EP0135552A1 - Method and apparatus for optical enhancement of graphical data arrays - Google Patents

Abstract

Method and apparatus for the optical improvement of graphic data, for example seismic lines, in order to contribute to the visual interpretation of such data, comprising an anamorphotic optical system (13) of lenses, prisms or mirrors to allow reproduction on a photographic film (14) of a reduced image of graphic data on a computer output (8), the reduction with respect to the X axis of the reduced image being different from the reduction with respect to Y axis. The image thus produced selectively condenses the graphic data on one or more axes in order to visually improve the characteristics contained in the data. Instead of an anamorphotic optical system, it is possible to use a video camera and a magnetic tape to record an image that can be viewed later with reduced dimensions.

Description

"METHOD AND APPARATUS FOR OPTICAL ENHANCEMENT OF GRAPHICAL DATA ARRAYS"

This invention relates to a method and apparatus for optically enhancing graphical data arrays for visual interpretation and is particularly although not exclusively suitable for optical enhancement of complex patterns such as seismographs and the like.

In the interpretation of various patterns, e.g. seismographs, multi-channel electrocardiographs, encephlographs and other similar complex patterns representing a graphical information record, it is necessary to visually interpret such information as at present there is no known reliable alternative thereto.

Graphical information such as a seismograph is visually presented as a plurality of substantially parallel bands plotted or printed on a substantially continuous strip of film or paper as a computer printout web. Information relating to the duration and intensity of a reflected shock- wave is processed by a digital computer which may give rise to an elongate printout representing various geological structures and strata. The information is usually printed as a plurality of substantially parallel bands or sine curves of varying period and amplitude. The area under the positive lobes of the curve may be fully blackened during the printout and thus the visual pattern so produced is at least partially enhanced to reveal certain geological occurrences to a skilled analyst of such seismographic data.

At present, it is particularly difficult, even for a skilled pattern analyst, to readily recognise minor pattern variations in a complex seismograph which may represent an area of significant geological interest.

Anamorphotic lens systems are used in the motion picture field to permit projection of motion pictures onto "Cinemascope" type screens which have an aspect ratio of approximately 2-^:1 compared with a conventional screen aspect ratio of approximately 1- :1. To maintain correct geometrical reproduction of the original scene, the image on the positive film must be unnaturally compressed so that its scale horizontally is half its scale vertically. Thus if the original object seen by the camera was a circle, then the image on the positive film, achieved through an anamorphotic taking lens must be an ellipse. This ellipse when projected on the screen via an anamorphotic projection lens attachment, will then appear once more as a circle. A similar anamorphotic system is employed in photocopying apparatus having a reduction or expansion facility. Such copying systems employ a basic spherical system on either side of which are disposed cylindrical members. In one plane the cylindrical members have no power and the spherical member operates at a particular magnification whilst in the other plane the cylindrical members combine with the spherical member to achieve a different magnification. In this system the cylindrical members are arranged with parallel axes in the same plane. The present invention is concerned with a novel method and apparatus employing an anamorphotic image "squeezing" in one or more projection planes by employing an optical image transmission system or its electronic analogue.

Accordingly, it is an aim of the present invention to permit optical enhancement of a graphical record such as a complex pattern array to assist in the visual analysis and interpretation thereof.

It is a further aim of the invention to provide an apparatus for the optical enhancement of graphical arrays. According to one aspect ofthe invention there is provided a method of optically enhancing graphical arrays for visual interpretation comprising:- transmission of light rays -from a graphical array through at least one anamorphotic optical system whereby an image so formed undergoes relative dimensional reduction on at least one planar axis.

Preferably said anamorphotic optical system comprises cylindrical lenses.

Preferably said anamorphotic optical system comprises a series of elongate prisms or reflective surfaces such as curved mirrors.

Preferably said method comprises transmission of light rays through at least two anamorphotic optical systems whereby selective relative rotation between said systems about a transmission axis enables selective relative reduction or expansion of an image so formed on either of at least one planar axis or at least two planar axes substantially at right angles to each other.

Preferably said method includes the step whereby said optically enhanced image is recorded on a photosensitive recording medium.

According to another aspect of the invention there is provided a method of optically enhancing a graphical array for visual interpretation comprising:- conversion of an optical image of a graphical array to electromagnetic signals and retrievably recording said electromagnetic signals in a storage medium therefor, and selectively reconverting information stored as electromagnetic signals to an optical image with relative dimensional reduction in at least one planar axis.

