WO2022122110A1

WO2022122110A1 - Imaging structures

Info

Publication number: WO2022122110A1
Application number: PCT/EP2020/084791
Authority: WO
Inventors: Eero Salmelin; Mikko Aulis PERÄLÄ; Mikko Muukki
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2020-12-07
Filing date: 2020-12-07
Publication date: 2022-06-16
Also published as: CN116615760A

Abstract

In some examples, an imaging structure is provided which is configured to generate data representing an image of an object or scene. The imaging structure, which may be part of a device such as user equipment (e.g., a smart device) can comprise a first image capture device that is able to generate image data in a first wavelength band within a first field of view, and a second image capture device that is able to generate image data in a second wavelength band within a second field of view, wherein the second field of view is within the first field of view.

Description

IMAGING STRUCTURES

TECHNICAL FIELD

Aspects relate, in general, to imaging structures, and more particularly, although not exclusively, to imaging structures for use in systems to generate spectral and/or depth information relating to an object or scene to be imaged.

BACKGROUND

Fast and reliable sensing of surroundings can be desirable in, for example, augmented reality systems, image processing systems, and autonomous vehicle technologies. In such systems, image data generated by a camera can be used to overlay information over real world images, or interpret the surrounding environment for, e.g., collision avoidance and so on.

T o augment data collected from, e.g., RGB sensor-based cameras, data collected from other imaging sources can be used. For example, spectral cameras, which collect and process data from multiple regions of the electromagnetic (EM) spectrum, can be used to enable identification mapping and measurement of surface and material properties. As another example, 3D depth sensing can be used to obtain accurate, repeatable and real-time 3D information from the surrounding environment. However, spectral and depth sensing cameras are typically low resolution and have a narrow field of view. Thus, in comparison to other image capture devices, which can have relatively large fields of view, the use of spectral and/or depth sensing system is limited in its application to many real-world situations.

SUMMARY

According to a first aspect, there is provided an imaging structure for generating data representing an image of an object or scene, the imaging structure comprising a first image capture device to generate image data in a first wavelength band within a first field of view, and a second image capture device to generate image data in a second wavelength band within a second field of view, wherein the second field of view is within the first field of view.

In some examples, one of the image capture devices can be a spectral camera. That is, a camera that is configured to generate image data representing multiple (typically narrow) wavelength ranges of the electromagnetic spectrum (spectral bands). This multispectral data can offer important insights into the surrounding environment that can be used in multiple applications. Such additional insight provided by a spectral device for a scene or object captured using the RGB camera can include, for example, the use of spectral information in the identification of illuminants in outdoor or indoor scenes, which can enable superior automatic white balance (AWB) operation along with ensuring colour accuracy within an image. Other applications could be image segmentation, semantic understanding, skin detection and other material detection. In an example, one of the image capture devices can be a visible light (e.g., RGB sensor based) camera.

In an implementation of the first aspect, the first image capture device can comprise an RGB image sensor element. That is, the first image capture device can comprise a device configured to detect visible light. The second image capture device can comprise an image sensor element configured to generate image data in a wavelength band outside of the human visible region of the electromagnetic spectrum. In an example, the second image capture device can comprise a depth sensor configured to generate depth data representing a measure of distance between the second image capture device and the object or scene. The second image capture device is configured to modify the position of the second field of view relative to the first field of view. In an example, the second field of view (that is, the field of view of the second image capture device) can be changed relative to or within the first field view. For example, a salient object or region of interest that is detected in the first field of view can be used as the focus for the second field of view, which may thus be moved so as to enable the salient object or region of interest to fall within the second field of view.

In a further implementation of the first aspect, the imaging structure can further comprise a third image capture device to generate image data in a third wavelength band within a third field of view, wherein the third field of view is within the first field of view. In an example, the third image capture device can comprise a depth sensor configured to generate depth data representing a measure of distance between the third image capture device and the object or scene.

With the advent of augmented reality, depth information has many uses and 3D range imaging is an enabling technology for many application areas where fast and reliable observation of the environment is needed. Using the depth sensor, accurate, repeatable and real-time 3D-information from surrounding space can enable improvements and developments of new applications. 3D depth sensing is also coming increasingly important as the augmented and real world are blending together. Thus, frames from the first image capture device, which may be a wide-angle conventional camera for example, can be analysed to detect areas of interest. Another camera with a scanning function, and spectral and/or depth sensing abilities, may be guided to scan the detected area of interest.

