Patent Publication Number: US-9405981-B2

Title: Optimizing the detection of objects in images

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of and claims priority from U.S. patent application Ser. No. 13/277,936 filed on Oct. 20, 2011, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to the detection of objects in digital images, and more particularly relates to optimizing the detection of objects in digital images using camera sensors deployed in a human assistive environment. 
     BACKGROUND OF THE INVENTION 
     Digital image based object detection, especially with respect to traffic sign recognition (TSR), has seen increased attention over the past few years. For example, object detection systems are currently being implemented in advanced driver assistance systems (ADAS). Conventional object detection methods usually involve two stages. First, in the detection stage, image regions that contain candidates of target objects are detected or localized. Then, in the recognition stage, such regions are further analyzed to recognize the specific content. However, these conventional object detection systems and methods generally require a large amount of computing resources, have slow detection speeds, and can be inaccurate. 
     SUMMARY OF THE INVENTION 
     In one embodiment, a method for detecting objects in a digital image is disclosed. The method comprises receiving at least positional data associated with a vehicle. Geographical information associated with the positional data is received. A probability of detecting a target object within a corresponding geographic area associated with the vehicle is determined based on the geographical data. The probability is compared to a given threshold. An object detection process is at least one of activated and maintained in an activated state in response to the probability being one of above and equal to the given threshold. The object detection process detects objects of interest within at least one image representing at least one frame of a video sequence of an external environment. 
     In another embodiment, another method for detecting objects in a digital image is disclosed. The method comprises receiving at least one image representing at least one frame of a video sequence of an external environment of a vehicle. A set of environmental conditions associated with a geographic area corresponding to a location of the vehicle is identified. An illumination model is selected based on the set of environmental factors. The at least one image is processed with respect to the illumination mode. 
     In yet another embodiment, an information processing system for detecting objects in a digital image is disclosed. The information processing system comprises a memory and a processor that is communicatively coupled to the memory. The information processing system also comprises an object detection system that is communicatively coupled to the memory and the processor. The object detection system is configured to perform a method. The method comprises receiving at least positional data associated with a vehicle is received. Geographical information associated with the positional data is received. A probability of detecting an object of interest within a corresponding geographic area associated with the vehicle is determined based on the geographical data. The probability is compared to a given threshold. An object detection process is at least one of activated and maintained in an activated state in response to the probability being one of above and equal to the given threshold. The object detection process detects objects of interest within at least one image representing at least one frame of a video sequence of an external environment. 
     In a further embodiment, a computer program product for detecting objects in a digital image is disclosed. The computer program product comprises a storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method. The method comprises receiving at least positional data associated with a vehicle is received. Geographical information associated with the positional data is received. A probability of detecting a target object within a corresponding geographic area associated with the vehicle is determined based on the geographical data. The probability is compared to a given threshold. An object detection process is at least one of activated and maintained in an activated state in response to the probability being one of above and equal to the given threshold. The object detection process detects objects of interest within at least one image representing at least one frame of a video sequence of an external environment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying figures where like reference numerals refer to identical or functionally similar elements throughout the separate views, and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention, in which: 
         FIG. 1  is a block diagram illustrating a high level overview of a system for detecting objects in digital images according to one embodiment of the present invention; 
         FIG. 2  is a transactional diagram illustrating a multi-stage operating mode of the system in  FIG. 1  according to one embodiment of the present invention; 
         FIG. 3  is an operational flow diagram illustrating one example of a process for activating/deactivating one or more components of the system in  FIG. 1  according to one embodiment of the present invention; 
         FIG. 4  is an operational flow diagram illustrating one process optimizing an object detection process performed by the system of  FIG. 1  according to one embodiment of the present invention; and 
         FIG. 5  is a block diagram illustrating a more detailed view of an information processing system according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely examples of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure and function. Further, the terms and phrases used herein are not intended to be limiting; but rather, to provide an understandable description of the invention. 
     The terms “a” or “an”, as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and/or having, as used herein, are defined as comprising (i.e., open language). The term coupled, as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically. 
