GB2255192A

GB2255192A - Image reproduction using cine or tv cameras

Info

Publication number: GB2255192A
Application number: GB9107807A
Authority: GB
Inventors: Josef Victor Stanzig
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-04-12
Filing date: 1991-04-12
Publication date: 1992-10-28
Also published as: GB9107807D0

Abstract

A method of three-dimensional image reproduction involves the provision of a plurality of different images of a scene as produced by means of a plurality of mutually spaced lenses and viewing the scene by repetitively sequentially viewing the image at a repetition rate sufficient to ensure that the images are merged by the persistence of vision of the observer. The system is suitable for cinematography and T.V. cameras for carrying out the method to produce films or signals suitable for display on conventional equipment. As shown, a cine camera 1 has two lenses 2, 3, spaced apart by the interocular distance D. Each lens has shutter 4, 5 and a prism 6, 7 so that the shutters can be opened alternately and synchronised with the movement of the cine film and thus alternate frames F2, F4, F6 are exposed to the image through lens 2. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO THREE-DIMENSIONAL IMAGE REPRODUCTION This invention relates to three-dimensional image reproduction and is suitable for application to both cine projection and television transmission.

A pair of human eyes observes a view in threedimensions due to the fact that the eyes are spaced apart so that each eye sees a similar view but from a slightly different direction, which is the reason that we can see and recognise depth (3D). Attempts have been made in the past to provide on a flat surface an image that gives the impression of depth. One way that has achieved this effect in paper illustrations and on the cinema screen is to superimpose two views of the same scene taken from different viewpoints, each view being reproduced in a specific colour.

In order to view such images it is necessary to wear special spectacles each lens of which is in fact a colour filter which permits passage of light of a different one of the two coloured images so that each eye sees a different one of the two images and the brain interprets these two images in depth in the manner similar to the observation of a normal three-dimensional scene. The clear disadvantage of this arrangement is that it is necessary to wear these special spectacles to see a three-dimensional image, furthermore the image is unclear when viewed without spectacles and it is not possible to reproduce an accurately coloured image.

The present invention seeks to overcome the previously mentioned disadvantages and to provide a method suitable for use in both cinematographic reproduction and in television.

The invention has been arrived at from an appreciation that the eyes provide a persistence of vision in that when observing one picture which is replaced by another the image of the first picture still lingers on although the new picture is accepted like the first one. This is of course why it is possible to observe as a moving image the repetitive sequence of pictures projected on to a cinema screen or produced on the screen of a television. The human eye can accept up to eight pictures per second separately, but if the change of picture is much higher than eight per second the continuity of vision due to the persistence of vision will result in the observation of a continually varying scene and not a sequence of pictures. Based on this understanding the present invention was conceived.

According to one aspect of the present invention there is provided a method of three-dimensional image reproduction comprising the steps of providing a plurality of different images of a scene as produced by viewing from a plurality of viewpoints and viewing the scene by repetitively sequentially viewing the images at a repetition rate sufficient to ensure that the images are merged by the persistence of vision of the observer. In such a method the brain is in fact receiving images in sequence taken from different viewpoints and it merges those images to provide an interpretation of depth. Such images are preferably produced by employing a plurality of mutually spaced lenses.

It is possible to employ two lenses in which case the scene is viewed by repetitively alternating between the two images. The images produced by each of the lenses may be converted to a television signal and each lens may form part of an individual television camera to provide a signal representative of the scene viewed thereby with repetitive sequential transfer of the images for viewing being effected by repetitively switching between the signals. The switching may be effected at the sequential picture repetition rate of the television system or in the case of an interlaced television transmission system at the sequential frame repetition rate.

The method is also applicable to cine recording in which case the images produced by the two lenses may be transferred to a photographic recording film in which case viewing is effected by optical projection of that film. The images may be recorded in sequence on the film at a repetition rate corresponding to the shutter speed of the camera.

