Method and system for stray light compensation

Abstract

A method and system for stray light compensation are disclosed. The method includes: acquiring a first image using a first imaging device covering a first field of view; acquiring a second image using a second imaging device covering a second field of view, wherein the second field of view is larger than the first field of view, and wherein the first field of view is included in the second field of view; estimating a stray light component in a pixel of the first image from pixel data of a pixel in the second image; and compensating for stray light in the first image by subtracting the estimated stray light component in the pixel of the first image. In addition, a system for stray light compensation is disclosed.

Description

Technical Field

[0001] The present invention relates to stray light compensation, and in particular to stray light compensation in images captured by a digital camera. Background Art

[0002] Stray light is light in an optical system, such as a camera, that is not desired in its design. Stray light may come from the intended light source, but along a different path than intended, or it may come from a different light source than intended. Stray light may also be referred to as lens flare. Lens flare occurs when light is scattered or propagated in a lens arrangement. More precisely, light is scattered by the lens arrangement itself, for example by internal reflection and forward scattering from material defects in the lens of the lens arrangement. Lens flare can make an image look "washed out" by reducing contrast and color saturation (adding light to dark image areas, and adding white to color saturated areas to reduce their saturation). Lens flare is especially caused by bright light sources. Lens flare is therefore a secondary effect that is widely distributed over the entire image and is not usually visible, although it does reduce the signal-to-noise ratio, i.e. the contrast in the image. Lens flare therefore places an operating limit on the dynamic range in the image. In particular, the level of detail in the darker parts of the image is limited by lens flare.

[0003] It is necessary to reduce lens flare / stray light, or compensate for the lens flare / stray light present in the image by some means. Summary of the invention

[0004] In view of the above, an object of the present invention is to provide compensation for stray light present in an image, especially a digital image.

[0005] The object is to mitigate, alleviate or eliminate one or more of the above mentioned deficiencies and disadvantages in the art, singly or in any combination, and to solve at least the above mentioned problems.

[0006] According to a first aspect, a method for stray light compensation is provided. The method comprises: acquiring a first image with a first imaging device covering a first field of view; acquiring a second image with a second imaging device covering a second field of view, wherein the second field of view is larger than the first field of view and wherein the first field of view is included in the second field of view; estimating a stray light component in a pixel of the first image from pixel data of the pixel in the second image; and compensating for stray light in the first image by subtracting the estimated stray light component in the pixel of the first image. Thus, an improved first image is provided in which stray light is reduced. It should be noted that even if the stray light compensation discussed above is not perfectly calibrated, the applied stray light compensation is still valuable because the stray light compensation provides an improved signal-to-noise ratio in the first image. Thus, an increased dynamic range is provided in the first image. A possible effect of the stray light compensation of the present invention is that it provides compensation for stray light from light sources outside the field of view of the first imaging device. This is because such stray light component is estimated based on a second image captured by a second imaging device, which has a larger field of view than the first imaging device.

[0007] Estimating stray light components in pixels of the first image may include filtering the second image through a series of Gaussian filters to form a series of filtered second images; and linearly combining the filtered second images to form a stray light image including stray light components from pixels in the first image.

[0008] Estimating the stray light component in the pixels of the first image may include one or more of the following: determining the portion of the second image that overlaps with the first image; compensating for exposure differences between the second image and the first image; compensating for differences in gain settings of the first imaging device and the second imaging device; compensating for differences in pixel density between the second image and the first image; compensating for differences in viewing angles between the second image and the first image; and compensating for differences in aperture settings of the first imaging device and the second imaging device.

[0009] According to a second aspect, a non-transitory computer-readable storage medium is provided. The non-transitory computer-readable storage medium has instructions stored thereon, and when the instructions are executed on a device having processing capabilities, the method according to the first aspect is implemented.

[0010] According to a third aspect, a system for stray light compensation is provided. The system includes: a first imaging device covering a first field of view and configured to acquire a first image; a second imaging device covering a second field of view and configured to acquire a second image, wherein the second field of view is larger than the first field of view, and wherein the first field of view is included in the second field of view; and a circuit configured to perform a stray light compensation function. The stray light compensation function is configured to: estimate a stray light component in a pixel of the first image based on pixel data of a pixel in the second image; and compensate for stray light in the first image by subtracting the estimated stray light component in the pixel of the first image.

