Patent Publication Number: US-2009220169-A1

Title: Image enhancement

Description:
BACKGROUND 
     It is appreciated that certain techniques can be used to improve the quality of digital images. For example, “unsharp mask” algorithms may be implemented to enhance the perceived texture of digital images. However, such unsharp mask algorithms are based on non-edge preserving Gaussian smoothing filters. That is, unsharp mask algorithms essentially separate low frequency image components from high frequency image components via a Gaussian smoothing filter. This allows the respective components to be modulated by a constant to adjust their relative contributions. Generally, the high frequency components comprise the textures and some contributions from the edges within the images, while the low frequency components comprise large smooth regions plus the remaining edge contributions. Thus, the high frequency components can be modulated (e.g., increased) to accentuate textures as desired. However, since the high frequency components also comprise some portion of the edges within the image (when separated out with Gaussian smoothing filters), the edges within the image are also enhanced when textures are accentuated by modulating high frequency components. While this is generally not an issue for small amounts of enhancement, it becomes problematic when more substantial adjustments are made. For example, when the high frequency components are increased beyond a certain threshold, ringing artifacts or halos may be introduced around sharp edges in a scene. Such ringing artifacts or halos are undesirable, at least, because they can distract the viewer by introducing erroneous edges. Accordingly, there is room for improvement in digital image enhancement. 
     SUMMARY 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key factors or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. 
     As provided herein, the quality of a digital image can be enhanced while mitigating the formation of ringing artifacts or halos within the image. That is, bilateral filtering is implemented to allow textures and edges of an image to be adjusted separately. More particularly, bilateral filtering is used to decompose an image into two component images: a detail feature image and a large-scale feature image, where the image&#39;s textures are primarily comprised within the detail image, and the image&#39;s edges are primarily comprised within the large-scale feature image. By decomposing the image into these two sub-images and then globally scaling their respective magnitudes, it is possible to adjust the textures within the image substantially independent of the edges in the image and vice versa. It can be appreciated that this allows the apparent amount of texture in the scene to be enhanced while mitigating the formation of ringing artifacts or halos around edges in the image. 
     To the accomplishment of the foregoing and related ends, the following description and annexed drawings set forth certain illustrative aspects and implementations. These are indicative of but a few of the various ways in which one or more aspects may be employed. Other aspects, advantages, and novel features of the disclosure will become apparent from the following detailed description when considered in conjunction with the annexed drawings. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a flow chart illustrating an exemplary method for digital image enhancement. 
         FIG. 2  illustrates an exemplary digital image. 
         FIG. 3  illustrates an exemplary digital image where ringing artifacts or halos are introduced in the image due to the type of enhancement mechanism(s) employed. 
         FIG. 4  illustrates an exemplary digital image where the details/textures of the image are independently enhanced as provided herein. 
         FIG. 5  illustrates an exemplary digital image where the large-scale/edges of the image are independently enhanced as provided herein. 
         FIG. 6  illustrates an exemplary digital image where both the details/textures and large-scale/edges of the image are enhanced as provided herein. 
         FIG. 7  is a component block diagram illustrating an exemplary system configured to facilitate digital enhancement. 
         FIG. 8  is a component block diagram illustrating an exemplary digital enhancement technique as provided herein. 
         FIG. 9  is an illustration of an exemplary slider control that may be used to adjust details/textures of a digital image as provided herein. 
         FIG. 10  is an illustration of an exemplary slider control that may be used to adjust large-scale/edges of a digital image as provided herein. 
         FIG. 11  is an illustration of an exemplary computer-readable medium comprising processor-executable instructions configured to embody one or more of the provisions set forth herein. 
         FIG. 12  illustrates an exemplary computing environment wherein one or more of the provisions set forth herein may be implemented. 
     
    
    
     DETAILED DESCRIPTION 
     The claimed subject matter is now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the claimed subject matter. It may be evident, however, that the claimed subject matter may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the claimed subject matter. 