According to another aspect of the invention there is provided a cine camera comprising means for producing a plurality of different images of a scene taken from different viewpoints, means for directing the images to the film focal position sequentially and repetitively in synchronism with the shutter mechanism to expose the film with sequentially changing different views of the scene.

The means for producing the plurality of images may comprise a plurality of mutually spaced lenses. The means for directing the image may be synchronised with the shutter mechanism such that the recorded image is sequenced for each shutter opening of the shutter mechanism.

According to yet another aspect of the invention there is provided a television camera device comprising means for providing a television signal representative of a scanned image, wherein the camera device is provided with means for producing a plurality of different images of a scene taken from different viewpoints and means for scanning the images and for providing a repetitive sequence of television signals representative of different views of the scene. The means for producing a plurality of different images may comprise a plurality of mutually spaced lenses. An individual camera may be provided for each lens to enable the generation of television signals representative of a different view of the scene and a switch device may be provided for routing the signals from each of the cameras sequentially and repetitively to an output.The switching device may be synchronised with the shutter.

An alternative television camera arrangement constructed in accordance with the invention comprises a camera for each lens, each camera providing a television signal representative of a different view of the scene, which signals are coupled with a combining device, the cameras having shutter operating mechanisms arranged to ensure that they open sequentially and that only one shutter is open at a time.

The cine camera or television camera may comprise a prism or mirror for each lens arranged to refract or reflect the incoming light so that the image produced from each lens occurs at a common position.

In a particular embodiment the camera has two lenses producing two images of a scene which are repetitively alternated to produce the different views of the scene. The lenses may be mutually spaced by distance approximating to the distance between a pair of human eyes.

In yet another aspect of the invention there is provided a vision aid for a person having monocular vision, the aid comprising means for producing a plurality of images of a scene taken from different viewpoints and means for directing the images to the eye of the person sequentially and repetitively at a repetition rate sufficient to ensure that the images are merged by persistence of vision.

In order that the invention and its various other preferred features may be understood more easily, some embodiments thereof will now be described, by way of example only, with reference to the drawings in which: Figure 1 is a schematic illustration of a cine camera constructed in accordance with one aspect of the invention, and Figure 2 is a schematic illustration of a television camera device constructed in accordance with another aspect of the invention.

Figure 1 shows a cine camera 1 having a pair of lenses 2 and 3 spaced apart on the camera body by a distance D substantially similar to the distance between a pair of human eyes. Each lens is provided with a shutter 4,5 which shutters are driven synchronously such that when one shutter is open the other shutter is closed. Behind each lens there is provided a 900 prism 6,7 each arranged to direct incoming light from its associated lens to a common focal plane 8 such that if both images were present at the same time they would be in overlapping registration. Cine film 9 is transported by a conventional transport mechanism (not illustrated) from an unexposed film container 10 to an exposed film container 11.The film transport mechanism is synchronised with the shutters such that the film is stationary each time one of the shutters is opened in a manner similar to that employed in a conventional camera but of course in this case two shutters are involved.

The operation of the camera of Figure 1 will now be described commencing from the position illustrated. Here, shutter 4 is open permitting the image of a scene as viewed by lens 2 to be directed via the prism 6 to the focal plane 8 to expose film frame F4. During this exposure the shutter 5 is closed so no image from lens 3 reaches the focal plane 8, the dotted line purely indicating the light path that would occur if the shutter were to be open. The shutter 4 then closes and the film transport mechanism causes the film to be advanced by one frame in readiness for the next exposure. When the next frame F5 of film is in position the shutter 5 opens whilst the shutter 4 remains closed and the image of the scene as viewed by the lens 3 is now directed via the prism 7 to the focal plane to expose frame F5.By continuous repetition of this operation at the normal shutter speed of the cine camera a continuous sequence of frames is produced in which the odd numbered frames are views provided by lens 3 and the odd number frames are views provided by lens 2.

The film produced by the camera 1 can be employed in a conventional cine projector and when observed by a viewer the two images will effectively be combined due to persistence of vision and the overall impression will be of a scene having three-dimensional depth.

