Patent Publication Number: US-2011069086-A1

Title: Detail-in-Context Presentations in Client/Server Systems

Description:
RELATED APPLICATIONS 
     The application claims priority under 35 U.S.C. §120 as a continuation-in-part of U.S. patent application Ser. No. 12/388, 437, filed Feb. 18, 2009 which is a continuation of U.S. application Ser. No. 10/989,070 (U.S. Pat. No. 7,495,678), filed Nov. 16, 2004, which claims priority to Canadian Application No. 2,449,888, filed Nov. 17, 2003; U.S. patent application Ser. No. 11/542,120, filed Oct. 4, 2006 which claims priority to U.S. Provisional Application No. 60/727,507, filed Oct. 18, 2005; and U.S. patent application Ser. No. 10/682,298, filed Oct. 10, 2003 which claims priority to Canadian Application 2,407,383, filed Oct. 10, 2002, the entire disclosures of each of the above listed applications are hereby incorporated by reference. 
    
    
     BACKGROUND 
     Modern computer graphics systems, including virtual environment systems, are used for numerous applications such as mapping, navigation, flight training, surveillance, and even playing computer games. In general, these applications are launched by the computer graphics system&#39;s operating system upon selection by a user from a menu or other graphical user interface (“GUI”). A GUI is used to convey information to and receive commands from users and generally includes a variety of GUI objects or controls, including icons, toolbars, drop-down menus, text, dialog boxes, buttons, and the like. A user typically interacts with a GUI by using a pointing device (e.g., a mouse) to position a pointer or cursor over an object and “clicking” on the object. 
     One problem with these computer graphics systems is their inability to effectively display detailed information for selected graphic objects when those objects are in the context of a larger image. A user may require access to detailed information with respect to an object in order to closely examine the object, to interact with the object, or to interface with an external application or network through the object. For example, the detailed information may be a close-up view of the object or a region of a digital map image. 
     While an application may provide a GUI for a user to access and view detailed information for a selected object in a larger image, in doing so, the relative location of the object in the larger image may be lost to the user. Thus, while the user may have gained access to the detailed information required to interact with the object, the user may lose sight of the context within which that object is positioned in the larger image. This is especially so when the user must interact with the GUI using a computer mouse or keyboard. The interaction may further distract the user from the context in which the detailed information is to be understood. This problem is an example of what is often referred to as the “screen real estate problem”. 
     SUMMARY 
     According to one aspect, there is provided a method for generating a presentation of a region-of-interest in an original image for display on a display screen of a client coupled over a network to a server, comprising: establishing a lens having a focal region for the region-of-interest at least partially surrounded by a shoulder region; if the lens is in transit between first and second locations for the region-of-interest in the original image, applying the lens to the original image by a first method to generate the presentation at the client; and, if the lens is stationary in the original image, receiving the presentation from the server, the server applying the lens to the original image by a second method to generate the presentation. 
     In the above method, the first method may require less resources than the second method. The lens may have a shape and the second method may more accurately reflect the shape of the lens in the presentation than the first method. The shoulder region may have a shape and the second method may more accurately reflect the shape of the shoulder region in the presentation than the first method. The second method may include displacing the original image onto the lens to produce a displaced image and projecting the displaced image onto a plane in a direction aligned with a viewpoint for the region-of-interest. The first method may include: creating a focal region image for the focal region by scaling the original image within the focal region by a focal region magnification; creating a shoulder region image for the shoulder region by scaling the original image within the shoulder region by a shoulder region magnification, the shoulder region magnification being less than the focal region magnification; and, overlaying the focal region image and the shoulder region image on the original image. The method may further include receiving a signal indicating the transit between the first and second locations from a graphical user interface (“GUI”) displayed over the lens on the display screen. The method may further include, if the lens is stationary in the original image, sending a signal from the client to the server requesting the presentation. The method may further include, if the lens is stationary in the original image and if the server is unavailable, applying the lens to the original image by the first method to generate the presentation at the client. And, the method may further include displaying the presentation on the display screen. 
     In accordance with further aspects there is provided an apparatus such as a data processing system, a method for adapting this system, as well as articles of manufacture such as a computer readable storage medium having program instructions recorded thereon for practicing the method. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the embodiments will become apparent from the following detailed description, taken in combination with the appended drawings, in which: 
         FIG. 1  is a graphical representation illustrating the geometry for constructing a three-dimensional perspective viewing frustum, relative to an x, y, z coordinate system, in accordance with elastic presentation space graphics technology; 
         FIG. 2  is a graphical representation illustrating the geometry of a presentation in accordance with elastic presentation space graphics technology; 
         FIG. 3  is a block diagram illustrating a data processing system adapted for implementing an embodiment; 
         FIG. 4  is a partial screen capture illustrating a GUI having lens control elements for user interaction with detail-in-context data presentations in accordance with an embodiment; 
         FIG. 5  is a screen capture illustrating a presentation having a rectangular inset lens in accordance with an embodiment; 
         FIG. 6  is a top view illustrating the structure of a pyramid lens in accordance with an embodiment; 
         FIG. 7  is a side view illustrating the pyramid lens of  FIG. 6  in accordance with an embodiment; and, 
         FIG. 8  is a flow chart illustrating operations of modules within the memory of a data processing system for generating a presentation of a region-of-interest in an original image for display on a display screen, the data processing system coupled over a network to a server, in accordance with an embodiment. 
     
    
    
     It should be noted that throughout the appended drawings, like features are identified by like reference numerals. 
     DETAILED DESCRIPTION 
     In the following description, the term “data processing system” is used herein to refer to any machine for processing data, including the computer systems and network arrangements described herein. The techniques described herein may be implemented in any computer programming language, e.g., an operating system. The techniques may also be implemented in hardware. 
     The “screen real estate problem” generally arises whenever large amounts of information are to be displayed on a display screen of limited size. Known tools to address this problem include panning and zooming. While these tools are suitable for a large number of visual display applications, they become less effective where sections of the visual information are spatially related, such as in layered maps and three-dimensional representations, for example. In this type of information display, panning and zooming are not as effective as much of the context of the panned or zoomed display may be hidden. 
     A recent solution to this problem is the application of “detail-in-context” presentation techniques. Detail-in-context is the magnification of a particular region-of-interest (the “focal region” or “detail”) in a data presentation while preserving visibility of the surrounding information (the “context”). This technique has applicability to the display of large surface area media (e.g. digital maps) on computer screens of variable size including graphics workstations, laptop computers, personal digital assistants (“PDAs”), and cell phones. 