     Turning initially to  FIG. 1 , an exemplary methodology  100  is illustrated for enhancing a digital image by separately adjusting the textures (e.g., details) and edges (e.g., large-scale features) of the image. At  102  the image to be processed is obtained, and a bilateral filter is applied to the image at  104 . The bilateral filter effectively separates the image into two component images: a detail feature image and a large-scale feature image, where the image&#39;s textures are primarily comprised within the detail image, and the image&#39;s edges are primarily comprised within the large-scale feature image. More particularly, the bilateral filter outputs the large-scale features, and the detail features correspond to the difference between the original image and the large-scale features. 
     With the image decomposed into a detail (e.g., texture) image and a large-scale (e.g., edge) image, the respective magnitudes of the different images are adjusted independently at  106  to achieve a desired result. Once the detail and large-scale image are adjusted (independently) as desired, these images are recombined at  108  to render the original, but adjusted, base image, and the methodology ends thereafter. It will be appreciated that two arrows are illustrated between  104  and  106 , and between  106  and  108 . This is to illustrate that the detail and large-scale images are separate images and that they can be independently adjusted or otherwise acted upon as desired before being recombined into a single image at  108 . It will also be appreciated that it may be advantageous to perform bilateral filtering operations logarithmically. Accordingly, an optional first logarithmic operation may be performed on the subject image just after it is acquired at  102  and a second logarithmic (e.g., exponent or inverse logarithmic) operation may be performed just after the recombination at  108 . 
     By way of example,  FIGS. 2-6  demonstrate at least some of the advantages of enhancing a digital image as provided herein. More particularly,  FIGS. 2-6  illustrate a lake view type of scene  200  comprising a body of water  202 , waves or ripples  204  on the water  202 , logs  206 ,  208  next to the water  202 , and a stone  210  next to the water  202  with some texture or ridges  212  on the stone  210 .  FIG. 2  illustrates the original image before any processing is performed.  FIG. 3  illustrates the image processed with conventional techniques, such that undesired ringing artifacts, perceived as halos,  214  are produced around the edges in the image. That is, one or more “unsharp mask” algorithms that employ non-edge preserving Gaussian smoothing filters are utilized to separate low frequency image components from high frequency image components. However, since the high frequency components comprise both the textures and the edges within the image when obtained with a non-edge preserving Gaussian smoothing filter, the edges are somewhat overemphasized when the textures are accentuated by adjusting (e.g., increasing) the high frequency components. Accordingly, even though the textures (e.g., ripples  204  on the water  202  and features  212  on the stone  210 ) are darkened or emphasized as desired in  FIG. 3 , the edges of the stone  210 , lake  202 , and logs  206 ,  208  are emphasized to such an extent that they exhibit ringing effects or halos. It can be appreciated that this is undesirable as it can, among other things, make the image appear to have unwanted erroneous edges as perceived by the human visual system. 
       FIG. 4 , on the other hand, illustrates the scene  200  after merely textures in the image are enhanced using the method described herein to achieve a more desirable behavior. That is, a bilateral filter is applied to the original image to establish a detail feature image and a large-scale feature image, where the image&#39;s textures are primarily comprised within the detail image and edges within the image are primarily comprised within the large-scale image. Accordingly, merely the detail image is adjusted to render the image illustrated in  FIG. 4  wherein the textures of the ripples  204  on the water  202  and the features  212  of the stone  210  appear darker. It will be appreciated, however, that very little, if any, of the edges may be visible in an actual detail feature image since substantially all of the large-scale features may be removed from the original image to generate a detail feature image. Nevertheless, edges or large-scale features are included in the detail feature image of  FIG. 4  for purposes of illustration. 
     It will also be appreciated that while enhancements are generally illustrated herein as features having a heavier line weight or that are darker, enhancements or adjustments as mentioned herein are not intended to be so limited. Rather, the more salient point is that the textures and edges can be adjusted independently of one another, regardless of whether they are darkened, lightened, shaded, hatched, colored, etc. Accordingly, unlike the situation in  FIG. 3 , where enhancing textures  204 ,  212  also enhances edges and thus leads to halos or ringing effects  214  (e.g., because both textures and edges are comprised within the high frequency components), the textures  204 ,  212  are enhanced independently of edges in  FIG. 4  so that the appearance of halos or ringing effects is substantially mitigated. 
