Camera and method for forming a recording of an image of at least a part of an object

Camera and method for forming a registration of an image of at least a part of an object

The invention relates to a camera for forming a registration of an image of at least a part of an object, comprising:

- a registration element for forming a registration of the image;

- an optic for projecting the image onto the recording element; and

- optionally releasable positioning means for positioning the camera relative to the object.

Such a camera is for instance known from EP-A-1 094 349, in which a camera is shown with four light sources emitting respective light beams, the camera being at the correct distance and at a correct angle relative to the object when the four light beams intersect at the height of the object. A disadvantage of the camera from EP-A-1 094 349 is that the camera cannot be positioned properly with respect to an object with a non-flat surface.

It is an object of the invention to obviate the above drawback. In particular, it is an object of the invention to provide a camera that can be precisely positioned relative to an object with a non-flat surface, such that a sharp image of the object can be recorded.

For this purpose, the camera of the type mentioned in the preamble is distinguished from the known camera in that the positioning means comprise three light sources for emitting only three respective calibration light beams to the object, which light sources are arranged to be in a fixable and / or reproducible position relative to of the registration element and / or the optic, wherein reflected light beams reflected by the object can be received by the recording element via the optic, and wherein three locations are defined in the recording element, such that received reflected calibration light beams can coincide with the three locations.

Because the positioning means comprise three light sources, wherein three calibration light beams are emitted which, when the camera is positioned correctly with respect to the object, coincide with three locations defined in the recording element, the camera is dependent on three reflective locations for a correct positioning. in the object instead of a single incident location. When a single incident location is in a non-planar part of the object, it may be that the camera appears to be positioned correctly with respect to that one incident location, but it is not relative to the rest of the object. At three reflection locations, this probability is reduced such that the camera according to the invention can be positioned with a high probability relative to the object. A high degree of accuracy and / or adjustability and / or reproducibility can be achieved. The calibration light beams have a cross-section that is preferably small with respect to at least the part of the object, such that the camera can be accurately positioned with respect to the object. Preferably, the cross-section of the calibration light beams can be so small that one could speak of calibration light rays.

It is noted that calibration light beams are also understood to mean negative calibration light beams. A negative light beam is here understood to mean that the three light sources emit a light beam with an interruption therein, wherein precisely the interruption can coincide the three locations for correct positioning.

It is further noted that a light source is understood to mean that a light beam emits. This could, for example, also be only one lamp that emits three light beams, the lamp therefore comprising three light sources. A lamp could, for example, also emit only one positive light beam with three interruptions therein, so that three negative light beams are emitted. There are also three light sources for the three negative light beams.

For example, the coincidence of the received reflected calibration beams with the three locations in the recording element can be determined automatically.

Prior to the first use, the camera is preferably adjusted such that with the aid of the known spatial geometry of the camera and a possible fictional reference surface which is at an angle, for example perpendicular, to the optical axis of the optic and that is located at a certain distance from the optical center of the optic, it is determined, that the possible fictional emitted calibration light beams coincide with the three locations in the recording element upon reflection of this reference plane. This has the advantage that the camera can be adjusted without the presence of the object of which a registration is being formed. The camera can optionally be adjusted in the manner described above whenever desired, for example when one of the light sources is displaced from the known position relative to the optic.

In a preferred embodiment of the camera according to the invention, the camera comprises optical display means for displaying the recording, which display means are arranged for displaying the three locations and the received reflected calibration light beams.

By using the optical display means, the user can easily visually determine whether the reflected calibration beams coincide with the three defined locations in the recording element. In this way the correct positioning of the camera relative to the object can easily take place.

For example, the display means are selected from the group comprising: an optical focusing means, a camera display, and a computer screen.

The camera comprises coupling means for coupling the camera to a computer for supplying the registration to the computer. The computer may, for example, be in the vicinity of the camera, such that the camera and the computer are coupled to each other over a short distance. Alternatively, the computer may be located at a greater distance from the camera, such that the remote recording of the camera can be processed. The computer can be arranged such that it automatically reports on an input registration.

