the other yellow-blue solution, which has the advantages listed so far. In the solution according to the invention, the basic criteria for selecting colors are the same: the two colors together contain all three primary colors, the images should be separated as much as possible, the light intensity contrast between the two colors that can be perceived by humans should be as small as possible; for this reason, the ideal choice for the glasses according to the invention is red-cyan, which we will use in the further description, but the invention works for other colors, i.e. other spectral components of the visible spectrum as well.

The device according to the invention is used for generating a three-dimensional view, where image information corresponding to a first perspective and image information corresponding to a second perspective comprise at least a first and a second spectral component, preferably consisting of red and cyan components.

-5With the image forming device 10 shown in Figure 1, preferably an LCD monitor, images containing the first spectral component of the first perspective and the second spectral component of the second perspective, and images containing the second spectral component of the first perspective and the first spectral component of the second perspective are alternately displayed.

According to the invention, a perspective separation device 11 is used, which comprises a first part 11a separating the displayed spectral components of the first perspective for a first eye by polarization and a second part 11b separating the displayed spectral components of the second perspective by polarization for a second eye.

The perspective separation device 11 according to the invention comprises in both parts 11a, 11b a first PR polarizing filter acting on the first spectral component, this is for example the red polarizing filter, and a second PC polarizing filter acting on the second spectral component, this is preferably the cyan polarizing filter. The second PC polarizing filter has a polarization direction different from the polarization direction of the first PR polarizing filter, preferably perpendicular to it according to the figure. The perspective separation device 11 further comprises a polarization rotating device 12, which is operated synchronously with the image forming device 10 to separate the perspectives for the given eyes, and which alternately switches the polarization of the light emerging from the image forming device 10 between the polarization directions of the first and second PR, PC polarizing filters.

The LCD monitor emits polarized light. The image on the monitor for both eyes is thus produced in such a way that when the left eye lens is red and the right eye lens is cyan, the red pixels on the monitor show the image intended for the left eye, and the green and blue pixels show the image intended for the right eye. When the eye lenses switch, the same thing happens, only in reverse.

If we change the state of the lenses after each state at the frequency of the monitor, then all colors reach our eyes, we get 3D glasses without color limitations, which have much less vibration than shutter glasses. We can change the lenses much less often, for example every half or a minute. In this case, we get glasses that have no vibration at all, are just as limited in colors as anaglyph, but do not tire the eyes as much,

-6because it does not statically distort colors in one direction for the eyes, and the eyes have the opportunity to regenerate.

The operation of polarizing filters acting on individual spectral components (colors) is as follows. Each polarizing filter has a function that shows how efficiently it can polarize light rays of a given wavelength. This efficiency is most often highest in the wavelength range of light visible to the human eye. The glasses according to the invention use polarizing filters that do not polarize the entire spectrum visible to the human eye, but only a part of it, preferably red or cyan light. This polarizing filter, for example, when polarizing red light, completely transmits the cyan range, and only half of the red due to polarization. The theoretically perfect PR polarizing filter polarizes red light has a light transmittance of 100% in the cyan range, 50% in the red range, and appears slightly cyan in appearance. In the case of two crossed polarizing filters, if one polarizes red light and the other polarizes the entire visible range, the light transmission in the cyan range is 50% and in the red range is 0%. The opposite is true for a PC polarizing filter that polarizes cyan light.

In Figure 1, it can be seen that the first PR polarizing filter is arranged in the second part 11b with a polarization direction parallel to the polarization direction of the first PR polarizing filter arranged in the first part 11a of the perspective separating device 11, and as shown in Figure 2, the polarization rotating device 12 operates in antiphase with respect to the two parts 11a, 11b. Of course, the opposite of this is also conceivable, when the corresponding polarizing filters in the parts of the perspective separating device 11 are arranged with polarization directions perpendicular to each other; in this case, the polarization rotating device 12 operates in the same phase with respect to the two parts 11a, 11b.

According to the invention, one or more LCD panels are preferably used as polarization rotating means 12. When the LCD panels are off, they rotate the plane of polarization by 90°, and when they are on, i.e. when an electric current is applied, they allow light to pass through without rotation. If an LCD panel is placed between two polarizing filters placed at the appropriate angle, we obtain an LCD shutter that can allow or block light when an electric current is applied. If light polarized over the entire visible spectrum is projected onto an LCD panel and the other side of the panel is

-7If we place a polarizing polarizing filter in the red and cyan regions perpendicular to the polarization direction, we get a chip that can be switched between transmitting red and cyan light under the influence of an electric current.

