Axis Ab

Jesper Bengtsson

Thomas Winzell

Emanuel Johansson

Mats Bylander

Niclas Danielsson

Xing Danielsson Fan

Anthony Hawkins

Anton Jakobsson

Ann-Sofie Rase

Tuong Lam

A method for reducing a dynamic range of an image, whereby first and second images have pixel values of a first bit depth. One or more peak regions and a representative pixel value for each peak region is identified in a histogram of the pixel values in the first image. For pixel values in the first image that are within a peak region, a pixel value difference is calculated as a difference between the pixel value and the representative pixel value of the peak region. For pixel values in the first image that are outside of the peak regions, the pixel value difference is zero. The pixel values of the second image are transformed to reduce the bit depth to a second bit depth. The pixel value differences calculated from the first image are then added to the pixel values of the transformed second image.

Method and a device for reducing a dynamic range of an image

There is provided a method for capturing a sequence of image frames in a thermal camera having a microbolometer detector comprising: capturing a first sequence and a second sequence of image frames with a shutter of the thermal camera being in a closed state and an open state, respectively. While capturing each of the first and the second sequence, an integration time of the microbolometer detector is switched between a plurality of integration times according to one or more repetitions of a temporal pattern of integration times. The method further comprises correcting image frames in the second sequence that are captured when the integration time is switched to a particular position within the temporal pattern of integration times using image frames in the first sequence that are captured when the integration time is switched to the same particular position within the temporal pattern of integration times.

Method and a thermal camera having a microbolometer detector for capturing a sequence of image frames

Methods and apparatus, including computer program products, for detecting malfunction in a thermal camera. A first average response value is determined for a first shutter image captured by an image sensor in the thermal camera. A second average response value is determined of a second shutter image captured by the image sensor in the thermal camera. The first average response value and the second average response value are compared. In response to determining that the first average response value and the second average response value differ by more than a predetermined value, an indication of a malfunction of the thermal camera is provided.

Thermal health monitoring sensor

Methods and apparatus, including computer program products, for detecting a problem with a thermal camera. A current contrast value is determined for the thermal camera. It is determined whether the current contrast value deviates from a reference contrast value by more than a predetermined value. In response to determining that the current contrast value deviates from the reference contrast value by more than a predetermined value and for more than a predetermined period of time, an indication of a problem with the thermal camera is provided.

Thermal camera health monitoring

A method for updating a fixed pattern noise matrix comprises: calculating a first difference between a target and first different images in a video stream to obtain a first differential matrix; calculating a second difference between the target and second different images in the video stream to obtain a second differential matrix; identifying a set of candidate positions for fixed pattern noise by: locating first and second sets of positions in the first differential matrix at which a difference deviates from predetermined values, finding a set of overlapping positions between the first and second sets of positions, and adjusting the set of overlapping positions. The adjusted set of overlapping positions is used for fixed pattern noise. Furthermore, each position in the set of candidate positions is updated, wherein the updated fixed pattern noise value at each position is based on a value at a corresponding non-adjusted position in the differential matrix.

Updating a fixed pattern noise matrix

A method and a controller for controlling a video processing unit to facilitate detection of newcomers in a first environment. The method comprises: capturing a thermal image of a human object in the first environment, the first environment being associated with a first climate; calculating, based on the thermal image, a thermal signature of a portion of the human object; determining that the human object has entered the first environment from a second environment when the thermal signature of the portion of the human object deviates from a predetermined thermal signature associated with the first environment, wherein the second environment is associated with a second, different, climate; and controlling the video processing unit to prioritize the human object over other human objects when processing video frames depicting the human object together with the other human objects.

Method and controller for controlling a video processing unit to facilitate detection of newcomers in a first environment

A method and a system for filtering thermal image data. The method comprises: capturing thermal image data by a thermal image detector; forming a signal distribution of intensity values; identifying a first part in the signal distribution of intensity values, the first part being a peak having an intensity width equal to or smaller than a predetermined intensity span being based on a resolution parameter of the thermal image detector; identifying a second part having an intensity width larger than the predetermined intensity span; determining an intensity range between the first part and the second part; and filtering, if the intensity range is larger than a predetermined minimum intensity range, the thermal image data by excluding thermal image data forming part of the first part.

Method and system for filtering thermal image data

An apparatus is disclosed for structural fixed pattern noise reduction in a video stream. A method may include, for each target pixel in a first image frame, defining a first target pixel patch, and defining a first search area comprising the first target pixel patch; for each pixel in the first search area, comparing a first pixel patch around the pixel with the first target pixel patch, and using the pixel when calculating an average for the target pixel. The method may include, in a second image frame, localizing a second target pixel, and defining a second search area comprising the second target pixel; for each pixel in the second search area, comparing a second pixel patch around the pixel of the second search area with the first target pixel patch, and using the pixel in the second search area when calculating an average for the target pixel.

Method for fixed pattern noise reduction and use of such method

A method for increasing enhancing local contrast in a thermal image for a class of objects having a thermal characteristic is provided. The method including providing thermal image data representing a first thermal image, where the first thermal image is acquired by an absolute calibrated thermal imaging system, redistributing the thermal image data having a first intensity distribution into a second intensity distribution using a predetermined redistribution function, where the predetermined redistribution function is based on the thermal characteristic, such that the local contrast is enhanced for the class of objects, outputting the redistributed thermal image data as the thermal image. An apparatus for enhancing local contrast in a thermal image for a class of objects having a thermal characteristic is further provided.

Method and apparatus for enhancing local contrast in a thermal image

There is provided a method for pre-processing a video stream for subsequent motion detection processing. The method comprises receiving a video stream of images, wherein each image in the video stream is represented by a first plurality of bits; enhancing the video stream of images by, for each image in the video stream: comparing the image to at least one previous image in the video stream so as to identify pixels where the image differs from the at least one previous image in the video stream, enhancing the image in those pixels where the image differs from the at least one previous image in the video stream; and converting the enhanced video stream of images so as to produce a converted video stream of images for subsequent motion detection processing, wherein each image in the converted video stream is represented by a second plurality of bits being lower than the first plurality of bits.

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Lund, Sweden

Jesper Bengtsson