     In the detail-in-context discourse, differentiation is often made between the terms “representation” and “presentation”. A representation is a formal system, or mapping, for specifying raw information or data that is stored in a computer or data processing system. For example, a digital map of a city is a representation of raw data including street names and the relative geographic location of streets and utilities. Such a representation may be displayed visually on a computer screen or printed on paper. On the other hand, a presentation is a spatial organization of a given representation that is appropriate for the task at hand. Thus, a presentation of a representation organizes such things as the point of view and the relative emphasis of different parts or regions of the representation. For example, a digital map of a city may be presented with a region magnified to reveal street names. 
     In general, a detail-in-context presentation may be considered as a distorted view (or distortion) of a portion of the original representation or image where the distortion is the result of the application of a “lens” like distortion function to the original representation. A detailed review of various detail-in-context presentation techniques such as “Elastic Presentation Space” (“EPS”) (or “Pliable Display Technology” (“PDT”)) may be found in a publication by Marianne S. T. Carpendale, entitled “A Framework for Elastic Presentation Space” (Carpendale, Marianne S. T., A Framework for Elastic Presentation Space (Burnaby, British Columbia: Simon Fraser University, 1999)), and incorporated herein by reference. 
     In general, detail-in-context data presentations are characterized by magnification of areas of an image where detail is desired, in combination with compression of a restricted range of areas of the remaining information (i.e. the context), the result typically giving the appearance of a lens having been applied to the display surface. Using the techniques described by Carpendale, points in a representation are displaced in three dimensions and a perspective projection is used to display the points on a two-dimensional presentation display. Thus, when a lens is applied to a two-dimensional continuous surface representation, for example, the resulting presentation appears to be three-dimensional. In other words, the lens transformation appears to have stretched the continuous surface in a third dimension. In EPS graphics technology, a two-dimensional visual representation is placed onto a surface; this surface is placed in three-dimensional space; the surface, containing the representation, is viewed through perspective projection; and the surface is manipulated to effect the reorganization of image details. The presentation transformation is separated into two steps: surface manipulation or distortion and perspective projection. 
       FIG. 1  is a graphical representation illustrating the geometry  100  for constructing a three-dimensional (“3D”) perspective viewing frustum  220 , relative to an x, y, z coordinate system, in accordance with elastic presentation space (EPS) graphics technology. In EPS technology, detail-in-context views of two-dimensional (“2D”) visual representations are created with sight-line aligned distortions of a 2D information presentation surface within a 3D perspective viewing frustum  220 . In EPS, magnification of regions-of-interest and the accompanying compression of the contextual region to accommodate this change in scale are produced by the movement of regions of the surface towards the viewpoint (“VP”)  240  located at the apex of the pyramidal shape  220  containing the frustum. The process of projecting these transformed layouts via a perspective projection results in a new 2D layout which includes the zoomed and compressed regions. The use of the third dimension and perspective distortion to provide magnification in EPS provides a meaningful metaphor for the process of distorting the information presentation surface. The 3D manipulation of the information presentation surface in such a system is an intermediate step in the process of creating a new 2D layout of the information. 
       FIG. 2  is a graphical representation illustrating the geometry  200  of a presentation in accordance with EPS graphics technology. EPS graphics technology employs viewer-aligned perspective projections to produce detail-in-context presentations in a reference view plane  201  which may be viewed on a display. Undistorted 2D data points are located in a base plane  210  of a 3D perspective viewing volume or frustum  220  which is defined by extreme rays  221  and  222  and the base plane  210 . The VP  240  is generally located above the centre point of the base plane  210  and reference view plane (“RVP”)  201 . Points in the base plane  210  are displaced upward onto a distorted surface or “lens”  230  which is defined by a general 3D distortion function (i.e., a detail-in-context distortion basis function). The direction of the perspective projection corresponding to the distorted surface  230  is indicated by the line FPo-FP  231  drawn from a point FPo  232  in the base plane  210  through the point FP  233  which corresponds to the focal point, focus, or focal region  233  of the distorted surface  230 . Typically, the perspective projection has a direction  231  that is viewer-aligned (i.e., the points FPo  232 , FP  233 , and VP  240  are collinear). 
     EPS is applicable to multidimensional data and is well suited to implementation on a computer for dynamic detail-in-context display on an electronic display surface such as a monitor. In the case of two dimensional data, EPS is typically characterized by magnification of areas of an image where detail is desired  233 , in combination with compression of a restricted range of areas of the remaining information (i.e., the context)  234 , the end result typically giving the appearance of a lens  230  having been applied to the display surface. The areas of the lens  230  where compression occurs may be referred to as the “shoulder”  234  of the lens  230 . The area of the representation transformed by the lens may be referred to as the “lensed area”. The lensed area thus includes the focal region  233  and the shoulder region  234 . Typically, the distorted surface, distortion function, or lens  230  provides a continuous or smooth transition from the base plane  210  through the shoulder region  234  to the focal region  233  as shown in  FIG. 2 . However, of course, the distorted surface, distortion function, or lens  230  may have a number of different shapes (e.g., truncated pyramid, etc.). To reiterate, the source image or representation to be viewed is located in the base plane  210 . Magnification  233  and compression  234  are achieved through elevating elements of the source image relative to the base plane  210 , and then projecting the resultant distorted surface onto the reference view plane  201 . EPS performs detail-in-context presentation of n-dimensional data through the use of a procedure wherein the data is mapped into a region in an (n+1) dimensional space, manipulated through perspective projections in the (n+1) dimensional space, and then finally transformed back into n-dimensional space for presentation. EPS has numerous advantages over conventional zoom, pan, and scroll technologies, including the capability of preserving the visibility of information outside  210 ,  234  the local region of interest  233 . 
     For example, and referring to  FIGS. 1 and 2 , in two dimensions, EPS can be implemented through the projection of an image onto a reference plane  201  in the following manner. The source image or representation is located on a base plane  210 , and those regions of interest  233  of the image for which magnification is desired are elevated so as to move them closer to a reference plane situated between the reference viewpoint  240  and the reference view plane  201 . Magnification of the focal region  233  closest to the RVP  201  varies inversely with distance from the RVP  201 . As shown in  FIGS. 1 and 2 , compression of regions  234  outside the focal region  233  is a function of both distance from the RVP  201 , and the gradient of the function (i.e., the shoulder function or drop-off function) describing the vertical distance from the RVP  201  with respect to the horizontal distance from the focal region  233 . The resultant combination of magnification  233  and compression  234  of the image as seen from the reference viewpoint  240  results in a lens-like effect similar to that of a magnifying glass applied to the image. Hence, the various functions used to vary the magnification and compression of the source image via vertical displacement from the basal plane  210  are described as lenses, lens types, or lens functions. Lens functions that describe basic lens types with point and circular focal regions, as well as certain more complex lenses and advanced capabilities such as folding, have previously been described by Carpendale. 