According to the invention, the three-dimensional view can be achieved with a single LCD chip (or one LCD chip per eye) as a polarization rotation device 12, but the switching preferably also includes a phase blocking the display for both eyes. For this, in the polarization rotation device 12, the light passes through two polarization rotation elements LCD1, LCD2, preferably two LCD chips. The advantages of this will be mentioned in connection with Figure 8.

As shown in Figure 1, the polarization rotating elements LCD1, LCD2 enclose the first and second PR, PC polarizing filters, and in the direction of light propagation, after the second LCD2 polarization rotating element, an additional PF polarizing filter with the same polarization direction as one of the PR, PC polarizing filters, acting on both spectral components, or preferably acting on the entire (full) spectrum, is arranged.

The control diagram of the device shown in Figure 1 is illustrated in Figure 2. Due to the identically designed (polarizing filter orientation) parts 11a, 11b, the polarization rotating elements LCD1, LCD2 must be operated in antiphase for perspective separation. At the top (DISPLAY) is the control of the image forming device 10, i.e. preferably an LCD monitor, on which REDbai+CYANbetter and CYANbetter+REDbetter images are alternately displayed; this is indicated by the states R+C and C+R in the figure. The indicated time period T is the frequency of the monitor.

The middle bar shows the control of the polarization rotating elements LCD1 and LCD2 in section 11a, and the bottom bar shows the control of the polarization rotating elements LCD1 and LCD2 in section 11b. The sequence displayed by section 11a for the left eye is shown at the top of section 11a, where R represents the red image, B represents the black image, and C represents the cyan image. The sequence displayed by section 11b contains the red and cyan images in antiphase, so the perspective separation function is implemented with the illustrated control. In this case, three states of a lens are possible: red, cyan, and black.

Figure 3 shows another advantageous embodiment of the invention, in which the polarization rotating elements LCD1, LCD2 enclose one of the PR polarizing filters, and the other PC polarizing filter is arranged after the second LCD2 polarization rotating element in the direction of light propagation. The polarization rotating device 12 is used in this embodiment

In the case of the -8 shape, there are two LCD panels per eye. The control of this embodiment is shown in Figure 4. In this case, four states of the lens are possible: red, cyan, black, and transparent (the latter is not created during operation, but may be useful when turned off).

Figure 5 shows a diagram of a further possible arrangement, and Figure 6 shows its control. The advantage of this embodiment is that the first LCD1 polarization rotating element can also be a so-called pi-cell LCD, which has better switching properties. Here, the LCD1, LCD2 polarization rotating elements are arranged in front of the first and second PR, PC polarizing filters in the direction of light propagation, and they enclose an additional PF polarizing filter with the same polarization direction as one of the PR, PC polarizing filters, acting on both spectral components.

Among the embodiments 1, 3 and 5, it is worth choosing the one for a given application in which the quality of the polarizing filters and the LCD chips results in a better level of operation. The advantage of the embodiment shown in Figure 1 is that the separation efficiency is higher, but during operation the background for the user alternates between red and cyan colors. The embodiment according to Figure 3 has a weaker separation but a static background. The embodiment shown in Figure 5 is similar to the embodiment shown in Figure 1, with the difference that here the polarization rotating element LCD1 - which can also be a fast pi cell LCD - switches the full blanking phase, and during the full blanking phase the polarization rotating element LCD2 has more time to switch. However, the embodiment shown in Figure 1 does not require such a high switching speed as in the case of the polarization rotating element LCD1 of the embodiment according to Figure 5. The decision between the embodiments can therefore be made based on the efficiency of the separation in the given application, the ability to compensate for the imperfection of the separation, the external lighting conditions of the application, and the switching speed of the LCD panels.

In the embodiments shown in Figures 1, 3 and 5, the image forming device 10 is an LCD monitor that inherently emits polarized light, and the perspective separating device 11 is designed in the form of active 3D glasses. In the case of non-polarizing monitors, the monitor must be equipped with a separate polarizing filter to implement the system, or a separate polarizing filter must be placed in front of the lenses.

An important aspect of the invention is therefore that the polarization receiving device 10 that receives polarized light and alternately switches its polarization 12 • ♦ ·· ·· « · * : .· .··. .· : ·

-9 has a rotating device. In other words, this means that the external polarizing filter has been removed from the state-of-the-art active 3D glasses operating on the polarization principle and placed on the display (this is a given in LCD monitors). In this way, during the operation of the active 3D glasses, there are only image transitions on the display and the background is stable (possibly changing red-cyan colors). This greatly reduces the feeling of flicker.