       FIG. 5  illustrates the image  200  where the edges within the scene are enhanced (instead of the textures). That is, after the bilateral filter is applied to the original image to obtain the detail and large-scale feature images, the large-scale feature image is independently adjusted to enhance the edges within the image. Similar to the discussion with regard to  FIG. 4 , it will be appreciated that very little if any of the texture may be visible in an actual large-scale feature image since substantially all of the details may be removed or subtracted out of the original image in rendering a large-scale feature image. Nevertheless, textures or detail features are included in the large-scale feature image of  FIG. 5  for purposes of illustration. 
     After the detail feature image (e.g., textures) and the large-scale feature image (e.g., edges) within the image are adjusted independently as desired ( FIGS. 4 and 5 , respectively), these images are recombined to render the adjusted image which is illustrated in  FIG. 6 . Again, it will be appreciated that while both the textures and edges within the image are illustrated as being darkened in  FIG. 6 , the important point is that the textures and the edges can be adjusted independently of one another. Accordingly, the textures within the image could just have easily been made very light relative to the edges and vice versa (while mitigating the appearance/occurrence of halos or ringing effects). 
     Turning to  FIG. 7 , a schematic block diagram of an exemplary system  700  configured to enhance the appearance of a digital image is illustrated. The system  700  comprises an image acquisition component  702 , a decomposition component  704 , an adjustment component  706 , and a re-composition component  708 . The image acquisition component  702  obtains the base image to be acted upon and then forwards the same to the decomposition component  704 . The decomposition component  704  implements bilateral filtering to break the original image into two component images: a detail feature image and a large-scale feature image, where the image&#39;s textures are primarily comprised within the detail feature image and the image&#39;s edges are primarily comprised within the large-scale feature image. More particularly, bilateral filtering renders the large-scale features, and the detail features are thus determined from the difference between the original image and the large-scale features. 
     The decomposition component  704  outputs the detail and large-scale feature images to the adjustment component  706  which is configured to adjust, respectively, the textures and edges of the image (independently of one another). With the textures and edges adjusted as desired, the (adjusted) detail and large-scale feature images are forwarded from the adjustment component  706  to the re-composition component  708 . The re-composition component  708  renders the adjusted original image from the adjusted detail and large-scale feature images. 
       FIG. 8  is a functional block diagram  800  illustrating an exemplary technique for enhancing the appearance of a digital image. The original image  802  to be acted upon is input, and an optional first logarithmic operation  804  is performed on the image  802  in the illustrated example. It will be appreciated that performing the logarithmic operation may be advantageous to accommodate subsequent operations, for example. A bilateral filter  806 , for example, is then applied to the logarithmic input image, where it is desirable to perform this processing in the ln(x) log domain for two reasons. First, the bilateral filter defines radiometric differences (edges) in scale space, therefore, edges are based on percentage differences, not absolute differences. Secondly, the difference between the original image and the bilateral image in scale space (the detail features) will instead be a modulation field of the original image, as opposed to absolute differences. In this manner, the magnitude of the details in the output image will adapt to the local intensity of the large-scale features (which, perceptually, is desirable). 
     It will be appreciated that the bilateral filter is an edge-preserving smoothing filter in both domain and range. In the domain (spatial), it acts as a typical Gaussian smoothing filter. In the domain (radiometric differences), it merely combines pixel values together that are close to the value at the center of the kernel, based upon a Gaussian distribution. This serves to mitigate smoothing across edges. Note that it is assumed that the scaling of the image components is a linear function in scale space (resulting in a gamma remapping in linear space). For consistency within results when dealing with ln(x) space, image values may be scaled between 0 and 1. Also, prior to scaling, the minimum possible image value should be made larger than 0, as 0 is undefined in ln(x) space. 
     The bilateral filter comprises: 
     
       
         
           
             
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     Where some of the nomenclature is defined as follows: 
     BO Bilateral Filter 
     gO Gaussian or Pseudo-Gaussian Function (normalization is unnecessary) 
     I Original Input Image 
     s Pixel Being Solved 
     p A Pixel within the Kernel Ω Surrounding s 
     Ω The Kernel surrounding s (Typically a Square Region) 
     σ h  The Spatial Falloff of the Bilateral Filter (e.g., 4 pixels for 1 Megapixel resolution images). This may vary depending on how far the subject was from the camera when the image was acquired and what the image comprises. For example, if the subject is far away from the camera then the magnitude of this coefficient may be lower. Similarly, if the subject is detected to be a face (e.g., through facial recognition software) then certain settings deemed appropriate for facial/portrait images may be used. 
