WO1998017067A1

WO1998017067A1 - Method and device for suggesting depth in two-dimensional images

Info

Publication number: WO1998017067A1
Application number: PCT/NL1997/000579
Authority: WO
Inventors: Klaus Herbert Günter WENGER
Original assignee: Wenger Klaus Herbert Guenter
Priority date: 1996-10-15
Filing date: 1997-10-15
Publication date: 1998-04-23

Abstract

Component images or image frames which, when displayed sequentially on a two-dimensional screen, lead to the perception of a sharply defined image by the human eye, are displayed in shifted relationship relative to each other, in order to suggest depth in the static or dynamic image. Said distance is adjusted for every pixel in dependance on the desired depth and the possible direction of movement in the image. To that end manipulation of the pixel matrix takes place.

Description

METHOD AND DEVICE FOR SUGGESΗNG DEPTH IN TWO-DIMENSIONAL IMAGES

The present invention relates to a method for displaying 5 images on a screen, wherein depth is suggested through manipulation of component images in the overall image being displayed on the screen.

The present invention also relates to a device for 0 carrying out the method, which device comprises a screen and image manipulation means connected to the screen, which function to suggest depth in an overall image being displayed through manipulation of component images .

15

Such a method and device, wherein a three-dimensional effect or depth is suggested in an overall image being displayed by vision signal manipulation, is generally known. Two component images making up one overall image

20 are displayed simultaneously on the screen in a manner which is known per se. The viewer has at his disposal optical means, such as special spectacles, which enable him to see a first component image displayed in colour with one eye and the second component image displayed in

25 another colour with the other eye, or to see one component image in one direction of polarisation with one eye, and the other component image in the other direction of polarisation with the other eye. Manipulation of the relative positions on the screen of

30 the two component images being displayed simultaneously provides the viewer with a perception which suggests to him that the overall image which is eventually formed in his brain possesses depth.

35 One drawback of the known method and device is that they are not suitable for being used in any manner other than with said optical means in a room which is specially equipped and arranged for that purpose, such as a cinema or an attraction on the fair. Furthermore the image built up in a known manner from simultaneously displayed component images is blurred too much when viewed without optical means to permit meaningful viewing. Moreover, this technology is not available to the individual consumer. Let alone that it would be suitable for being used on a screen in the form of a common television screen, without costly equipment being required.

The object of the present invention is to provide a method and a device for carrying out said method for displaying images having a depth effect on a screen, in a manner wherein relatively simple and inexpensive equipment is needed only at the consumer's end in order to obtain the desired depth effect in the overall images being displayed, whilst no extra equipment at all is needed, both at the broadcaster's end and at the receiver's end, for displaying common images on television for those consumers who set no store by this depth effect.

In order to accomplish that objective the method according to the invention is characterized in that the component images are displayed sequentially.

The device according to the invention is furthermore characterized in that said image manipulation means include means for sequentially displaying the component images .

One advantage of the method and the device according to the invention is that by displaying the manipulated component images sequentially on the screen, an image having a depth effect is obtained for a viewer using the aforesaid optical means, whilst a satisfactorily perceptible overall image is obtained even if said optical means are not used, due to the fact that the component images are displayed sequentially.

As regards the consumer market, the present invention is also suitable for realising depth on a common TV set by connecting relatively simple equipment thereto. Another advantage is the fact that the signal being emitted by the broadcasting station does not need to be adapted for that purpose, so that TV viewers who do not wish to acquire any additional equipment for obtaining a depth effect can normally continue to watch the image they are familiar with. A special application of the present invention is the semi-professional or professional production and/or adaptation of film images or film fragments, video clips or animations.

According to another aspect of the method according to the invention it becomes possible to provide for a continuous depth effect in the overall image being displayed on the screen, so that an optimally true-to- nature depth effect can be suggested, by displaying corresponding elements in the overall image, which are included in every one of the component images, an adjustable distance apart.

According to another aspect of the method according to the invention the introduction of depth or a depth effect in the overall image can be realised by adjusting the aforesaid distance in dependence on the direction of movement and/or the desired depth in the overall image.

