WO1984000825A1

WO1984000825A1 - Method of recording and reproducing visual information for three-dimensional reproduction, apparata for recording and reproducing three-dimensional pictures

Info

Publication number: WO1984000825A1
Application number: PCT/HU1983/000041
Authority: WO
Inventors: Laszlo Schuler
Original assignee: KISUEZEMI INNOVACIOS IRODA
Current assignee: KISUEZEMI INNOVACIOS IRODA
Priority date: 1982-08-09
Filing date: 1983-08-09
Publication date: 1984-03-01
Anticipated expiration: 1986-02-09
Also published as: JPS59501964A; EP0115519A1

Abstract

Method of recording visual information for three-dimensional reproduction, a method of three-dimensional projection in picture transmission, an apparatus for recording three-dimensional pictures and an apparatus for projecting stereoscopic pairs of lantern slides. The essence of the invention is that a first-type and a second-type image corresponding to left eye and right eye information are recorded or reproduced in a weighted number or/and with weighted light intensity in order to materially enhance illusion of three-dimensional projection.

Description

METHOD OF RECORDING AND REPRODUCING VISUAL INFORMATION FOR THREE-DIMENSIONAL REPRODUCTION APPARATA FOR RECORDING AND REPRODUCING THREE-DIMENSIONAL PICTURES.

The invention relates to a method of recording visual information for three-dimensional reproduction thereof and a method of reproducing three-dimensional pictures in picture transmission systems, wherein images of first and second types are used according to left eye and right eye information. The invention relates further to apparata for reproducing visual information in a way as to ensure illusion of three- dimensional projection. The methods and apparata according to the invention may be used in any link of a picture transmission chain using traditional photosensitive or electromagnetic carrier of information and obeying shooting, recording, playing back and reproducing images. They render reproduction of still pictures possible in a way whereby the illusion of a three-dimension image can be enhanced.

The prior art includes some different methods of reproducing visual information in a way as materially to enhance the illusion of depth. The best of them are the holographic techniques, however, the technical problems linked with them are not sufficiently solved as far.

One of the traditional solutions is the method of polarised light or of anaglyph reproducing whereby light polarised perpendicularly or complementary colours are applied for projecting two images of a picture. The images should be observed by means of spectacles made of special material or of complementary colour. These methods require sophisticated techniques of recording and carrying spectacles makes observation inconvenient. Another possibility of projecting with illusion of depth is disclosed in the T S-PS 3,963,332 issued on June 15, 1976 to Stewart L. Sheldon et al. The method described is based on a special film prepared for example according to the US-PS 3,019,698 issued on February 6, 1972 also to Stewart L. Sheldon. The adjacent frames of the film strip correspond to right and left eye images (the left eye image will be further called first-type image and the right eye image second- type image). The film strip is forwarded before respective inputs of a two-way optical system built-up with prisms for separating the light ways. Prom the outputs of the optical system the images are projected to a given place. The projector of the identified patent comprises shutter means for interrupting always one of the light ways, and a shutter disc for relatively high frequency interruption. This solution has the dis advantage that the projector has a complicated construction and before projecting requires adjusting with high accuracy in order to have the two images projected on the same surface.

The invention is directed on avoiding the disadvantages of the know solutions of ensuring illusion of three-dimension images.

The invention is based on the recognition that the principle of time-sharing recording and projection being outlined vaguely from, but uncompletely realised in the above identified U.S. patent is very advantageous in shooting, recording, projecting and reproducing three-dimension images. This principle and the recognition can be recapitulated as follows:

1) The first-type image corresponding to the left eye image and the second-type image corresponding to the right eye image should be reproduced in the same place and in that way that the corresponding points of the image should be realised by means of light beams meeting one another on this common place of a screen.

The two types of images should not have the same duration, an altering reproduction of frames thereof is possible, however, it is not necessary. The durations can be different in dependence on the character of the image and on other requirement. This means that in the filmstrip may comprise a different number of frames of different type images. Experience shows that at most six frames of given type image may be included in a series thereafter the frames of other type image should be projected if applying traditional speed of projecting frames.

