Infrared camera with image processing modes for maritime applications

Systems and methods disclosed herein provide an image capture component adapted to capture an infrared image, a control component adapted to provide a plurality of selectable processing modes to a user, receive a user input corresponding to a user selected processing mode, generate a control signal indicative of the user selected processing mode and transmit the generated control signal. The user selected processing modes, for example, may be directed to maritime applications, such as night docking, man overboard, night cruising, day cruising, hazy conditions, and/or shoreline modes. The systems and methods further provide a processing component adapted to receive the generated control signal from the control component, process the captured infrared image according to the user selected processing mode, and generate a processed infrared image, and a display component adapted to display the processed infrared image.

TECHNICAL FIELD

The present disclosure relates to infrared imaging systems and, in particular, to infrared camera modes for maritime applications.

BACKGROUND

Infrared cameras are utilized in a variety of imaging applications to capture infrared images and some image processing techniques allow for suppression of unwanted features, such as noise, and/or refinement of captured infrared images. For example, infrared cameras may be utilized for maritime applications to enhance visibility under various conditions for a naval crew. However, there generally are a number of drawbacks for conventional maritime implementation approaches for infrared cameras.

One drawback of conventional infrared cameras is that a user is generally not allowed to switch between different processing techniques during viewing of the infrared image or the optimal settings may be difficult to determine by the user. Another drawback is that user-controlled processing may occur post capture, after initial processing has been performed, which generally lessens the user's input and control and may result in a less than desirable image being displayed.

As a result, there is a need for improved techniques for providing selectable viewing controls for infrared cameras. There is also a need for improved infrared camera processing techniques for maritime applications.

SUMMARY

Systems and methods disclosed herein provide user selectable processing techniques and modes of operation for infrared cameras in accordance with one or more embodiments. Systems and methods disclosed herein also provide improved processing techniques of infrared images for maritime applications in accordance with one or more embodiments.

In accordance with an embodiment of the present disclosure, a system comprises an image capture component adapted to capture an infrared image and a control component adapted to provide a plurality of selectable processing modes to a user, receive a user input corresponding to a user selected processing mode, and transmit a control signal indicative of the user selected processing mode. The system further comprises a processing component adapted to receive the control signal from the control component, process the captured infrared image according to the user selected processing mode, and generate a processed infrared image. The system further comprises a display component adapted to display the processed infrared image.

In one implementation, the selectable processing modes may include a night docking mode that causes the processing component to histogram equalize and scale the captured infrared image to generate the processed infrared image. In another implementation, the selectable processing modes may include a man overboard mode that causes the processing component to apply a high pass filter to the captured infrared image to generate the processed infrared image. In another implementation, the selectable processing modes may include a night cruising mode that causes the processing component to extract a detailed part and a background part from the captured infrared image, separately scale the detailed part, separately histogram equalize and scale the background part, and add the detailed part to the background part to generate the processed infrared image. In another implementation, the selectable processing modes may include a day cruising mode that causes the processing component to extract a detailed part and a background part from the captured infrared image, separately scale the detailed part, separately histogram equalize and scale the background part, and add the detailed part to the background part to generate the processed infrared image. In another implementation, the selectable processing modes may include a hazy conditions mode that causes the processing component to apply a non-linear low pass filter on the captured infrared image, and then histogram equalize and scale the filtered image to generate the processed infrared image. In yet another implementation, the selectable processing modes may include a shoreline identification (e.g., a horizon or landline identification) that may be provided to the display component. In still another implementation, the system may further include a night display mode, wherein the display component is adapted to display the processed infrared image in a red color palette or a green color palette.

In accordance with another embodiment of the present disclosure, a method includes capturing an infrared image, providing a plurality of selectable processing modes to a user, receiving a user input corresponding to a user selected processing mode, and processing the captured infrared image according to the user selected processing mode. The method further includes generating a processed infrared image and displaying the processed infrared image.

DETAILED DESCRIPTION

In accordance with an embodiment of the present disclosure,FIG. 1shows a block diagram illustrating an infrared imaging system100for capturing and processing infrared images. Infrared imaging system100comprises a processing component110, a memory component120, an image capture component130, a display component140, a control component150, and optionally a sensing component160.

In various implementations, infrared imaging system100may represent an infrared imaging device, such as an infrared camera, to capture images, such as image170. Infrared imaging system100may represent any type of infrared camera, which for example detects infrared radiation and provides representative data (e.g., one or more snapshots or video infrared images). For example, infrared imaging system100may represent an infrared camera that is directed to the near, middle, and/or far infrared spectrums. Infrared imaging system100may comprise a portable device and may be incorporated, for example, into a vehicle (e.g., a naval vehicle, a land-based vehicle, an aircraft, or a spacecraft) or a non-mobile installation requiring infrared images to be stored and/or displayed.