       FIG. 3  is a block diagram of a data processing system  300  adapted to implement an embodiment. The data processing system  300  is suitable for generating, displaying, and adjusting detail-in-context lens presentations in conjunction with a detail-in-context graphical user interface (“GUI”)  400 , as described below. The data processing system  300  includes an input device  310 , a central processing unit (“CPU”)  320 , memory  330 , a display  340 , and an interface device  350 . The input device  310  may include a keyboard, a mouse, a trackball, a touch sensitive surface or screen, a position tracking device, an eye tracking device, or a similar device. The CPU  320  may include dedicated coprocessors and memory devices. The memory  330  may include RAM, ROM, databases, or disk devices. The display  340  may include a computer screen, terminal device, a touch sensitive display surface or screen, or a hardcopy producing output device such as a printer or plotter. And, the interface device  350  may include an interface to a network (not shown) such as the Internet and/or another wired or wireless network. Thus, the data processing system  300  may be linked to other data processing systems (not shown) by a network (not shown). For example, the data processing system  300  may be a client and/or server in a client/server system. The data processing system  300  has stored therein data representing sequences of instructions which when executed cause the method described herein to be performed. Of course, the data processing system  300  may contain additional software and hardware. 
     Thus, the data processing system  300  includes computer executable programmed instructions for directing the system  300  to implement the embodiments described herein. The programmed instructions may be embodied in one or more hardware or software modules  331  resident in the memory  330  of the data processing system  300 . Alternatively, the programmed instructions may be embodied on a computer readable medium (such as a CD disk or floppy disk) which may be used for transporting the programmed instructions to the memory  330  of the data processing system  300 . Alternatively, the programmed instructions may be embedded in a computer-readable signal or signal-bearing medium that is uploaded to a network by a vendor or supplier of the programmed instructions, and this signal-bearing medium may be downloaded through an interface (e.g.,  350 ) to the data processing system  300  from the network by end users or potential buyers. 
     As mentioned, detail-in-context presentations of data using techniques such as pliable surfaces, as described by Carpendale, are useful in presenting large amounts of information on limited-size display surfaces. Detail-in-context views allow magnification of a particular region-of-interest (e.g., the focal region)  233  in a data presentation while preserving visibility of the surrounding information  210 . In the following, a GUI  400  is described having lens control elements that can be implemented in software (and/or hardware) and applied to the control of detail-in-context data presentations. The software (and/or hardware) can be loaded into and run by the data processing system  300  of  FIG. 3 . 
       FIG. 4  is a partial screen capture illustrating a GUI  400  having lens control elements for user interaction with detail-in-context data presentations. Detail-in-context data presentations are characterized by magnification of areas of an image where detail is desired, in combination with compression of a restricted range of areas of the remaining information (i.e. the context), the end result typically giving the appearance of a lens having been applied to the display screen surface. This lens  410  includes a “focal region”  420  having high magnification, a surrounding “shoulder region”  430  where information is typically visibly compressed, and a “base”  412  surrounding the shoulder region  430  and defining the extent of the lens  410 . In  FIG. 4 , the lens  410  is shown with a circular shaped base  412  (or outline) and with a focal region  420  lying near the center of the lens  410 . However, the lens  410  and focal region  420  may have any desired shape. As mentioned above, the base of the lens  412  may be coextensive with the focal region  420 . 
     In general, the GUI  400  has lens control elements that, in combination, provide for the interactive control of the lens  410 . The effective control of the characteristics of the lens  410  by a user (i.e., dynamic interaction with a detail-in-context lens) is advantageous. At any given time, one or more of these lens control elements may be made visible to the user on the display surface  340  by appearing as overlay icons on the lens  410 . Interaction with each element is performed via the motion of an input or pointing device  310  (e.g., a mouse) with the motion resulting in an appropriate change in the corresponding lens characteristic. As will be described, selection of which lens control element is actively controlled by the motion of the pointing device  310  at any given time is determined by the proximity of the icon representing the pointing device  310  (e.g., cursor) on the display surface  340  to the appropriate component of the lens  410 . For example, “dragging” of the pointing device at the periphery of the bounding rectangle of the lens base  412  causes a corresponding change in the size of the lens  410  (i.e., “resizing”). Thus, the GUI  400  provides the user with a visual representation of which lens control element is being adjusted through the display of one or more corresponding icons. 
     For ease of understanding, the following discussion will be in the context of using a two-dimensional pointing device  310  that is a mouse, but it will be understood that the techniques may be practiced with other 2D or 3D (or even greater numbers of dimensions) input devices including a trackball, a keyboard, a position tracking device, an eye tracking device, an input from a navigation device, etc. 
     A mouse  310  controls the position of a cursor icon  401  that is displayed on the display screen  340 . The cursor  401  is moved by moving the mouse  310  over a flat surface, such as the top of a desk, in the desired direction of movement of the cursor  401 . Thus, the two-dimensional movement of the mouse  310  on the flat surface translates into a corresponding two-dimensional movement of the cursor  401  on the display screen  340 . 
     A mouse  310  typically has one or more finger actuated control buttons (i.e., mouse buttons). While the mouse buttons can be used for different functions such as selecting a menu option pointed at by the cursor  401 , a single mouse button may also be used to “select” a lens  410  and to trace the movement of the cursor  401  along a desired path. Specifically, to select a lens  410 , the cursor  401  is first located within the extent of the lens  410 . In other words, the cursor  401  is “pointed” at the lens  410 . Next, the mouse button is depressed and released. That is, the mouse button is “clicked”. Selection is thus a point and click operation. To trace the movement of the cursor  401 , the cursor  401  is located at the desired starting location, the mouse button is depressed to signal the computer  320  to activate a lens control element, and the mouse  310  is moved while maintaining the button depressed. After the desired path has been traced, the mouse button is released. This procedure is often referred to as “clicking” and “dragging” (i.e., a click and drag operation). It will be understood that a predetermined key on a keyboard  310  could also be used to activate a mouse click or drag. In the following, the term “clicking” will refer to the depression of a mouse button indicating a selection by the user and the term “dragging” will refer to the subsequent motion of the mouse  310  and cursor  401  without the release of the mouse button. 
     The GUI  400  may include the following lens control elements: move, pickup, resize base, resize focus, fold, magnify, zoom, and scoop. Each of these lens control elements has at least one lens control icon or alternate cursor icon associated with it. In general, when a lens  410  is selected by a user through a point and click operation, the following lens control icons may be displayed over the lens  410 : pickup icon  450 , base outline icon  412 , base bounding rectangle icon  411 , focal region bounding rectangle icon  421 , handle icons  481 ,  482 ,  491  magnify slide bar icon  440 , zoom icon  495 , and scoop slide bar icon (not shown). Typically, these icons are displayed simultaneously after selection of the lens  410 . In addition, when the cursor  401  is located within the extent of a selected lens  410 , an alternate cursor icon  460 ,  470 ,  480 ,  490 ,  495  may be displayed over the lens  410  to replace the cursor  401  or may be displayed in combination with the cursor  401 . These lens control elements, corresponding icons, and their effects on the characteristics of a lens  410  are described below with reference to  FIG. 4 . 