2) The illusion of depth in the viewer of the projected image may be very good also in the case when the two types of images are separated by images of disappearing type having decreasing light intensity, i.e. the light intensity of an image of given type will be decreased to zero during projection of some frames, and thereby the illusion of overlapping of the images will be assured by means of light intensity. Another advantageous possibility of making use of the light intensity is that first- and second-type images are projected in a time-proportion 1:3, however, the image projected in a less number of frames will be reproduced with higher light intensity. 3) It can be also advantageous to record and reproduce not only first- and second-type images but images with perspectives corresponding to different view-points between left and right eye images, and if necessary beyond them. In this way images corresponding to different points of an "observational ellipsoid" can be recorded. The use of these connected perspective can amplify the illusion of depth and they can appear in different numbers, if necessary also in stohastic distribution. 4) As experience shows a very good illusion of depth can be reached if frequency of altering the images is 2,4 ; 9,6; 38,4 or 153,6 Hz + 20 %. These average data are of subjective character and depend on the person observing the images. The difference for different persons can be as high as + 20 % The first low value seems to be especially advantageous when reproducing lantern slides.

5) The three-dimension image should be shot or recorded in a way as to ensure illusion of depth in the last link of a picture transmission chain without any modification thereof. This means that it is desired to reproduce images with illusion of three-dimensionality on a film screen or in a tv-set without modification thereof. In case of still pictures the object of invention is to have a projector of accordingly modified construction.

The object of the invention is to make use of the above recognition and thereby to elaborate methods for and apparata of assuring the illusion of a three- dimensional image in any link of a complex picture transmission chain. It is especially important to elaborate methods and apparata cooperating with traditional methods and apparata of picture reproducing for this aim. Under traditional methods and apparata the televisor is also to be understood.

Por solving the problem of the three-dimension projecting it has been elaborated a method of recording visual information whereby on a carrier of suitable material, as on a magnetic tape, magnetic plate or a photosensitive strip first-type and second-type images corresponding to a left eye and a right eye images are recorded and according to the invention the first- type and second-type images are recorded in weighted numbers and/or with weighted light intensity. The weighted number means that the first-type and second- type images should be recorded according to ϋie conditions: their number can be equal, different or variable in a regular way or irregular according to a defined rule or a random process. The random character of the variability means that at least one and at most six frames of a given type image are followed by at least one and at most six frames of the other type image, obeying - according to the recognition - frames containing other perspectives than the perspectives corresponding to first-type and second-type images. The weighted light intensity means that the first- type and/or the second-type images are recorded on frames with modulated light intensity wherein the light intensity of recording the frame is chosen according to a given rule.

It can be advantageous to interrupt, for example by shutter means, the way of the light beam during recording a frame with first-type or second-type image. In this way an empty frame can be recorded if it is desired.

It is also advantageous to record perspectives complementary to the perspectives of the first-type and second-type images, i.e. between and beyond them.

It has been also elaborated a method of assuring illusion of three-dimensionality during reproduction of images, whereby first-type and second-type images carrying information corresponding to a left eye and a right eye images are reproduced in the same place in a time succession and according to the invention the first-type and second-type images are reproduced in weighted numbers and/or with weighted light intensity.

It is especially advarriageoud to reproduce a three-dimensional image of a pair of stereoscopic lantern slides with frequency about 2,4 Hz. Beyond this value it is also advantageous to reproduce them with frequency about 9,6; 38, 4 ; and 153,6 Hz. The reproduction with modulation of the light intensity seems also to be very advantageous.

In order to reach the object set it has been elaborated also an apparatus for recording or reproducing three-dimensional images, comprising means for creating images according to left and right sides, wherein according to the invention the means for creating images comprise units for regulating light intensity. The proposed apparatus is foreseen in first line for recording, however, the principle can be advantageously realised by reproducing latern slides.

The regulating unit may be equipped with electrooptical means arranged before or behind the means for creating images. The electrooptical means comprise advantageously a controlled unit on the basis of liquid crystals or on a Kerr-cell.

It is especially advantageous during recording to use electronic cameras the outputs of which are connected with electronical means for queueing the output signals of the cameras. It can be also advantageous to assure the work of cameras during controlled time periods alternately.