Processing component110comprises, in one embodiment, a microprocessor, a single-core processor, a multi-core processor, a microcontroller, a logic device (e.g., a programmable logic device configured to perform processing functions), a digital signal processing (DSP) device, or some other type of generally known processor. Processing component110is adapted to interface and communicate with components120,130,140,150and160to perform method and processing steps as described herein. Processing component110may comprise one or more mode modules112A-112N for operating in one or more modes of operation, which is described in greater detail herein. In one implementation, mode modules112A-112N define preset display functions that may be embedded in processing component110or stored on memory component120for access and execution by processing component110. Moreover, processing component110may be adapted to perform various other types of image processing algorithms in a manner as described herein.

In various implementations, it should be appreciated that each of mode modules112A-112N may be integrated in software and/or hardware as part of processing component110, or code (e.g., software or configuration data) for each of the modes of operation associated with each mode module112A-112N, which may be stored in memory component120. Embodiments of mode modules112A-112N (i.e., modes of operation) disclosed herein may be stored by a separate computer-readable medium (e.g., a memory, such as a hard drive, a compact disk, a digital video disk, or a flash memory) to be executed by a computer (e.g., a logic or processor-based system) to perform various methods disclosed herein. In one example, the computer-readable medium may be portable and/or located separate from infrared imaging system100, with stored mode modules112A-112N provided to infrared imaging system100by coupling the computer-readable medium to infrared imaging system100and/or by infrared imaging system100downloading (e.g., via a wired or wireless link) the mode modules112A-112N from the computer-readable medium. As described in greater detail herein, mode modules112A-112N provide for improved infrared camera processing techniques for real time applications, wherein a user or operator may change the mode while viewing an image on display component140.

Memory component120comprises, in one embodiment, one or more memory devices to store data and information. The one or more memory devices may comprise various types of memory including volatile and non-volatile memory devices, such as RAM (Random Access Memory), ROM (Read-Only Memory), EEPROM (Electrically-Erasable Read-Only Memory), flash memory, etc. Processing component110is adapted to execute software stored in memory component120to perform methods, processes, and modes of operations in manner as described herein.

Image capture component130comprises, in one embodiment, one or more infrared sensors (e.g., any type of infrared detector, such as a focal plane array) for capturing infrared image signals representative of an image, such as image170. In one implementation, the infrared sensors of image capture component130provide for representing (e.g., converting) a captured image signal of image170as digital data (e.g., via an analog-to-digital converter included as part of the infrared sensor or separate from the infrared sensor as part of infrared imaging system100). Processing component110may be adapted to receive the infrared image signals from image capture component130, process the infrared image signals (e.g., to provide processed image data), store the infrared image signals or image data in memory component120, and/or retrieve stored infrared image signals from memory component120. Processing component110may be adapted to process infrared image signals stored in memory component120to provide image data (e.g., captured and/or processed infrared image data) to display component140for viewing by a user.

Display component140comprises, in one embodiment, an image display device (e.g., a liquid crystal display (LCD)) or various other types of generally known video displays or monitors. Processing component110may be adapted to display image data and information on display component140. Processing component110may also be adapted to retrieve image data and information from memory component120and display any retrieved image data and information on display component140. Display component140may comprise display electronics, which may be utilized by processing component110to display image data and information (e.g., infrared images). Display component140may receive image data and information directly from image capture component130via processing component110, or the image data and information may be transferred from memory component120via processing component110. In one implementation, processing component110may initially process a captured image and present a processed image in one mode, corresponding to mode modules112A-112N, and then upon user input to control component150, processing component110may switch the current mode to a different mode for viewing the processed image on display component140in the different mode. This switching may be referred to as applying the infrared camera processing techniques of mode modules112A-112N for real time applications, wherein a user or operator may change the mode while viewing an image on display component140based on user input to control component150.

Control component150comprises, in one embodiment, a user input and/or interface device having one or more user actuated components, such as one or more push buttons, slide bars, rotatable knobs or a keyboard, that are adapted to generate one or more user actuated input control signals. Control component150may be adapted to be integrated as part of display component140to function as both a user input device and a display device, such as, for example, a touch screen device adapted to receive input signals from a user touching different parts of the display screen. Processing component110may be adapted to sense control input signals from control component150and respond to any sensed control input signals received therefrom. Processing component110may be adapted to interpret the control input signal as a value, which will be described in greater detail herein.

Control component150may comprise, in one embodiment, a control panel unit500(e.g., a wired or wireless handheld control unit) having one or more push buttons adapted to interface with a user and receive user input control values, as shown inFIG. 5and further described herein. In various implementations, one or more push buttons of control panel unit500may be utilized to select between the various modes of operation as described herein in reference toFIGS. 2-4. For example, only one push button may be implemented and which is used by the operator to cycle through the various modes of operation (e.g., night docking, man overboard, night cruising, day cruising, hazy conditions, and shoreline), with the selected mode indicated on the display component140. In various other implementations, it should be appreciated that control panel unit500may be adapted to include one or more other push buttons to provide various other control functions of infrared imaging system100, such as auto-focus, menu enable and selection, field of view (FoV), brightness, contrast, gain, offset, spatial, temporal, and/or various other features and/or parameters. In another implementation, a variable gain value may be adjusted by the user or operator based on a selected mode of operation.