The camera preferably comprises a fourth light source for transmitting a recording light beam to the object. A registration light beam is also understood to mean a registration light beam.

Such a fourth light source has the advantage that a different light source can possibly be used for this than for the calibration light beams. The fourth light source can in particular be suitable for illuminating a specific part of the object for forming the registration.

In an embodiment of the camera according to the invention, the fourth light source emits a fan-shaped beam or a parallel beam.

A parallel beam or a fan-shaped beam is particularly suitable as incident light, since with the aid of such a beam a 2D depth profile of the object can be properly established. The fan-shaped bundle can be either a diverging bundle or a flat fan-shaped bundle.

Optionally, light can be projected by the or each recording light source with a known pattern, such as, for example, in the form of lines, or a grid or net (constructed from, for example, lines or dots), or many different geometric shapes in an ordered or unordered pattern. Optionally use can be made, for example, of multi-line lasers or of movable projection of the laser lines, also referred to as scanning. Optionally use can be made of a camera that moves relative to the object, for example by connecting the camera to a standard whose movement in the space can be controlled, for example electronically. Optionally, use can be made of a moving object, for example a rotating wheel. A dynamic image can optionally be obtained by recordings made in succession over time.

In another embodiment of the camera according to the invention, the wavelengths of the three transmitted calibration light beams and / or the recording light beam have a narrow bandwidth, also referred to as multi-spectral light.

In another embodiment of the camera according to the invention, the wavelengths of the three transmitted calibration light beams and / or the recording light beam are mutually different.

The light sources can optionally be switched on and off quickly in a specific order, to distinguish the light emitted by the light sources.

The invention furthermore relates to a method for forming a registration of an image of at least a part of an object using a camera as described above, which method comprises the steps of:

a) providing the camera, comprising:

- a registration element for forming a registration of the image;

- an optic for projecting the image onto the recording element; and

- optionally releasable positioning means for positioning the camera relative to the object, which positioning means comprise three light sources for emitting only three respective calibration light beams to the object, which light sources are arranged to be in a fixable and / or reproducible position relative to the object registration element and / or the optic, wherein reflected light beams reflected by the object can be received by the recording element via the optic, and wherein three locations are defined in the recording element such that received reflected calibration light beams can coincide with the three locations;

b) moving the camera such that each of the three reflected reflected light beams received coincides with a respective location in the recording element; and

c) forming a registration of the image.

With a method according to the invention, the camera can be positioned correctly relative to an object in that all degrees of freedom of the position of the camera relative to the object are obviated at the moment that each of the three received reflected calibration light beams coincides with a respective location in the registration element.

An additional advantage of the method according to the invention is that the registration of the object can take place without the camera being brought into contact with the object.

Preferably the method comprises the steps of:

d) defining two object locations on the surface of the object;

e) mutual movement of the camera and the object such that two of the three transmitted calibration light beams are each received and reflected by the object in the area of ​​a respective object location; and

f) defining a convention with respect to the third calibration light beam that is not received and reflected by the object in the area of ​​an object location.

By defining two object locations on the surface of the object, a specific part of the object can be registered each time. In this way not only a registration is provided in which the camera is correctly positioned to form a sharp registration, but also a registration of the same determined part of the object in each case. When two object locations are determined, a convention must be defined with respect to the third calibration light beam that is not received by the object in the area of ​​one of the two defined object locations and is reflected. Such a convention may, for example, comprise that the third calibration light beam is always to the left of the two object locations when the camera is directed at the object from a certain direction.

More preferably, the method comprises the steps of:

g) defining three object locations on the surface of the object; and

h) the relative displacement of the camera and the object such that each of the three transmitted calibration light beams in the area of ​​a respective object location are received by the object and are reflected.

By defining three object locations on the surface of the object, whereby the calibration light beams coincide with the respective object locations, it can be achieved that each time a registration is formed of a certain part of the object, just as with two object locations. Defining three object locations has the advantage over two object locations that no convention is needed.