Por light modulation it can be proposed to use mechanical means, as a shutter disc with openings variosly permitting and denying the passage of light or a shutter disc made of transparent material coated on one side on defined parts with non-transparent layer etc.

The mechanical means are advantageously connected to an electric motor in order to ensure drive. Another proposed apparatus is foreseen for projecting stereoscopic pairs of lantern slides and comprises at least two ways of light and a light source, wherein according to the invention the light source is connected to means for regulating light intensity. The regulating means can be a circuit for controlling light output of lamps, shuttering unit in the way of the light before a lamp etc. In the proposed apparatus it is advantageous to use an optical unit for joining the light ways before projecting.

The methods and apparata according to the inven tion make controlling the projected images so possible as to materially enhance the high plastic illusion of depth produced in the eyes of a viewer. With the above and other incidental objects in view as will more fully appear in the specification, the invention consists of tie methods, the features of apparata, the parts and combination thereof and the mode of operation as hereinafter described or illustrated in the accompanying drawings or their equivalents.

Referring to the accompanying drawing, wherein are shown some embodiments of the invention Figure 1 is a diagram showing the principle of the proposed methods, Figure 2 is a cross-section of a camera comprising an adapter for carrying out the proposed method of recording, Figure 3 is a cross-section of an adapter for carrying out the method as proposed, Figure 4 is a cross-section of a recording adapter for registration of a higher number of perspectives, Figure 5 is the cross-section of a unit capable of recording two overlapping perspectives with means of a camera, Figure 6 is the cross-section of an adapter for recording six perspectives by means of a camera, Figure 7 is the cross-section of an arrangement with two electronic cameras, Figure 8 is the cross-section of an other arrangement with-two electronic cameras, Figure 9 is the cross-section of an apparatus for sighting lantern slides, Figure 10 is the cross-section of an apparatus for projecting lantern slides in side view, and Figure 11 is the coss-section of the apparatus according to Fig. 10 in top view..

When realising the method according to the invention first-type images according to left eye information with average light intensity I_L and second- type images according to right eye information with average light intensity l_R should be shot (Fig. 1) in a number n of frames. The images follow one another and the number of frames of gien type image alters. The following solutions seem to be especially advantageous:

1) at least one and at most six frames of the first-type image alter with at least one and at most six frames of the second-type image; the respective numbers can change in a fully probabilistic manner when defining them by means of a generator of random numbers or according to the content of the recorded picture (perspective, plane, etc.),

2) the first-type and second-type images are recorded or reproduced alternatively in equal numbers of frames,

3) the first-type image is continouosly recorded or reproduced and interrupted or suppressed for example after or at each third frame by a second-type image wherein the second-type image should be recorded and reproduced with definitely higher light intensity than the first- type one, 4) the number and the light intensity of the frames of the first-type and second-type images as well are changed, taking care for ensuring approximatively stable summaric light intensity of the images of two types . The method according to the invention can be carried out during recording, as well reproducing. The reproduction by this method is expecially advantageous when carrying out for projecting lantern slides with illusion of depth. According to the recognition leading to the invention it may be advantageous to reproduce between the first-type and second-type images such images which correspond to perspectives lying next to and particularly between that of first-type and second-type images. In this case different perspectives defined by an "observational ellipsoid" can be recorded, wherein the ellipsoid obeys also the perspectives corresponding to first-type and second-type images, which advantageously define the focus points of the ellipsoid. According to experience excellence three-dimensionality can be reached in such way that one or more of the perspectives from the observational ellipsoid are selected and recorded between the first-type and second-type images. A possible explanation of this fact is that such transitional or adjusting perspectives as well the transient frames with modulation of the light intensity help eye in passing over from left side information to right side information by sampling which seems to be the basic mechanism of three-dimensional vision.