     σ i  The Radiometric Difference Falloff of the Bilateral Filter (e.g., 0.3) 
     k Large-Scale Feature Scalar 
     m Detail Feature Scalar 
     Accordingly, the large-scale features  808  of the image are output from the bilateral filter  806 . The large-scale features of the image are at times also referred to as the large-scale feature image. In establishing the large-scale feature image  808 , pixels which are similar to one another are combined together to substantially remove texture, leaving regions of similar intensity that have sharp edges but little to nothing else. This promotes edge retention and is accomplished in a manner that is much faster than other edge preservation techniques, such as anisotropic diffusion, for example. It will be appreciated that large-scale features generally comprise the information (e.g., edges) that most humans utilize to recognize objects. 
     The large-scale feature image  808  is applied to a differencing operation  810 , as is the original image  802 . Since the large-scale feature image  808  substantially comprises the edges of the image, the difference between this image  808  and the original image  802  corresponds to the textures of the image, which is referred to as the detail feature image. The detail feature image  812  generally comprises the subtle variations differentiating pixels whose values are near, but not necessarily similar, to one another. The detail feature image  812  is output from the differencing block  810  and is fed to a multiplier block  814  to selectively adjust the magnitude thereof. In the illustrated example, the detail feature image  812  is multiplied by a constant m in the multiplier block  814  to increase (e.g., m&gt;1) or decrease (e.g., m&lt;1) the magnitude of the detail feature image, and thus the relative amount of texture presented therein. 
     Similarly, the large-scale feature image  808  is applied to a multiplier block  816  to selectively adjust the magnitude thereof. In the illustrated example, the large-scale feature image  808  is multiplied by a constant k in the multiplier block  816  to increase (e.g., k&gt;1) or decrease (e.g., k&lt;1) the magnitude of the large-scale feature image, and thus the intensity of the edges presented therein. The adjusted large-scale feature image  808   a  and the adjusted detail feature image  812   a  are applied to an addition block  818  and a second optional logarithmic operation (e.g., expo)  820  is performed to recombine the images and render the original, but adjusted, image  802   a  back in the linear domain. Nevertheless, the first  804  and second  820  logarithmic operations are said to be optional as the foregoing calculations can also be performed in linear space. 
     It will be appreciated that the resultant image R  802   a  (e.g., the original adjusted image) can be obtained in the linear domain according to R=k(B(I,σ h ,σ i ))+m(I−B(I,σ h ,σ i )). 
     The large-scale feature image  808  L is determined according to L=B(I,σ h ,σ i where B(Input,σ h ,σ i )s is the bilateral filter. 
     The detail feature image D  812  is thus determined according to D=I−L, where I is the input image  802  and L is the large-scale feature image  808 . 
     The resultant image R  802   a  can also be thought of as R=(kL+mD), where m  814  is the detail image scalar, and k  816  is the large-scale image scalar 
     The adjusted large-scale feature image  808   a  can thus be thought of as L σ =kL and the adjusted detail feature image  812   a  can be thought of as D θ =mD such that the resultant image R  802   a  corresponds to R=L σ +D θ . 
     In the logarithmic domain, the resultant image R  802   a  can be determined according to R=exp(k(B(ln(I),σ h ,σ i ))+m(ln(I)−B(ln(I),σ h ,σ i ))). 
     The large-scale feature image  808  L is determined according to L=B(ln(I),σ h ,σ i ) and the detail feature image D  812  is determined according to D=ln(I)−L, where I is the input image  802  and L is the large-scale feature image  808 . Nevertheless, it will be appreciated that L and D in the logarithmic domain are different than L and D in the linear domain (above). 
     The resultant image R  802   a  can also be thought of as R=exp(kL+mD), where m  814  is the detail image scalar, and k  816  is the large-scale image scalar. 