     In general, when a lens  410  is selected by a point and click operation, bounding rectangle icons  411 ,  421  are displayed surrounding the base  412  and focal region  420  of the selected lens  410  to indicate that the lens  410  has been selected. With respect to the bounding rectangles  411 ,  421  one might view them as glass windows enclosing the lens base  412  and focal region  420 , respectively. The bounding rectangles  411 ,  421  include handle icons  481 ,  482 ,  491  allowing for direct manipulation of the enclosed base  412  and focal region  420  as will be explained below. Thus, the bounding rectangles  411 ,  421  not only inform the user that the lens  410  has been selected, but also provide the user with indications as to what manipulation operations might be possible for the selected lens  410  though use of the displayed handles  481 ,  482 ,  491 . Note a bounding region may also have a shape other than generally rectangular. Such a bounding region could be of any of a great number of shapes including oblong, oval, ovoid, conical, cubic, cylindrical, polyhedral, spherical, etc. 
     Moreover, the cursor  401  provides a visual cue indicating the nature of an available lens control element. As such, the cursor  401  will generally change in form by simply pointing to a different lens control icon  450 ,  412 ,  411 ,  421 ,  481 ,  482 ,  491 ,  492 ,  440 . For example, when resizing the base  412  of a lens  410  using a corner handle  491 , the cursor  401  will change form to a resize icon  490  once it is pointed at (i.e., positioned over) the corner handle  491 . The cursor  401  will remain in the form of the resize icon  490  until the cursor  401  has been moved away from the corner handle  491 . 
     Lateral movement of a lens  410  is provided by the move lens control element of the GUI  400 . This functionality is accomplished by the user first selecting the lens  410  through a point and click operation. Then, the user points to a point within the lens  410  that is other than a point lying on a lens control icon  450 ,  412 ,  411 ,  421 ,  481 ,  482 ,  491 ,  492 ,  440 . When the cursor  401  is so located, a move icon  460  is displayed over the lens  410  to replace the cursor  401  or may be displayed in combination with the cursor  401 . The move icon  460  not only informs the user that the lens  410  may be moved, but also provides the user with indications as to what movement operations are possible for the selected lens  410 . For example, the move icon  460  may include arrowheads indicating up, down, left, and right motion. Next, the lens  410  is moved by a click and drag operation in which the user clicks and drags the lens  410  to the desired position on the screen  340  and then releases the mouse button  310 . The lens  410  is locked in its new position until a further pickup and move operation is performed. 
     Lateral movement of a lens  410  is also provided by the pickup lens control element of the GUI. This functionality is accomplished by the user first selecting the lens  410  through a point and click operation. As mentioned above, when the lens  410  is selected a pickup icon  450  is displayed over the lens  410  near the centre of the lens  410 . Typically, the pickup icon  450  will be a crosshairs. In addition, a base outline  412  is displayed over the lens  410  representing the base  412  of the lens  410 . The crosshairs  450  and lens outline  412  not only inform the user that the lens has been selected, but also provides the user with an indication as to the pickup operation that is possible for the selected lens  410 . Next, the user points at the crosshairs  450  with the cursor  401 . Then, the lens outline  412  is moved by a click and drag operation in which the user clicks and drags the crosshairs  450  to the desired position on the screen  340  and then releases the mouse button  310 . The full lens  410  is then moved to the new position and is locked there until a further pickup operation is performed. In contrast to the move operation described above, with the pickup operation, it is the outline  412  of the lens  410  that the user repositions rather than the full lens  410 . 
     Resizing of the base  412  (or outline) of a lens  410  is provided by the resize base lens control element of the GUI. After the lens  410  is selected, a bounding rectangle icon  411  is displayed surrounding the base  412 . For a rectangular shaped base  412 , the bounding rectangle icon  411  may be coextensive with the perimeter of the base  412 . The bounding rectangle  411  includes handles  491 ,  492 . These handles  491 ,  492  can be used to stretch the base  412  taller or shorter, wider or narrower, or proportionally larger or smaller. The corner handles  491  will keep the proportions the same while changing the size. The middle handles (not shown) will make the base  412  taller or shorter, wider or narrower. Resizing the base  412  by the corner handles  491  will keep the base  412  in proportion. Resizing the base  412  by the middle handles will change the proportions of the base  412 . That is, the middle handles change the aspect ratio of the base  412  (i.e., the ratio between the height and the width of the bounding rectangle  411  of the base  412 ). When a user points at a handle  491  with the cursor  401  a resize icon  490  may be displayed over the handle  491  to replace the cursor  401  or may be displayed in combination with the cursor  401 . The resize icon  490  not only informs the user that the handle  491  may be selected, but also provides the user with indications as to the resizing operations that are possible with the selected handle. For example, the resize icon  490  for a corner handle  491  may include arrows indicating proportional resizing. The resize icon (not shown) for a middle handle may include arrows indicating width resizing or height resizing. After pointing at the desired handle  491  the user would click and drag the handle  491  until the desired shape and size for the base  412  is reached. Once the desired shape and size are reached, the user would release the mouse button  310 . The base  412  of the lens  410  is then locked in its new size and shape until a further base resize operation is performed. 
     Resizing of the focal region  420  of a lens  410  is provided by the resize focus lens control element of the GUI. After the lens  410  is selected, a bounding rectangle icon  421  is displayed surrounding the focal region  420 . For a rectangular shaped focal region  420 , the bounding rectangle icon  421  may be coextensive with the perimeter of the focal region  420 . The bounding rectangle  421  includes handles  481 ,  482 . These handles  481 ,  482  can be used to stretch the focal region  420  taller or shorter, wider or narrower, or proportionally larger or smaller. The corner handles  481  will keep the proportions the same while changing the size. The middle handles  482  will make the focal region  420  taller or shorter, wider or narrower. Resizing the focal region  420  by the corner handles  481  will keep the focal region  420  in proportion. Resizing the focal region  420  by the middle handles  482  will change the proportions of the focal region  420 . That is, the middle handles  482  change the aspect ratio of the focal region  420  (i.e., the ratio between the height and the width of the bounding rectangle  421  of the focal region  420 ). When a user points at a handle  481 ,  482  with the cursor  401  a resize icon  480  may be displayed over the handle  481 ,  482  to replace the cursor  401  or may be displayed in combination with the cursor  401 . The resize icon  480  not only informs the user that a handle  481 ,  482  may be selected, but also provides the user with indications as to the resizing operations that are possible with the selected handle. For example, the resize icon  480  for a corner handle  481  may include arrows indicating proportional resizing. The resize icon  480  for a middle handle  482  may include arrows indicating width resizing or height resizing. After pointing at the desired handle  481 ,  482 , the user would click and drag the handle  481 ,  482  until the desired shape and size for the focal region  420  is reached. Once the desired shape and size are reached, the user would release the mouse button  310 . The focal region  420  is then locked in its new size and shape until a further focus resize operation is performed. 