In another embodiment, control component150may comprise a graphical user interface (GUI), which may be integrated as part of display component140(e.g., a user actuated touch screen), having one or more images of, for example, push buttons adapted to interface with a user and receive user input control values.

Optional sensing component160comprises, in one embodiment, one or more various types of sensors, including environmental sensors, depending upon the desired application or implementation requirements, which provide information to processing component110. Processing component110may be adapted to communicate with sensing component160(e.g., by receiving sensor information from sensing component160) and with image capture component130(e.g., by receiving data from image capture component130and providing and/or receiving command, control or other information to and/or from other components of infrared imaging system100).

In various implementations, optional sensing component160may provide data and information relating to environmental conditions, such as outside temperature, lighting conditions (e.g., day, night, dusk, and/or dawn), humidity level, specific weather conditions (e.g., sun, rain, and/or snow), distance (e.g., laser rangefinder), and/or whether a tunnel, a covered dock, or that some type of enclosure has been entered or exited. Optional sensing component160may represent conventional sensors as would be known by one skilled in the art for monitoring various conditions (e.g., environmental conditions) that may have an affect (e.g., on the image appearance) on the data provided by image capture component130.

In some embodiments, optional sensing component160(e.g., one or more of sensors106) may comprise devices that relay information to processing component110via wireless communication. For example, sensing component160may be adapted to receive information from a satellite, through a local broadcast (e.g., radio frequency) transmission, through a mobile or cellular network and/or through information beacons in an infrastructure (e.g., a transportation or highway information beacon infrastructure) or various other wired or wireless techniques.

In various embodiments, components of image capturing system100may be combined and/or implemented or not, as desired or depending upon the application or requirements, with image capturing system100representing various functional blocks of a system. For example, processing component110may be combined with memory component120, image capture component130, display component140and/or sensing component160. In another example, processing component110may be combined with image capture component130with only certain functions of processing component110performed by circuitry (e.g., a processor, a microprocessor, a microcontroller, a logic device, etc.) within image capture component130. In still another example, control component150may be combined with one or more other components or be remotely connected to at least one other component, such as processing component110, via a control wire to as to provide control signals thereto.

FIG. 2shows a method200for capturing and processing infrared images in accordance with an embodiment of the present disclosure. For purposes of simplifying discussion ofFIG. 2, reference may be made to image capturing system100ofFIG. 1as an example of a system, device or apparatus that may perform method200.

Referring toFIG. 2, an image (e.g., infrared image signal) is captured (block210) with infrared imaging system100. In one implementation, processing component110induces (e.g., causes) image capture component130to capture an image, such as, for example, image170. After receiving the captured image from image capture component130, processing component110may optionally store the captured image in memory component120for processing.

Next, the captured image may optionally be pre-processed (block215). In one implementation, pre-processing may include obtaining infrared sensor data related to the captured image, applying correction terms, and/or applying temporal noise reduction to improve image quality prior to further processing. In another implementation, processing component110may directly pre-process the captured image or optionally retrieve the captured image stored in memory component120and then pre-process the image. Pre-processed images may be optionally stored in memory component120for further processing.

Next, a selected mode of operation may be obtained (block220). In one implementation, the selected mode of operation may comprise a user input control signal that may be obtained or received from control component150(e.g., control panel unit500ofFIG. 5). In various implementations, the selected mode of operation may be selected from at least one of night docking, man overboard, night cruising, day cruising, hazy conditions, and shoreline mode. As such, processing component110may communicate with control component150to obtain the selected mode of operation as input by a user. These modes of operation are described in greater detail herein and may include the use of one or more infrared image processing algorithms.

In various implementations, modes of operation refer to preset processing and display functions for an infrared image, and infrared imagers and infrared cameras are adapted to process infrared sensor data prior to displaying the data to a user. In general, display algorithms attempt to present the scene (i.e., field of view) information in an effective way to the user. In some cases, infrared image processing algorithms are utilized to present a good image under a variety of conditions, and the infrared image processing algorithms provide the user with one or more options to tune parameters and run the camera in “manual mode”. In one aspect, infrared imaging system100may be simplified by hiding advanced manual settings. In another aspect, the concept of preset image processing for different conditions may be implemented in maritime applications.

Next, referring toFIG. 2, the image is processed in accordance with the selected mode of operation (block225), in a manner as described in greater detail herein. In one implementation, processing component110may store the processed image in memory component120for displaying. In another implementation, processing component110may retrieve the processed image stored in memory component120and display the processed image on display component150for viewing by a user.

Next, a determination is made as to whether to display the processed image in a night mode (block230), in a manner as described in greater detail herein. If yes, then processing component110configures display component140to apply a night color palette to the processed image (block235), and the processed image is displayed in night mode (block240). For example, in night mode (e.g., for night docking, night cruising, or other modes when operating at night), an image may be displayed in a red palette or green palette to improve night vision capacity for a user. Otherwise, if night mode is not necessary, then the processed image is displayed in a non-night mode manner (e.g., black hot or white hot palette) (block240).