     Operating Environment 
     According to one embodiment,  FIG. 1  illustrates a general overview of one operating environment  100  for detecting objects in one or more frames/images. In particular,  FIG. 1  shows an information processing system  102  that can be implemented within a vehicle such as an automobile, motorcycle, watercraft, and the like. Additionally, the system  102  can be communicatively coupled to a user assisted training environment for training purposes. The system  102  includes, among other things, an object detection system (ODS)  104 , one or more imaging systems  106 , and one or more global positioning systems (GPS)  108 . The system  102  also comprises an image database  110 , GPS data  112 , a geographic information database  114 , an illumination model database  116 , an appearance model database  118 , and an object template database  120 . 
     The image database  110  comprises one or more frames/images  122 . The frames/images  122 , in one embodiment, represent frames of a video sequence (or still photo sequence) of an external environment captured by one or more imaging devices (e.g., cameras) of the imaging system  106 . Two or more of these imaging devices can have overlapping field of views. The geographic information database  114  comprises geographic information  124  such as, but not limited to, maps and mapping information, points-of-interests and associated information (e.g., addresses, phone numbers, etc.), and any other information that can be utilized in a mapping or navigational environment. 
     The appearance model database  118  comprises appearance models  126  for various environmental factors such as, but not limited to, weather conditions (e.g., sunny, cloudy, overcast, raining, snowing, snow cover, etc.), seasons (e.g., winter, spring, summer, fall), time of day (e.g., morning, afternoon, dusk, night), and the like. These appearance models  126  model how a given object appears as a result of the above environmental factors. For example, an object can appear or be perceived differently between day time and night time. Objects can appear or be perceived differently based on the angle of view as well. The appearance models  126  allow the ODS  104  to account/compensate for this variability in appearance/perception. 
     The illumination model database  116  comprises illumination modes  128  such as illumination specific models, illumination invariant models, and synthesized illumination models that are utilized by the ODS  104  to compensate for current illumination conditions (e.g., lighting and reflection conditions) of the external environment. Each of these illumination model types are discussed in greater detail below. The object template database  120  comprises a plurality of object templates  130  that are utilized by the ODS  104  when detecting a target object within the frames/images  122 . In one embodiment, the object database  120  comprises object templates for each type of object that is detectable by the ODS  104 , such as (but not limited to) street signs, traffic signs, stop lights, road markings, addresses, business/building signs, billboards, buildings, businesses, headlights, road hazards, cars, pedestrians, animals, etc. 
     An object template  130  can be one or more actual images associated with a detectable object. For example, if one type of object detectable by the ODS  104  is a gas station sign, an object template  130  can be an actual image of a gas station sign for a given gas station of interest. A given gas station can be associated with multiple different gas station signs. Therefore, images of each of these different signs can be included in the object database  120  as a single object template or as separate object templates. Also, images of the detectable object at various angles, lighting conditions, and environmental conditions can also be stored as a template(s). This allows for a more robust detection process to be performed by the ODS  104 . However, in another embodiment, a minimal number of images are used as object templates for each detectable object/object type. In this embodiment, the appearance models  126  and/or illumination models  128  can be applied to the object templates to account/compensate for various angles, lighting conditions, and environmental conditions under which an object may be captured by the imaging system  106 . This allows the ODS  104  to maintain/retrieve fewer object templates  130  (and associated images), thereby saving storage space and processing resources while still providing a robust and accurate object detection process. In addition to (or in replacement of) images of a detectable object, an object template  130  can comprise information that has been extrapolated from an image of a given object of interest. This allows the information representing an image to be stored as compared to the image itself, thereby saving storage space. 
     It should be noted that each of the above databases and their components are discussed in greater detail below. It should also be noted that one or more of the geographic information database  114 , the appearance model database  118 , the illumination model database  116 , and the object database  120  can reside on a remote system (not shown) that is communicatively coupled to the system  102  via one or more networks (not shown). The data from one or more of these databases can be transmitted to the system  102  as needed, thereby reducing the storage space required by the system  102 . 