     Folding of the focal region  420  of a lens  410  is provided by the fold control element of the GUI. In general, control of the degree and direction of folding (i.e., skewing of the viewer aligned vector  231  as described by Carpendale) is accomplished by a click and drag operation on a point  471 , other than a handle  481 ,  482 , on the bounding rectangle  421  surrounding the focal region  420 . The direction of folding is determined by the direction in which the point  471  is dragged. The degree of folding is determined by the magnitude of the translation of the cursor  401  during the drag. In general, the direction and degree of folding corresponds to the relative displacement of the focus  420  with respect to the lens base  410 . In other words, and referring to  FIG. 2 , the direction and degree of folding corresponds to the displacement of the point FP  233  relative to the point FPo  232 , where the vector joining the points FPo  232  and FP  233  defines the viewer aligned vector  231 . In particular, after the lens  410  is selected, a bounding rectangle icon  421  is displayed surrounding the focal region  420 . The bounding rectangle  421  includes handles  481 ,  482 . When a user points at a point  471 , other than a handle  481 ,  482 , on the bounding rectangle  421  surrounding the focal region  420  with the cursor  401 , a fold icon  470  may be displayed over the point  471  to replace the cursor  401  or may be displayed in combination with the cursor  401 . The fold icon  470  not only informs the user that a point  471  on the bounding rectangle  421  may be selected, but also provides the user with indications as to what fold operations are possible. For example, the fold icon  470  may include arrowheads indicating up, down, left, and right motion. By choosing a point  471 , other than a handle  481 ,  482 , on the bounding rectangle  421  a user may control the degree and direction of folding. To control the direction of folding, the user would click on the point  471  and drag in the desired direction of folding. To control the degree of folding, the user would drag to a greater or lesser degree in the desired direction of folding. Once the desired direction and degree of folding is reached, the user would release the mouse button  310 . The lens  410  is then locked with the selected fold until a further fold operation is performed. 
     Magnification of the lens  410  is provided by the magnify lens control element of the GUI. After the lens  410  is selected, the magnify control is presented to the user as a slide bar icon  440  near or adjacent to the lens  410  and typically to one side of the lens  410 . Sliding the bar  441  of the slide bar  440  results in a proportional change in the magnification of the lens  410 . The slide bar  440  not only informs the user that magnification of the lens  410  may be selected, but also provides the user with an indication as to what level of magnification is possible. The slide bar  440  includes a bar  441  that may be slid up and down, or left and right, to adjust and indicate the level of magnification. To control the level of magnification, the user would click on the bar  441  of the slide bar  440  and drag in the direction of desired magnification level. Once the desired level of magnification is reached, the user would release the mouse button  310 . The lens  410  is then locked with the selected magnification until a further magnification operation is performed. In general, the focal region  420  is an area of the lens  410  having constant magnification (i.e., if the focal region is a plane). Again referring to  FIGS. 1 and 2 , magnification of the focal region  420 ,  233  varies inversely with the distance from the focal region  420 ,  233  to the reference view plane (RVP)  201 . Magnification of areas lying in the shoulder region  430  of the lens  410  also varies inversely with their distance from the RVP  201 . Thus, magnification of areas lying in the shoulder region  430  will range from unity at the base  412  to the level of magnification of the focal region  420 . 
     Zoom functionality is provided by the zoom lens control element of the GUI. Referring to  FIG. 2 , the zoom lens control element, for example, allows a user to quickly navigate to a region of interest  233  within a continuous view of a larger presentation  210  and then zoom in to that region of interest  233  for detailed viewing or editing. Referring to  FIG. 4 , the combined presentation area covered by the focal region  420  and shoulder region  430  and surrounded by the base  412  may be referred to as the “extent of the lens”. Similarly, the presentation area covered by the focal region  420  may be referred to as the “extent of the focal region”. The extent of the lens may be indicated to a user by a base bounding rectangle  411  when the lens  410  is selected. The extent of the lens may also be indicated by an arbitrarily shaped figure that bounds or is coincident with the perimeter of the base  412 . Similarly, the extent of the focal region may be indicated by a second bounding rectangle  421  or arbitrarily shaped figure. The zoom lens control element allows a user to: (a) “zoom in” to the extent of the focal region such that the extent of the focal region fills the display screen  340  (i.e., “zoom to focal region extent”); (b) “zoom in” to the extent of the lens such that the extent of the lens fills the display screen  340  (i.e., “zoom to lens extent”); or, (c) “zoom in” to the area lying outside of the extent of the focal region such that the area without the focal region is magnified to the same level as the extent of the focal region (i.e., “zoom to scale”). 
     In particular, after the lens  410  is selected, a bounding rectangle icon  411  is displayed surrounding the base  412  and a bounding rectangle icon  421  is displayed surrounding the focal region  420 . Zoom functionality is accomplished by the user first selecting the zoom icon  495  through a point and click operation When a user selects zoom functionality, a zoom cursor icon  496  may be displayed to replace the cursor  401  or may be displayed in combination with the cursor  401 . The zoom cursor icon  496  provides the user with indications as to what zoom operations are possible. For example, the zoom cursor icon  496  may include a magnifying glass. By choosing a point within the extent of the focal region, within the extent of the lens, or without the extent of the lens, the user may control the zoom function. To zoom in to the extent of the focal region such that the extent of the focal region fills the display screen  340  (i.e., “zoom to focal region extent”), the user would point and click within the extent of the focal region. To zoom in to the extent of the lens such that the extent of the lens fills the display screen  340  (i.e., “zoom to lens extent”), the user would point and click within the extent of the lens. Or, to zoom in to the presentation area without the extent of the focal region, such that the area without the extent of the focal region is magnified to the same level as the extent of the focal region (i.e., “zoom to scale”), the user would point and click without the extent of the lens. After the point and click operation is complete, the presentation is locked with the selected zoom until a further zoom operation is performed. 