The 3D glasses without an external polarizing filter can also be used as passive glasses; in this solution, the left and right parts of the 3D glasses must be placed in opposite positions. This is advantageous if the glasses are intended to be used in both a universal, active and passive form.

On the other hand, as shown in Figure 7, the polarization rotating device 12 may also be arranged at the image forming device 10, for example at the projector 13, and then the first and second parts 11a, 11b of the perspective separating device 11 may be designed in the form of passive 3D glasses.

We can also make passive glasses with colored polarizing filters. To do this, we need to create a screen that can change the direction of polarization. In the case of a linear polarizing filter, the two polarization states of the screen are perpendicular to each other. Both lenses of the passive glasses have red and cyan PR, PC polarizing filters perpendicular to each other, and the left lens is perpendicular to the right lens, so the red PR polarizing filter of the left lens is parallel to the cyan PC polarizing filter of the right lens and the cyan PC polarizing filter of the left lens is parallel to the red PR polarizing filter of the right lens. In this arrangement, in one polarization state of the screen, the cyan of the left lens is the right red, and in the other, the left red is the right cyan.

Such a screen can be produced, for example, by projection, for which it is advisable to place an LCD panel in front of a DLP projector. If we produce the image with the projector 13 in the manner described above, and control the LCD panel synchronously with the projector 13, and use the polarization-maintaining screen 14, the desired screen is created. With such a solution, we can achieve similar image quality with a simple 85 Hz DLP projector as with the most professional projectors specially designed for 3D.

The invention can also be used in the case of LCD projectors. In the case of LCD projectors, a complete blanking phase may also be necessary. In this case, an additional LCD panel

-10 can be placed in front of the projector and the original LCD panel, and another polarizing filter. This additional LCD panel can block the projector image under the influence of current, so we can reach the complete blocking phase. In this case, the glasses can have three states: left red, right cyan; left cyan, right red; left black, right black.

If we want to use passive glasses, but not with a projection display, or with a projection display, but with an image projected from behind onto a depolarizing screen, then we can use an LCD panel that completely covers the screen to produce the polarizing image in the opposite direction. Here too, it is possible to use one or two LCD panels, depending on whether the complete blocking phase is needed.

In DLP projectors, the invention can be applied in accordance with another preferred embodiment. In the previous embodiments, the spectral components were the red and cyan components of the image information, and during the display of an image, the spectral components were displayed simultaneously. In DLP projectors, the image is displayed in such a way that the colors, i.e. the R, G, B spectral components, appear one after the other within an image display period. First, a red, then a green, then a blue image appears, but our eyes perceive this together due to the high frequency. The essence of this embodiment of the invention is that the shutter glasses or other previously described invention glasses change state several times within an image display period. For example, it is advantageous if the glasses change state three times within an image display period. In this case, the vibration is dramatically reduced, since the frequency increases three times, and all the colors of the image still reach the eyes during two image display periods. In this case, the image for the left and right eyes must be prepared and then sent to the projector in such a way that the different colored components of the color image represent different perspectives, depending on the state of the glasses. The operation of the embodiment is illustrated in Table 1.

Sent image Projector Left lens Image seen during the display period Picture seen Right lens Image seen during the display period Picture seen Rb, Gj, Bb R Passes R&B R+G+B Cover G R+G+B G Cover Passes B Passes Cover Rj, Gb, Bj R Cover G Passes R&B G Passes Cover B Cover Passes

Table 1

For example, if our shutter is capable of a slower frequency, it may also be advantageous to only change the state of the glasses every two color changes. This is illustrated in Table 2.

Sent image Projector Left lens Picture seen Right lens Picture seen Rb, Gb, Bj R Passes R+G R+ 2G+ B 2R+ 2G+ 2B Cover B R+ B 2R+ 2G+ 2B G Passes Cover B Cover Passes Rj, Gb, Bb R Cover G+B Passes R G Passes Cover B Passes Cover Rj, Gj, Bb R Cover B R+ B Passes R+G R+ 2G+ B G Cover Passes B Passes Cover Rb, Gj, Bj R Passes R Cover G+B G Cover Passes B Cover Passes

Table 2

-12A DLP projector system can be implemented with both active and passive glasses. In the active case, we can use traditional shutter glasses or an arrangement already described that includes the front polarizing filter on the image forming device. In the passive case, we can also use traditional polarized glasses. In this case, an active polarizing filter must be placed in front of the projector, which alternately changes the direction of polarization. This can be, for example, an LCD chip or a mechanical structure equipped with polarizing filters.

