AU767947B2 - Stereo display with colour matching and positional registering - Google Patents

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Stereo display with colour matching and positional registering The following statement is a full description of this invention, including the best method of performing it known to us: Freehills Carter Smith Beadle Melboume\004022482 Printed 26 March 2002 (15:13) page 2 Freehills Carter Smith Beadle Melboume\004022482 Printed 26 March 2002 (15:13) page 2 1*~ 1 STEREO DISPLAY WITH COLOUR MATCHING AND POSITIONAL

REGISTERING

The present invention relates to a computer imaging or vision technique for the creation and analysis of three dimensional images, of-particular but not exclusive application in the creation and analysis of images of the retinal wall of the eye, and in other three dimensional medical imaging fields. The invention also has application in the detection of anomalies of the ocular fundus, and in the early diagnosis, treatment and observation of diseases such as glaucoma and macular degeneration.

The ability to visualise objects in stereo, or in three dimensions, is a function of the position of the organs of sight, the eyes, and the manner in which the human brain processes visual information. The eyes are offset from one another, resulting in a slightly different view of an object being presented to each eye. The brain 'combines' the left and right perspectives, such that a single image, i 15 conveying information about depth, is perceived. Unlike the eye, conventional imaging methods, such as slide, film and video images, present only two dimensional images of an object.

~The ocular fundus and optic disc possess, like most objects, a three dimensional structure. A better appreciation of fundus topography can, therefore, 20 be gained from stereo photography and stereoscopic viewing. Stereo fundus photography can create three dimensional images of the optic nerve head. Using a fundus camera, the photographer produces two images of the ocular fundus, from the perspective of his or her left and right eye. The two images must then be aligned, and viewed with a stereo slide viewer, or a light table coupled with a pair of plus lenses. Alternatively, the images may be projected through 2 a polarised material onto a screen, with the stereo pair polarised at 900 to each other. The observer must view the images through polarising glasses with a polarising filter in front of each eye. These devices enable the left and right eye to "see" its corresponding image so that a stereo representation may be perceived (see Saine Tyler (1997) for an overview of stereo imaging techniques).

Stereo examination of the ocular fundus provides useful information about the health of the eye, to guide diagnostic and treatment decisions. However, the clinician is most interested in observing the evolution of fundus topography over time. Comparing a patient's stereo fundus photographs at regular intervals may allow the clinician to 15 review subtle changes in the architecture of the optic nerve head. However, these images, often taken at different times, by different people or in different lighting conditions, may possess variable characteristics, in terms of magnification, colour and the positioning of features in the image. These variations in image quality 0..0 could be mistaken for changes in the topography of the optic nerve head.

Computer technology can overcome some of these problems through the use of image processing techniques. Colour matching techniques can eliminate colour and tonal differences between images of the same object taken on separate occasions, while image registration can minimise scale, translation and rotation variation. Regular computerized imaging of the ocular fundus is, therefore, a useful ophthalmic technique, enabling the clinician to make diagnostic decisions, track the course of a disease and to measure the effectiveness of treatment.

A number of digitized systems of image analysis have been developed to aid in the quantitative analysis of stereo images, such as that illustrated in US Patent 5,519,485.

3 This patent describes a computerized, stereo image, measuring apparatus, suitable for topographical mapping and capable of displaying, and varying the magnification of, stereo images, and performing measurements relating to the three dimensional structure of the object being imaged. A control device or central processing unit controls the function of this system. Left and right images are introduced, from a scanner or the like, into two separate optical disc drives. Images are displayed on a high resolution, stereo, display device comprising; a left and right monitor, a half mirror, a polarizing filter in front of each display unit and orthogonal polarized glasses worn by the observer. A feature extractor may be used to extract features from the image data through designated left and right measuring points.

0• US Patent 5,270,924 describes an ophthalmic image 'o processing system that is able to recognize the difference between the left and right images of a stereo pair and to distinguish the top and bottom of the images, so that they 00. may be stored without confusion. Another image processing system, the IMAGEnet, from Topcon Corporation, comprises a computerised image processing system for fluorescein angiography pictures, and fundus photography. This system 25 may digitally enhance stereo images using sharpening and contrast stretching tools. Analysis functions, such as line area measurement, enable quantitative analysis of a number of separate images. However, this product has proven to be somewhat impractical in a clinical setting, as it requires long processing times and only registers images for translation differences in the X and Y directions.