In another embodiment of the method according to the invention, the method comprises the step of:

i) transmitting a recording light beam to the object, which recording light beam is received and reflected by the object, such that the reflected recording light beam is received by the recording element.

By emitting a recording light beam, a certain part of the object can be exposed, so that the object is clearly visible in the formed registration.

Preferably the method comprises the steps of:

j) defining a reference plane that is angled with respect to an optical axis of the optic and that is at a predetermined distance from the optical center of the optic; and

k) determining the perpendicular distance between the reference plane and a location in which the recording light beam is received by the object and is reflected.

By determining the perpendicular distance between the reference plane and the location in which the recording light beam is received by the object and is reflected, a depth profile of the object can easily be determined. Such a depth profile can be used in particular for checking objects for wear. Namely, a user can easily determine how the object wears at certain places, since the depth of the object can be a measure of the wear.

The reference plane can also be used to set the camera without the presence of the object of which a recording is being made, as described above. The reference plane can be accurately determined independently of the object, whereby the camera can be accurately adjusted.

Another advantage of defining the reference plane is that this reference plane can be used to set the camera prior to first use or whenever it is desired.

In a preferred embodiment of the method according to the invention, it comprises the steps of:

l) forming a number of registrations of images of at least the part of the object, wherein each time a subsequent registration is formed after a specific time unit; and

m) comparing the number of registrations with each other.

As indicated above, with the camera and the method according to the invention a registration of an image of at least a part of an object can be formed, wherein the position of the camera relative to the object is correct and / or wherein the same part of each an object can be registered. This principle can advantageously be applied for forming a number of registrations of the object at successive times, such that changes of the object over time can be determined. The determined time unit can be any suitable time unit, which time unit can be the same or different. Determining changes in the surface of the object can, for example, be used advantageously for determining the wear of an object.

In particular, the method according to the invention can be used in tests on the skin of a patient. By forming a registration of, for example, a skin wound each time after a certain time unit has elapsed, it can easily be established whether the wound is recovering or whether the wound is actually worsening. In diabetic patients, it can happen that patients get a wound on their feet due to a combination of impaired blood and nerve supply. Since it can be difficult for patients to make a registration of an image of the foot, with the camera positioned correctly, this method can be used very suitably for this. Furthermore, the method is very advantageous when examining the skin, because in the method according to the invention the camera is not brought into contact with the skin. This can reduce the risk of contamination.

In another preferred embodiment of the method according to the invention, it comprises the steps of:

n) forming a number of recordings of images of in each case at least the part of a number of objects; and

o) the mutual comparison of those registrations.

By each time forming a registration of the same part of a number of objects, these registrations can be compared with each other for determining similarities and differences between similar objects. This can be used particularly advantageously for determining wear, whereby it can easily be determined whether a certain object wears out faster than another similar object.

In the method described above for forming a registration of at least a part of an object, the registration can be formed with respect to at least one of the following of at least the part of the object: a depth of the surface; a certain shape; a size; a limit; and a border. Optionally, a number of partial registrations can be combined to form a total registration.

Optionally, in the method described above for forming a registration of at least a part of an object, use can be made of a correction of ambient light, also referred to as error light correction.

The invention can in particular relate to a method for forming a registration of an image of at least a part of a biological and / or living surface, in particular the skin of an individual. For example, a registration may be made of a skin defect.

The invention also relates to a method for analyzing one or more registrations of an image of at least a part of one or more objects, wherein the or each registration is formed using a camera as described above, and by a method such as previously described. For example, in the analysis the registration can be merged with other information about the object. The analysis can, for example, take place remotely from the camera, by which is meant that the formation of the registration and the analysis of the registration can take place separately from each other. The analysis could place after a certain time unit after forming the record, which particular time unit can be any suitable time unit. In this way the formation of the registration and the analysis of the registration can take place separately from each other.

Preferably two or more registrations of an image of at least a part of one or more objects are formed, the method for analyzing the registrations comprising the steps of:

p) comparing the two or more registrations with each other; and

q) determining differences between the two or more registrations.