The first and/or second and/or third image capture device may be defined by separate subareas of an image capture sensor. For example, an image capture sensor may be utilised that is capable of generating depth and/or spectral information. Accordingly, a single image sensor may be used to capture data, e.g., sequentially, for visible and non-visible regions of the EM spectrum, and depth information.

In an example, the first image capture device is a wide-angle camera. The second image capture device can be a spectral imaging device, wherein the second wavelength band comprises at least one of: 300nm - 1000nm, 650nm - 1000nm, and 1000nm - 2000nm. The third image capture device can generate image data in at least one of the wavelength bands: 800nm - 1000nm, 100nm - 1500nm, and a post-1500nm band. In an example, at least one of the first and image capture device and the second image capture device are so configured as to prevent generation of image data corresponding to the third wavelength band. At least one of the first and image capture device and the second image capture device can comprise a filter configured to block electromagnetic radiation from the third wavelength band.

According to a second aspect, there is provided a method for generating an image of an object or scene, the method comprising generating first image data representing a first image in a first wavelength band of the electromagnetic spectrum using a first image capture device having a first field of view, analysing the first image data to determine the presence of a salient portion of the first image, and on the basis of the analysis, generating second image data of the salient portion in a second wavelength band of the electromagnetic spectrum using a second image capture device having a second field of view that is narrower than the first field of view of the first image capture device. Third image data, representing a third image in a third wavelength band of the electromagnetic spectrum, can be generated using a third image capture device having a third field of view. In an example, the position of the second field of view of the second image capture device can be adjusted relative to the first field of view. The position of the third field of view of the third image capture device can be adjusted relative to the first field of view.

In an implementation of the second aspect, on the basis of a determined position of the salient portion within the first field of view, a current position of the second field of view can be adjusted so that the determined position and the current position coincide. That is, a salient object or region of interest that is detected in the first field of view can be used as the focus for the second field of view, which may thus be moved so as to enable the salient object or region of interest to fall within the second field of view. The same considerations apply in terms of a third field of view, described herein, which may also be adjusted to enable a salient object or region of interest to fall within the third field of view.

Adjusting of the current position of the second (or indeed third) field of view can be effected or achieved by mechanical or by electronic means. For example, an image capture device can be physically moved and/or rotated so as to change a field of view thereof. In an example, a field of view associated with a sub-portion of a sensor element of an image capture device can be used, where different sub-portions correspond to different fields of view.

In an example, output image data, representing an output image comprising information derived from at least one of the first, second and third image data, can be generated. The output image can comprise a depth map of the object or scene. The output image can comprise a spectral image of the object or scene.

According to a third aspect, there is provided a non-transitory machine-readable storage medium encoded with instructions for generating image data representing an object or scene, the instructions executable by a processor of a machine whereby to cause the machine to generate first image data representing a first image in a first wavelength band of the electromagnetic spectrum using a first image capture device having a first field of view, analyse the first image data to determine the presence of a salient portion of the first image, and on the basis of the analysis, generate second image data of the salient portion in a second wavelength band of the electromagnetic spectrum using a second image capture device having a second field of view that is narrower than the first field of view of the first image capture device.

In an implementation of the third aspect, the non-transitory machine-readable storage medium can be further encoded with instructions executable by the processor of the machine whereby to cause the machine to generate third image data representing a third image in a third wavelength band of the electromagnetic spectrum using a third image capture device having a third field of view. Instructions can further cause the machine to adjust the position of the second field of view of the second image capture device relative to the first field of view; adjust the position of the third field of view of the third image capture device relative to the first field of view; on the basis of a determined position of the salient portion within the first field of view, adjust a current position of the second field of view so that the determined position and the current position coincide; operate an actuator to adjust the position of at least one of: the second field of view and the third field of view; generate output image data representing an output image comprising information derived from at least one of the first, second and third image data.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, reference is now made, by way of example only, to the following descriptions taken in conjunction with the accompanying drawings, in which:

Figure 1 is a schematic representation of an imaging structure according to an example;

Figure 2 is a schematic representation of an imaging structure according to an example;

Figure 3 is a schematic representation of a system according to an example; and

Figure 4 is a flowchart of a method according to an example.