In various implementations, the night mode of displaying images refers to using a red color palette or green color palette to assist the user or operator in the dark when adjusting to low light conditions. During night operation of image capturing system100, human visual capacity to see in the dark may be impaired by the blinding effect of a bright image on a display monitor. Hence, the night mode setting changes the color palette from a standard black hot or white hot palette to a red or green color palette display. In one aspect, the red or green color palette is generally known to interfere less with human night vision capacity. In one example, for a red-green-blue (RGB) type of display, the green and blue pixels may be disabled to boost the red color for a red color palette. In another implementation, the night mode display may be combined with any other mode of operation of infrared imaging system100, as described herein, and a default display mode of infrared imaging system100at night may be the night mode display.

Furthermore in various implementations, certain image features may be appropriately marked (e.g., color-indicated or colorized, highlighted, or identified with other indicia), such as during the image processing (block225) or displaying of the processed image (block240), to aid a user to identify these features while viewing the displayed image. For example, as discussed further herein, during a man overboard mode, a suspected person (e.g., or other warm-bodied animal or object) may be indicated in the displayed image with a blue color (or other color or type of marking) relative to the black and white palette or night color palette (e.g., red palette). As another example, as discussed further herein, during a night time or daytime cruising mode and/or hazy conditions mode, potential hazards in the water may be indicated in the displayed image with a yellow color (or other color or type of marking) to aid a user viewing the display. Further details regarding image colorization may be found, for example, in U.S. Pat. No. 6,849,849, which is incorporated herein by reference in its entirety.

In various implementations, processing component110may switch the processing mode of a captured image in real time and change the displayed processed image from one mode, corresponding to mode modules112A-112N, to a different mode upon receiving user input from control component150. As such, processing component110may switch a current mode of display to a different mode of display for viewing the processed image by the user or operator on display component140. This switching may be referred to as applying the infrared camera processing techniques of mode modules112A-112N for real time applications, wherein a user or operator may change the displayed mode while viewing an image on display component140based on user input to control component150.

FIGS. 3A-3Eshow block diagrams illustrating infrared processing techniques in accordance with various embodiments of the present disclosure. As described herein, infrared imaging system100is adapted to switch between different modes of operation so as to improve the infrared images and information provided to a user or operator.

FIG. 3Ashows one embodiment of an infrared processing technique300as described in reference to block225ofFIG. 2. In one implementation, the infrared processing technique300comprises a night docking mode of operation for maritime applications. For example, during night docking, a watercraft or sea vessel is in the vicinity of a harbor, jetty or marina, which have proximate structures including piers, buoys, other watercraft, other structures on land. A thermal infrared imager (e.g., infrared imaging system100) may be used as a navigational tool in finding a correct docking spot. The infrared imaging system100produces an infrared image that assists the user or operator in docking the watercraft. There is a high likelihood of hotspots in the image, such as dock lights, vents and running motors, which may have a minimal impact on how the scene is displayed.

Referring toFIG. 3A, the input image is histogram equalized and scaled (e.g., 0-511) to form a histogram equalized part (block302). Next, the input image is linearly scaled (e.g., 0-128) while saturating the highest and lowest (e.g., 1%) to form a linearly scaled part (block304). Next, the histogram-equalized part and the linearly scaled part are added together to form an output image (block306). Next, the dynamic range of the output image is linearly mapped to fit the display component140(block308). It should be appreciated that the block order in which the process300is executed may be executed in an different order without departing from the scope of the present disclosure.

In one embodiment, the night docking mode is intended for image settings with large amounts of thermal clutter, such as a harbor, a port, or an anchorage. The settings may allow the user to view the scene without blooming on hot objects. Hence, infrared processing technique300for the night docking mode is useful for situational awareness in maritime applications when, for example, docking a watercraft with low visibility.

In various implementations, during processing of an image when the night docking mode is selected, the image is histogram equalized to compress the dynamic range by removing “holes” in the histogram. The histogram may be plateau limited so that large uniform areas, such as sky or water components, are not given too much contrast. For example, approximately 20% of the dynamic range of the output image may be preserved for a straight linear mapping of the non-histogram equalized image. In the linear mapping, for example, the lowest 1% of the pixel values are mapped to zero and the highest 1% of the input pixels are mapped to a maximum value of the display range (e.g., 235). In one aspect, the final output image becomes a weighted sum of the histogram equalized and linearly (with 1% “outlier” cropping) mapped images.

FIG. 3Bshows one embodiment of an infrared processing technique320as described in reference to block225ofFIG. 2. In one implementation, the infrared processing technique320comprises a man overboard mode of operation for maritime applications. For example, in the man overboard mode, image capturing system100may be tuned to the specific task of finding a person in the water. The distance between the person in the water and the watercraft may not be known, and the person may be only a few pixels in diameter or significantly larger if lying close to the watercraft. In one aspect, even t a person may be close to the watercraft, the person may have enough thermal signature to be clearly visible, and thus the man overboard display mode may target the case where the person has weak thermal contrast and is far enough away so as to not be clearly visible without the aid of image capturing system100.