Although the camera described employs prisms to deflect the light to the focal plane it will be appreciated that other means may be employed for example mirrors to reflect incoming light in the desired direction. Preferably two mirrors are used so that the final image is not reversed.

Although the described embodiment employs two individual shutters which are synchronised with the film transport mechanism it will be appreciated that a similar operation can be effected by a single shutter element for example a wheel disposed between the two lenses and the prisms which has a peripheral cut-out which during rotation of the wheel in synchronism with the film transport mechanism results in the cut-outs moving into registration with each of the lenses in turn.

The television camera device 12 of Figure 2 employs some elements which provide similar functions to the cine camera of Figure 1 and for ease of description similar elements have been given the same reference numerals and will not be further described in detail. The lenses 2 and 3 each form part of an individual television camera 13,14 the output signals from which are a conventional television format signal and are fed to a switching device 15. The switching device is synchronised with the shutters 4 and 5 and arranged such that when shutter 4 is opened the output of camera 13 is selected and fed to an output 16 for recordal, transmission or for driving a television display.

During this period the shutter 5 is closed, the shutter 4 is then closed and the shutter 5 is opened and the switch 15 selects the output of camera 14 to be routed to the output 16. This procedure is continued repetitively such that the output is constituted by a sequence of television pictures alternating between the views observed by lenses 2 and 3.

For an interlaced scanning television system each shutter may be arranged to remain open for the period required to scan a single frame or alternatively for the period required to scan a complete picture comprising a number of interlaced frames.

Instead of employing a switching device 15 it may be sufficient to employ a combiner of the outputs of the two cameras as only one camera will provide an output signal at any one time.

Instead of employing two cameras 13 and 14 a single camera could be employed with the images from the two lenses being directed alternately to that camera by the various possibilities mentioned in connection with Figure 1 e.g. the prism arrangement and in this case no switching device 15 or combiner would be required.

The signal produced by the camera device is suitable for use with conventional existing television transmission and display systems and similarly to the picture produced by projection of the film of the camera of Figure 1 the observer sees a sequence of pictures alternating between two different views of the same subject which by persistence of vision is interpreted as a combined image having the impression of three-dimensional depth.

Whilst it is envisaged that a spacing between the lenses substantially similar to the spacing between a pair of human eyes will provide a suitable three-dimensional effect it is envisaged that different distances between lenses may be employed and may result in even greater benefit. Furthermore, although in principle the use of two lenses is thought to interpret a scene in a manner similar to that provided by two human eyes it is possible that by employing additional lenses e.g. 3 or 4 cameras and selecting those in a repetitive sequence may result in an improvement in the impression of depth. Such arrangements are considered to fall within the scope of this invention.

The embodiments described involve the production of a picture which is constituted by alternate views from the camera lenses however this may not be essential at all shutter speeds and it may be possible or indeed advantageous to arrange the sequence such that several frames from one lens are viewed followed by several frames from the subsequent lens and so on. Particularly in the case of high shutter speeds and persistence of vision effect mentioned earlier where it was stated that the eyes can interpret a repetition picture rate of greater than eight pictures per second as a single image then the view could be changed for example at a rate much higher than 8 every second.

Such an arrangement is considered to fall within the scope of this invention.

A further application of the invention is as a vision aid for a one eyed person (monocular vision) to restore to the person the impression of depth or 3D that is provided by the two eyes of a normally sighted person. Such an aid is constructed in a manner similar to the television camera or cine camera previously described but the plurality of images taken from different view points is directed to the eye of the person sequentially and repetitively at a repetition rate sufficient to ensure that the images are merged by the persistence of vision. Such an aid could be incorporated into a hat or into hand held binoculars or a telescope.

Although both of the cine camera and television camera devices as described employ a plurality of lenses, it would also be possible to employ a single lens and arrange that the scene is reflected or refracted to the lens from two different viewpoints in which case the shutters would be positioned between the viewpoint and the lens. Such an arrangement is considered to fall within the scope of this invention.

