DE102011106810B4 - Thermal imaging camera and method for image analysis and / or image processing of an IR image with a thermal imaging camera - Google Patents

Abstract

Thermal imaging camera (1), wherein a selection means (7) is formed, which is arranged for selecting at least one image area (9, 18) in an IR image (8, 14) taken with the thermal imaging camera (1), and wherein the selected image area (9, 18) is smaller than the IR image (8, 14), an image analysis and / or image processing unit (10) is formed which is capable of performing at least one image analysis and / or image processing step for the selected at least one image region (9 , 18), characterized in that the image analysis and / or image processing unit (10) comprises an input means (22) for inputting at least one emission and reflectance value as an image area related parameter.

Description

The invention relates to a thermal imaging camera.

It is known to take IR images with thermal imaging cameras. Here, the IR image is created by the output signal of an IR radiation detector is evaluated and processed.

On the way to the fully processed IR image, the IR image goes through different processing stages. The IR image can thus consist of the raw data of the IR radiation detector, of offset-corrected data of the output signal or of radiometric data, the radiometric data allowing a visual detection of the measurement result.

For visual representation, it is customary that the measurement result is displayed in false color representation. For this purpose, a color palette is used, which allows the conversion of the temperature readings or the corresponding RAW values / raw data into easily visually to be detected color values.

In this case, the color palette contains a table-like or formula-like assignment rule which describes a one-dimensional curve in a color model or color space. With this assignment rule it is possible to convert the temperature values into color values.

However, the color palette requires an adjustment of its value range if the captured IR image has an unusually large or an unusually small contrast between the temperature values. This can occur, for example, if an unusually hot or unusually cold object is picked up in front of a much cooler or substantially warmer background.

When selecting the pallet used, the user must therefore find a compromise that meets the needs for all image areas of the recorded IR image.

In the evaluation of the processed IR images, it has also become customary to apply special analysis methods to the IR image. Examples of such analysis methods are the determination of a minimum temperature value, the determination of a maximum temperature value, the determination of a mean temperature value, the determination of a scattering of the temperature values and other methods which as a result contain or provide information for the statistical evaluation of the recorded IR image.

Finally, it is urgently necessary for the calculation of realistic temperature values that radiation-physical properties of the recorded scene, in particular emissivity values, reflectance values or transmittance values, are known.

The invention further relates to a method for image analysis and / or image processing of an IR image with a thermal imaging camera.

Such methods are known from the above-mentioned preparation of the IR image.

From the US 5317395 A a thermal imaging camera according to the preamble of claim 1 is known, in which for a selected image area with a time processor, a temporal analysis and processing for individual or grouped pixels is performed.

From the US 7171328 B1 For example, a method for measuring thermal properties using a long-wavelength infrared thermal image is known in which a multispectral thermal image of a target area is captured and a digital elevation model is created and image areas adjacent to terrain-induced shadows are selected.

From the US 2003/0140775 A1 For example, a method and apparatus for targeting and viewing a controlled system using a common three-dimensional data set is known, wherein a LADAR system scans a scene and provides a three-dimensional image, where the image is further processed to recognize and segment potential targets. Here, the segmentations representing the potential targets are further processed by feature recognition and classification techniques to identify the target.

From Davis, James W .; SHARMA, Vinay: Robust background subtraction for person detection in Thermal Imagery. IEEE Computer Society Conference on Computer Vision and Pattern Recognition Workshops (CVPRW'04), 27-02 June 2004. In: Conference Proceedings, pp. 128-135, segmentation means for automatic selection of image areas in thermal images are known.

From BHANU, Bir: Automatic Target Recognition: State of the Art Survey. In: IEEE Transactions to Aerospace and Electronic Systems, AES-22, July 1986, no. 4, pp. 364-379, a review of the prior art regarding the segmentation of thermal images is known.

From the US 2010/0058222 A1 the use of false color representations for thermal images is known.

From the DE 10 2005 009 626 A1 a camera is known for tracking objects with an image sensor unit for generating image data and with a processing unit for processing the image data transferred from the image sensor unit to the processing unit, the processing unit having an ROI selection unit for selecting image areas of interest for the object tracking and a tracking unit. Unit to detect tracking data of objects to be tracked from the image data.

The invention has for its object to improve the performance characteristics of a thermal imaging camera.