     The ODS  104 , in one embodiment, comprises a GPS data processor  132 , a geographical information processor  134 , an environment processor  136 , an object appearance processor  137 , an illumination processor  138 , and an object detector  140 . It should be noted that one or more of these components can reside outside of the ODS  104 . It should also be noted that the functions of one or more of these components can be combined into a single component as well. The GPS data processor  132  processes/analyzes the GPS data  112  provided by the GPS system  108 . For example, the GPS data processor  132  can analyze the GPS  112  data to determine information such as (but not limited to), the current time, vehicle velocity, vehicle direction, location of the vehicle, vehicle elevation, etc. The geographical information processor  134  utilizes the GPS data  112  to identify geographic information  124  associated with the vehicle&#39;s current position/location and surrounding area. For example, based on location information within the GPS data  112  the geographical information processor  134  identifies a map within the geographic information database  114  that corresponds to the location information of the GPS data  112 . 
     The environment processor  136  determines a current context of the environment in which the vehicle is travelling. For example, the environment processor  136  can determine the type of geographic area that the vehicle is located within such as a rural area or an urban area. The environment processor  136  can further determine a more granular context such as whether the current area is a wooded area, a mountainous area, a desert area, an industrial area, a downtown of a city, a suburb, etc. The ODS  104  uses this environmental/geographical context information to determine the probability that a target object is within the current area of the vehicle. 
     The environment processor  136  can also determine environmental factor/condition information such as current weather conditions (e.g., sunny, cloudy, overcast, raining, snowing, snow cover, foggy, etc.), seasons (e.g., winter, spring, summer fall), time of day (e.g., morning, afternoon, dusk, night). In one embodiment, time-of-day information can also include average lighting/illumination information associated with a given area for a given time of day such as morning, afternoon, dusk, and night. The environment processor  136  can determine these factors/conditions by analyzing the frames/images  122  being captured by the imaging system  106 . Environmental factors/conditions can also be determined from weather information transmitted with the GPS data  112 . The environment processor  136  can also retrieve/receive environmental factor/condition information from one or more remote systems. In another embodiment, a user can enter the environmental factor/condition information into the ODS  104 . These types of environmental factors/conditions can be used by the ODS  104  to identify appropriate appearance models  126  and/or illumination models  128  for an object template  130  and/or the frames/images  122  captured by the imaging system  106  to optimize the object detector  104  with respect to the current environmental factors/conditions. 
     In yet another embodiment, substantially static environmental information such as season information (e.g., a calendar of seasons) and time of day information (e.g., time of sunrise, time of sunset, etc.) can be preloaded into the geographic information database  114  (or another database). Dynamic environmental information such as weather information, the current time, vehicle direct/velocity/elevation can be provided to the geographic information database  114  by one or more of the components in the system  102  such as the GPS data processor  132 , and/or by one or more remote systems that are communicatively coupled to the system  102  via one or more networks (wired and/or wireless). This dynamic information can be received/retrieved by the system  102  at given intervals and/or on demand (e.g., when the environment processor  136 , appearance processor  137 , and/or illumination processor  138  requires the environment factor/condition for a given vehicle location). 
     The appearance processor  137  first identifies the right appearance models  126  based on the environment context information determined by the environment processor  136 , and then applies such models to the right object templates  130 , so as to generate appearance-adapted object templates. Such appearance-adapted object templates are later used to identify the objects-of-interest when processing the frames/images  122  captured by the imaging system  106 . For example, the appearance processor  137  selects an appearance model  126  based on the time-of-day, season, weather conditions, etc., that has been detected by the environment processor  136  and automatically generates an adapted object template based on existing object template  130 . This new object template is then used when processing a frame/image  122 . 
     The illumination processor  138  first generates an illumination-adapted object template given an object template  130  (or an appearance-adapted object template if the appearance processor  137  is activated) by applying one of the following three illumination models: illumination specific model, illumination invariant model, and synthesized illumination model. The purpose of performing illumination adaptation, in one embodiment, is to match or normalize the object&#39;s current illumination condition with or against that of the object template  130 . This illumination-adapted object template is later used to detect objects-of-interest when processing the frames/images  122  captured by the imaging system  106 . This allows the ODS  104  to take into consideration various illumination conditions when performing the object detection process. 