One embodiment of the device according to the invention preferably comprises distance controlling means, which include hardware and/or software implemented pixel file processing means for influencing the position of the pixels of the component images.

The present invention also relates to a method wherein component images suggesting depth in an overall image perceived with the aid of optical means are displayed on a screen.

The present invention also relates to a device comprising a screen and optical means disposed between said screen and a viewer, which optical means function to suggest depth in the overall image built up from the component images being perceived.

Such a method and device are known from Dutch patent No. 1004273 to the present applicant. It is explained therein how depth is suggested to a viewer in an overall image formed by sequentially displaying component images when viewing said overall image via optical means. From the said patent it is furthermore known, in the case of moving images, to display the component images, which are each built up of pixels, a variable distance apart by means of pixel manipulation in order to perceive true-to-nature overall images suggesting depth.

The viewer thereby has at his disposal optical means, such as special spectacles, as a result of which a first component image displayed in one colour is perceived with one eye, and the second component image displayed in another colour is perceived with the other eye, for example, or special spectacles, as a result of which one component image is perceived in one direction of polarisation with one eye, and the other component image is perceived in the other direction of polarisation with the other eye.

The drawback of this is that in both cases the viewer needs to wear optical means in the form of special colour or polarisation-selective spectacles in order to be able to experience a depth effect, which is extra awkward for a viewer who wears glasses. The object of the invention is to provide a method and device wherein it is not necessary to wear special spectacles in order to experience depth in the overall image being perceived.

In order to accomplish that objective the method as well as the device according to the invention are characterized in that said optical means possess light transmitting properties which are dependent on the direction of illumination.

The use of optical means having light transmitting properties which are dependent on the direction of illumination, also called the angle of incidence, leads to the advantage that the optical means thus configured can be placed near the screen. In that case the location of said optical means will be much more advantageous and less awkward for the viewer than the originally necessary place of the special spectacles on the viewer's head.

It is even possible for several viewers seated in a particular area in front of the screen with the optical means to enjoy the depth effect simultaneously by viewing images on the screen via the optical means disposed near said screen. The result of the use of the optical means having light transmitting properties which are dependent on the direction of illumination is that pixels of the one component image being displayed at one location on the screen at a certain point in time are transmitted differently, that is, brighter or less bright, to one eye of the viewer than to the other eye. As a result of this one component image is distributed better over the two eyes than the other component image as far as its brightness is concerned, and a depth effect is created in the perception by the viewer of the overall image made up of the two component images . According to the teachings of NL-1004273 the desired depth effect is obtained when the component images are displayed practically simultaneously, but sequentially in time, on the screen.

In possible embodiments which are relatively simple to manufacture the respective optical means have a concentrical relief structure built up of strips or points, which is quite similar to the surface structure of a Fresnel lens.

The invention and its concomitant advantages will now be explained in more detail with reference to the accompanying drawing, wherein:

Figure 1 is a diagrammatic representation of a cube perceived by the left eye, which is shown for the purpose of illustration;

Figure 2 shows the representation of Figure 1, seen through the right eye in this case;

Figure 3 shows a moving image, likewise for the purpose of illustration, which can be given a depth effect (D) in accordance with the invention;

Figure 4 is a diagrammatic representation of an pixel file, which can be subjected to processing in order to realise the present invention;

Figure 5 is a diagrammatic representation of a device according to the invention;

Figure 6 shows a possible manner of manipulating component images, such as image frames, in order to obtain distance (Δd) therebetween and thus suggest depth in the perception of the overall image; and Figure 7 shows a curve associated with one direction of movement, which illustrates an example of the possible trend of distance Δd as a function of depth D.

and wherein:

Figure 8 is a diagrammatic view of a first arrangement of the device according to the invention;

Figure 9 is a diagrammatic view of a second possible arrangement of the device according to the invention;

Figure 10 shows a diagram by means of which the principle of the method and the device according to the invention are explained in more detail in a possible embodiment built up of strips, which comprises two planes of refraction; and

Figure 11 shows another possible embodiment according to the invention, which is built up of points and which comprises three planes of refraction.

