WO2001063355A1

WO2001063355A1 - Image modifying apparatus and method

Info

Publication number: WO2001063355A1
Application number: PCT/GB2000/000689
Authority: WO
Inventors: Michael Pia
Original assignee: Mike Pia Video And Film Company Ltd.
Priority date: 2000-02-25
Filing date: 2000-02-25
Publication date: 2001-08-30
Also published as: AU2815300A

Abstract

An image modifying apparatus for an image capture device, eg. a film camera. The apparatus includes optical means (1) for relaying an image from an image plane to a plane of focus, and means (4) for modifying an image at said image plane, the apparatus being adapted for mounting on or adjacent the image capture device such that the plane of focus coincides with an image capture plane (e.g. the plane of the film in a film camera) of the image capture device. When used in conjunction with a lens to focus an image of an object onto the image plane, the image plane can serve as a preliminary plane of focus where the image is accessible to be modified before it is relayed to the plane of focus coinciding with the image capture plane. Thus, it becomes possible to superimpose an effect onto an image of an object focussed at the preliminary plane of focus and to capture the combination of the two, that is the modified image, in real time at the primary plane of focus.

Description

IMAGE MODIFYING APPARATUS AND METHOD

FIELD OF THE INVENTION

The present invention relates to image modifying apparatus for an image capture device, for example a film, video or digital camera. The invention is particularly, although not necessarily exclusively, applicable to the field of visual effects.

BACKGROUND TO THE INVENTION

A number of different types of apparatus exist for modifying images captured by cameras. Such visual effects apparatus range from relatively simple filters or slides that are placed in front of the lens of a stills or moving image camera to modify the image in real time as it is being captured, to sophisticated, expensive digital processing systems used to manipulate pre-captured digital images .

The various types of image modifying apparatus available today each have their own strengths and weaknesses. Filters and slides are relatively inexpensive and have the advantage that the image is captured at the outset in the desired modified form; there is no need for a further, separate modification operation. However, there are limitations to the range of visual effects possible using this simple technology because, for example, it is not possible to have the image of the object and the effect being added to it by the filter or slide both in sharp focus, particularly where the object and the filter/slide are spaced apart by a considerable distance.

In contrast, there are few, if any, limitations on the effects possible using digital image processing methods and, since the effect is added after the image is captured, the problem of out of focus effects simply does not occur. However, the cost of the apparatus required for this type of image modification can be prohibitive and real-time capture of modified images is not possible.

SUMMARY OF THE INVENTION

In a first aspect the present invention provides an image modifying apparatus for an image capture device, comprising optical means for relaying an image from an image plane to a plane of focus, and means for modifying an image at said image plane, the apparatus being adapted for mounting on or adjacent the image capture device such that the plane of focus coincides with an image capture plane (e.g. the plane of the film in a film camera) of the image capture device. The apparatus can be used in conjunction with a focusing means, for instance an optical lens, to focus an image of an object onto the image plane. The image plane then serves as a preliminary plane of focus where the image is accessible to be modified before it is relayed to the plane of focus coinciding with the image capture plane, which will be referred to as the primary plane of focus herein. Thus, it becomes possible to superimpose an effect onto an image of an object focused at the preliminary plane of focus and to capture the combination of the two, that is the modified image, m real time at the primary plane of focus . The invention also provides, in a second aspect, a method of image capture comprising focusing an image of an object onto a preliminary plane of focus, modifying the image at said preliminary plane of focus, relaying the modified image via optical means to a primary plane of focus, and capturing the modified image at said primary plane of focus.

In a third aspect, there is provided an image modifying apparatus comprising a tubular casing having one end adapted for attachment to an image capture device, a chamber at or adjacent the other end of the casing, means for mounting a lens on the apparatus for focusing an image of an object onto an image plane within the chamber, means for modifying or superimposing upon an image m the chamber at the image plane and optical means m the casing for relaying an image from the image plane to a primary plane of focus beyond said one end of the casing, the apparatus being adapted so that the primary plane of focus coincides with an image capture plane of the image capture device.

The invention also provides, in further aspects: (1) an image modifying apparatus m accordance with the first or third aspects set forth above, comprising focusing means for focusing an image of an object onto the image plane; and (2) an image capture device comprising or in combination with an image modifying apparatus as set forth above .