Referring toFIG. 3B, image capture component130(e.g., infrared camera) of image capturing system100is positioned to resolve or identify the horizon (block322). In one implementation, the infrared camera is moved so that the horizon is at an upper part of the field of view (FoV). In another implementation, the shoreline may also be indicated along with the horizon. Next, a high pass filter (HPF) is applied to the image to form an output image (block324). Next, the dynamic range of the output image is linearly mapped to fit the display component140(block326). It should be appreciated that the block order in which the process320is executed may be executed in an different order without departing from the scope of the present disclosure.

In one example, horizon identification may include shoreline identification, and the horizon and/or shoreline may be indicated by a line (e.g., a red line or other indicia) superimposed on a thermal image along the horizon and/or the shoreline, which may be useful for user or operators to determine position of the watercraft in relation to the shoreline. Horizon and/or shoreline identification may be accomplished by utilizing a real-time Hough transform or other equivalent type of transform applied to the image stream, wherein this image processing transform finds linear regions (e.g., lines) in an image. The real-time Hough transform may also be used to find the horizon and/or shoreline in open ocean when, for example, the contrast may be low. Under clear conditions, the horizon and/or shoreline may be easy identified. However, on a hazy day, the horizon and/or shoreline may be difficult to locate.

In general, knowing where the horizon and/or shoreline are is useful for situational awareness. As such, in various implementations, the Hough transform may be allied to any of the modes of operation described herein to identify the horizon and/or shoreline in an image. For example, the shoreline identification (e.g., horizon and/or shoreline) may be included along with any of the processing modes to provide a line (e.g., any type of marker, such as a red line or other indicia) on the displayed image and/or the information may be used to position the infrared camera's field of view.

In one embodiment of the man overboard mode, signal gain may be increased to bring out minute temperature differences of the ocean, such as encountered when looking for a hypothermic body in a uniform ocean temperature that may be close to the person's body temperature. Image quality is traded for the ability to detect small temperature changes when comparing a human body to ocean temperature. Thus, infrared processing technique320for the man overboard mode is useful for situational awareness in maritime applications when, for example, searching for a man overboard proximate to the watercraft.

In various implementations, during processing of an image when the man overboard mode is selected, a high pass filter is applied to the image. For example, the signal from the convolution of the image by a Gaussian kernel may be subtracted. The remaining high pass information is linearly stretched to fit the display range, which may increase the contrast of any small object in the water. In one enhancement of the man overboard mode, objects in the water may be marked, and the system signals the watercraft to direct a searchlight at the object. For systems with both visible and thermal imagers, the thermal imager is displayed. For zoom or multi-FoV systems, the system is set in a wide FoV. For pan-tilt controlled systems with stored elevation settings for the horizon, the system is moved so that the horizon is visible just below the upper limit of the field of view.

In one embodiment, the man overboard mode may activate a locate procedure to identify an area of interest, zoom-in on the area of interest, and position a searchlight on the area of interest. For example, the man overboard mode may activate a locate procedure to identify a position of a object (e.g., a person) in the water, zoom-in the infrared imaging device (e.g., an infrared camera) on the identified object in the water, and then point a searchlight on the identified object in the water. In various implementations, these actions may be added to process200ofFIG. 2and/or process320ofFIG. 3Band further be adapted to occur automatically so that the area of interest and/or location of the object of interest may be quickly identified and retrieved by a crew member.

FIG. 3Cshows one embodiment of an infrared processing technique340as described in reference to block225ofFIG. 2. In one implementation, the infrared processing technique340comprises a night cruising mode of operation for maritime applications. For example, during night cruising, the visible channel has limited use for other than artificially illuminated objects, such as other watercraft. The thermal infrared imager may be used to penetrate the darkness and assist in the identification of buoys, rocks, other watercraft, islands and structures on shore. The thermal infrared imager may also find semi-submerged obstacles that potentially lie directly in the course of the watercraft. In the night cruising mode, the display algorithm may be tuned to find objects in the water without distorting the scene (i.e., field of view) to the extent that it becomes useless for navigation.

In one embodiment, the night cruising mode is intended for low contrast situations encountered on an open ocean. The scene (i.e., field of view) may be filled with a uniform temperature ocean, and any navigational aids or floating debris may sharply contrast with the uniform temperature of the ocean. Therefore, infrared processing technique340for the night cruising mode is useful for situational awareness in, for example, open ocean.

Referring toFIG. 3C, the image is separated into a background image part and a detailed image part (block342). Next, the background image part is histogram equalized (block344) and scaled (e.g., 0-450) (block346). Next, the detailed image part is scaled (e.g., 0-511) (block348). Next, the histogram-equalized background image part and the scaled detailed image part are added together to form an output image (block350). Next, the dynamic range of the output image is linearly mapped to fit the display component140(block352). It should be appreciated that the block order in which the process340is executed may be executed in an different order without departing from the scope of the present disclosure.