An apparatus capable of realising the method as proposed in recording visual information is to be seen in Fig. 2. It comprises an adapter 2 connected to a camera 1, which adapter 2 in this concrete embodiment is characterized by comprising two light ways. In the adapter 2 there are beam directing means 3 cooperating with mirrors 4, 5, 6. The beam directing means 3 includes a semitransparent mirror or an"electromirror" which is built up with liquid crystals and under influence of a contolling voltage becomes reflective, and is transparent if failing voltage. The mirrors 4, 5, 6 are advantageously flat glas elements. The mirror 4 is arranged before a diaphragm 7, and the mirror 6 before a diaphragm 8. The diaphragms 7 and 8 should be capable of limiting light intensity and if necessary of interrupting the light beam. They may comprise liquid crystal elements or mechanical closing means etc. In the adapter 2 there is a preferably low voltage current source 9 supplying a drive circuit 10 controlled by regulating units 11 and a swifch element. The adapter 2 is arranged in fitting elements 12 on the pipe-shaped objective 16 of the camera 1 and a shading element 15 (e.g. rubber bellow) ensures that light cannot flow in. The beam directing means 3 are directed to the objectise 16. Before the diaphragms 7 and 8 closing plates 13 and 14 are arranged.

The beam directing means 3 advantageously comprise an electromirror in form of a liquid crystal plate being transparent if not being under influence of an electric field. A low voltage about 17 range ensures that this plate will be fully reflective. This means, that without energizing it the light from the mirror 5 and if energizing the light from the mirror 6 will be passed to the camera 1. The same way of operation can be ensured by using semi- transparent mirrors, too. The alternation of first-type and second-type images coming from the diaphragms 7 and 8 and corresponding to left eye and right eye information is ensured by the beam directing means 3 cooperating with the drive circuit 10. The alteration is possible also by using diaphragms 7 and 8 with liquid crystal element or mechanical construction for closing the corresponding input of the light beam. In tha case it is the semi- transparent mirror more advantageous. The electromirror is very advantageous if directing add interrupting the light beam should be carried out by a common unit.

The diaphragms 7 and 8 can be arranged in the inner space of the adapter 2 (Fig. 3). In this case a box-shaped unit is the more advantageous with black walls 17 in vertical and horizontal planes lying parallel to the way of the light beam. In the way of light beam there is a window 18. The diaphragm 7 is arranged oppositely to the window 18 and the diaphragm 8 to the vertical black wall 17. The beam directing means 3 i.e. an electromirror or a semi-transparent mirror is arranged between the diaphragms 7 and 8 in order to pass the light in always one of the two directions. This solution is advantageous because there is a replaceable unit arranged in the adapter 2 before the objective 16 which can be changed if desired. The window 18 can be made of glass or it is possible to leave it out. The glass window 18 protects the full replaceable unit from the dust and other pollution.

An adapter 2 for recording a higher (or infinite) number of perspectives (Fig. 4.) comprises piano-parallel lefracting means 19. These means may consist of flint glass, a liquid of high refractive index as carbon disulfid or hydroqαinone etc. or other material of high refractive index. The piano-parallel refracting means 19 are fitted to a shaft of a stepping motor 20 ensuring alternating movement. This movement is effected in a way that the piano-parallel refracting means 19 are moving before a convex lens 21 or other unit producing convergent beam in a way that its long refracting side is always covering the width of the opening of the lens 21 and therefore the edges between the greater upper and smaller side surfaces cannot be before the opening. The moving plano- parallel refracting means 19 pass light changing always perspectives. The perspectives, passed to the objective 16 can be defined by suitable regulation or control of the stepping motor 20. It is possible to determine whether more or less images be recorded in respective perspectives.

In a lot of usage it can be advantageous to pass two partly covering perspectives to a common camera 1 (Fig. 5). In this way the two covering perspectives are represented by light beams passed through diaphragms 7 and 8 and a window 18 therebetween. The light beam is passed to an electromirror 22 and a mirror 4. From the electromirror 22 the light beam is projected through a liquid crystal diaphragm 23 and/or directly to the mirror 6. A mirror 25 projects the beam to a semi- transparent mirror or to an electromirror 26.