In apparatus according to the invention, the optical means for relaying the image preferably comprises a series of optical lenses. It is particularly desirable that the optical means relays the image with minimal optical distortion, so a lens arrangement with substantially no optical distortion is preferably chosen. Known relay lenses/optics may be used. The means for modifying the image at the image plane can, for example, take the form of one or more filters or slides already known m the art, positioned at or close to that plane. Since the effect introduced by such a filter or slide is superimposed over an image which can be sharply focused at or very close to the actual plane at which the effect is being introduced, in addition to being focused at the image capture plane, the resulting modified image can be markedly improved over those achieved using known filter/slide lens combinations. Furthermore, because both the image of the object and the effect can be captured m focus, it becomes possible to introduce, in real time, more complex, yet realistic effects than had previously been thought possible. For example, a variety of optical elements may be placed at or close to the first image plane, i.e. the preliminary plane of focus, to distort the image, whilst maintaining it m focus. Another possibility is to position a liquid containing slide at or close to the image plane, enabling various effects to be achieved by agitating the liquid, for example by blowing air or other gases therethrough. Other effects may be achieved by using slides through which gaseous or even solid substances can pass, for instance by being blown therethrough.

Effects such as these or alternative effects may be achieved by introducing an appropriate light source, which may be coloured, into the vicinity of the image plane . It may also be desirable to provide means for manoeuvring the slides, optical elements or other means provided to modify the object image, relative to the optical path. For example, means may be provided for traversing a slide left to right and/or up and down across the image plane to introduce relative motion at the primary plane of focus between the object and the effect. Rotation about or movement along the optical path may also be provided for.

It is preferred that embodiments of the apparatus of the invention can each be used to provide a plurality of differing effects. To achieve this a number of interchangeable image modification means may be provided, for example as a series of cartridges or slides (containing e.g. fluids, gases, optical elements, etc.) mountable in a chamber of the apparatus close to or coincident with the image plane.

It is also desirable that embodiments of the invention can be adapted for use with a variety of different image capture devices, for example different makes and models of film camera, which may require different forms of connection with the apparatus. Preferably, therefore, the apparatus comprises interchangeable mounts at one end for attachment to the different types of camera, or other image capture device, and advantageously also at the opposite end for mounting a variety of different types of lens for focusing an image onto the image plane.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention is described below, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a side view of a visual effects apparatus according to an embodiment of the present invention;

Fig. 2(a) and (b) schematically illustrate an effects slide for use with the apparatus of Fig. 1;

Fig. 3 illustrates the lens configuration used in the apparatus of Fig. 1; and

Figs. 4(a) and (b) , show stills images of a motion picture test filmed using apparatus in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT The two principal components of the illustrated apparatus are a relay optic 1 retained in a cylindrical casing 7, and an effects chamber 4 mounted on one end of the casing 7. The effects chamber 4 is adapted to carry one or more slides or cartridges which serve to modify an image focused in the chamber 4. The relay optic is formed by an arrangement of optical lens elements, in this example the arrangement being symmetrical about a mid-point along the length of the optic 1 (see Fig. 3) to provide a 1:1 ratio of image sizes from one end of the optic to the other. In other embodiments, alternative relay optics may be used to magnify or reduce the relayed image.

The apparatus can be interposed between the focal plane (i.e. the plane of the film or other image receptor) of a camera and a camera lens to provide an optical path extending through, in order, the camera lens (not shown) , the effects chamber 4, the relay optic 1 and on to the plane of the film, or other image capture plane in the camera .

A camera lens mount 11a for mounting the apparatus to the camera (not shown) is provided at the end of the casing 7 opposite the effects chamber 4, and a further lens mount lib is provided in front of the effects chamber 4 for the camera lens (not shown) . It is preferred that a number of interchangeable lens mounts are provided, both for the camera end and the effects chamber end of the relay optic, so that the apparatus can be used with a number of different cameras and/or lenses, having different forms of connector, simply by changing the corresponding mount on the apparatus . A support structure 8,9 supports the relay optic casing 7, and a lens support 2 is slidably supported on and extends upwardly from this structure in front of the effects chamber 4. The lens mount lib is carried on the lens support 2.

With the aim of preventing ambient light from entering the apparatus other than through the camera lens, a light seal 12 is provided between the relay optic casing 7 and the effects chamber 4, and a bellows cover 3 extends between the effects chamber 4 and the lens support 2.