In various implementations, during processing of an image when the night cruising mode is selected, the input image is split into detailed and background image components using a non-linear edge preserving low pass filter (LPF), such as a median filter or by anisotropic diffusion. The background image component comprises a low pass component, and the detailed image part is extracted by subtracting the background image part from the input image. To enhance the contrast of small and potentially weak objects, the detailed and background image components may be scaled so that the details are given approximately 60% of the output/display dynamic range. In one enhancement of the night cruising mode, objects in the water are tracked, and if they are on direct collision course as the current watercraft course, they are marked in the image, and an audible alarm may be sounded. For systems with both visible and thermal imager, the thermal imager may be displayed by default.

In one embodiment, a first part of the image signal may include a background image part comprising a low spatial frequency high amplitude portion of an image. In one example, a low pass filter (e.g., low pass filter algorithm) may be utilized to isolate the low spatial frequency high amplitude portion of the image signal (e.g., infrared image signal). In another embodiment, a second part of the image signal may include a detailed image part comprising a high spatial frequency low amplitude portion of an image. In one example, a high pass filter (e.g., high pass filter algorithm) may be utilized to isolate the high spatial frequency low amplitude portion of the image signal (e.g., infrared image signal). Alternately, the second part may be derived from the image signal and the first part of the image signal, such as by subtracting the first part from the image signal.

In general for example, the two image parts (e.g., first and second parts) of the image signal may be separately scaled before merging the two image parts to produce an output image. For example, the first or second parts may be scaled or both the first and second parts may be scaled. In one aspect, this may allow the system to output an image where fine details are visible and tunable even in a high dynamic range scene. In some instances, as an example, if an image appears less useful or degraded by some degree due to noise, then one of the parts of the image, such as the detailed part, may be suppressed rather than amplified to suppress the noise in the merged image to improve image quality.

FIG. 3Dshows one embodiment of an infrared processing technique360as described in reference to block225ofFIG. 2. In one implementation, the infrared processing technique360comprises a day cruising mode of operation for maritime applications. For example, during day cruising, the user or operator may rely on human vision for orientation immediately around the watercraft. Image capturing system100may be used to zoom in on objects of interest, which may involve reading the names of other watercraft, and searching for buoys, structures on land, etc.

Referring toFIG. 3D, the image is separated into a background image part and a detailed image part (block362). Next, the background image part is histogram equalized (block364) and scaled (e.g., 0-511) (block366). Next, the detailed image part is scaled0-255(block368). Next, the histogram-equalized background image part and the scaled detailed image part are added together to form an output image (block370). Next, the dynamic range of the output image is linearly mapped to fit the display component140(block372). It should be appreciated that the block order in which the process360is executed may be executed in an different order without departing from the scope of the present disclosure.

In one embodiment, the day cruising mode is intended for higher contrast situations, such as when solar heating leads to greater temperature differences between unsubmerged or partially submerged objects and the ocean temperature. Hence, infrared processing technique360for the day cruising mode is useful for situational awareness in, for example, high contrast situations in maritime applications.

In various implementations, during processing of an image when the day cruising mode is selected, the input image is split into its detailed and background components respectively using a non-linear edge preserving low pass filter, such as a median filter or by anisotropic diffusion. For color images, this operation may be achieved on the intensity part of the image (e.g., Y in a YCrCb format). The background image part comprises the low pass component, and the detailed image part may be extracted by subtracting the background image part from the input image. To enhance the contrast of small and potentially weak objects, the detailed and background image parts may be scaled so that the details are given approximately 35% of the output/display dynamic range. For systems with both visible and thermal imagers the visible image may be displayed by default.

FIG. 3Eshows one embodiment of an infrared processing technique380as described in reference to block225ofFIG. 2. In one implementation, the infrared processing technique380comprises a hazy conditions mode of operation for maritime applications. For example, even during daytime operation, a user or operator may achieve better performance from an imager using an infrared (MWIR, LWIR) or near infrared (NIR) wave band. Depending on vapor content and particle size, a thermal infrared imager may significantly improve visibility under hazy conditions. If neither the visible nor the thermal imagers penetrate the haze, image capturing system100may be set in hazy conditions mode under which system100attempts to extract what little information is available from the chosen infrared sensor. Under hazy conditions, there may be little high spatial frequency information (e.g., mainly due, in one aspect, to scattering by particles). The information in the image may be obtained from the low frequency part of the image, and boosting the higher frequencies may drown the image in noise (e.g., temporal and/or fixed pattern).

Referring toFIG. 3E, a non-linear edge preserving low pass filter (LPF) is applied to the image (block382). Next, the image is histogram equalized (block384) and scaled (block386) to form a histogram equalized output image. Next, the dynamic range of the output image is linearly mapped to fit the display component140(block388). It should be appreciated that the block order in which the process380is executed may be executed in an different order without departing from the scope of the present disclosure.