Figures 1 and 2 show, not to scale, images of a cube 1 seen through the left-hand eye and the right-hand eye respectively of a viewer. In Figure 1 left-hand lateral surface 2 of the illustrated part of cube 1 is larger than in Figure 2, in which it is compressed, as it were. Exactly the reverse applies to right-hand lateral surface 3 , with lateral surface 3 of Figure 2 being elongated, as it were. Base 4 of Figure 2 is likewise partially elongated in one direction and partially compressed in another direction in comparison with base 4 of Figure 1. From these two impressions of cube 1 the viewer's brain forms an overall image of a cube 1, which image also possesses depth. Upon comparison of Figures 1 and 2 it appears that contours C of the cube in the two figures are spaced further apart for points located near the eyes than for points located further away from the eyes. This is illustrated by means of the diagram of Figure 7, which shows said distance Δd as a function of depth D in the image. In that case it applies that Δd = 0 in the vanishing point that lies on horizon 5 in

Figure 3. When the component images of Figures 1 and 2 are presented sequentially to the left eye and the right eye by optical means which are known per se, such as special spectacles which transmit a different colour or a different polarisation for each eye, whilst contours C of the two images are spaced correctly as a result of the correct adjustment of Δd for each point on the contour, the viewer is given an overall impression of a static, spatial three-dimensional cube.

This technique may also be used if the image is a moving image. This is indicated by means of an arrow M in Figure 3. If the one image remains unchanged in that case, for example, the only thing that is necessary in order to obtain dynamic depth in the image is to take into account the change in Δd and the direction of movement itself when a change occurs in the second component image. Although it is simple from a technical point of view to leave one component image unchanged, it is also possible to manipulate both component images, if desired.

Translated into terms of pixel files, in which video information is stored in digital form, for example, the pixel data is processed in such a manner as to cause the desired relative shifting of the information in the component images. Figure 4 shows a pixel file, for example File 1, of one component image, which is processed by image manipulation means 6 shown in Figure 5 of a device 7 for carrying out this technique, and which is converted into a File 1', which is passed to a screen, usually, but not necessarily so, a TV screen 8, together with the original component image corresponding therewith, namely File 1. File 1 will then include the image information of one component image, whilst File 1' will include the image information of the other component image, which latter information includes image information which has been manipulated in dependence on the direction of movement and the desired depth.

The pixels of the relevant image are shifted in dependence on the direction of movement and the desired depth in accordance with the curve of Figure 7, which is to be determined empirically, whereby the pixels lying on horizon 5 remain unchanged, however. Such shifting may take place in X-direction or in Y-direction, and possibly for only a portion of the component image. At pixel level a shift means that the pixels which lie on horizon 5, and which lie in a pixel matrix of the pixel file on the extreme right in Figure 4, are held in place, whilst all pixels not lying there will shift slightly in the component image over distance Δd. Said shifting takes place by means of distance controlling means 8 in the form of image matrix cutting, retaining, elongating, rotating, transposing, translating and/or reflecting means, which are incorporated in image manipulation means 6. Said manipulation for example takes place by cutting away one or more of the pixels located furthest to the left, depending on Δd, after which the image matrix of Figure 4 is pulled to the left (arrow L) , as it were, whilst a new adaptation to the original number of pixels is carried out, whereby the contents of said pixels are shifted along in a gradual, elastic manner. In this way the position of all pixels of each component image is shifted, and when the other component images are displayed sequentially, a continuous depth effect is obtained for every area in the eventual overall image to be seen on screen 9 of device 7. Insofar as this is desired, all kinds of matrix-like and consequently simple hardware and/or software implemented pixel processing techniques may be used for obtaining the desired depth effect in the overall image on the screen.