Preferably said stored electromagnetic information is presented as an image on a videoscreen.

Preferably said stored electromagnetic information is presented as a visual image on a photosensitive recording medium.

According to yet another aspect of the invention there is provided an apparatus for optically enhancing graphical arrays for visual interpretation comprising:- at least one anamorphotic optical system; and means to record an image transmitted by said anamorphotic optical system.

WIPO Preferably anamorphotic optical system comprises cylindrical lenses.

Preferably said anamorphotic optical system comprises elongate prisms. Preferably said means to record said image comprises a photosensitive recording medium.

According to a further aspect of the invention there is provided an apparatus for optically enhancing a graphical array for visual interpretation comprising:- means to convert an optical image of a graphical array to electromagnetic signals; means for retrievably recording said electromagnetic signals in a storage medium; and means for selectively reconverting said stored electromagnetic information as an optical image with a relative dimensional reduction in at least one planar axis.

Preferably said apparatus includes means for presenting said optical image on a videoscreen.

Preferably said apparatus includes means for presenting said optical image on a photosensitive recording medium.

Preferably the apparatus is adapted to continuously record an optically enhanced image from an elongate graphical array by relative movement between said graphical array and said apparatus.

Various preferred embodiments of the invention will now be described with reference to the accompanying drawings in which:-

FIGS. 1-3 illustrate various anamorphotic lens systems.

FIGS. 4 and 5 represent a "normal" image and a uni-axial "enhanced" image of seismographic data.

FIGS. 6 and 7 represents a bi-axially enhanced image,

FIG. 8 illustrates a schematic representation of one embodiment of the apparatus.

OMPI FIG. 9 illustrates an alternative form of apparatus.

In FIG. 1 the anamorphotic system comprises a paired series of elongate or "bar-like" achro atised prisms 1 and 2, shown in cross section, which successively compress a parallel bundle of light rays.

FIG. 2 illustrates a preferred alternative embodiment comprising elongate or "bar-like" cylindrical lens system 3 and 4, shown in cross section. Lens system 3 comprises a positive lens system and lens system 4 comprises a negative system to compress one image plane to the desired ratio.

The compression factor for the parallel bundle of light rays shown in FIGS. 1 and 2 is the ratio =■-=• of the "bar-like" prism systems shown in FIG. 1. The cylindrical lens system shown in FIG. 2 has no power in the plane extending normally to the drawings (i.e. through the longitudinal axis of the "bar-like" lens systems) , thus there is no image compression in that plane. Depending upon the degree of compression required, negative lens system 4 illustrated in FIG. 2 may be replaced by a further positive lens system or alternatively an additional positive/negative paired system may be employed in the path of the compressed bundle of light rays illustrated in FIG. 2 in D2 to further compress an image in a desired plane. In the optical enhancement of a graphical array presented as a large object area, a conventional spherical condensing lens system may be employed between the image plane and the anamorphotic system thus further reducing the onoplanarly compressed image to a suitable image area at the focal point.

Variable expansion or compression of an image may be achieved e.g. by the arrangement shown in FIG. 3 by relative inward movement of the two prisms 5 and 6 of the anamorphotic system which decreases the degree of image compression whereas swinging the prisms apart increases the

SNATlO degree of compression. A spherical correcting lens system 7 is provided to obtain a parallel light path.

The operation of the Invention will now be described with reference to FIG. 4 which illustrates portion of a conventional computer printout of the digital reflection data obtained for a geological structure. A number of geological events are represented by substantially continuous, parallel, strong signals extending through the field of interest. When viewed in a plane normal to the plane of the drawings it barely can be seen that there is a slight hump or inclination in certain of the lines in the region of the centre of the region of interest.

When the image of FIG. 4 is condensed with a compression ratio of approximately 2:1 in the horizontal plane, as shown In FIG. 5, these inclinations become substantially more pronounced and are readily visible to the naked eye. The difficulties of visually interpreting seismological data, where seismic events are represented as a series of discontinuous signals is, however, substantially greater. When the lower region of FIG. 4 is condensed with a compression ratio of 2:1 as shown in FIG. 5 pronounced humps or inclinations can be seen within the corresponding region represented by the discontinuous signals. A skilled interpreter of graphically represented seismological data can thus, with the assistance of monoplanar image compression, readily locate seismic events which might otherwise have been overlooked in a normal inspection procedure. Although the longitudinal or X plane data is substantially compressed, the vertical or Y plane data remains unaltered, thus the spacing (represented by time or distance) between signals remains the same.