The red-cyan color scheme with a DLP projector - in the case of traditional shutter glasses control - is not advantageous because we only achieve that we shift the vibration by a third of the period, but the vibration remains the same. This is illustrated in Table 3.

Projector R G B R G B R G B R G B R G B R G B Glasses red cyan red cyan red cyan Picture shown X X X X X X X X X

Table 3

In addition to the above, a solution to reduce vibration is to shift the glasses control according to Table 4.

Projector R G B R G B R G B R G B R G B R G B Glasses red cyan red cyan red cyan red Picture shown X X X X X X X X X

Table 4

Another solution is to use other colors for color filtering, as shown in Table 5.

Projector R G B R G B R G B R G B R G B R G B Glasses R&B G R&B G R&B G Picture shown X X X X X X X X X

Table 5

-13For both passive and active 3D glasses, we can use linear and circular polarizing filters. For active glasses, we must take into account that LCD monitors emit linearly polarized light. For circularly polarized passive glasses, we must put red and cyan polarizing filters polarized in opposite directions in the left and right lenses so that the red polarizing filter of the left lens is polarized in the same direction as the cyan polarizing filter of the right, and the cyan polarizing filter of the left is polarized in the same direction as the red polarizing filter of the right.

LCD monitors operate at a lower refresh rate than CRT monitors, so we can perceive more flicker when using 3D glasses. In addition to this, in known solutions, the flicker is further increased by the fact that 3D glasses usually flicker the entire field of view, i.e. also the areas outside the display. An important part of the invention is to reduce the disturbing effect of flicker in such a way that the 3D glasses only cause the switching of the view on the image forming device 10, i.e. preferably on the LCD monitor, while the rest of the field of view remains static. This is essentially achieved by moving the polarizing filter from the side facing the image forming device 10 to the image forming device 10 from the 3D glasses used in known solutions - in which a polarizing filter is arranged on both sides of the LCD panel (in the case of LCD monitors with inherently polarized light emission, this polarizing filter is not needed). This preferred arrangement characterizes all embodiments of the invention and has proven to be extremely advantageous in practical applications.

The above-mentioned full blanking phase is advantageous when the two images are simultaneously visible on the display for a while during the image refresh. For example, in the case of LCD monitors, the update is done pixel by pixel, i.e. the pixels of the previous image are replaced by the new pixels on the display one by one. In the case of LCD monitors, therefore, some image is always visible on the display surface.

This means that if we use traditional shutter glasses and synchronous control with an LCD monitor, the image at the top of the monitor will still be good, 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.

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-14, but moving towards the bottom of the monitor this is gradually exchanged, so that a proper stereo image is only seen in the narrow upper few rows of the monitor. The control electronics according to the invention therefore not only performs the state change of the left and right eyes, but also applies a full masking phase, as shown in Figures 2, 4, 6 and 8, when it masks both eyes. While the monitor is updating the screen, or a large part of it, the controller of the 3D glasses 25 switches on the full masking, so that the range where the user does not see a stereo image can be narrowed down to a few rows of the screen. If we shift the synchronization rate appropriately, we can distribute these few rows at the top and bottom of the screen.

The complete masking phase can be achieved in the case of color multiplexing with an additional LCD chip per eye and its appropriate control, as described above.

The first row of Figure 8 shows the cycle when the left eye is red (R) and the right eye is cyan (C). The 3D glasses 25 are in the R+C state between the first two monitor displays, and then after the next image begins to be updated in the main, central area of the monitor, the 3D glasses 25 switch to the full blanking phase. This gives the user the view shown on the right side of the figure, in which a stereo image is visible in the main part of the image, and only in the less used lower and upper bands the inverted stereo image appears. The result of the next cycle and blanking is shown in the bottom row of the figure.

The total masking phase is also part of the invention and can be used not only with polarization color multiplexing solutions, but also with any other systems that pose similar problems, for example with simple shutter glasses, or for example with shutter glasses without a front polarizing filter as already described.

According to the invention, dynamic full masking! phase control can also be implemented. By increasing the full masking! phase, the area where the stereo image quality is good increases, but the perceived brightness decreases. However, with the reduced perceived brightness, the vibration also decreases. There is always an optimal full masking! measure. It is therefore advisable to control its extent by software. For example, if an overall brighter image is displayed on the display, which would vibrate to a greater extent and is also clearly visible in darker conditions, then, for example, the full masking! can be increased

-15 degree of masking, thus finding an optimal compromise for the given new situation. Since the brightness of the monitor is usually not or only difficult to control by software, the above dynamic control can be a good solution for this as well. Another setting option is to adjust the position of the complete masking phase. Blocking is usually performed during the update of the image lines in the middle range of the LCD display. However, blocking can also be performed during the update of the image lines determined on the LCD display based on the displayed image information. In this case, if for some reason it is more important to see clearly in space at the top of the display than at the bottom, then the complete masking phase can be shifted towards the top of the monitor.