In various implementations, during processing of an image when the hazy conditions mode is selected, a non-linear, edge preserving, low pass filter, such as median or by anisotropic diffusion is applied to the image (i.e., either from the thermal imager or the intensity component of the visible color image). In one aspect, the output from the low pass filter operation may be histogram equalized and scaled to map the dynamic range to the display and to maximize contrast of the display.

FIG. 3Fshows one embodiment of an infrared processing technique390as described in reference to block225ofFIG. 2. In one implementation, the infrared processing technique390comprises a shoreline mode of operation for maritime applications.

Referring toFIG. 3F, the shoreline may be resolved (block392). For example as discussed previously, shoreline identification (e.g., horizon and/or shoreline) may be determined by applying an image processing transform (e.g., a Hough transform) to the image (block392), which may be used to position the infrared camera's field of view and/or to provide a line (e.g., any type of marker, such as a red line(s) or other indicia on the displayed image. Next, the image is histogram equalized (block394) and scaled (block396) to form an output image. Next, the dynamic range of the output image is linearly mapped to fit the display component140(block398). It should be appreciated that the block order in which the process390is executed may be executed in a different order without departing from the scope of the present disclosure.

In one implementation, the information produced by the transform (e.g., Hough transform) may be used to identify the shoreline or even the horizon as a linear region for display. The transform may be applied to the image in a path separate from the main video path (e.g., the transform when applied does not alter the image data and does not affect the later image processing operations), and the application of the transform may be used to detect linear regions, such as straight lines (e.g., of the shoreline and/or horizon). In one aspect, by assuming the shoreline and/or horizon comprises a straight line stretching the entire width of the frame, the shoreline and/or horizon may be identified as a peak in the transform and may be used to maintain the field of view in a position with reference to the shoreline and/or horizon. As such, the input image (e.g., preprocessed image) may be histogram equalized (block394) and scaled (block396) to generate an output image, and then the transform information (block392) may be added to the output image to highlight the shoreline and/or horizon of the displayed image.

Moreover, in the shoreline mode of operation, the image may be dominated by sea (i.e., lower part of image) and sky (i.e., upper part of image), which may appear as two peaks in the image histogram. In one aspect, significant contrast is desired over the narrow band of shoreline, and a low number (e.g., relatively based on the number of sensor pixels and the number of bins used in the histogram) may be selected for the plateau limit for the histogram equalization. In one aspect, for example, a low plateau limit (relative) may reduce the effect of peaks in the histogram and give less contrast to sea and sky while preserving contrast for the shoreline and/or horizon regions.

FIG. 4shows a block diagram illustrating a method400of implementing modes410A-410E and infrared processing techniques related thereto, as described in reference to various embodiments of the present disclosure. In particular, a first mode refers to night docking mode410A, a second mode refers to man overboard mode410B, a third mode refers to night cruising mode410C, a fourth mode refers to day cruising mode410D, and a fifth mode refers to hazy conditions mode410E.

In one implementation, referring toFIG. 4, processing component110of image capturing system100ofFIG. 1may perform method400as follows. Sensor data (i.e., infrared image data) of a captured image is received or obtained (block402). Correction terms are applied to the received sensor data (block404), and temporal noise reduction is applied to the received sensor data (block406).

Next, at least one of the selected modes410A-410E may be selected by a user or operator via control component150of image capturing system100, and processing component110executes the corresponding processing technique associated with the selected mode of operation. In one example, if night docking mode410A is selected, then the sensor data may be histogram equalized and scaled (e.g., 0-511) (block420), the sensor data may be linearly scaled (e.g., 0-128) saturating the highest and lowest (e.g., 1%) (block422), and the histogram equalized sensor data is added to the linearly scaled sensor data for linearly mapping the dynamic range to display component140(block424). In another example, if man overboard mode410B is selected, then infrared capturing component130of image capturing system100may be moved or positioned so that the horizon is at an upper part of the field of view (FoV), a high pass filter (HPF) is applied to the sensor data (block432), and the dynamic range of the high pass filtered sensor data is then linearly mapped to fit display component140(block434). In another example, if night cruising mode410C is selected, the sensor data is processed to extract a faint detailed part and a background part with a high pass filter (block440), the background part is histogram equalized and scaled (e.g., 0-450) (block442), the detailed part is scaled (e.g., 0-511) (block444), and the background part is added to the detailed part for linearly mapping the dynamic range to display component140(block446). In another example, if day cruising mode410D is selected, the sensor data is processed to extract a faint detailed part and a background part with a high pass filter (block450), the background part is histogram equalized and scaled (e.g., 0-511) (block452), the detailed part is scaled0-255(block454), and the background part is added to the detailed part for linearly mapping the dynamic range to display component140(block456). In still another example, if hazy condition mode410E is selected, then a non-linear low pass filter (e.g., median) is applied to the sensor data (block460), which is then histogram equalized and scaled for linearly mapping the dynamic range to display component140(block462).