The invention will be explained in more detail below with reference to figures shown in a drawing, wherein:

figures 1A-1C show a camera according to the invention in perspective;

figures 2A-2C show the registration element of the camera of figures 1A-1C;

figures 3A-3C show the registration element of a camera according to a second embodiment;

figures 4A-4C show the registration element of a camera according to a third embodiment;

figures 5A, 5B show a schematic side view of the camera of figures 1A-C;

figure 6 shows a schematic representation of a reference surface; and

figure 7 shows a camera according to a fourth embodiment of the invention in perspective.

Figures 1A-1C show a camera 1 for forming a registration of an image of at least a part of an object 2. The camera 1 comprises a recording element 3 for forming a recording of the image, an optic 4 for projecting the image onto the recording element 3 and three light sources 5-7, which light sources 5-7 are fixedly connected to the camera 1 by means of respective connecting rods 8-10, such that the light sources 5-7 are arranged fixedly relative to the optic 4. In other embodiments of the camera 1, the light sources 5-7 can be arranged releasably relative to the camera, the position of the light sources 5-7 relative to the optic 4 being reproducible.

In figure 1A three locations 11-13 in the registration element 3 are defined. The camera 1 is correctly positioned with respect to the object 2 when calibration light beams emitted from the light sources 5-7 and reflected from the object 2, which in the figures are represented as calibration light rays, coincide with these three respective locations 11-13.

Figure 1A shows fictional calibration light rays 14-16. The camera can be adjusted by these fictional calibration light beams 14-16 relative to a fictional reference plane (not shown) prior to first use or when desired, which is perpendicular to an optical axis of the optic 4 and at a certain distance from the optical center of the optic 4, to reflect fictionally and to receive it in the recording element

3. When the camera is positioned correctly with respect to this fictional reference plane, the locations in the recording element 3 where the fictional calibration light rays 14-16 are received coincide with the three defined locations 11-13. In this way the camera 1 can be set independently of the object 2. The fictional calibration light rays may also be 14-16 real calibration light rays.

Figures IB and IC show the camera 1 when it is positioned incorrectly or correctly relative to the object 2, respectively. The transmitted calibration light rays 20, 22, 24 are reflected by the object 2 and received as reflected calibration light rays 21, 23, 25 in respective receiving locations 2628 in the recording element 3. Figure 1B shows that the receiving locations 26-28 do not coincide with the defined locations 11-13. This shows that the camera is positioned incorrectly relative to the object 2. The user can now move the camera 1 and the object 2 relative to each other until the received reflected calibration light rays 21, 23, 25 coincide with locations 11-13 in the registration element 3. For example, it can be automatically fixed whether the receiving locations 26-28 coincide with the defined locations 11-13. When the camera 1 has optical display means for displaying the recording (not shown), the coincidence of the receiving locations 26-28 and the defined locations 11-13 can also be visually determined by the user.

Figure 2 shows schematically the situation in which the locations 11-13 are defined in the recording element 3 (A), the situation in which the receiving locations 26-28 do not coincide with the defined locations 11-13, or incorrect positioning of the camera relative to of the object (B), and the situation where the receiving locations 26-28 coincide with the defined locations 11-13, or correct positioning of the camera relative to the object (C).

Figures IB and IC furthermore show object locations 30-32 which are defined on the surface of the object 2. The object locations 30-32 can for instance be marked on the surface of the object 2 or they can be natural marking points. For example, when the object 2 is the skin of a person, a marker may be present in the form of a birthmark, or a location on a birthmark. The camera 1 can now always be aimed at a specific part of the object 2 by the calibration light rays

20,22,24 in the area of ​​a respective object location 2032 by having the object 2 received and reflected. It is clear that two object locations are sufficient if a specific convention is defined with respect to the third calibration light beam. The convention may include, for example, that calibration light beam 23 to the right of the object locations 30, 32 is received by the surface of the object 2 and is reflected when the camera 1 is in the position shown, the light source 5 being the upper light source and the object location 30 the upper object location. In this way, only two object locations would have to be defined. Instead of object locations, there can also be shape recognition of a part of the surface of the object 2, the camera 1 forming a registration of the object 2 when the determined shape is recognized. For the skin, this can be, for example, the shape of the birthmark, or the shape of a wound edge. By defining object locations or shape recognition it can be achieved that each time the determined part of the object 2 is registered, so that different registrations formed at different times of the same object 2 or of different similar objects 2 can easily be compared with each other. As a result, surfaces of similar objects 2 can be compared with each other or changes in a surface of an object 2 can be monitored.