An important part of the invention is therefore a pair of 3D glasses for an image forming device 10 that alternately displays image information corresponding to a first perspective and image information corresponding to a second perspective in time, the operation of which image forming device 10 includes an image refresh period in which image information corresponding to both perspectives is at least partially visible, and the 3D glasses are designed to block the view during at least part of the image refresh period.

A common shortcoming of known 3D glasses is that the separation of the two images for the two eyes is not perfect, i.e. the left eye sees the image of the right eye to a certain extent and vice versa (ghost image). This results in the 3D effect often not being achieved for novice users and even for advanced users the distance at which the virtual objects are further removed from the monitor plane so that the user still perceives them in space decreases. The more ghostly the image, the more the quality of the view deteriorates and the less our brain is "tricked", i.e. the more it sees the shape in the plane of the display. The ghost image filter according to the invention prevents the image of the right eye from leaking into the left eye and the image of the left eye from leaking into the right eye, thus creating the 3D effect more easily and making the contrast in space more visible.

The degree of ghosting also depends on the quality and operating principle of the 3D display system. By reducing or eliminating ghosting, we can not only produce a better image, but also use a cheaper, lower quality 3D display for the given task.

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-16 The ghost image filter according to the invention operates by combining the image produced for one eye with the reduced intensity negative, inverse, of the image produced for the other eye and displaying it as such. Thus, a reduced intensity version of the negative of the image of the other eye is added to the images intended for each eye. The intensity of the negative image component must be adjusted to fully compensate for the ghost image that filters through.

Figure 9 shows a block diagram of an example! 20 ghosting filter for interleaved 3D. The 20 ghosting filter is designed to be installed between the computer and the monitor, but the ghosting filter function can also be implemented on the video card, for example, or the software can create such images from scratch.

The vertical sync signal received and output by the ghost filter 20 is denoted by VSin and VSout, and the horizontal sync signal is denoted by HSin and HSout. The RGB signals arriving at the ghost filter 20 are fed to the monitor via a switching unit 21. The incoming R| _N , Gin and B| _N signals are also fed to an inverter unit 22, with which the RGB inverse is produced - with an intensity adjustable by potentiometers 23 - and is also fed to the switching unit 21.

The ghost filter 20 is advantageously applicable in an interleaved display mode, in which the even and odd lines can be controlled separately. In this case, the image information corresponding to one perspective is preferably displayed in the even picture lines and the image information corresponding to the other perspective is displayed in the odd picture lines by the image forming device 10, and when displaying one perspective with the ghost filter 20, the negative image of the other perspective with reduced intensity is displayed in the picture lines of the other perspective. Such display of the lines is carried out by the switching unit 21 controlled by the horizontal sync signal.

The active 3D glasses 25 are preferably controlled by a glasses control unit 24, which is part of the ghost filter 20, and which outputs the left eye control signal CSl and the right eye control signal CSr based on the horizontal sync signal. The glasses control unit 24 may also derive the control from the horizontal sync signal, which is indicated by a dashed line.

The intensity of the ghosting filter can be adjusted with the potentiometers 23. By slightly over-extending the filter, an extra spatial effect can be achieved. In the case of an LCD monitor

-17It is advisable to set the ghosting level to be more intense at the top and bottom of the screen.

Figure 10 shows a block diagram of another preferred embodiment of the ghost filter 20. This embodiment is preferred in the case of the color multiplexing 3D glasses already described (Figures 1, 3, 5). The additional potentiometers 26 in the embodiment are optional; they can be used to compensate for possible color distortions of the color 3D glasses. In color multiplexing solutions, it is possible that the color masking does not affect the different colors equally. Color distortion can also be a problem in DLP projector solutions. Theoretically, color correction can be performed by adjusting the setting options of the image forming device, but in this case this affects the ghost filtered image and both eyes. It may therefore be advisable to provide the possibility of controlling these in the control electronics.

The characteristics of the ghosting filter can also be tuned if necessary. In ghosting filtering, the inverse image is usually generated linearly, but it may be justified not to generate the linear inverse of the original image, but to give some weight to the given pixels of the inverse image depending on the light intensity. The appropriate characteristic curve mainly depends on the properties of the given display. The ideal curve may be different in different areas of the display (depending on the total masking phase). The desired characteristic may also be different for different colors, and in extreme cases it may also happen that, for example, the left eye ghosts to a greater extent than the right, and in this case the ideal curve may be different for the eyes. The curve can be tuned in software or hardware.