[0011] The resolution of the second imaging device may be lower than the resolution of the first imaging device.

[0012] The first imaging device and the second imaging device may be configured to capture the first image and the second image simultaneously.

[0013] The second imaging device may be configured to capture the second image such that the second image is less saturated than the first image.

[0014] The second imaging device may comprise a fixed focus lens arrangement.

[0015] The second imaging device may be separate from the first imaging device.

[0016] According to a fourth aspect, there is provided a camera comprising the system according to the third aspect.

[0017] When applicable, the above features of the method also apply to the second aspect, the third aspect or the fourth aspect. To avoid unnecessary repetition, please refer to the above.

[0018] Further scope of application of the present invention will become apparent from the detailed description given below. However, it should be understood that the detailed description and specific examples, although indicating preferred embodiments of the present invention, are given by way of illustration only, as various changes and modifications within the scope of the present invention will become apparent to those skilled in the art from the detailed description.

[0019] Therefore, it should be understood that the present invention is not limited to the specific components of the described systems or the actions of the described methods, because such systems and methods are variable. It should also be understood that the terms used herein are only for the purpose of describing specific embodiments and are not intended to be limiting. It must be noted that, as used in the specification and the appended claims, the words "one", "the" and "said" are intended to indicate the presence of one or more elements, unless the context clearly indicates otherwise. Thus, for example, a reference to "a device" or "the device" may include several devices, etc. In addition, the words "comprise", "include" and similar expressions do not exclude other elements or steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other aspects of the present invention will now be described in more detail with reference to the accompanying drawings. The drawings should not be considered limiting; rather, they are for explanation and understanding.

[0021] As illustrated in the figures, the sizes of layers and regions may be exaggerated for illustrative purposes and are therefore provided to illustrate the overall structure. Like reference numerals refer to like elements throughout.

[0022] Figure 1 A system for stray light compensation is illustrated.

[0023] Figure 2 is a schematic diagram of the scene viewed from above the stray light compensation system.

[0024] Figure 3 yes Figure 2 of the scheme.

[0025] Figure 4a is a photograph taken by the first imaging device of the stray light compensation system before stray light compensation is applied. Figure 3 A view of the scene in .

[0026] Figure 4b is the value after stray light compensation is applied. Figure 4a The view in the same view.

[0027] Figure 5 is a block diagram of a method for stray light compensation. DETAILED DESCRIPTION

[0028] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the present invention are shown. However, the present invention may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; on the contrary, these embodiments are provided for completeness and completeness and to fully convey the scope of the present invention to the skilled person.

[0029] The point spread function describes how an optical system would characterize an ideal point source of light, i.e. the impulse response of the system. The modulation transfer function is the Fourier transform of the point spread function, i.e. the frequency response of the system. In the case of an ideal lens (without taking into account diffraction), the point spread function would be an infinitely narrow pulse whose Fourier transform would be 1 for all frequencies (i.e. no frequencies would be altered by the system). Thus, for an ideal lens with perfect focus, all the light emitted from a single point in the scene would hit a single point on the sensor. In reality, the point spread function is never infinitely narrow, some light will always hit nearby pixels and a small fraction will even hit distant pixels. In the frequency domain, this can be seen as a gradual roll-off of higher frequencies in the frequency response modulation transfer function. For a real lens, the point spread function varies depending on a number of factors, such as the color of the light, the offset from the optical axis, and the depth of field. Developing a lens will be a compromise between cost and performance, such that the lens can be optimized to handle "normal" scenes well enough, i.e. the point spread function should be narrow enough to produce a good enough image in typical situations.

[0030] As the boundaries of high dynamic range imaging are pushed, the demands on the lens are increasing. High dynamic range scenes typically contain at least some parts that are significantly brighter than the rest of the scene. Since the point spread function is not ideal, some of the light from the bright areas will propagate to the adjacent darker pixels, causing undesired shifts in these pixels, reducing the contrast of the actual signal in the dark areas. Even if only a small portion of the light from the bright areas is propagated to the dark areas, this can mean a significant contribution to these areas. This effect becomes significantly worse as the dynamic range (i.e., the bright-to-dark ratio) increases. The loss of contrast in dark areas adjacent to bright areas can be considered a first-order limitation of the dynamic range of the lens, as it limits the ability to measure contrast in dark areas. In theory, if we have perfect knowledge of the point spread function, it would be possible to reconstruct the ideal image by deconvolution (i.e., deconvolution) using the point spread function. However, even if we manage to perfectly subtract the stray light shift, we still suffer from the photon shot noise introduced by the stray light, i.e., there is a physical limit to the measurable dynamic range for a given lens system due to the photon shot noise. Of course, this can be avoided by collecting more photons and reducing the temporal and / or spatial resolution.