DESCRIPTION

Example embodiments are described below in sufficient detail to enable those of ordinary skill in the art to embody and implement the systems and processes herein described. It is important to understand that embodiments can be provided in many alternate forms and should not be construed as limited to the examples set forth herein. Accordingly, while embodiments can be modified in various ways and take on various alternative forms, specific embodiments thereof are shown in the drawings and described in detail below as examples. There is no intent to limit to the particular forms disclosed. On the contrary, all modifications, equivalents, and alternatives falling within the scope of the appended claims should be included. Elements of the example embodiments are consistently denoted by the same reference numerals throughout the drawings and detailed description where appropriate.

The terminology used herein to describe embodiments is not intended to limit the scope. The articles “a,” “an,” and “the” are singular in that they have a single referent, however the use of the singular form in the present document should not preclude the presence of more than one referent. In other words, elements referred to in the singular can number one or more, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including,” when used herein, specify the presence of stated features, items, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, items, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein are to be interpreted as is customary in the art. It will be further understood that terms in common usage should also be interpreted as is customary in the relevant art and not in an idealized or overly formal sense unless expressly so defined herein.

According to an example, an imaging structure can be used to capture image data for use by a system such as an autonomous vehicle or mobile device for example. In an implementation, the imaging structure can be provided as part of the system in question. For example, the imaging structure can form an imaging module of a mobile device. The imaging structure can comprise multiple image capture devices that are configured to generate image data within respective wavelength bands of the EM spectrum. The image capture devices can comprise sensors sensitive to EM radiation in specific wavelength bands of the EM spectrum. The bands in question may overlap with one another or be separate/distinct from one another.

According to an example, the imaging structure comprises a first image capture device. The first image capture device can generate image data in a first wavelength band of the EM spectrum, which can, e.g., correspond to a visible part of the EM spectrum. In an example, the first image capture device is configured to generate image data within a first field of view. The first field of view can comprise an area that can be imaged using a sensor of the first image capture device. The area can comprise a horizontal component and a vertical component. A relatively large horizontal component is typically referred to as wide angle, such that the image capture device is capable of imaging a scene across a relatively large distance. An image captured using the first image capture device can be a wide-angle image. Field of view can be used interchangeably with the term angle of view. In an example, the first image capture device can be used for continuous image capture, or may be activated when desired.

Image data representing an image of a scene or object generated using the first image capture device can be analyzed in order to determine an area of interest or a salient portion. Such an area or portion may be determined using any number of suitable methods. For example, objects or regions of an image can be classified using a deep neural network, e.g., a convolutional neural network such as Retina-Net, R-CNN or YOLO.

Accordingly, images or frames of a wide-angle conventional camera for example, can be processed in order detect objects and object classes, which can then be used to select areas of interest within the images. Analysis of the images can be configured to detect areas of interest that are interesting to humans (e.g., faces, people, cats, dogs, main object of the photo and so on) and/or other image features such as, e.g., detecting and labeling sky, grass, skin, likely white and grey objects and so on.

A second image capture device can be used to generate image data in a second wavelength band. The second image capture device can be configured to generate image data within an area defining a second field of view. In an example, the second field of view is within the first field of view. That is, the second image capture device can generate an image comprising a sub-portion of an image captured using the first image capture device. The second image capture device can be configured to generate data representing spectral and/or depth information of the sub-portion.

According to an example, the second field of view (of the second image capture device) can be adjusted. That is, an area defining the second field of view can be moved within the first field of view. The second image capture device can therefore be considered to comprise a scanning function, which can be mechanically and/or electronically implemented. As such, an identified salient portion of an image captured using the first image capture device can be used as the focus or subject for the second image capture device. That is, the field of view of the second image capture device can be adjusted on the basis of an identified salient portion within the first field of view, corresponding to an image of the first image capture device. Thus, a sub-image generated by the second image capture device can comprise the identified salient portion, with the second field of view having been adjusted in order to enable an image of the identified portion to be captured using the second image capture device.