Heidelberg Engineering have also developed a method of imaging the fundus of the eye, using software which captures images from a confocal scanning laser ophthalmoscope (cSLO). A cSLO image is constructed from a series of "slices" taken at varying levels of the fundus.

4 The slices are "stacked" together to form a single representation of fundus topography, with an accompanying sense of volume. To allow analysis of the same region of interest on respective slices, the operator defines this region with a contour line. This defined area then is stored and aligned on subsequent images. A topographical representation of the fundus is produced by determining height measurements at each location on the cSLO's multiple captured images. Estimates are then made of topographic variables, such as the mean height of the fundus contour, the optic cup volume and the volume of the optic nerve rim.

Quantitative analysis in the Heidelberg system is based on *eoooe the intensity of the light reflected from the fundus. The 15 area of highest reflectance is equivalent to the fundus contour, the edge surrounding the optic nerve head. At .so. each level, or slice, the edge or fundus contour is determined, creating a topographic map of the fundus and enabling the calculation of the clinically important values "20 outlined above. However, if a lesion or vessel in the slice is more reflective than the contour, the position of that lesion will be considered the position of fundus o contour, a situation which may result in a misleading topographical picture.

Current computerised stereo imaging systems, such as those outlined above, may suffer from a number of practical disadvantages. Difficulties with image registration challenge the accuracy of analysis, while long processing times are a problem for clinical practice. Many of these systems produce only monochrome images which do not convey as much information as full colour images. In addition, none of the presently available systems provide a comparative measure for reviewing, in real time, three dimensional images in rapid sequence. There remains a need for an imaging system capable of producing full colour, registered, stereo images in real time. A novel, stereo 004020173 imaging method and apparatus has therefore been developed, for constructing a three dimensional view of an object, and for performing quantitative analysis of the resultant stereo photographs. The present invention enables images of a three dimensional subject, such as the ocular fundus, to be viewed in stereo, and for serial comparison to take place between colour matched and registered images of the same object.

It is therefore an object of the present invention to provide an improved imaging system capable of producing a virtual, three dimensional representation of an object, that also enables an observer to compare representations of the object taken at different times.

It is a further object of the present invention to provide an improved stereo image processing system which has the ability to colour correct and automatically or semi-automatically register images in a stereo pair, or a set of stereo pairs, compensating for differences in size, rotation and translation between the stereo 15 images.

ee According to the present invention there is provided a system for facilitating medical diagnosis by creating and visualising three dimensional images of the topography of an object, including: .i Image means for obtaining at least one pair of images of the same object from different angles; digitising means for digitising said images; image processing means for colour matching and registering said digitised images with a reference digitised image to form at least one pair of colour matched and registered images which correspond to said at least one pair of images; 004020173 6 controller means for converting said digitised images of said at least one pair of colour matched and registered images into one or more corresponding interlaced images; display means for displaying said one or more interlaced images either simultaneously or over a period of time; and visualizing means for enabling a viewer to see one or more of said interlaced images in three dimensions.

Preferably each image of a corresponding pair of images is obtained substantially simultaneously.

.ooo.) 10 Preferably each of the at least one pair of images are a stereo pair.

Preferably the system includes measuring means for measuring areas of interest in three dimensions, and calculating means for calculating desired measurements of the object.

Preferably, the display means and visualizing means are arranged to enable a viewer to see, in succession and in three dimensions, one of said one or *°more interlaced images and one or more corresponding interlaced images of said object obtained earlier, whereby to compare said three dimensional images for determining changes in the topography of the object over time.

Preferably the system includes a stereo flicker chronoscope for enabling a viewer to see one of said one or more interlaced images and said one or more corresponding interlaced images of said object obtained earlier.

Preferably the stereo flicker chronoscope is operable to serially display interlaced images.

The measuring means may be a three dimensional cursor.

004020173 7 Preferably the calculating means includes computer software.

Preferably the system includes result display means for displaying the results of the measurements.