     Alternatively, rather than choosing a point within the extent of the focal region, within the extent of the lens, or without the extent of the lens to select the zoom function, a zoom function menu with multiple items (not shown) or multiple zoom function icons (not shown) may be used for zoom function selection. The zoom function menu may be presented as a pull-down menu. The zoom function icons may be presented in a toolbar or adjacent to the lens  410  when the lens is selected. Individual zoom function menu items or zoom function icons may be provided for each of the “zoom to focal region extent”, “zoom to lens extent”, and “zoom to scale” functions described above. In this alternative, after the lens  410  is selected, a bounding rectangle icon  411  may be displayed surrounding the base  412  and a bounding rectangle icon  421  may be displayed surrounding the focal region  420 . Zoom functionality is accomplished by the user selecting a zoom function from the zoom function menu or via the zoom function icons using a point and click operation. In this way, a zoom function may be selected without considering the position of the cursor  401  within the lens  410 . 
     The concavity or “scoop” of the shoulder region  430  of the lens  410  is provided by the scoop lens control element of the GUI. After the lens  410  is selected, the scoop control is presented to the user as a slide bar icon (not shown) near or adjacent to the lens  410  and typically below the lens  410 . Sliding the bar (not shown) of the slide bar results in a proportional change in the concavity or scoop of the shoulder region  430  of the lens  410 . The slide bar not only informs the user that the shape of the shoulder region  430  of the lens  410  may be selected, but also provides the user with an indication as to what degree of shaping is possible. The slide bar includes a bar that may be slid left and right, or up and down, to adjust and indicate the degree of scooping. To control the degree of scooping, the user would click on the bar of the slide bar and drag in the direction of desired scooping degree. Once the desired degree of scooping is reached, the user would release the mouse button  310 . The lens  410  is then locked with the selected scoop until a further scooping operation is performed. 
     Advantageously, a user may choose to hide one or more lens control icons  450 ,  412 ,  411 ,  421 ,  481 ,  482 ,  491 ,  492 ,  440 ,  495  shown in  FIG. 4  from view so as not to impede the user&#39;s view of the image within the lens  410 . This may be helpful, for example, during an editing or move operation. A user may select this option through means such as a menu, toolbar, or lens property dialog box. 
     In addition, the GUI  400  maintains a record of control element operations such that the user may restore pre-operation presentations. This record of operations may be accessed by or presented to the user through “Undo” and “Redo” icons  497 ,  498 , through a pull-down operation history menu (not shown), or through a toolbar. 
     Thus, detail-in-context data viewing techniques allow a user to view multiple levels of detail or resolution on one display  340 . The appearance of the data display or presentation is that of one or more virtual lenses showing detail  233  within the context of a larger area view  210 . Using multiple lenses in detail-in-context data presentations may be used to compare two regions-of-interest at the same time. Folding enhances this comparison by allowing the user to pull the regions-of-interest closer together. Moreover, using detail-in-context technology, a region-of-interest can be magnified to pixel level resolution, or to any level of detail available from the source information, for in-depth review. The digital images may include graphic images, maps, photographic images, or text documents, and the source information may be in raster, vector, or text form. 
     For example, in order to view a selected object or region-of-interest in detail, a user can define a lens  410  over the object or region-of-interest using the GUI  400 . The lens  410  may be introduced to the original image to form a presentation through the use of a pull-down menu selection, tool bar icon, etc. Using lens control elements for the GUI  400 , such as move, pickup, resize base, resize focus, fold, magnify, zoom, and scoop, as described above, the user adjusts the lens  410  for detailed viewing of the object or region-of-interest. Using the magnify lens control element, for example, the user may magnify the focal region  420  of the lens  410  to pixel quality resolution revealing detailed information pertaining to the selected object or region-of-interest. That is, a base image (i.e., the image outside the extent of the lens) is displayed at a low resolution while a lens image (i.e., the image within the extent of the lens) is displayed at a resolution based on a user selected magnification  440 ,  441 . 
     In operation, the data processing system  300  employs EPS techniques with an input device  310  and GUI  400  for selecting objects or regions-of-interest for detailed display to a user on a display screen  340 . Data representing an original image or representation is received by the CPU  320  of the data processing system  300 . Using EPS techniques, the CPU  320  processes the data in accordance with instructions received from the user via an input device  310  and GUI  400  to produce a detail-in-context presentation. The presentation is presented to the user on a display screen  340 . It will be understood that the CPU  320  may apply a transformation to the shoulder region  430  surrounding the focal region  420  to affect blending or folding in accordance with EPS techniques. For example, the transformation may map the focal region  420  and/or shoulder region  430  to a predefined lens surface  230 , defined by a transformation or distortion function and having a variety of shapes, using EPS techniques. Or, the lens  410  may be simply coextensive with the region-of-interest or focal region  420 . 
     The lens control elements of the GUI  400  are adjusted by the user via an input device  310  to control the characteristics of the lens  410  in the detail-in-context presentation. Using an input device  310  such as a mouse, a user adjusts parameters of the lens  410  using icons and scroll bars of the GUI  400  that are displayed over the lens  410  on the display screen  340 . The user may also adjust parameters of the image of the full scene. Signals representing input device  310  movements and selections are transmitted to the CPU  320  of the data processing system  300  where they are translated into instructions for lens control. 
     Moreover, the lens  410  may be added to the presentation before or after the object or area is selected. That is, the user may first add a lens  410  to a presentation or the user may move a pre-existing lens into place over the selected object or region-of-interest. The lens  410  may be introduced to the original image to form the presentation through the use of a pull-down menu selection, tool bar icon, etc. 
     Advantageously, by using a detail-in-context lens  410  to select an object or region-of-interest for detailed information gathering, a user can view a large area (i.e., outside the extent of the lens  410 ) while focusing in on a smaller area (or within the focal region  420  of the lens  410 ) surrounding the selected object or region-of-interest. This makes it possible for a user to accurately gather detailed information without losing visibility or context of the portion of the original image surrounding the selected object or region-of-interest. 
     Thus, computer generated detail-in-context lens (or fisheye lens) presentations are a valuable tool for computer users. These presentations provide the ability to view data at multiple scales simultaneously, while preserving context, and maintaining continuity of data. 
     In order to render or generate such fisheye lens presentations, it is sometimes desirable or necessary to execute optimized or specialized rendering algorithms other than the displacement followed by perspective projection algorithm described above. These algorithms can be useful for overcoming limitations of hardware or software in any particular operating environment. As an example, United States Patent Application Publication No. 2003/0151625 by Shoemaker, which is incorporated herein by reference, discusses a rendering technique using pre-calculated texel coverages for the rendering of lenses. Also, United States Patent Application Publication No. 2003/0151626 by Komar et al., which is incorporated herein by reference, discusses the use of stretch bit-block transfer (“blit”) graphics operations for efficient rendering of pyramid shaped lenses. 