     The ODS  104  further comprises one or more object detectors  140 . The object detector  140  receives input from one or more of the various components of the system  102  discussed above. The object detector  140  utilizes the information received from these components to analyze the frames/images  122  for determining whether or not the frames/images  122  comprise a target object. In one embodiment, the object detector(s)  140  is a feature-based detector(s) and/or a machine-learning-based detector(s). However, other object detectors can be used as well. A detailed discussion on feature-based detectors and machine-learning-based detectors can be found in the commonly owned and co-pending U.S. application Ser. No. 13/085,985 entitled “Object Recognition Using HAAR Features and Histograms of Oriented Gradients”, and the commonly owned and co-pending U.S. application Ser. No. 13/086,023 entitled “Detection of Objects in Digital Images”, which are both hereby incorporated by reference in their entireties. 
     Objection Detection/Recognition within Digital Frames/Images 
     The ODS  104 , in one embodiment, operates in real time to automatically detect various objects of a given desired object type/class from frames/images  122  captured by the imaging system(s)  106  utilizing GPS and geographical information. It should be noted that the various examples of target objects given throughout the following discussion are non-limiting. In other words, the ODS  104  is able to detect any type of object. For example, the ODS  104  can detect buildings, landmarks (and other structures), vehicles, headlights, pedestrians, animals, and/or the like. 
     In one embodiment, the ODS  104  performs a multi-stage (multi-mode) process. For example, in one stage the ODS  104  identifies the current environmental context of an immediate area, surrounding area, and/or future area corresponding to a vehicle&#39;s current location to determine whether or not a target object is likely to be detected within a given amount of time or distance. If a target object is likely to be detected the ODS  104  activates object detection components of the system  102 . If a target object is not likely to be detected, the object detection components of the system  102  can be deactivated. This saves power and processing resources. 
     The following is a more detailed discussion with respect to the multi-stage (multi-mode) process of the ODS  104 . This discussion is given with respect to the transactional flow of  FIG. 2 . The first operating mode of the ODS  104  operates to determine whether or not the detector  140  and its associated components should be activated or deactivated. As discussed above, the GPS system  108  receives GPS data  112 . The GPS data processor  132  analyzes this data  112 , at  202 , to determine, for example, latitude and longitude coordinates of the vehicle, direction of travel, vehicle velocity, elevation, etc. This information is then passed to the geographical information processor  134 . The geographical information processor  134  uses this information, at  204 , to identify geographic information  124  such as a map associated with the current location of the vehicle, which is determined by the GPS data processor  132 . The map can be a street map, a topographical map, a satellite map, a combination thereof, or the like. The information processor  134  can switch between each of these map types as needed. 
     The environment processor  136  analyzes, at  206 , a corresponding map to determine an environmental context of the current area, future area, and/or surrounding area of the vehicle, at  208 . For example, the environment processor  136  can determine if the vehicle is currently located within or will be travelling into a rural area, an urban area, etc. The environment processor  136  can further determine a more granular context such as whether the area is a wooded area, a mountainous area, an industrial area, a downtown of a city, a suburb, etc. In one embodiment, the environment processor  136  is able to determine this context based on detected features within the map such as forests, buildings, houses, etc. In another embodiment, a map is associated with metadata describing the various areas within the map. Based on this metadata the environment processor  136  can determine an environmental context associated therewith. The environment processor  136  can also zoom out to a larger view of the map. This allows the environment processor  136  to analyze a larger area of the map to identify upcoming environmental contexts. For example, an initial view of the map may show that the vehicle is currently travelling in a rural area, but a zoomed-out view shows that a city is a given distance away. 