To achieve this object, the features of claim 1 are provided according to the invention in a thermal imaging camera. Thus, it is proposed, in particular, that a selection means is provided which is set up to select at least one image area in an IR image recorded by the thermal imaging camera, and in that an image analysis and / or image processing unit is provided which is capable of performing at least one image analysis and / or or image processing step is set up for the selected at least one image area. The advantage here is that one or more image analysis and / or image processing steps for the selected at least one image area are individually executable, so that an IR image of a scene with different objects can be processed intelligently and content related. Preferably, the selected area is smaller than the IR image or even smaller than one half or one quarter of the IR image.

It is particularly advantageous if the selection means is set up such that at least two or more image areas in a single IR image can be selected parallel to one another and independently of one another. This has the advantage that individual image analysis and / or image processing steps can be performed for the different selected image areas.

For example, it can be provided that the selection means is set up for manual selection. For this purpose, a number of geometric shapes for closed contours can be stored in the thermal imaging camera, which can be selected to select the at least one image area and adjusted to the desired size in the IR image. Preferably, the geometric shapes include at least rectangles, so that a selection of rectangular image areas is easily possible. After selecting a rectangular basic shape, for example, two diagonally opposite corners can be set for selecting the image area in the IR image, for example with a touch-sensitive display or with operating levers.

It can also be provided that the selection means comprises a segmentation means for the automated selection of the at least one image area. The advantage here is that the image area to be selected is automatically optimally tuned to a viewed object, so that the user can make a selection with a few operating steps.

It is particularly favorable if the geometric shape of the edge of the image area is initially specified or selected, and that subsequently the size of the image area is adjusted automatically or manually to an object by scaling and / or distortion.

To execute a desired. Bildanalyse- and / or image processing step may be provided that the image analysis and / or image processing unit comprises a setting means for setting a color and / or gray scale palette for a preferably independent of the rest of the IR image false color representation of the image area. The advantage here is that in this way details in objects, which have a high temperature in relation to the environment, yet are visually displayed well.

It may also be provided that the image analysis and / or image processing unit has an input means for inputting at least one image area related parameter, in particular for inputting at least one emission and / or transmission and / or reflectance value, or defining the image analysis and / or image processing step Parameters includes. The advantage here is that the radiometry by individual reflection temperature coefficient RTC and / or individual emissivity values or coefficients ε is more accurate feasible. For this purpose, the selection means for subdividing the IR image into a plurality of image areas is set up, wherein the image analysis and / or image processing unit is set up to execute at least one individual image area related image analysis and / or image processing step for the individual image areas of the subdivision of the IR image.

It can also be provided that the image analysis and / or image processing unit comprises an evaluation means which is set up to detect the change in the image position of the image area between two IR images. The advantage here is that in this way a movement of the thermal imaging camera relative to the scene to be recorded and / or a movement of objects in the scene can be considered or taken into account. For example, this can be achieved by calculating a cross-correlation for the respectively selected image area or by performing a feature analysis on the IR image, wherein the extracted features are compared with the features in the selected image area.

It can also be provided that the image analysis and / or image processing unit comprises a test device which is set up to detect overlaps of the image area with a default area or a further image area in the IR image. In this way, moving objects can be monitored to keep, for example, a prescribed minimum distance from each other. If an overlap is detected, a warning signal can be generated automatically.

It can also be provided that the image analysis and / or image processing unit comprises an adjustment means which is set up for the representation of the at least one image area on a display unit of the thermal imager, preferably independent of the remaining IR image. The advantage here is that details of the IR image, which are particularly interesting for the user compared to the rest of the image content of the IR image are displayed enlarged.

It may also be provided that the image analysis and / or image processing unit comprises an adjustment means which is set up for setting the image contrast factor independent of the remaining IR image for displaying the at least one image area on a display unit of the thermal imager. The advantage here is that different image contrast factors are adjustable for different image areas, so that details in a relation to the environment almost homogeneous temperature surface can be displayed.

It may also be provided that the image analysis and / or image processing unit comprises a setting means which is set up for setting the image sharpness factor preferably independent of the remaining IR image for displaying the at least one image area on a display unit of the thermal imaging camera. The advantage here is that the amount of information in uninteresting image areas can be reduced without possibly losing important information in interesting image areas.

In an embodiment of the invention, it can be provided that the image analysis and / or image processing unit comprises an adjustment means which is set up for setting the at least one image area on a display unit of the thermal imager, preferably independent of the remaining IR image. The advantage here is that in this way interesting image areas are graphically automatically highlighted over the rest of the IR image.