Generating data representing spectral and/or depth information from a salient portion in an, e.g., RGB image, can be used to provide improved and versatile information of areas of interest within an image. Thus, by guiding the field of view of the second image capture device to relevant sub-portion of the image of the first image capture device, disadvantages of scanning devices, such as narrow FOV and lower resolution are overcome and the advantages provided by the spectral and depth cameras can be widely utilized. Furthermore, as areas of interest are scanned (i.e., a sub-portion as opposed to the entire image), the amount of data to be analyzed is minimized. Thus, image data obtained from the first image capture device, which may be an RGB camera for example, can be used in combination with data from one or more scanning cameras to improve image quality of the first image capture device and enable a scene to be analyzed in order to provide additional information on, e.g., objects or surroundings, which can be leveraged by applications.

Figure 1 is a schematic representation of an imaging structure according to an example. The imaging structure 101 can be used to generate data 103 representing an image 105 of an object or scene. The imaging structure 101 comprises a first image capture 109 device to generate image data in a first wavelength band within a first field of view 1 13, and a second image capture device 1 11 to generate image data in a second wavelength band within a second field of view 115. The second field of view 1 15 is within the first field of view 1 13. That is, an imaging area defined by the second field of view 1 15 of the second image capture device 1 11 is provided within an imaging area defined by the first field of view 1 13 of the first image capture device 109. In the example of figure 1 , a horizontal component of the field of view of the second image capture device 1 11 is around 30 degrees, whereas a horizontal component of the field of view of the first image capture device 109 is around 100 degrees. It is therefore possible for the second field of view 1 15 to be moved around, relative to the first field of view 113, whilst staying within the imaging area defined by the first field of view 1 13 of the first image capture device 109. The field of view 1 13 of the first image capture device 109 may between, e.g., 60-360 degrees. The field of view 1 15 of the second image capture device 1 11 may between, e.g., 15-180 degrees. In an example, the imaging structure 101 may form part of a mobile device 107, such as a mobile device (e.g., smart phone) for example.

In the example of figure 1 , the first image capture device 109 comprises an RGB image sensor element. That is, the first image capture device 109 is in the form of an RGB camera, and can comprise a wide angle lens structure enabling it to image a relatively large field of view, such as that described above for example. In an example, the field of view 1 13 of the first image capture device 109 is wide in the sense that it is larger than the field of view 1 15. Thus, reference to wide angle can be interpreted to comprise cases in which a horizontal component of the field of view 1 13 of the first image capture device 109 is larger than a horizontal component of the field of view 1 15 of the second image capture device 1 11.

The position of the second field of view 115 of the second image capture device 1 11 can be modified relative to that of the first image capture device 109. For example, the second image capture device 111 or a component thereof (such a lens or lens arrangement) may be physically or mechanically moved in order to adjust its field of view 115.

Images captured by the first image capture device 109 can be continuously analyzed by an analysis module 117. For example, an Al based analysis function may be implemented in the analysis module 117 and trained to detect particular objects. In an implementation form, there can be a manual mode in which a user input is received in response to a user selecting from a, e.g., viewfinder image of device 107 (e.g., by tapping a desired point with a finger) an area to be scanned. Alternatively, a user may provide a textual or verbal input.

In an example, the second image capture device 1 11 can comprise two imaging sensors configured to provide data which may be used to perceive the environment. One of the imaging sensors may be a multispectral sensor. The properties of the multispectral sensor may be selected based on application. The spectral sensor/camera may be capable of imaging, for example, infrared -700nm-1 um, visible spectrum -400-700 nm (comprising RGB), ultraviolet -10-400 nm, or a combination thereof. In an example, optical filters may be used to capture a specific spectral range. A selected filter may depend on user input. The second imaging sensor may form part of a depth camera. The depth camera can be used to judge depth and distance between the device 1 11 and a subject for each point of an image. The distances may be calculated, for example, based on time-of-flight techniques. The depth camera may be used, for example, to measure distance and volume, as well as for object scanning, indoor navigation, obstacle avoidance, gesture recognition or object tracking. Data from the second sensor can therefore aid 3D imaging as well as improving augmented reality (AR) experiences.