The calibration of the ghosting filter 20 is preferably performed by switching both eyes to one eye (e.g. giving the left lens the signal of the right lens), then displaying a test pattern and tuning the ghosting filter until the pattern disappears.

It is advisable to implement ghosting filtering in a way that can be adjusted separately for colors and tuned separately for each eye.

Ghosting filtering is also part of the invention and can be applied not only to polarization color multiplexing solutions, but also to any other systems that produce a three-dimensional view. Part of the invention

Implementing ghosting filtering is particularly important for equipment and 3D glasses, as polarization rotations can be imperfect, so ghosting can easily occur.

Furthermore, the invention can be applied not only in connection with 3D display, but also in any system where different image information needs to be displayed for the two eyes, or in some cases, for the eyes of multiple users.

The invention is not limited to the exemplary embodiments shown, but further variations are possible within the scope of protection defined by the claims.

Claims (42)

-19Patent claims 1. An apparatus for generating a three-dimensional view, wherein image information corresponding to a first perspective and image information corresponding to a second perspective comprise at least a first and a second spectral component, and the apparatus comprises - an image forming device (10) for alternately displaying an image comprising a first spectral component of the first perspective and a second spectral component of the second perspective, and an image comprising a second spectral component of the first perspective and a first spectral component of the second perspective, the light emerging from the image forming device (10) being polarized, and - a perspective separation device (11) comprising a first part (11a) for separating the displayed spectral components of the first perspective by polarization for a first eye and a second part (11b) for separating the displayed spectral components of the second perspective by polarization for a second eye, characterized in that the perspective separation device (11) comprises - in both parts (11a, 11b) a first polarizing filter (PR) acting on the first spectral component and a second polarizing filter (PC) acting on the second spectral component, which has a polarization direction different from the polarization direction of the first polarizing filter (PR), and - a polarization rotating device (12) that alternately switches the polarization of the light emerging from the image forming device (10) between the polarization directions of the first and second polarizing filters (PR, PC) in synchronism with the image forming device (10), operating in a manner that separates the perspectives for the given eyes. 2. The device according to claim 1, characterized in that - the polarization directions of the first and second polarizing filters (PR, PC) are perpendicular to each other, - the first polarizing filter (PR) is arranged in the second part (11b) with a polarization direction parallel to the polarization direction of the first polarizing filter (PR) arranged in the first part (11a) of the perspective separating device (11), and - the polarization rotating device (12) operates in antiphase with respect to the two parts (11a, 11b). 3. The device according to claim 1, characterized in that - the polarization directions of the first and second polarizing filters (PR, PC) are perpendicular to each other, - the first polarizing filter (PR) is arranged in the second part (11b) with a polarization direction perpendicular to the polarization direction of the first polarizing filter (PR) arranged in the first part (11a) of the perspective separating device (11), and - the polarization rotating device (12) operates in the same phase with respect to the two parts (11a, 11b). 4. Device according to claim 2 or 3, characterized in that the switchings include a phase blocking the display for both eyes, and in the polarization rotating device (12) the light passes through two polarization rotating elements (LCD1, LCD2), preferably two LCD panels. 5. The device according to claim 4, characterized in that the polarization rotating elements (LCD1, LCD2) sandwich the first and second polarizing filters (PR, PC), and in the direction of light propagation, after the second polarization rotating element (LCD2), an additional polarizing filter (PF) with the same polarization direction as one of the polarizing filters (PR, PC) and acting on both spectral components is arranged. 6. The device according to claim 4, characterized in that the polarization rotating elements (LCD1, LCD2) sandwich one polarizing filter (PR), and the other polarizing filter (PC) is arranged after the second polarization rotating element (LCD2) in the direction of light propagation. 7. The device according to claim 4, characterized in that the polarization rotating elements (LCD1, LCD2) are arranged in front of the first and second polarizing filters (PR, PC) in the direction of light propagation, and they enclose a further polarizing filter (PF) with the same polarization direction as one of the polarizing filters (PR, PC), acting on both spectral components. 8. The device according to any one of claims 5-7, characterized in that the image forming device (10) comprises an LCD monitor, and the perspective separating device (11) is formed in the form of active 3D glasses (25). 9. The device according to claim 1, characterized in that the polarization rotating device (12) is arranged at the image forming device (10), and the first and second parts (11a, 11b) of the perspective separating device (11) are formed in the form of passive 3D glasses (25). 10. The device according to claim 9, characterized in that the image forming device (10) comprises a projector (13) or display covered with an LCD panel. 