     The environment processor  136  can further analyze the map to identify potential target objects or objects associated with target objects. For example, if the target object is a traffic sign, such as stop sign or a stop light, the environment processor  136  can analyze the map to determine if the current area or an upcoming area comprises any such target objects. The environment processor  136  can also determine if the map comprises items/features associated with a target object. For example, the environment processor  136  can analyze the map to determine if the map comprises an intersection, which is generally associated with a stop sign or stop light. The environment processor  136  is able to zoom into the map for a more granular/detailed view when trying to identify potential target objects. The environment processor  136  can also zoom-out to analyze a larger area. 
     Based on this determined environmental context the environment processor  136  can determine if a target object is likely to be found and either activate or deactivate the object detector  140  and associated components such as the imaging system  106 . For example, if a target object is a specific coffee shop and the environment processor  136  has determined that the vehicle is currently traveling in rural area or that the area in the map failed to comprise any buildings, the environment processor  136  determines that the probability of a target object being in this area is below (or equal to) a given threshold and deactivates (or keeps deactivated) the object detector  140 . However, if the current target object is a pedestrian and the environment processor  136  determines that the vehicle is entering a populated area then the environment processor  136  determines that the probability of a target object being in this area is above (or equal to) a given threshold and activates (or keep activated) the object detector  140 . 
     Also, the environment processor  136  can use the current scale of the map and the vehicle&#39;s current speed to estimate a given time frame until the vehicle reaches an area that is likely to comprise a target object. In this embodiment, the environment processor  136  can set a timer (or adjust an existing timer based on vehicle speed) for automatically activating the object detector  140  and its associated components. The same can be performed with respect to estimating when the vehicle will reach an area where target objects are not likely to be detected. A timer can then be set (or updated) for automatically deactivating the object detector  140  and its associated components such as the imaging system  106 , object appearance processor  137  and the illumination processor  138 . It should be noted that the above operating mode of determining whether to activate/deactivate the object detector  140  and its associated components is optional. In other words, the object detector  140  and its associated components can always be active or active only when manually activated by a user. 
     If the ODS  104  determines that the object detector  140  and its associated components should be activated (or remain activated), the ODS  104  then operates in a second operating mode for detecting target objects. Target objects and their classifications are represented in  FIG. 2  by the “Taxonomy” element  201 . It should be noted that in this mode the environmental context determined by the environment processor  136  can be passed to the object detector  140  or another component of the ODS  104 . Alternatively, the environmental context information can be stored during the first operating modes and later retrieved by the ODS  104  while operating in the second mode. 
     When the object detector  140  is in an activated state, the environment processor  136  can identify environment factor/condition information such as weather conditions (e.g., sunny, cloudy, overcast, raining, snowing, snow cover, etc.), seasons (e.g., winter, spring, summer fall), time of day (e.g., morning, afternoon, dusk, night), and the like, as shown at  210  in  FIG. 2 . It should be noted that this environment factor/condition can also be identified as part of the first operating mode discussed above as well. The object appearance processor  137  analyzes the environment factor/condition information gathered by the environment processor  136 . Based on this analysis the object appearance processor  137  selects an appearance model  126 , applies it to the target objects in the object template DB  120 , and generates appearance-adapted object templates. Such adapted object templates are used to detect objects-of-interests in the frames/images  122  captured by the imaging system  106 , at  212 . Alternatively, the appearance model  126  can be passed to the object detector  140  for performing an appearance normalization process on the frames/images  122  captured by the imaging system  106 , so that the objects&#39; appearances in the normalized frames/images match those of the objects in the object template DB  120 . As discussed above, an object can appear (or be perceived) differently within the frames/images  122  based upon the angle at which the object is viewed, the weather conditions, the current season, the time of day, illumination conditions, etc. Therefore, the appearance model  126  is used by the ODS  104  to normalize a captured frame/image  122  based on the current environment factors/conditions. This increases the accuracy of the object detector  140 . 
     In addition, the illumination processor  138  determines an illumination context associated with the area and/or surrounding area in which the vehicle is currently located and optionally a future area in which the vehicle may travel. It should be noted that the illumination context can be determined during the first mode/stage of operation discussed above. Also, the illumination context can be determined by either of the environment processor  136  and/or the illumination processor  138 . If the illumination processor  138  determines/obtains this information, the illumination processor  138  can perform the same process as described above with respect to the environment processor  136 . 