Preferably the object is the ocular fundus of an eye and the result display means is a polar graph centred on the optic nerve head.

Preferably the imaging means is a stereo camera, a digital camera, a digital stereo camera, a video camera or a scanning laser ophthalmoscope operable to record two different views of the object to be imaged.

Preferably the digitising means is a image scanner operable to digitize a slide film with high resolution, a digital camera, or any other apparatus operable to produce an image in, or convert an image into, a digital format.

Preferably the controller means and image processing means are one or more computer means.

Preferably the controller means and image processing means is software arranged to operate on said one or more computer means, said software being .:;.arranged to apply techniques of colour matching and image registration. The :software may include magnification changing means for changing image magnification in three dimensions and real time.

Preferably the display means is a video display monitor or the like.

Preferably the visualizing means includes a pair of Liquid Crystal Display goggles.

The present invention also provides an apparatus for facilitating medical diagnosis by viewing three dimensional images of the topography of an object, including: 004020173 8 image processing means for determining and correcting for colour, rotation, translation and scale differences between digitised images of at least one pair of images of the same object obtained from different angles and a reference digitised image to form at least one pair of colour matched and registered images which correspond to said at least one pair of images; controller means for converting said digitised images of said at least one pair of colour matched and registered images into one or more corresponding interlaced images; display means for displaying said one or more interlaced images either simultaneously over a period of time; and visualizing means for enabling a viewer to see one or more of said o o interlaced images in three dimensions.

The apparatus may include imaging means for obtaining said at least one pair of images of the same object from different angles.

15 The apparatus may also include digitising means for digitising said images obtained by said imaging means.

Preferably the apparatus includes measuring means for measuring specific characteristics of the object, calculating means for calculating desired measurements of the object and result display means for displaying the results of measurements.

Preferably, the display means and visualizing means are arranged to enable a viewer to see, in succession and in three dimensions, one of said one or more interlaced images, and one or more corresponding interlaced images of said object obtained earlier, whereby to compare said three dimensional images for determining changes in the topography of the object over time.

004020173 9 Preferably the apparatus includes a stereo flicker chronoscope for enabling a viewer to see one of said one or more interlaced images and said one or more corresponding interlaced images of said object obtained earlier.

Preferably the stereo flicker chronoscope is operable to enable viewers to see serially said interlaced images.

Preferably the measuring means includes a three dimensional cursor.

Preferably the measuring means includes a circular or elliptical template that may be superimposed over each optic disc, and which may be used to measure one or more parameters including neuro-retinal rim width and optic disc 10 cupping.

Preferably the calculating means includes computer software.

I

Preferably the pair of images are left and right images.

9* S" 0 Preferably the display means is arranged to display an approximately equal number of one or more horizontal lines from each image forming a pair of images, said horizontal lines being positioned alternately so that horizontal lines from different images forming a pair of images are positioned adjacent each other.

S. S Preferably the imaging means is a stereo camera, a digital camera, a digital stereo camera, a video camera, a scanning laser ophthalmoscope or any other suitable imaging means that is able to record two different views of the object to be imaged.

Preferably the digitising means is an image scanner that is able to digitize a slide film with high resolution, a digital camera, or any apparatus capable of producing or converting an image into a digital format.

Preferably the image processing means is custom software.

004020173 Preferably the controller means and image processing means is software arranged to operate on said one or more computer means, said software being arranged to apply colour matching and image registration methods for the correction of respective said differences in colour, and rotation, translation and scale. The image processing means may include magnification changing means for changing image magnification in three dimensions and real time.

Preferably the methods includes a colour matching technique utilising a linear adjustment method to match the mean and standard deviation of each colour component, and an automatic or semi-automatic technique for rotation and translation effects.

Preferably the display means includes a video display monitor or the like.

Preferably the visualizing means includes a pair of Liquid Crystal Display goggles.

Preferably the goggles are Vrex wireless or 3D Max goggles, and more preferably the LCD goggles are electronically coupled to the display means.

Preferably the result display means includes a polar graph centred on the optic nerve head.