11. The device according to claim 1, characterized in that it has a ghost filter (20) which is designed to combine the image produced for one eye with the reduced intensity negative of the image produced for the other eye. 12. The apparatus according to claim 11, characterized in that it has an image forming device (10) for displaying image information corresponding to one perspective in the even image rows and image information corresponding to the other perspective in the odd image rows, and a ghost image filter (20) for displaying a reduced intensity negative image of the other perspective in the image rows of the other perspective when displaying one perspective. 13. The apparatus of claim 1, wherein the spectral components are red and cyan components of the image information, and the spectral components are displayed simultaneously during display of an image. 14. The apparatus of claim 1, wherein the spectral components are red, green and blue components of the image information, wherein the spectral components are displayed sequentially in time during display of an image. 15. 3D glasses, for an image forming device (10) for alternately displaying an image comprising a first spectral component of a first perspective and a second spectral component of a second perspective, and an image comprising a second spectral component of the first perspective and a first spectral component of the second perspective, wherein light emerging from the image forming device (10) is polarized, said 3D glasses (25) comprising a first portion (11a) for separating the displayed spectral components of the first perspective by polarization for a first eye and a second portion (11b) for separating the displayed spectral components of the second perspective by polarization for a second eye, wherein - in both parts (11a, 11b) it comprises a first polarizing filter (PR) acting on the first spectral component and a second polarizing filter (PC) acting on the second spectral component, which has a polarization direction different from the polarization direction of the first polarizing filter (PR), and - a polarization rotating device (12) is used to alternately switch the polarization of the light emerging from the image forming device (10) between the polarization directions of the first and second polarizing filters (PR, PC) in synchronization with the image forming device (10), operating in a manner that separates the perspectives for the given eyes. 16. 3D glasses according to claim 15, characterized in that - the polarization directions of the first and second polarizing filters (PR, PC) are perpendicular to each other, - the first polarizing filter (PR) is arranged in the second part (11b) with a polarization direction parallel to the polarization direction of the first polarizing filter (PR) arranged in the first part (11a), and - the polarization rotating device (12) operates in antiphase with respect to the two parts (11a, 11b). 17. 3D glasses according to claim 15, characterized in that - the polarization directions of the first and second polarizing filters (PR, PC) are perpendicular to each other, - the first polarizing filter (PR) is arranged in the second part (11b) with a polarization direction perpendicular to the polarization direction of the first polarizing filter (PR) arranged in the first part (11a), and - the polarization rotating device (12) operates in the same phase with respect to the two parts (11a, 11b). 18. 3D glasses according to claim 16 or 17, characterized in that the switchings include a phase blocking the display for both eyes, and the polarization rotating device (12) forms part of the 3D glasses and comprises two polarization rotating elements (LCD1, LCD2), preferably two LCD panels. 19. 3D glasses according to claim 18, characterized in that the polarization rotating elements (LCD1, LCD2) sandwich the first and second polarizing filters (PR, PC), and in the direction of light propagation, after the second polarization rotating element (LCD2), an additional polarizing filter (PF) with the same polarization direction as one of the polarizing filters (PR, PC) and acting on both spectral components is arranged. 20. 3D glasses according to claim 18, characterized in that the polarization rotating elements (LCD1, LCD2) enclose one polarizing filter (PR), and the other polarizing filter (PC) is arranged after the second polarization rotating element (LCD2) in the direction of light propagation. 21. 3D glasses according to claim 18, characterized in that the polarization rotating elements (LCD1, LCD2) are arranged in front of the first and second polarizing filters (PR, PC) in the direction of light propagation, and they enclose a further polarizing filter (PF) with the same polarization direction as one of the polarizing filters (PR, PC), acting on both spectral components. 22. The 3D glasses of claim 15, wherein the spectral components are the red and cyan (blue + green) color components of the image information. 23. 3D glasses for producing a three-dimensional view, comprising image information corresponding to a first perspective and image information corresponding to a second perspective. -24 for an image forming device (10) performing time-varying display of information, the operation of which image forming device (10) includes an image refresh period in which image information corresponding to both perspectives is at least partially visible, characterized in that the image refresh period is designed to block the view in at least a part of it. 24. 3D glasses according to claim 23, characterized in that they have the design according to any one of claims 15-22. 25. Active 3D glasses for producing a three-dimensional view for an image forming device (10) that alternately displays image information corresponding to a first perspective and image information corresponding to a second perspective in time, comprising 3D glasses (25) - a first part (11a) separating the first perspective by polarization for a first eye and a second part (11b) separating the second perspective by polarization for a second eye, and - a polarization rotating device (12) operated in synchronism with the image forming device (10) to separate the perspectives for the given eyes, characterized in that there is a polarization rotating device (12) receiving polarized light from the image forming device (10) and alternately switching its polarization. 