     In one embodiment, the illumination context is determined based on illumination conditions such as lighting and reflectance conditions determined by the environment processor. These lighting and reflectance conditions can vary based on vehicle direction/velocity/elevation, weather conditions, season information, time of day information, and the like. This results in the illumination/reflective characteristics of an object within a frame/image to vary depending on environmental factors. For example, a traffic sign may appear different in an image depending on whether there is snow on the ground reflecting sun light onto the sign or whether there is cloud cover. 
     The illumination context is used by the illumination processor  138  to select one or more illumination models  128  for optimizing the object detector  140  with respect to the current illumination conditions that have been detected. 
     The illumination processor  138  selects one or more illumination models  128  based on the determined illumination context. The frames/images  122 , at  214 , and/or the object templates  130 , at  216 , are then processed based on the selected illumination model(s)  128 . Alternatively, the selected illumination model(s)  128  can be passed to the object detector  140  to optimize the detection process with respect to the illumination context that has been determined. 
     One type of illumination model that can be selected is an illumination specific model. An illumination specific model is a model that has been trained for a target object with respect to a specific illumination condition such as, dawn, daytime, dusk, night time, etc. For example, a target object such as a stop sign can be associated with an illumination specific models that have been trained with respect to the stop sign in early morning lighting conditions, daytime lighting conditions, twilight lighting conditions, and night time lighting conditions. Therefore, if the current illumination context indicates that the current lighting conditions correspond to twilight lighting conditions the illumination processor  138  can select a twilight illumination model. This illumination model can then be used by the ODS  104  to adjust/optimize the object detector  140  for twilight lighting conditions. Therefore, not only is the object detector  140  optimized for specific lighting conditions, the object detector is optimized for detecting a given target object in those specific lighting conditions. 
     Another type of illumination model is an illumination invariant model. This model type allows for the object detector  140  to be adjusted/optimized for various illumination conditions without having to maintain multiple illumination specific models for each detectable object. In this embodiment, the illumination processor  138  utilizes an illumination invariant model to normalize frames/images  122  captured by two or more imaging devices with overlapping field of views. This normalization process allows the detector object  140  to perform an accurate detection process across varying illumination conditions. One advantage of the illumination invariant model is that multiple illumination specific models for an object of interest do not need to be generated and maintained, thereby saving processing and storage resources. 
     An illumination invariant model utilizes epipolar geometry to solve corresponding features/shapes within the images. See, for example, P. Fua, Y. G. Leclerc, “Object-Centered Surface Reconstruction: Combining Multi-Image Stereo and Shading”, IJCV, 1995, which is hereby incorporated by reference in its entirety. With this model brightness of the corresponding points in the multiple camera views are related to provide constraints for assessing the illumination conditions and albedo of a target object. The illumination processor  138  also performs albedo and illumination assessment for applying illumination correction to the images to obtain illumination normalized images. By taking the albedo into account, the illumination processor  138  can improve object detection performance by confirming the existence of a target object within multiple camera views. When the illumination is normalized, the illumination processor  138  can apply the illumination invariant model to frames/images under varying lighting conditions. It should be noted that if multiple cameras are not available in the imaging system  106 , quotient-image based techniques can be used to obtain a normalized model of the target objects for more accurate matching. See, for example, Nishiyama, T. Kozakaya and O. Yamaguchi, “Illumination normalization using quotient image-based techniques”, Recent advances in face recognition, 2008, which is hereby incorporated by reference in its entirety. 
     The illumination processor  138  can also select/create a synthesized illumination model. A synthesized illumination model is created from at least one illumination specific model (e.g., a daytime illumination model) and an illumination invariant model. In other words, additional illumination specific models can be generated from a single illumination specific model and an illumination invariant model. This allows for illumination specific models to be generated at any granularity level without the cost of collecting training data for each such illumination condition. 