The present invention still further provides an apparatus for facilitating medical diagnosis by visualizing three dimensional, recreated views of the topography of an object, including: a stereo camera for obtaining at least one pair of images of the same object from different angles; digitising means for digitising said images; image processing means for determining and correcting for colour, rotation, translation and scale differences between said digitised images and a reference 004020173 11 digitised image to form at least one pair of colour matched and registered images which correspond to said at least one pair of images; controller means for converting said digitised images of said at least one pair of colour matched and registered images into one or more corresponding interlaced images, in which an interlaced image comprises an approximately equal number of one or more horizontal lines from each image forming a pair of images, said horizontal lines being positioned alternately so that horizontal lines from different images forming a pair of images are positioned adjacent each other; display means for displaying the display images either simultaneously or over a period of time; and visualizing means for enabling a viewer to see the displayed images in three dimensions.

Preferably the apparatus includes measuring means for measuring specific characteristics of the object, calculating means for calculating desired 15 measurements of the object, and result display means for displaying the results of measurements.

Preferably, the display means and visualizing means are arranged to enable a viewer to see, in succession and in three dimensions, one of said one of more interlaced images and one or more corresponding interlaced images of said object obtained earlier, whereby to compare said three dimensional images for determining changes in the topography of the object over time.

Preferably the apparatus includes a stereo flicker chronoscope for enabling a viewer to see one of said one or more interlaced images and said one or more corresponding interlaced images of said object obtained earlier.

Preferably said object may be any object in which three dimensional topographic data is desirable.

004020173 12 Preferably said object includes human or animal tissue.

Preferably said object includes an animal or human body part.

Preferably said tissue or body part is the fundus of the eye, specifically the optic nerve head region, or other ocular features of interest.

According to the present invention there is also provided a method for facilitating medical diagnosis by creating and visualising three dimensional images of the topography of an object including: colour matching and registering digitised images of at least one pair of images of the same object obtained from different angles with a reference digitised 10 image to form at least one pair of colour matched and registered images which correspond to said at least one pair of images; converting said digitised images of said at least one pair of colour matched and registered images into one or more corresponding interlaced images; displaying said one or more interlaced images either simultaneously or over 15 a period of time; and enabling a viewer to see one or more of said interlaced images in three dimensions.

The method may further comprise the step of obtaining said at least one pair of images of the same object from different angles.

The method may also include the step of digitising said images of said at least one pair of images.

Preferably, the step of displaying said one or more interlaced images further includes displaying, in succession, one of said one or more interlaced images and one or more corresponding interlaced images of said object obtained earlier, to 004020173 13 enable a viewer to see said interlaced images in three dimensions and compare said three dimensional images for determining changes in the topography of the object over time.

Preferably the method includes the step of comparing two or more of said one or more interlaced images.

Preferably the method further comprises the step of displaying one of said one or more interlaced images sequentially or flickering two or more of said one or more interlaced images to highlight change in the object or differences in topography of the object.

10 Preferably the method includes displaying the results of the measurements.

Preferably said digitising is performed in high resolution.

S• In order that the invention be more fully understood, some preferred embodiments will be described, by way of example, with reference to the following *drawings in which: 15 Figure 1 is a diagrammatic plan view of a system according to the present invention; Figure 2 is an explanatory diagram illustrating the process of producing an interlaced image; and Figure 3 is an illustration of a novel colour matching process according to a preferred embodiment of the present invention.

Referring to Figure 1, the first arrangement of an apparatus of the present invention includes a Nidek simultaneous stereo camera 1 and 2, for recording two different images 3 and 4, of the ocular fundus of patient's eye 9, taken from left and right viewing positions. Alternatively, the images may be captured on film and 14 Two different techniques may be used to align sequential input and reference images. The first method provides automated and precise image registration based on a normalized grey scale correlation. In this method, feature matching is obtained in both the input and reference images, whereby the same feature in both images is identified. A unique template is automatically selected from the input image and a similar template is identified, if it exists, from the reference or target image. The reference image is then registered according to the differences in the centre coordinates of the templates. To reduce the search time, the search area on the target image may be limited to double the size of the template surrounding the centre of the template. The normalized 15 grey scale correlation function reaches a maximum value of 1 when the input and reference image match exactly, or 0 when there is no correlation. By moving the template over the reference image, the correlation function is computed at each position. The position where the largest correlation value is obtained is considered the best match.