[0031] If we had access to an ideal (i.e. no stray light) image, estimating the stray light would be fairly straightforward and would simply involve convolving the ideal image with the point spread function. Unfortunately, we obviously cannot have access to an ideal image, so we use the actual image as an approximation. This may seem counterintuitive at first, but consider that:

[0032] psf – point spread function

[0033] imideal – Perfect image without any stray light

[0034] im stray – Stray light offset per pixel

[0035] im actual – The image actually measured on the sensor

[0036] According to the above definition:

[0037] im actual =im ideal +im stray

[0038] We want to calculate: im stray =im ideal *psf-im ideal

[0039] Instead, we calculate:

[0040] im actual *psf-im ideal +im stray *psf-im stray =im stray +im stray *psf-im stray =im stray *psf≈im stray

[0041] In other words, by using im actual As im ideal As an approximation of , we slightly overestimate the stray light since we incorrectly assume that it also contributes to the stray light (because it is convolved with the point spread function). Note that this can theoretically be solved by removing the stray light from im actual Subtract the previous estimate of im stray To improve ideal Approximate value of .

[0042] We also have the problem that performing a full resolution perfect PSF volume is extremely expensive and simply unrealistic. Instead, we assume that the point spread function can be adequately approximated by a sum of Gaussian filters of varying widths, i.e., by filtering the actual image with a sequence of Gaussian filters, we can reconstruct an approximation of the stray light as a linear combination of the filtering results.

[0043] Therefore, for a given lens arrangement, a point spread function that describes how light is spread by the lens arrangement can be estimated. The point spread function can then be used to predict the amount of stray light in an image captured using the lens arrangement. When estimating stray light in this way, a limiting factor is that only the light actually seen by the lens arrangement can be measured, and light from sources outside the field of view cannot be processed.

[0044] The present invention is based on the inventor's recognition that an estimation of stray light in pixels of an image captured by a first imaging device can be made from an image captured by another second imaging device. The second imaging device is arranged to have a larger field of view than the first imaging device. The field of view of the first imaging device will be included in the field of view of the second imaging device. In addition, typically, the second imaging device is arranged to capture an image that is less exposed than the image captured by the first imaging device. According to this, stray light components from light sources outside the field of view of the first imaging device in the image captured by the first imaging device can be estimated and compensated. Therefore, the present invention is based on a separate second imaging device with a wider field of view to obtain an image of a larger part of the scene covered by the first imaging device. In addition, the separate second imaging device is preferably configured so that the image captured by it and used to estimate the stray light in the image captured by the first imaging device has no saturated light sources. This can be ensured, for example, by using a different (usually lower) exposure for the image captured by the second imaging device than the image captured by the first imaging device. The image captured by the second imaging device can then be used to estimate and subtract the stray light from the image captured by the first imaging device. The second imaging device can be a camera with a lower resolution than the first imaging device. This is because typically the stray light component from light sources outside the field of view of the first imaging device is spatially low frequency. Furthermore, the second imaging device may even be a camera with fixed focus optics.

[0045] Figure 1A system 100 for stray light compensation is illustrated. The system 100 includes a first imaging device 110 and a second imaging device 120. The first imaging device 110 and the second imaging device 120 are typically separate imaging devices. The first imaging device 110 and the second imaging device 120 may be arranged in the same housing (i.e., a camera device in which two imaging devices are arranged). Alternatively, the first imaging device 110 and the second imaging device 120 may be separate devices, i.e., separate camera devices. Each imaging device 110, 120 includes a lens arrangement 112, 122 and an image sensor 114, 124. That is, the first imaging device 110 and the second imaging device 120 are typically digital cameras. The lens arrangement 122 of the second imaging device 120 may be a fixed focus lens arrangement. The lens arrangement 112 of the first imaging device 110 may be a zoom lens arrangement. The first imaging device 110 covers a first field of view 111. The second imaging device 120 covers a second field of view 121. The second field of view 121 is larger than the first field of view 111. The first field of view 111 is included in the second field of view 121. The first imaging device 110 is configured to capture one or more first images. Thus, the first imaging device 110 may be a still image camera or a video camera. The second imaging device 110 is configured to capture one or more second images. Thus, the second imaging device 120 may be a still image camera or a video camera. The resolution of the second imaging device 120 may be lower than the resolution of the first imaging device 110.