Many graphical arrays are presented in elongate form such as continuous computer printout paper or roll form graph paper when information representing either a large time span or a large distance span is to be presented. Such information may for example comprise an electrocardiograph, an encephalograph, or as mentioned above seismological survey information. A particular difficulty associated with collection and recording of seismic data is that after the "hard" information is processed through a computer and printed out on substantially continuous paper, the computer recording medium is often erased to make the medium (usually a magnetic tape) available for further use. At present, there is a substantial quantity of hard copy computer printouts being stored, the stored data having valuable geophysical information. However, due to its bulk such stored information cannot be reviewed rapidly and, if necessary, incorporated with newer or additional data. It is necessary to store such seismic information for long periods as although an initial analysis may be carried out this is usually done with a single purpose in mind, i.e. to locate oil and gas bearing structures or a particular mineral seam. It is common practice to subsequently re-examine such information either to confirm an earlier analysis or to re- analyse the data from a different view point with a different goal in mine.

In a modified form of the apparatus according to the invention, cylindrical lens systems of differing powers may be oriented on crossed axes to obtain differing reduction ratios in each of the X, Y axes.

FIG. 6 shows a different enhanced image of FIG. 4. This image was produced with a lens system comprising a pair of spaced anamorphotic cylindrical lenses. With respective axes at right angles to each other. A spherical lens is located in the light path between the anamorphic lenses. As the light rays from the object pass through the first cylindrical lens the image is compressed uniaxially, say on the X axis. The uniaxially compressed image is then further

OMPI

^ ™ reduced by the spherical lens on both the X and Y axis. As the light rays pass through the second cylindrical lens the image is then expanded on the Y axis to give the image shown in FIG. 6. It will be clear to a skilled addressee that depending on the nature of the object data and the enhancement required, the entire lens system may be rotated to expand the image on the X axis and compress on the Y axis. Further, other lens systems may be employed e.g. the spherical lens may be ahead of or behind the anamorphic lenses on the light path and multiple anamorphic systems of different powers may be employed both to reduce distortions and aberrations as well as to obtain differing enhancing effects.

As can be seen in FIG. 6 , the dual axis reduction has been achieved with excellent event and structural resolution without blurring or "fuzziness" normally associated with conventional optical image reduction systems. The various events are accurately retained while the structural features are clearly enhanced to emphasise those features for rapid identification and analysis.

FIG. 7 illustrates schematically one variation on the invention whereby elongate sheets or rolls of graphical information are continuously processed on to, say a roll of photographic film. In the drawings, a roll of continuous computer printout 8 is fed from a feed roll 9 to take up roll 10 over a planar viewing area 11 at a predetermined rate. Situated above viewing area 11 is a spherical compression lens system 12 and an anamorphotic lens system 13. A roll of photographic film 14 is situated above the anamorphotic lens system 13 to have exposed thereon the image transmitted by the optical system. Photographic film 14 is attached to a film transport system (not shown) which advances the photographic film at a rate proportional to the - compression factor of the anamorphotic lens system 13 and also proportional to the rate of travel of computer printout 8. The computer printout and film transport mechanisms are suitably operatively interconnected to maintain a relative transport rate proportional to the compression factor of the anamorphotic lens system and their progress may be continuous with a suitable shutter or rotating prism mechanism or alternatively stepwise with a suitably integrated shutter and transport mechanism.

It is desirable to retain elongate visual records such as computer printout of seismological surveys in a continuous form as it is often inappropriate to cut the continuous roll into a series of short, easily handled sections due to the need for the interpreter to be able to view a maximum amount of data in a linear format.