A second technique uses a semi-automatic method to register the stereo pairs. An even number of points from the input image and the approximately corresponding points from the 25 reference image are chosen. The best possible match for the points chosen on the reference image is found. The search area is limited to the area surrounding the points selected on the reference image. This may increase the speed as well as the accuracy of the correlation computation. The differences in the x and y directions for each point (input and reference points) are computed and the average of the differences in the x and y direction obtained. This will correct for any translation differences.

By connecting two points and calculating the angles with respect to a horizontal axis in the input and the reference 15 image, the difference in the angle can also be obtained.

The average angle difference for all the pairs of points will give an estimation for the overall rotation of the reference image. This technique is faster than the automatic method, but the fully automatic method may provide more accurate alignment.

The apparatus of the present invention can also supply means to view, in real time, registered, stereo images of i the same fundus in rapid sequence (stereo flicker chronoscopy). This technique allows comparison of two or three dimensional fundus images from the same patient, taken on different occasions. For example, a stereo pair 15 photographed in 1995 may be registered with a stereo image taken in 1997. As the display jumps from one image to the other, subtle changes in the structure of the optic disc can be easily perceived. Flickering between a number of registered images may help the clinician visualize any changes in fundus topography over time.

A three dimensional mouse pointer can also be used to manually measure structures of the optic nerve head or other areas of interest. The three dimensional mouse 25 pointer is an indicator which can not only be moved back and forth across the image plane on the monitor, but also perpendicular to that plane. Using a keyboard or other controls (not shown in Figure the perceived depth of the pointer can be changed. This 3D mouse is valuable for measurements to be made or the precise location of objects or structures to be determined. It allows the cursor to be placed, in the eyes of the viewer, on the surface of the optic nerve or another three dimensional structure.

Measuring means, in the form of a circular or elliptic template, can then be displayed and positioned over the optic disc by the operator, to aid in obtaining 16 measurements around the optic nerve head. Clinically important values regarding the extent of optic disc cupping and the width of the neuro-retinal rim can then be calculated. Differences in nerve-head rim measurements, between two chronologically separate images of the same fundus, can then be plotted in a polar fashion around the disc, with positive changes advancing beyond the edge of the disc and negative changes plotted towards the centre of the disc. A very good representation is thus displayed, allowing the operator to determine at a glance the size and position of any rim width changes. A quantitative measure of the change in optic nerve head rim measurements over .time is therefore provided.

15 Thus, the present invention provides a novel system in which three dimensional images of an object may be constructed and analysed. Comparison between images taken at different times and at different orientations is possible using the present invention.

The advantages of the various embodiments of the apparatus and method of the present invention are thus that: stereo images can be seen on a screen, rather the clinician having to bend over a light box; .25 a series of stereo images can be flickered ("stereo flicker chronoscopy"), which is not possible using only the slides, and without using a mechanical system such as a Deltascope; the edges of the optic disc, the start of optic disc cupping and the start of the floor of the optic cup can be seen much easier than from monoscopic images; the high resolution allows precise location of the edges of the neuro-retinal rim; colour adjustment and correction minimize errors due to change in colour of photographs attributable to the photographic process, pupil dilation, and lens changes; the flicker system (chronoscopy) and the measurements 004020173 17 system (chronometry) work together; registered and colour adjusted images are stored, and so do not have to be done over and over again; and a number of people can observe the stereo image on the computer screen simultaneously.

Modification within the scope of the invention may therefore be readily effected by a person skilled in the art. Other alternative embodiments would involve the use of one or two video cameras or a scanning laser ophthalmoscope to directly capture the image in a digital format. Any other single or stereo camera 10 or imaging device that is capable of creating an image of the optic nerve head from two viewing positions, simultaneously or sequentially, may also be utilised.

