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EP-3928505-B1 - METHOD, DEVICE, AND COMPUTER PROGRAM FOR SETTING PARAMETERS VALUES OF A VIDEO SOURCE DEVICE

EP3928505B1EP 3928505 B1EP3928505 B1EP 3928505B1EP-3928505-B1

Inventors

  • CITERIN, JOHANN
  • BELLESSORT, ROMAIN

Dates

Publication Date
20260506
Application Date
20200917

Claims (13)

  1. A method for setting parameters values of a video source device, the method comprising: obtaining a value of an image characteristic for a current image generated by the video source device set with initial parameters values; determining a satisfaction level for the image characteristic of the current image based on the obtained value, the satisfaction level representing a probability to fulfil a task from the point of view of the image characteristic; obtaining a set of candidates, a candidate being defined as a set of parameters values, each candidate being different from the other candidates of the set by a different value of at least one parameter; for each candidate, predicting an evolution of the satisfaction level for the image characteristic relatively to the satisfaction level determined while the video source device is set with the initial parameters values; selecting a candidate based on its predicted evolution of the satisfaction level; setting the parameters values of the video source device using the set of parameters values of the selected candidate, the method being characterised in that : there are a plurality of image characteristics, wherein a satisfaction level is determined for each image characteristic of the plurality, and wherein selecting a candidate is based on a determined score that represents a combination of the evolution of each of the satisfaction levels for the plurality of image characteristics, and in that the combination is a weighted combination in which the weight for a high value of an evolution of a satisfaction level is less than the weight for a low value of an evolution of another satisfaction level.
  2. The method according to claim 1, wherein the method further comprises generating a predictive function defining the satisfaction level for the image characteristic as a function of at least one parameter of the video source device.
  3. The method according to claim 1, wherein predicting the evolution of the satisfaction level comprises predicting the value of the image characteristic based on a value of at least one parameter.
  4. The method according to claim 2, wherein the input of the predictive function is a scalar resulting of one single parameter value or of a combination of a plurality of parameters values.
  5. The method according to claim 2, or 4, wherein if the obtained value for the image characteristic is different from a value generated by the predictive function for a given set of parameters values, the predictive function is updated so that the value generated by the updated predictive function is equal to the obtained value.
  6. The method according to any one of the preceding claims, wherein when a first evolution of the satisfaction level for a given image characteristic is negative, and a second evolution of the satisfaction level for the given image characteristic is positive, and the first and second evolutions of the satisfaction level for the given image characteristic get the same absolute value, the method comprises associating a respective weight to the first and second evolutions of the satisfaction level, such that a weight associated to the first evolution of the satisfaction level is superior to a weight associated to the second evolution of the satisfaction level.
  7. The method according to any one of the preceding claims, wherein at least some parameters use different scales, wherein a normalization function is applied beforehand, thereby obtaining normalized parameters which use the same scale.
  8. The method according to claim 7, wherein the image characteristic is the image contrast, which depends on exposure, wherein the exposure is defined as a sum of the normalized parameters values of the parameters among the list of gain, shutter and iris, alone or in combination, and of ambient light.
  9. The method according to claim 8, wherein the normalized parameters values of gain, iris, shutter and ambient light are expressed in decibels (dB), such that the transition of a predetermined value in dB of any of gain, iris, shutter and/or ambient light creates the same evolution on luminance.
  10. The method according to claim 9, wherein the ambient light of a scene captured by the video source device is computed using a luminance function based on a measured luminance of an image of the scene, and based on the normalized parameters values of the parameters for the image.
  11. A computer program product for a programmable apparatus, the computer program product comprising a sequence of instructions for implementing each of the steps of the method according to any one of claims 1 to 10 when loaded into and executed by the programmable apparatus.
  12. A non-transitory computer-readable storage medium storing instructions of a computer program for implementing each of the steps of the method according to any one of claims 1 to 10.
  13. A device comprising a processing unit configured for carrying out each of the steps of the method according to any one of claims 1 to 10.

Description

FIELD OF THE INVENTION The present invention relates to a method, device and computer program for setting parameters values of a video source device. BACKGROUND OF THE INVENTION Video-surveillance is based on cameras that are expected to record live footage with an image quality that is sufficient to fulfil its task or mission (e.g., being able to recognize a human person, or being able to read a license plate are common requirements), without leading to excessive resource consumption (bandwidth and recording resource in particular). Independently from the camera model, quality and resource consumption depend a lot on the camera parameters values, with huge differences between a camera with optimal parameters values vs a camera with default parameters values or, worse, with inadequate parameters values. In order to modify the camera parameters values, the following methods are used but with some drawbacks: Manual settings. Fixing the parameters values by the installer is a common procedure. However, it is costly since it requires a long installation time with a trained staff, several hours are sometimes necessary for a good setting in some cases. It is also not dynamic, which means that the fixed parameter may fail when conditions change (e.g. summer / winter). This is also sometimes difficult since the cameras menus are completely different from one camera to the other, which limits the number of cameras a staff is trained on.Embedded auto-settings. There are usually auto-exposure methods in the modern cameras. However, they may encounter some motion blur or some targets contrast issues, which is the reason why they actually work only in the most common cases (good lighting, slow moving targets). Some new, high-end cameras are equipped with target-detection hardware that makes it possible to have some more accurate auto-setting, as they are able to recognize the important parts of an image (the targets). However, this requires expensive additional embedded sensors and hardware that make it not an economic and realistic solution in most cases.Automated settings based on thorough calibration (e.g. measurements are made for every possible combination of parameters values). Errors may occur during calibration, and external elements may change significantly over time when compared to elements observed at calibration time. Therefore, such solutions lead to predictions that are not robust enough as they are too dependent on calibration data. The prior art of record also comprises document GB 2 570 448 A which discloses a method as per the preamble of claim 1. SUMMARY OF THE INVENTION Consequently, the known methods have such drawbacks that it is of interest to propose a method with reduced costs, i.e. not requiring complex and costly hardware or long time of specialized technician, versatile, i.e. easily adaptable to different types of camera or environments, or able to modify the parameters values due to environment modification without human intervention. The present invention has been devised to address one or more of the foregoing concerns. In a first aspect, the present invention provides a method for setting parameters values of a video source device as specified in claim 1. This aspect may comprise other features, alone or in combination, as disclosed in dependent claims 2 to 10. Among the advantages of these features, there are a progressive approach using an iterative method which converges quickly, the learning capabilities of the prediction functions over time, a fast setting of the video source, a generic and auto-adaptive approach which can be used on a large variety of video sources or installations, a fast and user-friendly installation. According to a second aspect of the invention, there is provided a computer program product as specified in claim 11. According to a third aspect of the invention, there is provided a non-transitory computer-readable storage medium as specified in claim 12. According to a fourth aspect of the invention, there is provided a device for setting the parameters values of a video source as specified in claim 13. At least parts of the methods according to the invention may be computer implemented. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a "circuit", "module" or "system". Furthermore, the present invention may take the form of a computer program product embodied in any tangible medium of expression having computer usable program code embodied in the medium. Since the present invention can be implemented in software, the present invention can be embodied as computer readable code for provision to a programmable apparatus on any suitable carrier medium. A tangible carrier medium may comprise a storage medium such as a floppy disk, a CD