It may be provided that the image analysis and / or image processing unit comprises an analysis means which is set up to determine at least one mean value, maximum value, minimum value and / or variance value of the temperature for the at least one image region. It can also be provided that further numerical values for a statistical evaluation of the image area are calculated or determined with the analysis means. The advantage here is that in this way numerical values for numerical further processing can be derived from the visual representation of the radiometric image. It is particularly advantageous if the analysis means are designed and set up to execute image-area-related analysis methods which derive desired numerical values from the IR image in a predefined manner. Thus, different, preferably preset, analysis methods can be carried out in a simple manner for the different image regions.

It is preferably provided that the selection means for manual selection comprises operating elements. These controls may also be provided by a touch-sensitive display.

The segmentation means, the evaluation means, the test means and / or the analysis means can be designed and set up in the embodiments according to the invention by suitable programming in the image analysis and / or image processing unit.

The image analysis and / or image processing unit can be implemented in a data processing unit.

The adjusting means and / or the input means can / have operating elements for manual operation, for example operating buttons, operating levers or also a touch-sensitive display.

To solve the problem is provided according to the invention in a method of the type mentioned that the IR image is taken with the thermal imager, that in the IR image at least one image area is selected with a selection means of the thermal imager and that for the at least one image area in an image analysis and / or image processing unit of Thermal image camera at least one image analysis and / or image processing step is performed. The advantage here is that the further processing and processing of a recorded IR image on the image content is individually tuned, so that an intelligent treatment is possible.

In the method according to the invention, in an IR image, a plurality of image regions are selected with the selection means and an individual image analysis and / or image processing step is carried out for each of the selected image regions.

It may be provided for this purpose that the thermal imaging camera has an optimization tool, with which the size and / or shape of the image area is optimally tuned to an object in the IR image.

It is particularly advantageous if in the method according to the invention a thermal imaging camera according to the invention is used.

The invention will now be described in detail with reference to an embodiment, but is not limited to this embodiment. Further exemplary embodiments result from the combination of one or more features of the protection claims with one another and / or with one or more features of the exemplary embodiment.

It shows:

1 in a three-dimensional oblique view from the front a thermal imaging camera according to the invention,

2 the thermal imaging camera according to 1 in a three-dimensional oblique view from behind,

3 a captured with a thermal imaging camera according to the invention IR image in a highly simplified, schematic representation and

4 a highly simplified, schematic representation of a processed IR image to explain the principle of the invention.

1 and 2 show three-dimensional views of the whole 1 designated thermal imaging camera according to the invention.

The thermal imager 1 has an IR optic 2 on, behind the inside of the thermal imager 1 in a conventional manner, an IR radiation detector 3 is arranged, with which by the IR optics 2 incident heat radiation into electrical measurement signals of an output signal are convertible.

The thermal imager 1 is designed as a handheld device and has a handle 4 on.

At the of the IR optics 2 facing away back 5 the thermal imager 1 is a display unit 6 trained, with which with the thermal imaging camera 1 recorded IR images 8th - If necessary, after a computational preparation - can be displayed.

In the illustrated embodiment according to 1 and 2 is the display unit 6 designed as a display.

At the back 5 is still a selection tool 7 arranged in the form of a control lever or control button.

With the selection tool 7 can be an image area 9 in the IR image 8th be selected by specifying the image area boundaries.

This in 2 exemplified for explanation IR image 8th is in 4 magnified reproduced.

Inside the thermal imager 1 is an image analysis and / or image processing unit in a data processing unit not further shown 10 formed and arranged, with which a predetermined number and sequence of different image analysis and / or image processing steps on the IR image 8th are feasible.

The image analysis and / or image processing unit 10 is set up so that the available image analysis and / or image processing steps for the selected image area 9 or the selected image areas are individually parameterizable and executable.

In addition to the selection means 7 with which a manual selection of the rectangular image areas 9 is possible in the thermal imager 1 a segmentation agent 11 set up with which the image area 9 automated, so computer-aided selectable.

This can be done, for example, by using a cursor 12 (see. 4 ) first via the selection means 7 a pixel 13 in the IR image 8th is selected, and that the segmentation means 11 then automatically the associated area 9 sets.

In addition, the display unit 6 be designed as a touch-sensitive display, via which the image areas 9 are directly selectable.