Thus, it is to be understood that this invention is not limited to the particular e e embodiments described by way of example hereinabove.

o S eS.°S e S o

Claims (54)

1. A system for facilitating medical diagnosis by creating and visualising three dimensional images of the topography of an object, including: imaging means for obtaining at least one pair of images of the same object from different angles; digitising means for digitising said images; image processing means for colour matching and registering said digitised images with a reference digitised image to form at least one pair of colour matched and registered images which correspond to said at least one pair of images; controller means for converting said digitised images of said at least one pair of colour matched and registered images into one or more corresponding interlaced images; display means for displaying said one or more interlaced images either simultaneously or over a period of time; and visualizing means for enabling a viewer to see one or more of said interlaced images in three dimensions.

2. A system as claimed in claim 1, including measuring means for measuring areas of interest in three dimensions, and calculating means for calculating desired measurements of the object.

3. A system as claimed in claim 2, wherein said measuring means is a three dimensional cursor.

4. A system as claimed in either claim 2 or claim 3, wherein said calculating means includes computer software. 004020173 19 A system as claimed in any one of claims 2-4, including result display means for displaying the results of the measurements.

6. A system as claimed in any one of claims 1-5 wherein said display means and visualizing means are arranged to enable a viewer to see, in succession and in three dimensions, one of said one or more interlaced images and one or more corresponding interlaced images of said object obtained earlier, whereby to compare said three dimensional images for determining changes in the topography of the object over time.

7. A system as claimed in claim 6 including a stereo flicker chronoscope for enabling a viewer to see one of said one or more interlaced images and said one or more corresponding interlaced images of said object obtained earlier. :o 8. A system as claimed in claim 7, wherein said stereo flicker S•chronoscope is operable to serially display interlaced images. 15 9. A system as claimed in claim 8, wherein said object is the ocular fundus of an eye and said result display means is a polar graph centred on the optic nerve head.

10. A system as claimed in any one of the preceding claims, wherein said imaging means is a stereo camera, a digital camera, a digital stereo camera, a video camera or a scanning laser ophthalmoscope operable to record two different views of the object to be imaged.

11. A system as claimed in any one of the preceding claims, wherein said digitising means is an image scanner operable to digitize a slide film with high resolution, a digital camera, or any other apparatus operable to produce an image in, or convert an image into, a digital format. 004020173

12. A system as claimed in any one of the preceding claims, wherein said controller means and image processing means are one or more computer means.

13. A system as claimed in any one of the preceding claims, wherein said controller means and image processing means is software arranged to operate on said one or more computer means, said software being arranged to apply techniques of colour matching and image registration.

14. A system as claimed in claim 13, wherein said software comprises magnification changing means for changing image magnification in three dimensions and real time.

15. A system as claimed in any one of the preceding claims, wherein said display means is a video display monitor or the like.

16. A system as claimed in any one of the preceding claims, wherein said visualizing means includes a pair of Liquid Crystal Display goggles. ee

17. An apparatus for facilitating medical diagnosis by viewing three dimensional images of the topography of an object, including: image processing means for determining and correcting for colour, rotation, .i translation and scale differences between digitised images of at least one pair of images of the same object obtained from different angles and a reference digitised image to form at least one pair of colour matched and registered images which correspond to said at least one pair of images; controller means for converting said digitised images of said at least one pair of colour matched and registered images into one or more corresponding interlaced images; display means for displaying said one or more interlaced images either simultaneously or over a period of time; and 004020173 21 visualizing means for enabling a viewer to see one or more of said interlaced images in three dimensions.

18. An apparatus as claimed in claim 17, including measuring means for measuring specific characteristics of the object, calculating means for calculating desired measurements of the object and result display means for displaying the results of measurements.

19. An apparatus as claimed in claim 18, wherein said measuring means includes a three dimensional cursor. An apparatus as claimed in claim 18 or claim 1i9, wherein said object 10 is the ocular fundus of an eye and said measuring includes a circular or elliptical template that may be superimposed over each optic disc, and which may be used to measure one or more parameters including neuro-retinal rim width and optic S.o. .disc cupping.

21. An apparatus as claimed in any one of claims 18-20, wherein said calculating means includes computer software. ~22. An apparatus as claimed in any one of claims 17-21 wherein said display means and visualizing means are arranged to enable a viewer to see, in succession and in three dimensions, one of said one or more interlaced images, and one or more corresponding interlaced images of said object obtained earlier, whereby to compare said three dimensional images for determining changes in the topography of the object over time.