Figure 2 is a schematic representation of an imaging structure according to an example. In the example of figure 2, a third image capture device 201 is provided. The third image capture device 201 is configured to generate third image data in a third wavelength band within a third field of view 203. In an example, the third field of view 203 is within the first field of view 1 13. The third field of view 203 may be distinct from or may partially overlap with the second field of view 115. The third image data can comprise image data of the determined salient portion, and may be used in combination with or in isolation from the second image data (i.e., that generated by the second image capture device).

In the example of figure 2, the second image capture device 11 1 may be a scanning spectral camera and the third image capture device 201 may be a scanning depth camera. The fields of view 1 15, 203 of the image capture devices 201 , 1 11 do not need to be the same, but, in an example, are both narrower than that of the first image capture device 109.

According to an example, data generated using the imaging structure can be used in various ways. For example, the data can be used to analyze and identify materials and objects and/or improve colors in an image captured using the first image capture device. For example, the spectral camera (e.g. the second image capture device) can comprise a multispectral sensor that is capable of generating a large amount of data of the surrounding environment. This data can be used to detect the type of illuminants present (both in an outdoor or indoor setting). That is, the spectral camera can be used to determine whether a source of illumination is, e.g., natural light (e.g., the sun) or artificial light (e.g., a lamp), which may not be possible in conventional cameras. Determination of an illumination can be used for adjustment of white balance in a captured image.

In other examples, data from a spectral camera can be used for image segmentation, semantic understanding, skin detection and other material detection. That is, unique spectral reflection and absorption characteristics of objects can be used in the analysis of data from the spectral camera.

Data generated by a depth camera (e.g., the third image capture device) can be used to obtain 3D information, which may be calculated from a 2D image series gathered with an increasing delay between, e.g., a laser pulse and shutter opening.

Examples in the present disclosure can be provided as methods, systems or machine- readable instructions, such as any combination of software, hardware, firmware or the like. Such machine-readable instructions may be included on a computer readable storage medium (including but not limited to disc storage, CD-ROM, optical storage, etc.) having computer readable program codes therein or thereon.

The present disclosure is described with reference to flow charts and/or block diagrams of the method, devices and systems according to examples of the present disclosure. Although the flow diagrams described above show a specific order of execution, the order of execution may differ from that which is depicted. Blocks described in relation to one flow chart may be combined with those of another flow chart. In some examples, some blocks of the flow diagrams may not be necessary and/or additional blocks may be added. It shall be understood that each flow and/or block in the flow charts and/or block diagrams, as well as combinations of the flows and/or diagrams in the flow charts and/or block diagrams can be realized by machine readable instructions.

The machine-readable instructions may, for example, be executed by a general-purpose computer, a special purpose computer, an embedded processor or processors of other programmable data processing devices to realize the functions described in the description and diagrams. In particular, a processor or processing apparatus may execute the machine- readable instructions. Thus, modules of apparatus may be implemented by a processor executing machine readable instructions stored in a memory, or a processor operating in accordance with instructions embedded in logic circuitry. The term 'processor' is to be interpreted broadly to include a CPU, processing unit, ASIC, logic unit, or programmable gate set etc. The methods and modules may all be performed by a single processor or divided amongst several processors.

Such machine-readable instructions may also be stored in a computer readable storage that can guide the computer or other programmable data processing devices to operate in a specific mode. For example, the instructions may be provided on a non-transitory computer readable storage medium encoded with instructions, executable by a processor.

Figure 3 is a schematic representation of system comprising an imaging structure, according to an example. System 300 comprises a processor 303 and a memory 305 storing instructions 307. In an example, system 300 can be a user equipment, such as a smart device. System 300 comprises an actuator 317. Actuator 317 can be used to adjust a field of view of an image capture device 1 11 , 201 (i.e. it can be used to adjust a field of view of the second and/or third image capture devices, whereby to adjust the second and/or third fields of view). For example, actuator 317 can be a linear actuator configured to translate an image capture device whereby to adjust a field of view thereof. Alternatively, actuator 317 can be a rotary actuator configured to adjust an position of an image capture device whereby to adjust a field of view thereof. In an example, actuator 317 can comprise a combination of linear and rotary actuators to effect a linear translation and adjustment.