[0046] The second field of view 121 preferably has a size arranged such that the second imaging device 120 reproduces all light sources from which light reaches the first imaging device 110 .

[0047] The second imaging device 120 is preferably configured to capture the second image such that the pixels of the second image are less exposed than the pixels of the first image. This achieves capturing a second image having less saturated pixels than the first image. Therefore, the second image preferably has less saturated pixels than the first image. According to a non-limiting example, the second imaging device 120 is configured to capture the second image such that at least 99% of the pixels of the second image are unsaturated. Therefore, it can be guaranteed that a small number of pixels in the second image are saturated. This provides improved stray light estimation. To achieve this, the second imaging device 120 is typically set to use a shorter exposure time than the first imaging device 110. However, other settings in the second imaging device 120 can also be used to ensure that a small number of pixels in the second image are saturated. Some non-limiting examples are: using a less sensitive image sensor in the second imaging device 120; adjusting the aperture of the second imaging device 120; and using a filter such as a neutral density filter in the second imaging device 120. The second imaging device 120 can also be configured to capture the second image as a double exposure image. The second imaging device 120 can even be a black and white camera. This is because the quality of the image captured by the second imaging device 120 is not critical, as long as the image captured thereby gives information about the position and brightness of light sources outside the field of view of the first imaging device 110 .

[0048] According to an exemplary embodiment, the first imaging device 110 is a detail view imaging device and the second imaging device 120 is a wide angle imaging device. The detail view imaging device covers a detail field of view and is configured to capture one or more detail view images. The wide angle imaging device covers a wide field of view and is configured to capture one or more wide angle images. The wide field of view is larger than the detail field of view. The detail field of view is included in the wide field of view.

[0049] The system 100 further includes a circuit 130. The circuit 130 is configured to perform overall control of the functions and operations of the system 100. The circuit 130 may include a processor 131 such as a central processing unit (CPU), a microcontroller, or a microprocessor. The processor 131 is configured to execute program codes stored in the memory 140 to perform the functions and operations of the system 100.

[0050] The memory 140 may be one or more of a buffer, a flash memory, a hard drive, a removable medium, a volatile memory, a non-volatile memory, a random access memory (RAM), or other suitable devices. In a typical arrangement, the memory 140 may include a non-volatile memory for long-term data storage and a volatile memory used as a system memory for the circuit 130. The memory 140 may exchange data with the circuit 130 via a data bus. There may also be accompanying control lines and an address bus between the memory 140 and the circuit 130.

[0051] The functions and operations of the system 100 may be implemented in the form of executable logic routines (e.g., lines of code, software programs, etc.) stored on a non-transitory computer-readable medium (e.g., memory 140) of the system 100 and executed by the circuit 130 (e.g., using the processor 131). In addition, the functions and operations of the system 100 may be stand-alone software applications, or form part of a software application that performs additional tasks associated with the system 100. The functions and operations described may be considered methods that the corresponding parts of the system are configured to perform. In addition, although the functions and operations described may be implemented in software, such functions may also be implemented via dedicated hardware or firmware, or some combination of hardware, firmware and / or software.

[0052] The circuit 130 is configured to perform a stray light compensation function 142. The stray light compensation function 142 is configured to estimate stray light components in pixels of an image captured by the first imaging device 110, which will be referred to as the first image below. This estimation is arranged to be performed based on pixel data of pixels in an image captured by the second imaging device 120, which will be referred to as the second image below. More precisely, the estimation is performed so that the pixel data in the second image is manipulated so that pixel data indicating stray light components in the first image from light sources outside the field of view of the first imaging device 110 can be estimated. For example, the second image can be processed by filtering the second image through a series of Gaussian filters to form a series of filtered second images; and linearly combining the filtered second images to form a stray light image including stray light components from pixels in the first image. For the system 100, the Gaussian filter to be used can be estimated empirically (i.e., by iteration). Therefore, the selection of the Gaussian filter to be used can be found by calibration of the system 100. Therefore, the stray light component of the pixel in the first image can be estimated based on the pixel value in the second image.