If the vision signal is a non-interlaced vision signal, the vision signal in question may be separated into (usually) two component images or semiframes, which may be subjected to the above-explained technique. Starting from television images, wherein each image is built up of component images in the form of an uneven and an even frame, the desired effect may also be achieved by the above-explained manipulation of frames. Figure 6 shows the uneven frames 1 of images l/l and 1/2, and also the even frames 2 of images 2/1 and 2/2. Frame l/l is left out, whilst even frame 2/1 is displayed on a new, but uneven frame l/l'. Even frame 1/2 of the next image 2 is then displayed on a new, but even frame 2/1'. New frames 1/1' and 2/1' form a new image 1'. Said displaying has introduced a time shift, which is 28 μs when a 50 Hz television and 625 lines are used, which time shift leads to a positional shift of the original image information, which results in the suggestion of depth in the new image. Making the time shift variable provides another possibility to control the mutual distance apart at which pixels of corresponding elements in the images can be displayed in order to obtain the desired, variable depth effect .

The sequential displaying of the component images always takes place within a very short period of time, which comes near the maximally feasible limit determined by the speed of light. In one possible preferred embodiment pixels from respective component images are sequentially displayed on the screen at intervals in the order of nanoseconds . Figures 8 and 9 diagrammatically show possible arrangements of a device 1', by means of which a depth effect is perceived without using spectacles when viewing an overall image formed on the basis of component images being displayed on a screen 2', as is for example described in NL-1004273. Besides screen 2', which may for example be a cathode ray tube or an LCD- screen, device 1' comprises optical means 3' having light transmitting properties which are dependent on the direction of illumination, which optical means are disposed at a small distance, for example of up to 30 cm, from the front side 4' of screen 2'. Preferably said optical means 3' are placed in abutment with front 4', or built into said front or housed or integrated therein, in order to provide for a minimal joint thickness or depth of screen 2' and optical means 3'.

A possible alternative is shown in the arrangement of Figure 9, which includes a mirror 5'. If it is decided to place the optical means 3' some distance away from screen 2, and the proper control for screen 2' is used, bearing in mind the image-reversing reflection by mirror 5', the mounting depth can be limited in a simple manner in comparison with the device shown in Figure 8 by suitably selecting the dimensions.

Figure 10 shows a facet 6' of the optical means 3' having a relief structure, a surface structure in this case, which gives said optical means the light transmitting properties which are dependent on the angle/direction at which light emitted by screen 2' falls on facet 6'. Facets 6' are arranged over the surface of optical means 6 " in a curved path or strip, in particular in concentric rings, as is the case with a Fresnel lens. In this embodiment the facets, only one of which is shown for easy reference, each have two planes of refraction 7' and 8'. In Figure 10 a pixel 9' from one component image lighting up on the screen illuminates plane of refraction 7' more than plane of refraction 8', due to the fact that plane of refraction 7' has a larger useful area. The light falling on facet 6' is refracted, whereby left eye L sees a larger part of pixel 9' from one component image than does right eye R. This is quite the reverse for another pixel 10' from the other component image. In other words, optical means 3' possess light transmitting properties which are dependent on the direction of the incident light from the pixels. Thus discrimination between the component images is a fact without spectacles being needed. A great many pixels of the component images and a great many facets are involved in the eventual perception of the overall image, which pixels and facets jointly provide the viewer or viewers with a perception of depth.

Apart from the relative proportions and the actual distances, the extent to which planes of refraction 7' and 8' are illuminated differently depends on the angle a between each of the planes of refraction 7' and 8' It has become apparent that angle , a facet 6' having a prismatic section in the present case, determines to a considerable degree the dimensions of an area G present in front of optical means 3', and within which depth can still be perceived to a sufficient extent.

Figure 11 shows a diagrammatic plan view of a facet 11 having three planes of refraction 12', 13' and 14' rising upwards in this case, which jointly comprise a pyramidic section of some kind. In that case the incidence of light - on the plane of drawing - from a pixel from one component image on planes of refraction 12', 13' and 14' is such that one eye receives more light from said pixel than does the other eye, whilst quite the reverse applies to the other pixel from the other component image. The same discriminatory or directionally selective operation of optical means 3 ' as already discussed before is obtained, therefore. The light that reaches eyes L and R in this embodiment now comes from every one of the three planes of refraction 12', 13' and 14', and that in a certain proportion to each other.