The instructions 307 are executable by the processor 303. The instructions 307 can comprise instructions to generate first image data 309 representing a first image in a first wavelength band of the electromagnetic spectrum using a first image capture device 109 having a first field of view 113, and analyse the first image data 309 to determine the presence of a salient portion 311 of the first image. On the basis of the analysis, the instructions 307 can comprise instructions to generate second image data 319 of the salient portion 31 1 in a second wavelength band of the electromagnetic spectrum using a second image capture device 1 11 having a second field of view 115 that is narrower than the first field of view 1 13 of the first image capture device 109. In an example, the second field of view 1 15 can be adjusted in order to enable the second image capture device 1 11 to image the salient portion 31 1 by using the actuator 317. That is, the actuator can be controlled using processor 303 to adjust the second field of view 1 15 so that the salient portion 311 is within the second field of view, thereby enabling second image data 319 of the salient portion 311 to be generated using the second image capture device 11 1. System 300 can generate output image data 323 representing an output image 325 comprising information derived from at least one of: the first, second and third image data.

On the basis of the analysis, the instructions 307 can comprise instructions to generate third image data 321 of the salient portion 311 in a third wavelength band of the electromagnetic spectrum using a third image capture device 201 having a third field of view 203 that is narrower than the first field of view 113 of the first image capture device 109. In an example, the third field of view 203 can be adjusted in order to enable the third image capture device 201 to image the salient portion 311 by using the actuator 317. That is, the actuator can be controlled using processor 303 to adjust the third field of view 203 so that the salient portion 311 is within the third field of view, thereby enabling third image data 321 of the salient portion 31 1 to be generated using the third image capture device 201 .

Accordingly, the system 300 can implement a method for generating an image of an object or scene in which a salient portion of an image captured using a first image capture device (e.g., an RGB camera) can be used as the basis to adjust the field of view of a second and/or third image capture device, whereby to enable additional information about the salient portion to be determined, such as depth and/or spectral information for example.

Such machine-readable instructions may also be loaded onto a computer or other programmable data processing devices, so that the computer or other programmable data processing devices perform a series of operations to produce computer-implemented processing, thus the instructions executed on the computer or other programmable devices provide a operation for realizing functions specified by flow(s) in the flow charts and/or block(s) in the block diagrams. Further, the teachings herein may be implemented in the form of a computer software product, the computer software product being stored in a storage medium and comprising a plurality of instructions for making a computer device implement the methods recited in the examples of the present disclosure.

Figure 4 is a flowchart of a method according to an example. In block 401 , first image data representing a first image in a first wavelength band of the electromagnetic spectrum is generated using a first image capture device having a first field of view. In block 403, the first image data is analysed to determine the presence of a salient portion of the first image. In block 405, on the basis of the analysis in block 403, second image data of the salient portion is generated in a second wavelength band of the electromagnetic spectrum using a second image capture device having a second field of view that is narrower than the first field of view of the first image capture device.

Claims

1. An imaging structure for generating data representing an image of an object or scene, the imaging structure comprising: a first image capture device to generate image data in a first wavelength band within a first field of view; a second image capture device to generate image data in at least a second wavelength band within a second field of view, wherein the second field of view is within the first field of view.

2. The imaging structure as claimed in claim 1 , wherein the first image capture device comprises an RGB image sensor element.

3. The imaging structure as claimed in claim 1 or 2, wherein the second image capture device comprises an image sensor element configured to generate image data in a wavelength band outside of the human visible region of the electromagnetic spectrum.

4. The imaging structure as claimed in claim 1 or 2, wherein the second image capture device comprises a depth sensor configured to generate depth data representing a measure of distance between the second image capture device and the object or scene.

5. The imaging structure as claimed in any preceding claim, wherein the second image capture device is configured to modify the position of the second field of view relative to the first field of view.

6. The imaging structure as claimed in any preceding claim, further comprising: a third image capture device to generate image data in a third wavelength band within a third field of view, wherein the third field of view is within the first field of view.

7. The imaging structure as claimed in claim 6, wherein the third image capture device comprises a depth sensor configured to generate depth data representing a measure of distance between the third image capture device and the object or scene.

8. The imaging structure as claimed in any preceding claim, wherein the first and/or second and/or third image capture device are defined by separate sub-areas of an image capture sensor.

9. The imaging structure as claimed in any preceding claim, wherein the first image capture device is a wide-angle camera.