[0053] The estimation of the stray light component in the pixels of the first image may further depend on other factors. Some non-limiting examples are: the field of view overlap between the first image and the second image; the exposure of the first image and the second image; the gain setting of the first imaging device 110 and the second imaging device 120; the pixel density of the first image and the second image; the viewing angle of the first imaging device 110 and the second imaging device 120; the focus setting of the first imaging device 110 and the second imaging device 120; and the aperture setting of the first imaging device 110 and the second imaging device 120.

[0054] In summary, by applying a transfer function to the pixel values ​​of the pixels in the second image, the stray light component of the pixels in the first image can be found. This transfer function conveys how the pixel values ​​of the pixels in the second image affect the stray light in the first image. That is, a transfer function can be applied to the pixel values ​​of the pixels in the second image to convey how the stray light affects the pixels in the first image. This transfer function may depend on one or more of the factors discussed above. For system 100, the transfer function can be estimated empirically (i.e., by iteration). Therefore, the transfer function to be used for system 100 can be found by calibration of system 100.

[0055] The stray light compensation function 142 is further configured to compensate for stray light in the first image by subtracting the estimated stray light component in the pixels of the first image. Thus, an improved first image is provided in which stray light is reduced.

[0056] Now combine Figure 2 , Figure 3 , Figure 4a and Figure 4b Applications of system 100 for stray light compensation are discussed. Figure 2 , a system 100 for stray light compensation is shown from above viewing a scene including a building 200, a person 210, and a light source 220. In this particular example, the light source 220 is the sun. Figure 3 middle, Figure 2 The scene is illustrated as being depicted by a first imaging device 110 having a first field of view 111 and a second imaging device 120 having a second field of view 121. The first field of view 111 is illustrated as covering a person 210 and a portion of a building 200. It is important to note that a light source 220 is outside the field of view 111 of the first imaging device 110. The second field of view 121 is illustrated as covering the person 210, the building 200, and the light source 220. Figure 4a , an image captured by the first imaging device 110 before stray light compensation is performed is illustrated. Figure 4b , which illustrates the image after stray light compensation has been performed. Figure 4a of the image.

[0057] If combined Figure 2 , Figure 3 and Figure 4a As discussed above, the light source 220 outside the field of view 111 of the first imaging device 110 affects the image captured by the first imaging device 110. Figure 2 As schematically illustrated by arrow 221 in the figure, light from a light source 220 outside the field of view 111 of the first imaging device 110 will reach the first imaging device 110. This light will affect the image captured by the first imaging device 110 as stray light / lens flare. Figure 4aAn example of an image captured by the first imaging device 110 is illustrated in FIG. Figure 4a In FIG. 1 , stray light from a light source 220 outside the field of view 111 of the first imaging device 110 mainly affects the upper left portion of the image. Figure 4a The dotted line pattern illustrates noise introduced in the image due to stray light from the light source 220 outside the field of view 111 of the first imaging device 110 .

[0058] exist Figure 4b , the image is shown after applying the stray light compensation function 142. Figure 4a As shown in the image Figure 4b As shown, after the stray light is compensated using the stray light compensation function 142, the signal-to-noise ratio in the image is enhanced. Figure 4b The details in the stray light compensated image shown in the figure will be better displayed. Figure 4b Through Figure 4a 205 on the building 220. The stray light compensation function 142 relies on image data from an image captured by the second imaging device 120, which has a field of view 121 that includes a light source 220 outside the field of view 111 of the first imaging device 110. Therefore, the stray light in the pixels of the image captured by the first imaging device 110 can be estimated from the image captured by the second imaging device 120.

[0059] Combination Figure 5 , a method 500 for stray light compensation will be discussed. Some of all steps of the method 500 may be performed by the system 100 described above. However, it will also be appreciated that some or all steps of the method 500 may be performed by one or more other devices having similar functionality. The method 500 includes the following steps. These steps may be performed in any suitable order.

[0060] A first image is acquired S502 using a first imaging device covering a first field of view.

[0061] A second image is acquired (S504) using a second imaging device covering a second field of view. The second field of view is larger than the first field of view. The first field of view is included in the second field of view.