23. An apparatus as claimed in claim 22 including a stereo flicker chronoscope for enabling a viewer to see one of said one or more interlaced images and said one or more corresponding interlaced images of said object obtained earlier.

24. An apparatus as claimed in claim 23, wherein said stereo flicker chronoscope is operable to enable a viewer to see serially said interlaced images. 004020173 22 An apparatus as claimed in any one of claims 17 to 24, wherein said pair of images are left and right images.

26. An apparatus as claimed in any one of claims 17 to 25, wherein the display means is arranged to display an approximately equal number of one or more horizontal lines from each image forming a pair of images, said horizontal lines being positioned alternately so that horizontal lines from different images forming a pair of images are positioned adjacent each other.

27. An apparatus as claimed in any one of claims 17-26 further comprising imaging means for obtaining said at least one pair of images of the same object from different angles, and digitising means for digitising said images obtained by said imaging means. S CS 0

28. An apparatus as claimed in any one of claims 17 to 27, wherein said imaging means is a stereo camera, a digital camera, a digital stereo camera, a video camera, a scanning laser ophthalmoscope or any other suitable imaging 15 means that is able to record two different views of the object to be imaged. Se

29. An apparatus as claimed in any one of claims 17 to 28, wherein said *digitising means is an image scanner that is able to digitize a slide film with high resolution, a digital camera, or any apparatus capable of producing or converting an image into a digital format. O°

30. An apparatus as claimed in any one of claims 17 to 29, wherein said controller means and image processing means are one or more computer means.

31. An apparatus as claimed in any one of claims 17 to 30, wherein said controller means and image processing means is software arranged to operate on said one or more computer means, said software being arranged to apply colour matching and image registration methods for the correction of respective said differences in colour, and rotation, translation and scale. 004020173 23

32. An apparatus as claimed in any one of claims 17 to 31, wherein said image processing means is custom software.

33. An apparatus as claimed in claim 32 wherein the image processing means comprises magnification changing means for changing image magnification in three dimensions and real time.

34. An apparatus as claimed in claim 32 wherein said methods include a colour matching technique utilising a linear adjustment method to match the mean and standard deviation of each colour component, and an automatic or semi-automatic technique for rotation and translation effects. eeeee 10 35. An apparatus as claimed in any one of claims 17 to 34, wherein said display means includes a video display monitor or the like.

36. An apparatus as claimed in any one of claims 17 to 35, wherein said visualizing means includes a pair of Liquid Crystal Display goggles. *e

37. An apparatus as claimed in claim 36, wherein said goggles are Vrex 15 wireless or 3-D Max goggles. S38. An apparatus as claimed in either claim 36 or 37, wherein said LCD S•goggles are electronically coupled to the display means.

39. An apparatus as claimed in any one of claims 18 or 20, wherein the result display means includes a polar graph centred on the optic nerve head.

40. An apparatus for facilitating medical diagnosis by visualizing three dimensional, recreated views of the topography of an object, including: a stereo camera for obtaining at least one pair of images of the same object from different angles; digitising means for digitising said images; 004020173 24 image processing means for determining and correcting for colour, rotation, translation and scale differences between said digitised images and a reference digitised image to form at least one pair of colour matched and registered images which correspond to said at least one pair of images; controller means for converting said digitised images of said at least one pair of colour matched and registered images into one or more corresponding interlaced images in which an interlaced image comprises an approximately equal number of one or more horizontal lines form each image forming a pair of images, said horizontal lines being positioned alternately so that horizontal lines from different images forming a pair of images.are positioned adjacent each other; display means for displaying said one or more interlaced images either :..*"simultaneously or over a period of time; Sovisualizing means for enabling a viewer to see the displayed images in three dimensions.

41. An apparatus as claimed in claim 40, including measuring means for measuring specific characteristics of the object, calculating means for calculating desired measurements of the object, and result display means for displaying the results of measurements.