     It should be noted that the ODS  104  is not required to utilize both the appearance models  126  and the illumination models  128 . For example, the ODS  104  can utilize only one of these model types  126 ,  128 . Once frames/images  122  and/or the object templates  130  have been processed with respect to at least one appearance model  126  and/or at least one illumination model  128  (or once these models have been passed to the object detector  140 ), the object detector  140  analyzes the frames/images  122  to determine whether or not a target object exists within the frames/images  122 . For example, in one embodiment, the object detector  140  compares the frames/images  122  to one or more corresponding processed object templates  130 . If the features identified within the frames/images  122  substantially match the features of the processed object template(s)  130  the object detector  140  determines that a target object has been identified within the frames/images  122 . The user can then be notified of the detected object or other actions can be performed. It should be noted that various object detection processes can be utilized by the object detector  140 . One example of an object detection process is discussed in U.S. patent application entitled “Object Recognition Using HAAR Features and Histograms of Oriented Gradients”, U.S. application Ser. No. 13/085,985. Another example of an object detection process is discussed in the U.S. patent application entitled “Detection of Objects in Digital Images”, U.S. application Ser. No. 13/086,023. 
     Operational Flow Diagram 
       FIG. 3  is an operational flow diagram illustrating one example of operating an object detection system in a first operating mode for activating or deactivating components of the object detection system. It should be noted that a more detailed discussion of this process was given above with respect to  FIGS. 1 and 2 . The operational flow diagram begins at step  302  and flows to step  304 . The ODS  104 , at step  304 , receives and analyzes GPS data  112 . The ODS  104 , at step  306 , obtains geographic information  124  such as, but not limited to, a map from a geographic information database  114 . 
     The ODS  104 , at step  308 , analyzes the geographic information to determine an environmental context associated with at least one of a current area, a surrounding area, and a future area in which the vehicle is currently traveling and/or will travel in the future. For example, the ODS  104  can determine if the vehicle is located within a rural area or an urban area. The ODS  104  can further determine a more granular context such as whether the current area is a wooded area, a mountainous area, an industrial area, a downtown of a city, a suburb, etc. As discussed above, the ODS  104  can also analyze the features of a map to determine if the current view of the map potentially comprises any target objects and/or features associated with a target object. 
     Based on this analysis, the ODS  104 , at step  310 , determines a probability of a target object being detected within the analyzed area of the map. The ODS  104 , at step  312 , then determines if this probability is one of above or equal to a given threshold. If the result of this determine is positive, the ODS  104 , at step  314 , activates the object detector  140  and any components required by the detector  140 . The control then flows to entry point A of  FIG. 4 . If the result of this determination is negative, the control flow returns to step  304 . 
       FIG. 4  is an operational flow diagram illustrating one example of operating an object detection system in a second operating mode in which an object detector and any required components are in an activated state. It should be noted that a more detailed discussion of this process was given above with respect to  FIGS. 1 and 2 . In this second operation mode the ODS  104 , at step  402 , determines an appearance context based on environmental factors/conditions such as, but not limited to, weather conditions (e.g., sunny, cloudy, overcast, raining, snowing, snow cover, etc.), seasons (e.g., winter, spring, summer fall), time of day (e.g., morning, afternoon, dusk, night), and the like. It should be noted that these environmental factors/conditions can also be determined by the ODS  104  during the first operating mode as well. These environmental factors/conditions can be identified from the GPS data  112 , from information in the geographic information database  114 , manually entered by a user, from frames/images  122  captured by the imaging system  106 , and the like. 
     The ODS  104 , at step  404 , then selects one or more appearance models  126  based on the appearance context that has been determined. The ODS  104 , at step  406 , then processes the frames/images  122  captured by the imaging system  106  and/or object templates  130  associated with detectable objects based on the one or more appearance models  126 . This processing either normalizes the appearance of objects within the frames/images  122 , or applies the one or more appearance models to the target object templates  130  to generate one or more appearance-adapted object templates, and/or optimizes the object detector  140  with respect to the current environmental factors/conditions. 