Figure 3A schematically shows the situation in which the locations 11-13 in the recording element 3 are defined for a second embodiment of the camera, in which the light sources emit fan-shaped beams. The fan-shaped bundles are reflected by the object and as receiving lines 260, 270, 280 in the recording element 3. Figure 3B shows the situation in which the receiving lines 260, 270, 280 do not coincide with the defined locations 11-13, or incorrect positioning of the camera relative to the object. Figure 3C shows the situation in which the receiving lines 260, 270, 280 coincide with the defined locations 11-13, or correct positioning of the camera relative to the object.

Fig. 4A schematically shows the situation in which the locations 11-13 in the recording element 3 are defined for a third embodiment of the camera, in which the light sources emit fan-shaped beams with an interruption therein, or in which the light sources emit a parallel beam and at the same time a perform so-called scan movement with an interruption therein. The beams are reflected by the object and as receiving lines 2600, 2700, 2800 with respective interruptions 2610, 2710, 2810 in the recording element 3. Figure 4B shows the situation in which the interruptions 2610, 2710, 2810 do not coincide with the defined locations 11-13, or incorrect positioning of the camera relative to the object. Figure 4C shows the situation in which the interruptions 2610, 2710, 2810 coincide with the defined locations 11-13, or correct positioning of the camera relative to the object.

Figures 5A and 5B show a reference plane 40 which is defined such that the reference plane 40 is perpendicular to an optical axis 41 of the optic 4 and is at a predetermined distance 61 from the optical center 42 of the optic 4.

Figure 5B shows a light source 50 for emitting a recording light beam that is represented as a recording light beam 51 to the object 2. The light source 50 can be the same as any of the three light sources 5-7, but can also be a fourth light source. The recording light beam 51 is received and reflected by the object 2 in location 52. In receiving location 53, the recording light beam 51 is received in the recording element 3.

In the case that the reference plane is perpendicular to the optical axis, a perpendicular distance 60 between the reference plane 40 and the location 52 in which the recording light beam 51 is received and reflected by the object 2 can be determined because this distance 60 is equal to the perpendicular distance 62 from location 52 to the main optical surface 63, which main optical surface 63 is perpendicular to the optical axis 41 and comprises the optical center 42, minus the perpendicular distance 61 between the optical center 42 and the reference plane 40 (see Figure 6). By moving the recording light beam 51 such that a different location 52 is illuminated each time, the depth of each of the locations 52 can be determined up to the reference plane 40. In this way a depth profile can be formed from the surface of the object 2.

The spatial position of the reflection location relative to the camera (recording element and / or optic) can be determined by applying optical principles, such as for example:

For a narrow parallel recording light beam, it holds that the reflect location is the intersection of the emitted recording light beam and that reflected light beam that travels as a straight line through the optical center and the location in the recording element in which the recording light beam is imaged; and • for other registration light beams, the position of the reflective location can be deduced using analysis methods such as, for example: 1) triangulation and / or 2) vector analysis with the optical center as the origin and application of world coordinates.

In Fig. 7, an alternative light source 500 is shown for emitting a fan-shaped recording light beam that is represented as recording light rays 510 to the object 2. In the manner described above, the perpendicular distance between the reference plane and the locations 520 in which the recording light rays 510 can pass through the object 2 are received and reflected are determined, whereby a depth profile can be formed from the surface of the object 2.

The invention is not limited to the embodiments shown, but also extends to variants within the scope of the appended claims.