     While these two patent applications discuss rendering techniques that are useful for situations where performance needs to be optimized, there is another situation where a specialized rendering technique can be useful. This is the situation where not all standard graphics operations are available for a given data processing system. For example, if pixel copying operations are not available, then the technique described by U.S. Patent Application Publication No. 2003/0151625 would not be possible, and if stretch blit operations are not available, then the technique described in U.S. Patent Application Publication No. 2003/0151626 would not be possible. 
     In the following, a method is described for rendering pyramid shaped fisheye lenses using a minimum of graphics operations. Specifically, just image rendering, image scaling, depth ordering, and image masking capabilities are used in an embodiment. This method is advantageous in environments in which standard graphics operations are not all available. An example of such an environment is a Web browser. While it is possible to run full-featured executables, such as a Java™ Applet or ActiveX™ control (in which a full array of graphics capabilities are available) in a browser, sometimes it is desirable to implement all functionality using basic browser capabilities, such as hypertext markup language (“HTML”) rendering, using the document object model (“DOM”), and basic scripting, such as JavaScript™ Recently, this approach has become particularly popular and has been referred to as asynchronous JavaScript and XML (“AJAX”), where XML refers to the extensible markup language. While the method is not limited to this particular environment, this environment is one in which the method may be advantageously used. 
     At the root of the problem of rendering lenses in an AJAX client (e.g., Web browser) is the fact that rendering operations in such a client are limited. For example, JavaScript™ has almost no capability for rendering. It is used instead for manipulating elements in the DOM. The DOM does provide some capabilities for the visual presentation of data. Accordingly, the relevant client capabilities are as follows: images can be placed at a particular location in the browser window; images can be resized; rendering order can be changed; and, images can be masked (i.e., rectangular regions can be defined for each image where rendering occurs, outside of which no rendering takes place). The lens rendering or generating method herein differs from that of U.S. Patent Application Publication No. 2003/0151626 in that the graphics operations used are different. According to a method, for instance, one or more of image rendering, image resizing, image ordering, and image masking are used. 
       FIG. 5  is a screen capture illustrating a presentation  500  having a rectangular inset lens  510  in accordance with an embodiment. A rectangular inset lens  510  is a special case of a pyramid lens where the shoulder region is of zero size. An inset lens  510  applied to an original image magnifies a portion of that original image. The inset lens  510  is typically positioned over the location (i.e., the region-of-interest) in the original image that corresponds to the data or image  520  contained in the inset lens  510 . The data or image  520  in the inset lens  510  may be derived from the same sources as the data for the original image, but in some circumstances the data may be derived from a different source. For example, a JPEG2000™ image may provide higher resolution data for an image  520  for the inset lens  510 . Alternatively, an image server may provide higher resolution tiles that can be stitched into an image  520  for the inset lens  510 . 
     In order to construct the presentation  500  of  FIG. 5 , first the original image is rendered. Next, the image(s) used to render the inset image  520  are obtained and are placed in the appropriate position relative to the original image. The inset image  520  may be comprised of one or more images. The images of the inset image  520  are layered in such a way that they are displayed over top of the original image. The presentation  500  thus has an inset image  520  and a surrounding contextual or context image  530 , the contextual or context image  530  being that portion of the original image not covered by the inset image  520 . The images for the inset image  520  may be scaled so that they appear at an appropriate scale on the display screen  340 . Finally, since the images for the inset image  520  may cover more of the screen  340  than is necessary for the inset image  520 , the images are masked such that they are only visible in the inset lens  510 . This produces a presentation  500  having an inset lens  510  with an inset image  520  that shows a magnified or scaled version of a region-of-interest in the original image which is in turn surrounded (or at least partially surrounded) by context  530  from the original image. 
     In  FIG. 5 , an alternate GUI  550  is shown for adjusting the lens  510 . The GUI  550  has a resize control element for adjusting the size of the inset image  520 . The resize control element may have an associated slide bar icon  551  and bar icon  552  for manipulation by a user to resize the inset image  520 . The GUI  500  also has a magnify control element for adjusting the magnification of the inset image  520 . The magnify control element may have associated increase and decrease buttons  553 ,  554  for selection by a user to increase or decrease the magnification of the inset image  520  by discrete or continuous amounts. 
     A pyramid fisheye lens may be considered as a rectangular inset lens (e.g.,  510 ) with an added shoulder region of variable magnification that joins the lens focal region (i.e., equivalent to the inset image  520  region of presentation  500  of  FIG. 5 ) with the surrounding contextual region (i.e., equivalent to the contextual image  530  region of the presentation  500  of  FIG. 5 ). The method for generating or rendering a pyramid fisheye lens is similar to that described above for an inset lens except that a number of renderings are performed at a scale or magnification that is in between the scale of the focal region and the scale of the contextual region (or original image) in order to approximate a smoothly varying lens shoulder region. 
       FIG. 6  is a top view illustrating the structure  600  of a pyramid lens  610  in accordance with an embodiment. And,  FIG. 7  is a side view illustrating the pyramid lens  610  of  FIG. 6  in accordance with an embodiment. The pyramid lens  610  includes a focal region  620  at least partially surrounded by a shoulder region  630 . Separating the focal region  620  from the shoulder region  630  is a focal bounds  621 . Separating the shoulder region  630  from the contextual region (i.e., the original image or the region of the original image to which the lens  610  is not applied)  640  is a lens bounds  612 . The shoulder region  630  has one or more intermediate levels  631 ,  632 ,  633 ,  634  each having a corresponding intermediate level image (which will also be referred to as  631 ,  632 ,  633 ,  634  in the following, for convenience). The focal region  620  has a corresponding focal region image or inset image (which will also be referred to as  620  in the following, for convenience). And, the contextual region  640  has a corresponding contextual region image or original image (which will also be referred to as  640  in the following, for convenience). 
     The method uses a layering technique which stacks multiple renderings or images (i.e., intermediate level images  631 ,  632 ,  633 ,  634 ) on top of one another in order to render a pyramid lens  610 . The method includes several steps (i.e., n steps). Step  1  consists of rendering the contextual image  640 . Steps  2  to n−1 consist of rendering the intermediate level images  631 ,  632 ,  633 ,  634 , where n is the number of intermediate levels (e.g., n=4 for  FIGS. 6 and 7 ). Step n consists of rendering the inset image  620  as described above with respect to  FIG. 5 . Since step  1  is straight forward (the contextual image  640  being the original image or that portion of the original image that the pyramid lens  610  is not applied to) and step n is as described above, the following description will focus on steps  2  to n−1. 
     Steps  2  to n−1 are similar to the inset image rendering step n. What differs is that with each step from step  2  to step n−1, the region that is masked, in terms of screen coordinates, grows progressively smaller, and the data magnification level increases (and hence the data source may change, if different data sources are being used for different scales or magnification levels). The end result is that all intermediate level images  631 ,  632 ,  633 ,  634  are hidden except for a thin boundary around their respective perimeters or bounds. The effect is similar to a number of picture frames being stacked within one another, with each picture frame showing its picture (or data) at a different scale. 