Claims

CLAIMS:

1. A method of three-dimensional image reproduction, comprising the steps of providing a plurality of different images of a scene as produced by viewing from a plurality of viewpoints and viewing the scene by repetitively sequentially viewing the images at a repetition rate sufficient to ensure that the images are merged by the persistence of vision of the observer.

2. A method as claimed in claim 1 in which the images are produced by employing a plurality of mutually spaced lenses.

3. A method as claimed in claim 2, wherein two lenses are employed and the scene is viewed by repetitively alternating between the two images.

4. A method as claimed in claim 2 or 3, wherein the images produced by each of the lenses are converted to a television signal.

5. A method as claimed in claim 4, in which each lens forms part of an individual television camera to provide a signal representative of the scene viewed thereby and repetitive sequential transfer of the images for viewing is effective by repetitively switching between the signals.

6. A method as claimed in claim 5, in which the switching is effected at the sequential picture repetition rate of the television system.

7. A method as claimed in claim 5, in which the switching is effective at the sequential frame repetition rate of an interlaced television transmission system.

8. A method as claimed in claim 2 or 3, in which the images produced by the two lenses are transferred to a photographic recording film and viewing is effected by optical projection of that film.

9. A method as claimed in claim 8, in which the images are recorded in sequence on the film at a repetition rate corresponding to the shutter speed of the camera.

10. A method of three-dimensional image reproduction substantially as described herein with reference to the drawings.

11. A cine-camera comprising means for producing a plurality of different images of a scene taken from different viewpoints, means for directing the images to the film focal position sequentially and repetitively in synchronism with the shutter mechanism to expose the film with sequentially changing different views of the scene.

12. A cine camera as claimed in claim 11, wherein the means for producing a plurality of images comprises a plurality of mutually spaced lenses.

13. A cine-camera as claimed in claim 11 or 12, wherein the means for directing the image is synchronised with the shutter mechanism such that the recorded image is sequenced for each shutter opening of the shutter mechanism.

14. A television camera device comprising means for providing a television signal representative of a scanned image, wherein the camera device is provided with means for producing a plurality of different images of a scene taken from a different viewpoint and means for scanning the images and for providing a repetitive sequence of television signals representative of different views of the scene.

15. A television camera device as claimed in claim 14, wherein the means for producing a plurality of images comprises a plurality of mutually spaced lenses.

16. A television camera device as claimed in claim 15, comprising a camera for each lens each camera providing a television signal representative of a different view of the scene and a switch device for routing the signals from each of the cameras sequentially and repetitively to an output.

17. A television camera device as claimed in claim 16, wherein the switch device is synchronised with the shutter.

18. A television camera device as claimed in claim 15, comprising a camera for each lens, each camera providing a television signal representative of a different view of the scene which signals are coupled with a combining device the cameras having shutter operating mechanisms arranged to ensure that they open sequentially and that only one shutter is open at a time.

19. A camera as claimed in claim 12, 13, 15, 16 or 17, comprising a prism for each lens arranged to refract the incoming light so that the image produced from each lens occurs at a common position.

20. A camera as claimed in claim 12, 13, 15, 16 or 17, comprising a mirror for each lens arranged to reflect the incoming light so that the image produced from each lens occurs at a common position.

21. A camera as claimed in any one of claims 12, 13, or 15 to 20, having two lenses producing two images of a scene which are repetitively alternated to produce the different views of the scene.

22. A camera as claimed in claim 21, wherein the lenses are mutually spaced by a distance approximating to the distance between a pair of human eyes.

23. A camera substantially as described herein with reference to and as illustrated in the drawings.

24. A vision aid for a person having monocular vision, the aid comprising means for producing a plurality of images of a scene taken from different viewpoints and means for directing the images to the eye of the person sequentially and repetitively at a repetition rate sufficient to ensure that the images are merged by persistence of vision.