For any of the modes (e.g., blocks410A-410E), the image data for display may be marked (e.g., color coded, highlighted, or otherwise identified with indicia) to identify, for example, a suspected person in the water (e.g., for man overboard) or a hazard in the water (e.g., for night time cruising, day time cruising, or any of the other modes). For example, as discussed herein, image processing algorithms may be applied (block470) to the image data to identify various features (e.g., objects, such as a warm-bodied person, water hazard, horizon, or shoreline) in the image data and appropriately mark these features to assist in recognition and identification by a user viewing the display. As a specific example, a suspected person in the water may be colored blue, while a water hazard (e.g., floating debris) may be colored yellow in the displayed image.

Furthermore for any of the modes (e.g., blocks410A-410E), the image data for display may be marked to identify, for example, the shoreline (e.g., shoreline and/or horizon). For example, as discussed herein, image processing algorithms may be applied (block475) to the image data to identify the shoreline and/or horizon and appropriately mark these features to assist in recognition and identification by a user viewing the display. As a specific example, the horizon and/or shoreline may be outlined or identified with red lines on the displayed image to aid the user viewing the displayed image.

Next, after applying at least one of the infrared processing techniques for modes410A-410E, a determination is made as to whether to display the processed sensor data in night mode (i.e., apply the night color palette) (block480), in a manner as previously described. If yes, then the night color palette is applied to the processed sensor data (block482), and the processed sensor data is displayed in night mode (block484). If no, then the processed sensor data is displayed in a non-night mode manner (e.g., black hot or white hot palette) (block484). It should be appreciated that, in night mode, sensor data (i.e., image data) may be displayed in a red or green color palette to improve night vision capacity for a user or operator.

FIG. 5shows a block diagram illustrating one embodiment of control component150of infrared imaging system100for selecting between different modes of operation, as previously described in reference toFIGS. 2-4. In one embodiment, control component150of infrared imaging system100may comprise a user input and/or interface device, such as control panel unit500(e.g., a wired or wireless handheld control unit) having one or more push buttons510,520,530,540,550,560,570adapted to interface with a user and receive user input control values and further adapted to generate and transmit one or more input control signals to processing component100. In various other embodiments, control panel unit500may comprise a slide bar, rotatable knob to select the desired mode, keyboard, etc., without departing from the scope of the present disclosure.

In various implementations, a plurality of push buttons510,520,530,540,550,560,570of control panel unit500may be utilized to select between various modes of operation as previously described in reference toFIGS. 2-4. In various implementations, processing component110may be adapted to sense control input signals from control panel unit500and respond to any sensed control input signals received from push buttons510,520,530,540,550,560,570. Processing component110may be further adapted to interpret the control input signals as values. In various other implementations, it should be appreciated that control panel unit500may be adapted to include one or more other push buttons (not shown) to provide various other control functions of infrared imaging system100, such as auto-focus, menu enable and selection, field of view (FoV), brightness, contrast, and/or various other features. In another embodiment, control panel unit500may comprise a single push button, which may be used to select each of the modes of operation510,520,530,540,550,560,570.

In another embodiment, control panel unit500may be adapted to be integrated as part of display component140to function as both a user input device and a display device, such as, for example, a user activated touch screen device adapted to receive input signals from a user touching different parts of the display screen. As such, the GUI interface device may have one or more images of, for example, push buttons510,520,530,540,550,560,570adapted to interface with a user and receive user input control values via the touch screen of display component140.

In one embodiment, referring toFIG. 5, a first push button510may be enabled to select the night docking mode of operation, a second push button520may be enabled to select the man overboard mode of operation, a third push button530may be enabled to select the night cruising mode of operation, a fourth push button540may be enabled to select the day cruising mode of operation, a fifth push button550may be enabled to select the hazy conditions mode of operation, a sixth push button560may be enabled to select the shoreline mode of operation, and a seventh push button570may be enabled to select or turn the night display mode (i.e., night color palette) off. In another embodiment, a single push button for control panel unit500may be used to toggle t each of the modes of operation510,520,530,540,550,560,570without departing from the scope of the present disclosure.

Where applicable, various embodiments of the invention may be implemented using hardware, software, or various combinations of hardware and software. Where applicable, various hardware components and/or software components set forth herein may be combined into composite components comprising software, hardware, and/or both without departing from the scope and functionality of the present disclosure. Where applicable, various hardware components and/or software components set forth herein may be separated into subcomponents having software, hardware, and/or both without departing from the scope and functionality of the present disclosure. Where applicable, it is contemplated that software components may be implemented as hardware components and vice-versa.

In various embodiments, software for mode modules112A-112N may be embedded (i.e., hard-coded) in processing component110or stored on memory component120for access and execution by processing component110. As previously described, the code (i.e., software and/or hardware) for mode modules112A-112N define, in one embodiment, preset display functions that allow processing component100to switch between the one or more processing techniques, as described in reference toFIGS. 2-4, for displaying captured and/or processed infrared images on display component140.

Embodiments described above illustrate but do not limit the disclosure. It should also be understood that numerous modifications and variations are possible in accordance with the principles of the present disclosure. Accordingly, the scope of the disclosure is defined only by the following claims.