     The adjusted large-scale feature image  808   a  can thus be thought of as L σ =kL and the adjusted detail feature image  812   a  can be thought of as D θ =mD such that the resultant image R  802   a  corresponds to R=exp(L θ +D σ ). 
     It will be appreciated that as an edge preserving filter, the bilateral filter provides a more perceptually-correct adjustment to the texture of digital images than traditional “unsharp mask” algorithms which are based on non-edge-preserving Gaussian filters. It will also be appreciated that a graphics processing unit or GPU of a computer can be utilized for the numerical processing necessary to implement the provisions set forth herein. 
     Turning to  FIGS. 9 and 10 , a couple of exemplary slider controls are illustrated that can be implemented to facilitate independent adjustments to the appearance of a digital image. For example, slider  900  can be moved to the left or to the right to decrease or increase, respectively, the relative magnitude of textures visible in the image. Similarly, slider  1000  can be moved to the left or to the right to decrease or increase, respectively, the relative magnitude of edges visible in the image. It will be appreciated that since the textures and edges are adjusted independently of one another, the emergence of halos or ringing effects is mitigated. In one example, such sliders can have presets depending on the type of imaging application at issue. It will be appreciated that the illustrated sliders are merely an example of one of many types of interfaces that a user could interact with to selectively adjust the large-scale and detail features within an image. 
     Still another embodiment involves a computer-readable medium comprising processor-executable instructions configured to apply one or more of the techniques presented herein. An exemplary computer-readable medium that may be devised in these ways is illustrated in  FIG. 11 , wherein the implementation comprises a computer-readable medium  1102  (e.g., a CD-R, DVD-R, or a platter of a hard disk drive), on which is encoded computer-readable data  1104 . This computer-readable data  1104  in turn comprises a set of computer instructions  1106  configured to operate according to one or more of the principles set forth herein. In one such embodiment  1100 , the processor-executable instructions  1106  may be configured to perform a method, such as the exemplary method  100  of  FIG. 1 , for example. In another such embodiment, the processor-executable instructions  1106  may be configured to implement a system, such as the exemplary system  700  of  FIG. 7 , for example. Many such computer-readable media may be devised by those of ordinary skill in the art that are configured to operate in accordance with the techniques presented herein. 
     Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims. 
     As used in this application, the terms “component,” “module,” “system”, “interface”, and the like are generally intended to refer to a computer-related entity, either hardware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a controller and the controller can be a component. One or more components may reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between two or more computers. 
     Furthermore, the claimed subject matter may be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof to control a computer to implement the disclosed subject matter. The term “article of manufacture” as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier, or media. Of course, those skilled in the art will recognize many modifications may be made to this configuration without departing from the scope or spirit of the claimed subject matter. 
       FIG. 12  and the following discussion provide a brief, general description of a suitable computing environment to implement embodiments of one or more of the provisions set forth herein. The operating environment of  FIG. 12  is only one example of a suitable operating environment and is not intended to suggest any limitation as to the scope of use or functionality of the operating environment. Example computing devices include, but are not limited to, personal computers, server computers, hand-held or laptop devices, mobile devices (such as mobile phones, Personal Digital Assistants (PDAs), media players, and the like), multiprocessor systems, consumer electronics, mini computers, mainframe computers, distributed computing environments that include any of the above systems or devices, and the like. 
     Although not required, embodiments are described in the general context of “computer readable instructions” being executed by one or more computing devices. Computer readable instructions may be distributed via computer readable media (discussed below). Computer readable instructions may be implemented as program modules, such as functions, objects, Application Programming Interfaces (APIs), data structures, and the like, that perform particular tasks or implement particular abstract data types. Typically, the functionality of the computer readable instructions may be combined or distributed as desired in various environments. 
       FIG. 12  illustrates an example of a system  1210  comprising a computing device  1212  configured to implement one or more embodiments provided herein. In one configuration, computing device  1212  includes at least one processing unit  1216  and memory  1218 . It will be appreciated that the processing unit  1216  may comprise a graphics processing unit or GPU to perform at least some of the numerically intensive processing necessary to implement the provisions set forth herein. Depending on the exact configuration and type of computing device, memory  1218  may be volatile (such as RAM, for example), non-volatile (such as ROM, flash memory, etc., for example) or some combination of the two. This configuration is illustrated in  FIG. 12  by dashed line  1214 . 