3 shows in a highly schematic representation with a thermal imaging camera 1 recorded IR image 14 before application of the method according to the invention.

The IR image 14 contains a scene with several objects 15 . 16 , which differ in their radiation physical properties from each other.

For example, the object has 15 an average temperature, which is significantly different from the mean temperature of the objects 16 differs.

For the radiometric representation of the IR image 14 is in the thermal imager 1 a color and / or gray scale palette 17 deposited.

Because the objects 15 . 16 are shown together, represents the selected color and / or gray value palette 17 a compromise that allows all objects 15 . 16 in a common false color representation.

However, the invention now uses the knowledge that it is much more useful, the objects 16 separated from the object 15 to prepare for radiometric representation.

Therefore, the user can use the selection tool 7 or in the manner described, the image area 9 and another image area 18 in the IR image 8th select the image area 9 the object 15 and the image area 18 the objects 16 contains.

The default is that the image areas 9 . 18 each have a rectangular shape, the size of each of the objects 15 . 16 is adjusted or is.

At the back 5 The thermal imager is an adjustment tool 19 in the form of a control knob or control lever or in the form of a touch-sensitive displays on the display unit 6 provided, via which the user the color and / or gray scale palette 20 . 21 can adjust separately for the image areas 9 . 18 each should be valid for false color representation.

For the remaining image areas of the IR image 8th retains the color and / or gray scale palette 17 still valid.

The image analysis and / or image processing unit 10 is set up so that after determining the color and / or gray scale palettes 17 . 20 . 21 the IR picture 8th is transformed so that in each area 9 . 18 the respectively valid color and / or gray value pallets 17 . 20 21 be applied to from the readings of the output signal of the IR radiation detector 3 a radiometric representation of the IR image 8th to create.

About input means 22 at the back 5 the thermal imager 1 or via the touch-sensitive display of the display unit 6 can also do the respective for the areas 9 . 18 and its complement in the IR image 8th valid image area related parameters are entered. These parameters can represent, for example, emissivity values and / or reflectance values with which the output signal of the image areas 9 . 18 associated pixels of the IR radiation detector 3 in each case a correct temperature with the image analysis and / or image processing unit 10 can be calculated. The image analysis and / or image processing unit 10 is therefore set up to provide a number of parameters for the execution of the intended image analysis and / or image processing steps, here for each selected image area 9 . 18 separated from each other individually and can be adjusted.

Used with the image analysis and / or image processing unit 10 a video sequence of IR images 8th . 14 processed, so can by comparing between the captured IR images 8th . 14 determine whether and around which vector the objects 15 . 16 in terms of the IR image 8th . 14 and / or have moved relative to each other.

For this purpose, the image analysis and / or image processing unit comprises an evaluation means 23 , with which the image position of the image areas 9 . 18 so in the IR picture 8th it can be changed that the objects 15 . 16 their relative positions in the image areas 9 . 18 maintained.

With one in the image analysis and / or image processing unit 10 trained test equipment 24 It is now possible to check whether the image areas changed or shifted in this way 9 . 18 collide or overlap. If this is the case, then the test equipment 24 generate an indication signal which approximates the object 15 to the objects 16 displays.

To details in the object 15 to better perceive the user can for the selected image area 9 specify a different image magnification factor than for the image area 18 , The image analysis and / or image processing unit 10 calculated after adjustment or presetting of the image magnification factors of the IR image 8th again, where now the object 15 opposite the objects 16 unnaturally enlarged.

In this way, image contrast factors, image sharpness factors and / or image softness drawing factors and / or further factors which characterize the form of representation can be defined and changed.

To obtain temperature values from the IR image 8th allows the user for the selected image areas 9 . 18 each define a sequence of analysis steps which, after being determined in the image analysis and / or image processing unit 10 for the individual image areas 9 . 18 is carried out individually.

These analysis steps can be, for example, the determination of at least one mean value, maximum value, minimum value and / or variance value of the temperature and / or a temperature value at the position of the cursor 12 for the respective image area 9 . 18 include.

In the illustrated embodiment, only two image areas 9 . 18 However, an arbitrary number of image areas can be selected and used.

For example, it can be provided that the IR image 14 for processing is automatically subdivided into image areas (completely), for example in image areas in a grid arrangement, wherein for the individual image areas in the image analysis and / or image processing unit 10 each automatically optimal parameters and / or analysis steps are determined and proposed, which are then executed as Bildanalyse- and / or image processing steps for the individual areas individually.