FIG. 8 shows yet another embodiment of the apparatus. A platform 10 comprising a pair of spaced parallel rails 11 supports an object bed 12 therebetween. The object bed surface is suitably a sheet of clear or opalized glass or acrylic material. Around the periphery of bed 12 is a series of perforations 14 connected underneath to a plenum chamber or manifold (not shown) . The plenum chamber or manifold in turn is connected to a vacuum pump 15. With the vacuum pump 15 in operation, a sheet of computer printout paper 13 when laid upon the surface of bed 12 is drawn against the- upper surface of the glass or acrylic material to form a smooth object surface on the computer printout film or paper free of surface irregularities. An array of lights 16 is provided beneath the object bed surface to provide backlighting for the computer printout if required. A carriage 17 is slidably mounted on side rails 11 to permit lengthwise travel thereof. The carriage 17 includes wheel means 18 engaging with the rails 11 in such a manner as to provide a smooth and accurate travel over the surface of bed 12. A photographic device 19 is mounted on the carriage 17 for selective vertical travel relative to the surface of bed 12. The vertical travel may be manually adjustable but, preferably, the vertical travel is achieved by an electrically operated drive means such as a stepping motor for accurate vertical positioning. The photographic device includes a large film cassette 20 and an image plane bed 21 having a window or slotted aperture 22 therein. The cassette unit includes a variable speed film advance mechanism 20a such as a stepping motor or the like to control the rate of film advance proportionately with the reduction ratio of the lens system and the relative rate of motion between the film and the object surface. The image plane bed 21 may be of metal or opaque material and the window slotted aperture may be comprised by a transparent window in the opaque material. The image plane bed 20 includes a peripheral row of apertures 23 connected to a manifold or plenum in a similar manner to object bed 12. Similarly to object bed 12, the plenum or manifold may be evacuated sufficiently to hold the photographic film in the region of the aperture in a flat plane of predetermined position but otherwise to allow film transport.

The device 19 also includes a bellows or like telescopic body 24 and a lens holder 25. Lens holder 25 holds either a fixed anamorphotic lens system or a variable lens system for differing magnification values. Suitably the lens components or systems are pivotably mounted in pivotal frames 26 in lens holder 25. A shutter assembly may also be provided in association with the lens holder if required. A number of lights 27 are mounted on carriage 17 for reflective .illumination of the object surface.

Accurate positioning of carriage 17 along the bed 12 or control of the rate of travel of the carriage may. be achieved by carriage mounted worm member 28 coacting with driven screw shaft 29. Shaft 29 is driven by a stepping motor 30.

Controls for carriage movement, device elevation, bellows extension or retraction film advance, computer printout advance, lighting, vacuum pumps etc. are provided in control panel 31 mounted on carriage 17.

Preferably all of the various control mechanisms are controlled by a microprocessor to ensure correct integration of relative rate of film transport compared with carriage speed in accordance with the magnification factor of the lens system.

In use, a web of computer printout 13 is laid over the surface of bed 12 and positioned laterally by means of mechanical, optical or powered guides and/or sensors 32. The web of computer printout 13 may if required be fed from a feed roll 13a positioned adjacent one end of bed 12 and taken up on a take-up roll 13b at the other end. The take-up roll 13b and feed roll 13a are provided with a suitable drive mechanism 13c such as a stepping motor or the like to feed or rewind the web of computer printout 13. A microprosessor controlled drive means is preferably employed to advance the computer printout web as required, either at a continuous controlled rate or at predetermined step-wise lengths. For this purpose, optical or electronic sensors may be used to accurately guide the computer printout web, i.e. by sensing the timing lines on the X axis and/or the seismic traces on the Y axis.

Initially the photographic device 19 is positioned over the computer printout web and an appropriate lens system is selected to obtain the desired reduction in the X,Y axes. With the film cassette 20 removed the image of the seismo- graphic print on the web is focussed accurately at the image plane of window or slot 22 by use of a thin translucent plastics sheet or the like. Focussing is achieved by vertical movement of the device 19 on carriage 17, the bellows 24 and/ or the lens system. Each cylindrical lens is individually movable relative to each other and to any spherical lens system which may be employed in the anamorphotic combination. This may be done by means of manual or electrically driven adjustment means. After focussing is complete the film cartridge 20 is replaced and the film is drawn into contact with the image plane bed 21 by activating the vacuum system.

Having selected the X, Y reduction ratios with a particular lens system, a relative speed rate is then set between film advance rate and carriage travel rate. For example, if the reduction in the X or longitudinal axis of the computer printout is 50% then the film is set to advance at 50% of the speed of the computer printout web relative to the lens system. A suitable integrated circuit is provided to control film advance speed in proportion to carriage advance speed.

With a length of computer printout web held onto the object bed surface 12 under the influence of the reduced air pressure maintained by pump 15, the carriage is set in motion to traverse the length of the object bed progressively photographing the data on the printout.