The bellows form of cover is used in preference to a cover of fixed length to allow for adjustment of the distance between the effects chamber and the lens support, and hence a lens mounted on it. This may be desirable, in addition to any focusing mechanism built into the lens used, to allow an image to be correctly focused onto a plane within the effects chamber, and/or to enable adjustment of the relative axial positioning of an image focused in the effects chamber 4 by the camera lens and an effects slide carried in the chamber. Other than such motion along the axis of the apparatus, however, the lens mount lib is fixed rigidly in relation to the optic casing 7.

In addition to, or as an alternative to focus control achieved via relative movement between the camera lens and the effects chamber/relay optic, the relay lens may be focusable itself.

It is also desirable to provide some control over the amount of light passing through the apparatus to the camera. This control can be accomplished, for example, by incorporating in the apparatus an iris diaphragm 10, or other device to control the size of an aperture in the light path through the apparatus, preferably located at the camera end of the relay optic 1. With such an arrangement the amount of light reaching the primary focal plane in the camera body can be controlled independently of the light admitted through the camera lens. This may be desirable, for instance, to allow maximum light to enter the relay optic 1 to enhance its performance, whilst ensuring that the film or other image receptor is not over-exposed. The effects chamber 4 is in the form of an enclosure into which a selected one or more of a number of interchangeable cartridges or slides can be inserted, each cartridge/slide providing a different effect; i.e. modifying an image in the effects chamber in a different way. The position and orientation of the cartridge or slide within the effects chamber may be adjustable to vary the effect achieved. This adjustability may be provided, for example, in orthogonal x and y directions perpendicular to the optical path through the apparatus, in a third orthogonal z direction parallel to that path and rotationally about an axis parallel to that path. It may be advantageous to motorise these motions so that they can be controlled remotely.

In use, the camera lens (not shown) is used to focus an aerial image of an external object in a preliminary plane of focus within the effects chamber 4. The relay optic 7 relays this image from the preliminary plane of focus to a primary plane of focus, beyond the camera end of the relay optic casing 7, coincident with the plane of the film or other image receptor in the camera.

Thus, at the preliminary plane of focus, within the effects chamber 4, there is a sharply focused image of the object which can be readily added to, distorted, or otherwise modified. The particular modification made depends on the slide (or slides) held in the effects chamber 4, but examples include:

(1) overlaying on the image a mask of moving bubbles or a mask of moving solid particles (for example coloured powder to simulate a sand or snow storm) - the applicant has found that combined images formed in this manner appear extremely realistic, respectively providing images that appear to have been shot underwater or in snow/sand storms without having to go to the expense and inconvenience of using underwater cameras in the first case and large wind machines in the latter cases;

(2) using solids, such as glass beads, held in a slide filled with a liquid such as a paraffin solution through which the beads will slowly fall under the influence of gravity; and

(3) placing an oil/water emulsion on a slide in the plane of the image to distort the image as globules of water, acting like miniature lenses, move around on the slide - Figs. 4(a) and (b) show stills images captured from a motion picture test using such an effects slide. Interestingly, it has been found that by moving such an effects slide (in the z direction) into and out of the preliminary plane of focus the effect can be "switched" on and off.

Many other effects are possible.

Fig. 2 schematically shows one example of a slide 17 for use with the apparatus of Fig. 1, Fig. 2(a) showing the slide from the side and Fig. 2(b) showing the slide face-on.

The slide 17 has an outer casing 18 defining a chamber 19 which holds a liquid. In this example, the casing includes a rectangular frame 18a forming the side walls and two, separate face panels 18b closing opposite sides of the frame 18a to form the chamber 19. Ring seals 13 are used to seal the joins between these parts. At the base of the chamber 19 there is an air inlet gallery or pipe 16 to which compressed air can be supplied from an external source, and an exhaust 15 for the air is provided at the top of the chamber 19. A plurality of such inlet arrangements and/or exhaust arrangements may be employed. Also, depending on the desired effect, the inlet may alternatively be located adjacent vertical sides of the chamber rather than at its base.