10. The imaging structure as claimed in any preceding claim, wherein the second image capture device is a spectral imaging device, and wherein the second wavelength band comprises at least one of: 300nm - 1000nm, 650nm - 1000nm, and t OOOnm ~ 2000nm.

1 1 . The imaging structure as claimed in claim 6 or 7, wherein the third image capture device is configured to generate image data in at least one of the wavelength bands: 800nm -

10OOnm, 10Onm - 1500nm, and a post-1500nm band.

12. The imaging structure as claimed in claim 6 or 7, wherein at least one of the first and image capture device and the second image capture device are so configured as to prevent generation of image data corresponding to the third wavelength band.

13. The imaging structure as claimed in claim 12, wherein at least one of the first and image capture device and the second image capture device comprise a filter configured to block electromagnetic radiation from the third wavelength band.

14. A method for generating an image of an object or scene, the method comprising: generating first image data representing a first image in a first wavelength band of the electromagnetic spectrum using a first image capture device having a first field of view: analysing the first image data to determine the presence of a salient portion of the first image; on the basis of the analysis, generating second image data of the salient portion in a second wavelength band of the electromagnetic spectrum using a second image capture device having a second field of view that is narrower than the first field of view of the first image capture device.

15. The method as claimed in claim 14, further comprising: generating third image data representing a third image in a third wavelength band of the electromagnetic spectrum using a third image capture device having a third field of view.

16. The method as claimed in claim 14 or 15, further comprising: adjusting the position of the second field of view of the second image capture device relative to the first field of view.

17. The method as claimed in claim 15, further comprising: adjusting the position of the third field of view of the third image capture device relative to the first field of view.

18. The method as claimed in any of claims 14 to 17, further comprising: on the basis of a determined position of the salient portion within the first field of view, adjusting a current position of the second field of view so that the determined position and the current position coincide.

19. The method as claimed in claim 18, wherein the adjusting of the current position of the second field of view is effected by mechanical or by electronic means.

20. The method as claimed in any of claims 14 to 19, further comprising: generating output image data representing an output image comprising information derived from at least one of the first, second and third image data.

21. The method as claimed in claim 20, wherein the output image comprises a depth map of the object or scene.

22. The method as claimed in any of claims 14 to 21 , wherein the output image further comprises a spectral image of the object or scene.

23. A non-transitory machine-readable storage medium encoded with instructions for generating image data representing an object or scene, the instructions executable by a processor of a machine whereby to cause the machine to: generate first image data representing a first image in a first wavelength band of the electromagnetic spectrum using a first image capture device having a first field of view; analyse the first image data to determine the presence of a salient portion of the first image; on the basis of the analysis, generate second image data of the salient portion in a second wavelength band of the electromagnetic spectrum using a second image capture device having a second field of view that is narrower than the first field of view of the first image capture device.

24. The non-transitory machine-readable storage medium as claimed in claim 23, further encoded with instructions executable by the processor of the machine whereby to cause the machine to: generate third image data representing a third image in a third wavelength band of the electromagnetic spectrum using a third image capture device having a third field of view.

25. The non-transitory machine-readable storage medium as claimed in claim 23 or 24, further encoded with instructions executable by the processor of the machine whereby to cause the machine to: adjust the position of the second field of view of the second image capture device relative to the first field of view.

26. The non-transitory machine-readable storage medium as claimed in claim 24, further encoded with instructions executable by the processor of the machine whereby to cause the machine to: adjust the position of the third field of view of the third image capture device relative to the first field of view.

27. The non-transitory machine-readable storage medium as claimed in claim any of claims 23 to 26, further encoded with instructions executable by the processor of the machine whereby to cause the machine to: on the basis of a determined position of the salient portion within the first field of view, adjust a current position of the second field of view so that the determined position and the current position coincide.

28. The non-transitory machine-readable storage medium as claimed in claim 25 or 26, further encoded with instructions executable by the processor of the machine whereby to cause the machine to: operate an actuator to adjust the position of at least one of: the second field of view and the third field of view.

29. The non-transitory machine-readable storage medium as claimed in claim any of claims 23 to 28, further encoded with instructions executable by the processor of the machine whereby to cause the machine to: generate output image data representing an output image comprising information derived from at least one of the first, second and third image data.