Carriage traverse is halted at a predetermined distance by an optical or electrical sensor means 33 which activates the control circuit to return the carriage to its initial position while at the same time advancing the computer printout web a suitable distance. The control circuit activates a shutter assembly associated with the lens system to open and close the shutter at the appropriate times.

It will be clear to a skilled addressee that there are many modifications which may be made to the above apparatus. Rather than scanning continuously the carriage may be set to advance step-wise to photograph discrete lengths of the computer printout web such as to obtain a continuous photographic record. Alternatively the carriage could be fixed and the computer printout could be traversed past the lens system. The apparatus may be oriented in any manner required such as vertically, horizontally etc. In the various embodiments of the apparatus possible according to the invention, it is important that the various drive means, sensor means and camera controls be highly precise in nature and operation to ensure a high resolution photographic record. In view of the relatively large dimensions of the object field, particularly in the X or longitudinal axis, it is preferred that the cylindrical lenses comprised in the anamorphotic system are ground to aberration effects towards the periphery of the image field. The invention also embraces an electronic analogue of the optical system described above. For example, instead of recording the re-quired information, after optical compression, onto a photographic recording medium, the image of the graphical array may be recorded with a video camera as electronic impulses on a magnetic tape. Compression of the image in a selected plane may occur electronically in a known means by proportioning the X or Y axis as required and either recording the compressed image on the electronic recording medium or alternatively transmitting same as a compressed image. -An image so recorded can then be viewed at leisure as a moving image on say a videoscreen whereby the velocity of transport of the image across the screen may be selectively varied and simultaneously the degree of compression in the X or Y axes can also be selectively varied. If required, selected portions of the electronically recorded image may then be presented as hard copy photographs or other paper images.

In a most preferred embodiment of the invention backlighting of the object is achieved by a light (not shown) mounted on the carriage 17 beneath the object bed surface 12. The light travels with the carriage during movement. If required, a fibre optic array may be employed as a light pathway. The array may be used in the restructuring of the image.

Claims

CLAIMS :

1. A method of optically enhancing graphical arrays for visual interpretation comprising:- transmission of light rays from a graphical array through at least one anamorphotic optical system whereby an image so formed undergoes relative dimensional reduction on at least one planar axis.

2. A method as claimed in claim 1 wherein said anamorphotic optical system includes cylindrical lenses.

3. A method as claimed in claim 1 wherein said anamorphotic optical system includes a series of elongate prisms.

4. A method as claimed in claim 1 wherein said anamorphotic optical system is comprised of curved reflect¬ ive surfaces.

5. A method as claimed in any preceding claim wherein light rays are transmitted through at least two anamorphotic optical systems whereby selective relative rotation between said systems about a transmission axis enables selective relative reduction or expansion of an Image so formed on either of at least one planar axis or at least two planar axes substantially at right angles to each other.

6. A method as claimed in any preceding claim wherein said method includes the step whereby said optically enhanced image is recorded on a photosensitive recording medium.

7. A method of optically enhancing a graphical array for visual interpretation comprising:- conversion of an optical image of a graphical array to electromagnetic signals and retrievably recording said electromagnetic-signals in a storage medium therefor, and selectively reconverting information stored as electromagnetic signals to an optical image with relative dimensional reduction in at least one planar axis.

8. An apparatus for optically enhancing graphical arrays for visual interpretation co prising:- at least one anamorphotic optical system; and means to record an image transmitted by said anamorphotic optical system.

9. An apparatus as claimed in claim 8 wherein said anamorphotic optical system comprises cylindrical lenses.

10. An apparatus as claimed in claim 8 wherein said anamorphotic optical system comprises elongate prisms.

11. An apparatus as claimed in any one of claims 8-10 wherein said means to record said image comprises a photosensitive recording medium.

12. An apparatus as claimed in any one of claims 8-10 including means to continuously record an optically enhanced image from an elongate graphical array by relative movement between said graphical array.and said apparatus.

13. An apparatus for optically enhancing a graphical array for visual interpretation comprising:- means to convert an optical image of a graphical array to electromagnetic signals; means for retrievably recording said electromagnetic signals in a storage medium; and means for selectively reconverting said stored electromagnetic information as an optical image with a relative dimensional reduction in at least one planar axis.