Of course it is also possible to use four planes or refraction, or more. Especially when optical means 3' are integrated in or on the front side 4' of screen 2' it will be advantageous to offer a wide choice of possibilities as regards the optical configuration, shape and arrangement of the respective optical means, for example when refracting structures in the shape of crystal structures are used as the structures which possess light transmitting properties which are dependent on the direction of illumination. This is advantageous in particular when using LCD-screens, into which the optical means 3' having the desired properties are integrated.

Claims

1. A method for displaying images on a screen, wherein depth is suggested through manipulation of component images in the overall image being displayed on the screen, characterized in that the component images are displayed sequentially.

2. A method according to claim 1, characterized in that corresponding elements in the overall image, which are included in every one of the component images, are displayed an adjustable distance apart.

3. A method according to claim 2, characterized in that said distance is adjusted in dependence on the direction of movement and/or the desired depth in the overall image .

4. A device for carrying out the method according to any one of the claims 1 - 3, which device comprises a screen and image manipulation means connected to the screen, which function to suggest depth in an overall image being displayed through manipulation of component images, characterized in that said image manipulation means include means for sequentially displaying the component images.

5. A device according to claim 4, characterized in that said image manipulation means comprise distance controlling means for controlling the mutual distance at which pixels of said corresponding elements are displayed in shifted relationship relative to each other.

6. A device according to claim 5, characterized in that said distance controlling means include hardware and/or software implemented pixel file processing means for influencing the position of the pixels of the component images.

7. A device according to claim 6, characterized in that said pixel file processing means include image matrix cutting, retaining, elongating, rotating, transposing, translating and/or reflecting means.

8. A device according to claim 4, 5, 6 or 7, characterized in that said component images are image frames or semiframes of the overall image.

9. A method wherein component images are displayed on a screen, which component images suggest depth in an overall image perceived with the aid of optical means, characterized in that said optical means possess light transmitting properties which are dependent on the direction of illumination.

10. A method according to claim 9, characterized in that said optical means possess a relief structure.

11. A method according to claim 10, characterized in that said relief structure extends in strips along curved lines over the surface of said optical means .

12. A method according to claim 10 or 11, characterized in that said relief structure follows a substantially concentrical ring pattern.

13. A method according to any one of the claims 10 - 12, characterized in that said relief structure has a prismatic section.

14. A method according to any one of the claims 10 -

13, characterized in that said relief structure has a surface structure built up of points and having a pyramidic section.

15. A device comprising a screen and optical means disposed between said screen and a viewer, which optical means function to suggest depth in the overall image built up from the component images being perceived, characterized in that said optical means possess light transmitting properties which are dependent on the direction of illumination.

16. A device according to claim 15, characterized in that said optical means possess a relief structure.

17. A device according to claim 16, characterized in that said relief structure extends in strips along curved lines over the surface of said optical means .

18. A device according to claim 16 or 17, characterized in that said relief structure follows a substantially concentrical ring pattern.

19. A device according to any one of the claims 16 - 18, characterized in that said relief structure has a prismatic section.

20. A device according to any one of the claims 16 - 17, characterized in that said relief structure has a surface structure built up of points and having a pyramidic section.

21. A device according to any one of the claims 15 - 20, characterized in that said optical means comprise at least two planes of refraction.

22. A device according to claim 21, characterized in that the angle between the various planes of refraction is a measure for the extent of the area within which a depth effect can be perceived.

23. A device according to claim 21 or 22, characterized in that said optical means are built up of substantially concentrically extending strips, wherein each strip has a prismatic section and comprises two planes of refraction.

24. A device according to claim 21 or 22, characterized in that said optical means are built up of substantially concentrically extending strips, wherein each strip comprises a series of projecting facets, which have a pyramidic section and which comprise three planes of refraction.