     In other embodiments, device  1212  may include additional features and/or functionality. For example, device  1212  may also include additional storage (e.g., removable and/or non-removable) including, but not limited to, magnetic storage, optical storage, and the like. Such additional storage is illustrated in  FIG. 12  by storage  1220 . In one embodiment, computer readable instructions to implement one or more embodiments provided herein may be in storage  1220 . Storage  1220  may also store other computer readable instructions to implement an operating system, an application program, and the like. Computer readable instructions may be loaded in memory  1218  for execution by processing unit  1216 , for example. 
     The term “computer readable media” as used herein includes computer storage media. Computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions or other data. Memory  1218  and storage  1220  are examples of computer storage media. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disks (DVDs) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by device  1212 . Any such computer storage media may be part of device  1212 . 
     Device  1212  may also include communication connection(s)  1226  that allows device  1212  to communicate with other devices. Communication connection(s)  1226  may include, but is not limited to, a modem, a Network Interface Card (NIC), an integrated network interface, a radio frequency transmitter/receiver, an infrared port, a USB connection, or other interfaces for connecting computing device  1212  to other computing devices. Communication connection(s)  1226  may include a wired connection or a wireless connection. Communication connection(s)  1226  may transmit and/or receive communication media. 
     The term “computer readable media” may include communication media. Communication media typically embodies computer readable instructions or other data in a “modulated data signal” such as a carrier wave or other transport mechanism and includes any information delivery media. The term “modulated data signal” may include a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. 
     Device  1212  may include input device(s)  1224  such as keyboard, mouse, pen, voice input device, touch input device, infrared cameras, video input devices, and/or any other input device. Output device(s)  1222  such as one or more displays, speakers, printers, and/or any other output device may also be included in device  1212 . Input device(s)  1224  and output device(s)  1222  may be connected to device  1212  via a wired connection, wireless connection, or any combination thereof. In one embodiment, an input device or an output device from another computing device may be used as input device(s)  1224  or output device(s)  1222  for computing device  1212 . 
     Components of computing device  1212  may be connected by various interconnects, such as a bus. Such interconnects may include a Peripheral Component Interconnect (PCI), such as PCI Express, a Universal Serial Bus (USB), firewire (IEEE 1394), an optical bus structure, and the like. In another embodiment, components of computing device  1212  may be interconnected by a network. For example, memory  1218  may be comprised of multiple physical memory units located in different physical locations interconnected by a network. 
     Those skilled in the art will realize that storage devices utilized to store computer readable instructions may be distributed across a network. For example, a computing device  1230  accessible via network  1228  may store computer readable instructions to implement one or more embodiments provided herein. Computing device  1212  may access computing device  1230  and download a part or all of the computer readable instructions for execution. Alternatively, computing device  1212  may download pieces of the computer readable instructions, as needed, or some instructions may be executed at computing device  1212  and some at computing device  1230 . 
     Various operations of embodiments are provided herein. In one embodiment, one or more of the operations described may constitute computer readable instructions stored on one or more computer readable media, which if executed by a computing device, will cause the computing device to perform the operations described. The order in which some or all of the operations are described should not be construed as to imply that these operations are necessarily order dependent. Alternative ordering will be appreciated by one skilled in the art having the benefit of this description. Further, it will be understood that not all operations are necessarily present in each embodiment provided herein. 
     Moreover, the word “exemplary” is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “exemplary” is not necessarily to be construed as advantageous over other aspects or designs. Rather, use of the word exemplary is intended to present concepts in a concrete fashion. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims may generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. 
     Also, although the disclosure has been shown and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art based upon a reading and understanding of this specification and the annexed drawings. The disclosure includes all such modifications and alterations and is limited only by the scope of the following claims. In particular regard to the various functions performed by the above described components (e.g., elements, resources, etc.), the terms used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary implementations of the disclosure. In addition, while a particular feature of the disclosure may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms “includes”, “having”, “has”, “with”, or variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.”