[0062] Estimating S506 stray light components in pixels of the first image from pixel data of pixels in the second image. Estimating S506 the stray light components in pixels of the first image may include: filtering the second image through a series of Gaussian filters to form a series of filtered second images; and linearly combining the filtered second images to form a stray light image including stray light components from pixels in the first image.

[0063] Estimation S506 may further include one or more of the following: determining a portion of the second image that overlaps with the first image; compensating for exposure differences between the second image and the first image; compensating for differences in gain settings of the first imaging device and the second imaging device; compensating for differences in pixel density between the second image and the first image; compensating for differences in perspective between the second image and the first image; and compensating for differences in aperture settings of the first imaging device and the second imaging device.

[0064] The stray light in the first image is compensated S508 by subtracting the estimated stray light component in the pixels of the first image. Thus, an improved first image is provided in which the stray light is reduced.

[0065] It is appreciated by those skilled in the art that the present invention is not limited to the preferred embodiments described above at all. On the contrary, numerous modifications and variations are possible within the scope of the appended claims.

[0066] For example, the first imaging device 110 and the second imaging device 120 can be configured to capture the first image and the second image simultaneously. In this context, "simultaneously" should be understood as the first image and the second image overlapping in time when they are captured. However, it should be understood that one of the images can be captured using a longer exposure time than the other. Typically, the second image is captured using a shorter exposure time than the first image in order to avoid overexposure of pixels in the second image. By capturing the first image and the second image simultaneously, the same lighting conditions are provided in both images. This provides better stray light compensation quality.

[0067] Additionally, variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

Claims

1. A method for stray light compensation, the method include: Acquiring a first image using a first imaging device covering a first field of view; acquiring a second image using a second imaging device covering a second field of view, wherein the second field of view is larger than the first field of view, and wherein the first field of view is included in the second field of view; and estimating a stray light component in a pixel of the first image from pixel data of a pixel in the second image; Characterized in that estimating the stray light component in the pixels of the first image comprises: filtering the second image through a series of Gaussian filters to form a series of filtered second images; and Linearly combining the filtered second images to form a stray light image including stray light components of pixels in the first image, and The method further includes compensating for stray light in the first image by subtracting the estimated stray light components in pixels of the first image.

2. The method according to claim 1, in, Estimating the stray light component in the pixels of the first image includes determining a portion of the second image that overlaps the first image.

3. The method according to claim 1, in, Estimating stray light components in pixels of the first image includes compensating for exposure differences between the second image and the first image.

4. The method according to claim 1, in, Estimating stray light components in pixels of the first image includes compensating for differences in gain settings of the first imaging device and the second imaging device.

5. The method according to claim 1, in, Estimating stray light components in pixels of the first image includes compensating for differences in pixel density between the second image and the first image.

6. The method according to claim 1, in, Estimating stray light components in pixels of the first image includes compensating for viewing angle differences between the second image and the first image.

7. A non-transitory computer-readable storage medium having instructions stored thereon, which, when executed on a device having processing capabilities, are used to implement the method according to claim 1.

8. A system for stray light compensation, the system include: a first imaging device covering a first field of view and configured to acquire a first image; as well as a second imaging device covering a second field of view and configured to acquire a second image, wherein the second field of view is larger than the first field of view, and wherein the first field of view is included in the second field of view; Characterized in that the system includes a circuit configured to perform a stray light compensation function, wherein the stray light compensation function is configured to: estimating stray light components in pixels of the first image from pixel data of pixels in the second image by filtering the second image by a series of Gaussian filters to form a series of filtered second images and linearly combining the filtered second images to form a stray light image including stray light components of pixels in the first image; and Stray light in the first image is compensated by subtracting the estimated stray light components in pixels of the first image.

9. The system according to claim 8, in, The resolution of the second imaging device is lower than the resolution of the first imaging device.

10. The system according to claim 8, in, The first imaging device and the second imaging device are configured to capture the first image and the second image simultaneously.

11. The system according to claim 8, in, The second imaging device is configured to capture the second image such that the second image is less saturated than the first image.

12. The system according to claim 8, in, The second imaging device comprises a fixed focus lens arrangement.

13. The system according to claim 8, in, The second imaging device is separate from the first imaging device.

14. A camera comprising the system according to claim 8.

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