42. An apparatus as claimed in claim 40 or 41 wherein said display means and visualizing means are arranged to enable a viewer to see, in succession and in three dimensions, one of said one of more interlaced images and one or more corresponding interlaced images of said object obtained earlier, whereby to compare said three dimensional images for determining changes in the topography of the object over time.

43. An apparatus as claimed in claim 42, including a stereo flicker chronoscope for enabling a viewer to see one of said one or more interlaced images and said one or more corresponding interlaced images of said object obtained earlier. 004020173 S

44. An apparatus as claimed in any one of claims 40 to 42, wherein said pair of images are left and right images. An apparatus as claimed in any one of claims 40 to 44, wherein said object is any object in which three dimensional topographic data is desirable.

46. An apparatus as claimed in any one of claims 17 to 45, wherein said object includes human or animal tissue.

47. An apparatus as claimed in any one of claims 17 to 46, wherein said object is a human or animal body part.

48. An apparatus as claimed in any one of claims 17 to 47, wherein said 10 object is an ocular feature such as the fundus of an eye or the optic nerve head region.

49. A method for facilitating medical diagnosis by creating and visualising three dimensional images of the topography of an object, including: colour matching and registering digitised images of at least one pair of images of the same object obtained from different angles with a reference digitised image to form at least one pair of colour matched and registered images which .i correspond to said at least one pair of images; converting said digitised images of said at least one pair of colour matched and registered images into one or more corresponding interlaced images; displaying said one or more interlaced images either simultaneously or over a period of time; and enabling a viewer to see one or more of said interlaced images in three dimensions. 004020173 26 A method as claimed in claim 49, further comprising the step of comparing two or more of said one or more interlaced images.

51. A method as claimed in claim 49, wherein said step of displaying said one or more interlaced images further includes displaying, in succession, one of said one or more interlaced images and one or more corresponding interlaced images of said object obtained earlier, to enable a viewer to see said interlaced images in three dimensions and compare said three dimensional images for determining changes in the topography of the object over time.

52. A method as claimed in claim 49, further comprising the step of i 10 displaying one of said one or more interlaced images sequentially or flickering two or more of said one or more interlaced images to highlight change in the object or differences in topography of the object. S•53. A method according to claim 49, further comprising the steps of measuring areas of interest in said one or more interlaced images, and calculating 0. 15 desired measurements of the object.

54. A method as claimed in claim 53, including displaying the results of said measurements. OO.. o o 55. A method as claimed in claim 49 further comprising the steps of: obtaining said at least one pair of images of the same object from different angles; and digitising said images of said at lest one pair of images.

56. A method as claimed in any one of claims 49 to 54, wherein said digitising is performed in high resolution.

57. A system as claimed in any one of claims 1 to 16, wherein said object includes human or animal tissue.

58. A system as claimed in any one of claims 1 to 16, wherein said object is a human or animal body part. 004020173 27

59. A system as claimed in any one of claims 1 to 16, wherein said object is an ocular feature such as the fundus of an eye or the optic nerve head region. A method as claimed in any one of claims 49 to 56, wherein said object includes human or animal tissue.

61. A method as claimed in any one of claims 49 to 56, wherein said object is a human or animal body part.

62. A method as claimed in any one of claims 49 to 56, wherein said object is an ocular feature as the fundus of an eye or the optic nerve head region. 10 63. A system as claimed in any one of claims 1-16 wherein each image i corresponding pair of images is obtained substantially simultaneously.

64. An apparatus as claimed in any one of claims 17-39 wherein each **.image of corresponding pair of images is obtained substantially simultaneously. An apparatus as claimed in any one of claims 40-48 wherein each image of corresponding pair of images is obtained substantially simultaneously.

66. A method as claimed in any one of claims 49-62 wherein each image of corresponding pair of images is obtained substantially simultaneously.

67. A system for facilitating medical diagnosis substantially as hereinbefore described with reference to the accompanying drawings.

68. An apparatus for facilitating medical diagnosis substantially as hereinbefore described with reference to the accompanying drawings. 004020173 V

69. A method for facilitating medical diagnosis substantially as hereinbefore described with reference to the accompanying drawings. The Lions Eye Institute of Western Australia Incorporated By its Registered Patent Attorneys Freehills Carter Smith Beadle 26 March 2002