The described thermal imaging camera 1 is thus for image analysis and / or image processing of an IR image according to the invention 8th . 14 set up in which in the IR image 8th . 9 which previously with the thermal imager 1 was taken, a desired number of image areas 9 . 18 is selected by appropriate default, the image analysis and / or image processing unit 10 is set up so that for each selected image area 9 . 18 separated image analysis and / or image processing steps can be performed.

With the thermal imager 1 is thus a selection tool 7 trained, with which in a recorded IR image 8th . 14 a desired number of image areas 9 . 18 is selectable, wherein an image analysis and / or image processing unit 10 is so programmatically set up that for each selected image area 9 . 18 an individually predetermined sequence of image analysis and / or image processing steps is executable and executed.

Claims (10)

Thermal camera ( 1 ), whereby a selection means ( 7 ), which is used to select at least one image area ( 9 . 18 ) in one with the thermal imager ( 1 ) recorded IR image ( 8th . 14 ) and the selected image area ( 9 . 18 ) smaller than the IR image ( 8th . 14 ), an image analysis and / or image processing unit ( 10 ) configured to execute at least one image analysis and / or image processing step for the selected at least one image area ( 9 . 18 ), characterized in that the image analysis and / or image processing unit ( 10 ) an input means ( 22 ) for inputting at least one emission and reflectance value as an image area related parameter. Thermal camera ( 1 ) according to claim 1, characterized in that the selection means ( 7 ) for manual selection, preferably for selection of rectangular image areas ( 9 . 18 ) is set up. Thermal camera ( 1 ) according to claim 1 or 2, characterized in that the selection means ( 7 ) a segmentation agent ( 11 ) for the automated selection of the at least one image area ( 9 . 18 ). Thermal camera ( 1 ) according to one of claims 1 to 3, characterized in that the image analysis and / or image processing unit ( 10 ) an adjustment means ( 19 ) for setting a color and / or gray scale palette ( 17 . 20 . 21 ) for a preferably from the remaining IR image ( 8th . 14 ) independent false color representation of the image area ( 9 . 18 ). Thermal camera ( 1 ) according to one of claims 1 to 4, characterized in that the image analysis and / or image processing unit ( 10 ) an evaluation means ( 23 ), which is used to detect the change in the image position of the at least one image area (FIG. 9 . 18 ) between two IR images ( 8th . 14 ) is set up. Thermal camera ( 1 ) according to one of claims 1 to 5, characterized in that the image analysis and / or image processing unit ( 10 ) a test equipment ( 24 ), which is used to detect overlaps of the image area ( 9 . 18 ) with a default area or further image area ( 9 . 18 ) in the IR image ( 8th ) is set up. Thermal camera ( 1 ) according to one of claims 1 to 6, characterized in that the image analysis and / or image processing unit ( 10 ) an adjustment means ( 25 ), which preferably differs from the rest of the IR image ( 8th . 14 ) independent adjustment of an image magnification factor and / or an image contrast factor and / or an image sharpness factor and / or a image softness factor for a representation of the at least one image region ( 9 . 18 ) on a display unit ( 6 ) of the thermal imager ( 1 ) is set up. Thermal camera ( 1 ) according to one of claims 1 to 7, characterized in that the image analysis and / or image processing unit ( 10 ) an analysis means ( 26 ), which is set up to determine at least one mean value, maximum value, minimum value and / or variance value of the temperature for the at least one image region. Method for image analysis and / or image processing of an IR image ( 8th . 14 ) with a thermal imaging camera ( 1 ), characterized in that the IR image ( 8th . 14 ) with the thermal imager ( 1 ) that in the IR image ( 8th . 14 ) at least one image area ( 9 . 18 ) with a selection means ( 7 ) of the thermal imager ( 1 ), the selected image area ( 9 . 18 ) smaller than the IR image ( 8th . 14 ), and that for the at least one image area ( 9 . 18 ) in an image analysis and / or image processing unit ( 10 ) of the thermal imager ( 1 ) at least one image analysis and / or image processing step is carried out, wherein at least one emission and reflectance value is determined as an image region-related parameter by means of an image analysis and / or image processing unit ( 10 ) input means ( 22 ) is entered. Method according to claim 9, characterized in that a thermal imaging camera ( 1 ) according to one of claims 1 to 8 is used.

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