     The ODS  104 , at step  408 , determines an illumination context based on the environmental factors/conditions as well. However, it should be noted that the system  104  is not required to determine both an appearance and illumination context. As discussed above, the illumination context identifies the various illumination conditions (e.g., lighting and reflectance) conditions of the environment in which the vehicle is traveling or will be travelling. The ODS  104 , at step  410 , then selects or generates one or more illumination models  128  based on the illumination context that has been determined. The ODS  104 , at step  412 , then processes the frames/images  122  captured by the imaging system  106  and/or object templates  130  associated with detectable objects based on the one or more illumination models  128 . This processing either normalizes the illumination of objects within the frames/images  122  and generates illumination invariant frames/images, or generates illumination specific or illumination synthesized frames/images, and generates illumination specific or illumination invariant or illumination synthesized object templates, and/or optimizes the object detector  140  with respect to the illumination conditions of the environment. 
     The ODS  104 , at step  414 , performs an object detection process on the fames/images  122  that have been processed using the appearance and/or illumination models  126 ,  128 . The ODS  104 , at step  416 , determines if a target object has been detected. If the result of this determination is negative, the control flow returns to step  402 . If the result of this determination is positive, the ODS  104 , at step  418 , notifies the user of the detected object and/or performs another action. The control flow then returns to step  402 . It should be noted that the ODS  104  can operate in both of the first and second modes simultaneously. For example, when the ODS  104  is in the second operating mode, the ODS  104  can continue to analyze the geographic information  124  for determining whether or not the object detector  140  should be deactivated. 
     Information Processing System 
       FIG. 5  is a block diagram illustrating an information processing system that can be utilized in embodiments of the present invention. The information processing system  500  is based upon a suitably configured processing system adapted to implement one or more embodiments of the present invention (e.g., the system  102  of  FIG. 1 ). Any suitably configured processing system can be used as the information processing system  500  in embodiments of the present invention. 
     The information processing system  500  includes a computer  502 . The computer  502  has a processor(s)  504  that is connected to a main memory  506 , mass storage interface  508 , network adapter hardware  510 , imaging system  106 , and GPS system  108 . A system bus  512  interconnects these system components. Although only one CPU  504  is illustrated for computer  502 , computer systems with multiple CPUs can be used equally effectively. The main memory  506 , in this embodiment, comprises the object detection system  104  and its components, the image database  110  and its contents, the geographic information database  114 , the illumination model database  116  and its contents, the appearance model database  118  and its contents, and the object template database  120  and its contents. 
     The mass storage interface  508  is used to connect mass storage devices, such as mass storage device  514 , to the information processing system  500 . One specific type of data storage device is an optical drive such as a CD/DVD drive, which can be used to store data to and read data from a computer readable medium or storage product such as (but not limited to) a CD/DVD  516 . Another type of data storage device is a data storage device configured to support, for example, NTFS type file system operations. 
     An operating system included in the main memory is a suitable multitasking operating system such as any of the Linux, UNIX, Windows, and Windows Server based operating systems. Embodiments of the present invention are also able to use any other suitable operating system. Some embodiments of the present invention utilize architectures, such as an object oriented framework mechanism, that allows instructions of the components of operating system to be executed on any processor located within the information processing system  500 . The network adapter hardware  510  is used to provide an interface to a network  511 . Embodiments of the present invention are able to be adapted to work with any data communications connections including present day analog and/or digital techniques or via a future networking mechanism. 
     Although the exemplary embodiments of the present invention are described in the context of a fully functional computer system, those of ordinary skill in the art will appreciate that various embodiments are capable of being distributed as a program product via CD or DVD, CD-ROM, or other form of recordable media, or via any type of electronic transmission mechanism. Also, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.), or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit” “module” or “system”. 
     Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium include computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. A computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. 
     A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. 
     Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing. 
     Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The program code may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user&#39;s computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (e.g., through the Internet using an Internet Service Provider). 
     Non-Limiting Examples 
     Although specific embodiments of the invention have been disclosed, those having ordinary skill in the art will understand that changes can be made to the specific embodiments without departing from the spirit and scope of the invention. The scope of the invention is not to be restricted, therefore, to the specific embodiments, and it is intended that the appended claims cover any and all such applications, modifications, and embodiments within the scope of the present invention.