If the electromirror 22 is transparent the light from the diaphragm 8 and window 18 is projected to mirrors 4 and 5 and therefrom to the semi-transparent mirror or elsetromirror 26 and therefrom to the camera 1. There are separating walls 24 in different places for avoiding disturbation caused by light. These walls 24 are intend to avoid non-desired light effects. As it is shown in Fig. 6 on the principle of the invention it can be realised an apparatus for recording and separating six perspectives. In this apparatus there are electromirrors 22 or semi-transparent mirrors cooperating with mirrors 4,5, 6 which project the light beams passed through electro-optical diaphragms 27 to camera 1. Herein is also a drive circuit 10 comprising a regulating element which ensures the way bf operating according to the conditions, and especially opening the electrooptical diaphragms 27 in a desired time-sequence. The drive circuit 10 should supply the controlling voltage to the electromirror 22 or semi-transparent mirror. In the Fig. 6 it is well visible that under influence of the mirror the light will be passed from the selected electrooptical diaphragm 27 to the objective 16. The above described embodiments are based on a unique camera 1. This is advantageous from the viewpoint that only one relatively expensive camera is sufficientto have a filmstrip for three-dimensional projection or for transmission images with illusion of depth. If there are more cameras it can be very advantageous to realise the recordtig unit with two cameras as shown in Fig. 7. This is especially advantageous in electronical picture recording systems, i.e. in television studios. In this way the picture to be shot is observed by two cameras 31, the output of which is connected to a signal processing unit 32. Before the cameras 31 there are adapters 33 comprising polarisation filter 34. Before the polarisation filter 34 there are rotational polarisation filter 35 connected with a shaft of a motor 36. The rotational polarisation filter 35 cooperates with a respective polarisation filter 34 and ensure a time-sequence of operation of the cameras 31. They are arranged in a way that always one of the cameras

31 produces an image. The time-sequence of the images can be realised by means of the signal processing unit 32 comprising i.e. gate units passing always the signal of one of the cameras 31 during a given time period.

According to Fig. 8 a two-camera recording unit can be equipped with electronic switching unit 38 connected by one of the outputs to the signal processing unit 32. It is of course possible that the signal processing unit

32 comprises circuits whereby an electronical switching unit 38 is necessary only on the output of one of the cameras 31. In a two-camera recording unit the suitable way of operation of the cameras 31 can be reached by means of polarisation units, mechanical, electrooptical, e.g. liquid crystal units. The same is to be seen in the case of one camera recording unit, wherein it can be very advantageous to interrupt the light beam by means of electromechanical unit arranged outside of the adapter 2, for example by means of rotating discs. For preparing images corresponding to a higher number of perspectives it can be advantageous to use a Kerr cell on the place of the piano-parallel refracting means 19, which is connected to a suitable source of energizing and to a suitable optical prism system.

For three-dimensional reproduction of still images (stereoscopic pairs of lantern slides) there are shown apparata in Fig. 9 to 11. Fig. 9 shows an apparatus for sighting lantern slides wherein frames 41 comprise the first-type and second-type image. Behind the frames 41 there are two light sources 39 connected to a control unit 40. It is possible of course to have only one light source 39 when the apparatus comprises means for selecting at least two light beams of equal intensity. Between a translucent screen 42 and the frames 41 there is a mirror 6 and beam directing means 3, e.g. a semi-transparent mirror or electromirror. The light beam is directed to the translucent screen 42 by the beam directing means 3. The screen 42 can be made of opal glass, waxpaper, etc. The essence of this apparatus lies in that the light sources 39 are controlled by a control unit 40 in a way that alternatively the firstor the second-type image is reproduced on the translucent screen 42. The alteration can be effected advantageously with frequency 2,4 or 9,6 Hz. In case of using lower frequency values it can be advantageous to use a control unit which is capable of modulating the light intensity of the light sources 39 in order to overlap the light intensity of the images.

An other apparatus for projecting lantern slides is shown in side-view in Fig, 10 and in top-view in Fig. 11. In this case the light source is surrounded from one side by a surface 43 for directing and separating light beams. From the latter the light beam is projected to the diaphragms 7 and 8 and therefrom through the frames 41 to the mirror 6 and the directing means 3. Before the latter there is an electromirror passing the light beam to a translucent screen 42 by means of a mirror 4. The optical element of the apparatus can be adjusted by means of a screw 44. An elecnrooptical diaphragm 46 serves to checking the adjusting. The electrooptical diaphragm 46 is arranged before a projecting lens 45 passing the image. Covering walls 24 ensure avoiding disturbating reflexion effects. One of these walls 24 can comprise the drive circuit 10 for controlling the liquid crystal and elctrooptical units of the apparatus. The circuit comprises generally some integral circuits and some passive elements and therefore it requires no greater place.