In use, air is forced into the chamber 19 through perforations provided in the inlet gallery 16 and bubbles up through the liquid. The perforations can be provided by a filter covering an exit from the gallery. Advantageously the size of the perforations can be selected to control the air bubble size. Preferably means are provided for controlling the size of the "perforations" or other openings from the inlet gallery to the chamber. It has been found that a particularly convenient way of controlling the "perforation size" is to use a coil spring as the inlet gallery. The spring is stretched to open up the coils to provide large "perforations" and vice versa. Preferably a valve is provided in the air supply system to control the flow rate of air through the chamber and provision may also be made for controlling the direction in which the air is blown into the chamber 19. Alternatively, where the slide 17 can be rotated relative to the effects chamber, the direction in which the air is blown into the slide 17 relative to an image focused on a plane in the effects chamber can be adjusted by virtue of this relative rotation.

To further enhance and/or alter the image in the effects chamber various different forms or illumination may be introduced to the chamber, for example using a fibre optic to deliver light, which may for example be coloured, from a suitable light source 5.

It will be appreciated that many variations to and modifications of the features specifically described above can be made within the scope of the invention, to achieve many different effects. For example, it may be desirable to work with an image in the effects chamber which is larger than that suitable for capture by the camera being used, in which case a relay optic which reduces the size of the relayed image can be employed. It may also be that the large image desired at the effects chamber is not provided by the camera lens being used, in which case further optical elements can be employed between the camera lens and the effects chamber to enlarge the image .

Another possibility is to include in the system, for example at one end or the other of the relay lens/optic, an optical element to manipulate the orientation of the relayed image. For example, the relay optic illustrated in Fig. 3 produces an inverted image at the camera and an image rectifying prism, eg. a dovetail prism, could be used to re-invert the image before it is captured by the camera.

Claims

1. Image modifying apparatus for an image capture device, comprising optical means for relaying an image from an image plane to a plane of focus, and means for modifying an image at said image plane, the apparatus being adapted for mounting on or adjacent the image capture device such that the plane of focus coincides with an image capture plane of the image capture device.

2. Apparatus according to claim 1, comprising focussing means to focus an image of an object onto the image plane .

3. Apparatus according to claim 1 or 2, wherein the optical means for relaying the image comprises a series of optical lenses.

4. Apparatus according to claim 3, wherein the series of optical lenses is a lens arrangement with substantially no optical distortion.

5. Apparatus according to any one of the preceding claims, wherein the means for modifying the image at the image plane comprises one or more filters or slides positioned at or close to that plane.

6. Apparatus according to any one of claims 1 to 4, wherein the means for modifying the image at the image plane comprises one or more optical elements placed at or close to the image plane to distort the image whilst maintaining it in focus .

7. Apparatus according to any one of claims 1 to 4, wherein the means for modifying the image at the image plane comprises a liquid containing slide at or close to the image plane, whereby various effects to be achieved by agitating the liquid.

8. Apparatus according to any one of claims 1 to 4, wherein the means for modifying the image at the image plane comprises a slide through which gaseous or solid substances can pass.

9. Apparatus according to any one of the preceding claims, comprising means for introducing a light source, which may be coloured, into the vicinity of the image plane .

10. Apparatus according to any one of the preceding claims, comprising means for manoeuvring the slides, optical elements or other means provided to modify the object image, relative to the optical path.

11. Apparatus according to any one of the preceding claims, comprising a plurality of interchangeable image modification means.

12. Apparatus according to claim 11, wherein the interchangeable image modification means comprise a series of cartridges or slides mountable m a chamber of the apparatus close to or coincident with the image plane .

13. Apparatus according to any one of the preceding claims, comprising interchangeable mounts at one end for attachment to the different image capture devices, and/or at the opposite end for mounting a variety of different types of lens for focussing an image onto the image plane .

14. Image modifying apparatus substantially as described herein with reference to and/or as illustrated m the accompanying drawings.

15. An image modifying apparatus comprising a tubular casing having one end adapted for attachment to an image capture device, a chamber at or adjacent the other end of the casing, means for mounting a lens on the apparatus for focussing an image of an object onto an image plane within the chamber, means for modifying or superimposing upon an image m the chamber at the image plane and optical means m the casing for relaying an image from the image plane to a primary plane of focus beyond said one end of the casing, the apparatus being adapted so that the primary plane of focus coincides with an image capture plane of the image capture device.

16. An image capture device comprising or in combination with an image modifying apparatus according to any one of the preceding claims.

17. A method of image capture comprising focussing an image of an object onto a preliminary plane of focus, modifying the image at said preliminary plane of focus, relaying the modified image via optical means to a primary plane of focus, and capturing the modified image at said primary plane of focus.