26. Active 3D glasses according to claim 25, characterized in that they have the design according to any one of claims 15-22. 27. A method for generating a three-dimensional view, wherein image information corresponding to a first perspective and image information corresponding to a second perspective comprise at least a first and a second spectral component, and the method - an image comprising the first spectral component of the first perspective and the second spectral component of the second perspective, and the first perspective -25 an image containing the second spectral component and the first spectral component of the second perspective is displayed alternately with polarized light, and - the displayed spectral components of the first perspective are separated by polarization for a first eye and the displayed spectral components of the second perspective are separated by polarization for a second eye, characterized in that - a first polarizing filter (PR) acting on the first spectral component and a second polarizing filter (PC) acting on the second spectral component are used for both eyes, which has a polarization direction different from the polarization direction of the first polarizing filter (PR), and - in synchronism with the display, the perspectives are separated for the given eyes, the polarization of the displayed light is switched alternately between the polarization directions of the first and second polarizing filters (PR, PC). 28. The method of claim 27, characterized in that - the polarization directions of the first and second polarizing filters (PR, PC) for the same eye are perpendicular to each other, - the first polarizing filter (PR) for the other eye is arranged with a polarization direction parallel to the polarization direction of the first polarizing filter (PR) for one eye, and - the switching is performed in antiphase for the two eyes. 29. The method of claim 27, characterized in that - the polarization directions of the first and second polarizing filters (PR, PC) for the same eye are perpendicular to each other, - the first polarizing filter (PR) for the other eye is arranged with a polarization direction perpendicular to the polarization direction of the first polarizing filter (PR) for one eye, and - the switching is performed in the same phase for both eyes. 30. The method according to claim 28 or 29, characterized in that a phase blocking the display for both eyes is inserted between the switchings. 31. The method of claim 30, characterized in that ghosting is performed, during which the image produced for one eye is combined with a reduced intensity negative of the image produced for the other eye. 32. The method according to claim 31, characterized in that the image information corresponding to one perspective is displayed in the even image rows, the image information corresponding to the other perspective is displayed in the odd image rows, and when displaying one perspective, the reduced intensity negative image of the other perspective is displayed in the image rows of the other perspective. 33. The method of claim 27, wherein the spectral components are red and cyan components of the image information, and the spectral components are displayed simultaneously during display of an image. 34. The method of claim 27, wherein the spectral components are red, green and blue components of the image information, wherein the spectral components are displayed sequentially in time during display of an image. 35. A method for producing a three-dimensional view for an image forming device (10), wherein the image forming device (10) alternately displays image information corresponding to a first perspective and image information corresponding to a second perspective in time, and in order to produce the three-dimensional view, the perspectives are separated for the given eyes and projected into the eyes, the operation of the image forming device (10) includes an image refresh period in which image information corresponding to both perspectives is at least partially visible, characterized in that projection into the eyes is blocked during at least a part of the image refresh period. 36. The method according to claim 35, characterized in that the image forming device (10) is an LCD display, preferably an LCD monitor. 37. The method of claim 36, characterized in that the blocking is performed during the updating of the image rows in the central region of the LCD display. 38. The method of claim 36, characterized in that the blocking is performed during the updating of image sequences determined on the LCD display based on the displayed image information. 39. The method according to claim 35, characterized in that the length of the blocking period is dynamically changed, preferably in such a way that the length of the blocking period is increased when a brighter image is displayed, and the length of the blocking period is reduced when a darker image is displayed. 40. The method of claim 35, wherein the blocking is also used to adjust the sensed brightness of the imaging device (10). 41. A ghosting method for a system for producing a three-dimensional view, in which image information corresponding to a first perspective and image information corresponding to a second perspective are displayed, characterized in that the ghosting is performed by combining and displaying the image information corresponding to one perspective with a reduced intensity negative of the image information corresponding to the other perspective. 42. The method according to claim 41, characterized in that the image information corresponding to one perspective is displayed in the even image rows, the image information corresponding to the other perspective is displayed in the odd image rows, and when displaying one perspective, the reduced intensity negative image of the other perspective is displayed in the image rows of the other perspective.