It can be advantageous to construct a projector for higher number of lantern slides cαresponding to more perspectives having an optical system for joining the different light ways adjusted to the respective lantern slides.

On the basis of the embodiments shown above it is obvious that the methods and apparata according to the invention are very advantageous when it is desired to make intervention in any link of a picture transmission system in order to have a three-dimensional image. The embodiments show that on the basis of electrooptical, electromechanical elements and solid state electronic components (as liquid crystal) capable of influencing the light is possible always to elaborate method or device according to the aim to be reached. The diaphragms 7 and 8 can be consisted of rotating discs with mechanical drive, discs covered with layer of different and variable light transparency, liquid crystals etc. The beam directing means 3 can be constructed on the basis of mechanical or other units capable of quick interrupting light beam. It. can be advantageous also to use prisms for separating light beams.

While in order to comply with the requirements the invention has been described in language more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that means and construction herein disclosed comprise but some of a higher number of modes of putting the invention into effect and the invention is therefore claimed in any of its firms and modifications within the scope of the appended claims.

Claims

CLAIMS :

1. Method of recording visual information for three-dimensional reproduction, whereby first-type and second-type images are recorded according to left eye and right eye information on a carrier, c ha r a c t e r i z e d by the step of recording the first-type and second-type images in a weighted number and/or with weighted intensity.

2. A method according to claim 1, wherein the first-type and second-type images are recorded in different and/or varying numbers of frames.

3. A method according to claim 1 or 2, wherein the first-type and/or second-type images are recorded with modulation of the light intensity.

4. A method according to any of claims 1 to 3, wherein the light way is interrupted in a controlled manner before recording a first-type or a second-type image.

5. A method according to any of claims 1 to 4, wherein images according to perspectives adjusted to the first-type and second-type images are recorded.

6. Method of three-dimensional projecting in picture transmission, whereby first-type and second- type images carrying left eye and right eye information are reproduced following one another on the same place, c h a r a c t e r i z e d by the step of reproducing the first-type and second-type images with weighted frequency and/or with weighted intensity.

7. A method according to claim 6, wherein the first-type and second-type images are still images reproduced alternatively with frequency at least 2,4 Hz.

8. A method according to claim 7, wherein the first-type and second-type images are reproduced with modulation of the light intensity.

9. Apparatus for recording three-dimensional pictures, comprising means for creating images according to left side and right side, c ha r a c t e r i z e d by arranging unit for regulating light intensity in the light way of the means for creating images.

10. An apparatus according to claim 9, wherein tie regulating unit comprises electrooptical means arranged before the input or after the output of the means for creating images.

11. An apparatus according to claim 10, wherein the electrooptical means are liquid crystal units as diaphragms (7, 8) connected to a drive circuit (10).

12. An apparatus according to claim 10, wherein the electrooptical means comprise a Kerr cell.

13. An apparatus according to claim 9, wherein the means for creating image are electronic cameras (31) connected to a signal processing unit (32) for queueing their output signals.

14. An apparatus according to claim 13, wherein there is a unit for alternative operating the cameras (3

15. An apparatus according to claim 9, wherein the regulating unit comprises light modulating means driven mechanically and arranged before the output of the means for creating images.

16. Apparatus for projecting stereoscopic pairs of lantern slides, comprising a light source, frames for fitting the slides and optical elements of projection, c h ar a c t e r i z e d by comprising at least two light ways and by including a regulating unit connected to the light source (39) for regulating the light intensity thereof.

17. An apparatus according to claim 16, wherein the regulating unit is capable of varying the light output of the light source (39).

18. An apparatus according to claim 16, wherein the regulating unit is capable of shuttering the light ways.

19. An apparatus according to any of claims 16 to 18, wherein there is an optical arrangement for joining the light ways.