     According to one embodiment, the change in region mask size can be varied in order to optimize for either quality or performance. If quality is to be optimized, then the mask can decrease in size to as little as 1 pixel per level  631 ,  632 ,  633 ,  634 . This makes the approximation of the shoulder accurate to the level of 1 pixel, the best possible for a typical display screen  340 . This will, however, result in possibly a large number of levels n being used, which may result in poor performance. The opposite strategy is to decrease the mask size in steps larger than 1 pixel per level  631 ,  632 ,  633 ,  634 . Decreasing the number of steps lowers the quality of the rendering, but uses fewer levels n, hence improving performance. 
     Regardless of how the change in region masking size per level  631 ,  632 ,  633 ,  634  is chosen, the change in coverage of the level in data space, and hence the magnification of the underlying data, is to be chosen appropriately. In this case, “appropriately” means, first, that the levels  631 ,  632 ,  633 ,  634  vary such that at the lens boundary  612  where the shoulder region  630  meets the contextual image  640  and at the focal bounds  621  where the shoulder region  630  meets the focus image  620 , the data (i.e., images  631 ,  634 ) in the shoulder region lines up with the adjoining data (i.e., images  640 ,  620 ) in the contextual and focal regions, and the magnification levels converge. The parameters defining the magnification and area of the levels  631 ,  632 ,  633 ,  634  may vary through the shoulder region  630 . That is, the shoulder function or drop-off function (see above) defining the “shape” of the shoulder  630  may be arbitrary. However, according to one embodiment, the shape of the shoulder function (or distortion function defining the shape of the lens) is continuous providing a smooth transition from the contextual region  640  through the shoulder region  630  to the focal region  620 . 
     According to one embodiment, the GUI  400  of  FIG. 4  may be used to adjust the lens  610 . For example, the scoop lens control element of the GUI  400  may be used to adjust the shape of the shoulder region  630  and hence the parameters defining the area of each level  631 ,  632 ,  633 ,  634 . As another example, the magnification control element (i.e., slide bar and bar icons  440 ,  441 ) of the GUI  400  may be used to adjust the magnification of the focal region  620  and shoulder region  630  and hence the parameters defining the magnification of each level  631 ,  632 ,  633 ,  634 . 
     According to another embodiment, the GUI  550  of  FIG. 5  may be used to adjust the lens  610 . 
     To reiterate, according to one embodiment, there is provided a method for generating a presentation of a region-of-interest in an original image  640  for display on a display screen  340 , comprising: establishing a focal region for the region-of-interest at least partially surrounded by a shoulder region (e.g., selected by a user); creating a focal region image  620  for the focal region by scaling the original image within the focal region by a focal region magnification; creating a shoulder region image  631  for the shoulder region by scaling the original image within the shoulder region by a shoulder region magnification, the shoulder region magnification being less than the focal region magnification; and, overlaying the focal region image  620  and the shoulder region image  631  on the original image  640  to thereby generate the presentation. 
     In the above method, the step of creating the focal region image  620  may further include masking regions of the original image  640  outside the focal region, the step of creating the shoulder region image  631  may further include masking regions of the original image  640  outside the shoulder region, and the step of overlaying may further include masking regions of the original image  640  within the focal and shoulder regions. The shoulder region image  631  may comprise a sequence of shoulder region images  631 ,  632 ,  633 ,  634  to smoothly (e.g., continuously) join the focal region image  620  to the original image  640 . Each of the sequence of shoulder region images  631 ,  632 ,  633 ,  634  may have a respective shoulder region magnification that increases from a shoulder region image  631  adjacent to the original image  640  to a shoulder region image  634  adjacent to the focal region image  620 . Each of the sequence of shoulder regions images  631 ,  632 ,  633 ,  634  may have a respective size that decreases from a shoulder region image adjacent  631  to the original image  640  to a shoulder region image  634  adjacent to the focal region image  620 . The method may further include receiving one or more signals to adjust the focal region through a graphical user interface (“GUI”)  400 ,  550  having means for adjusting at least one of a size of the focal region, a shape of the focal region, and the focal region magnification. The means for adjusting the size and shape may be at least one handle icon  481 ,  482  positioned on a perimeter  421 ,  621  of the focal region and the means for adjusting the focal region magnification may be at least one of a slide bar icon  440 ,  441 , an increase magnification button  553 , and a decrease magnification button  554 . The shoulder region magnification may be a function of the focal region magnification. The method may further include receiving one or more signals to adjust the shoulder region through a graphical user interface (“GUI”)  440 ,  550  having means for adjusting at least one of a size of the shoulder region, a shape of the shoulder region, and a shape of the function (e.g., the scoop or shape of the distortion function, shoulder function, or shoulder drop-off function, etc.). The means for adjusting the size and shape may be at least one handle icon  491  positioned on a perimeter  411 ,  412 ,  612  of the shoulder region and the means for adjusting the shape of the function may be a slide bar icon. The method may further include receiving one or more signals to adjust at least one of the focal region, the shoulder region, and the original image outside the shoulder region through a graphical user interface (“GUI”)  400  having means for at least one of: increasing the focal region magnification such that the focal region fills the display screen  340 ; increasing the focal and shoulder region magnifications such that the focal and shoulder regions fill the display screen  340 ; and, applying the focal region magnification uniformly to the focal region, the shoulder region, and the original image outside the shoulder region. The means may be a respective selectable zoom icon for each of the focal region, the shoulder region, and the original image outside the shoulder region. And, the means may be a respective selectable zoom area in each of the focal region, the shoulder region, and the original image outside the shoulder region. 
     Thus, there are a number of methods for generating detail-in-context presentations including the following: displacement followed by perspective projection (as described above and in U.S. Pat. No. 6,768,497 to Baar, et al, which is incorporated herein by reference); using pre-calculated texel coverages (as described in United States Patent Application Publication No. 2003/0151625 by Shoemaker); using stretch bit-block transfer (“blit”) operations (as described in United States Patent Application Publication No. 2003/0151626 by Komar et al.); and, using layering (and scaling, masking, etc.) as described above. 
     However, challenges remain with respect to generating detail-in-context presentations on the Internet and in other client/server applications where limitations on network bandwidth and server capacity may exist. In addition, limitations may exist with respect to the software installation and execution capabilities of client software (e.g., browser software) installed on clients coupled to a server. For example, in the case of an Internet “portal” site which may have thousands of users, the load on the server with respect to its rendering capacity and the impact on network bandwidth from thousands of connected clients may present significant design challenges. In addition, browser capabilities may be severely limited by security rules and other constraints at the client. Furthermore, it is often desirable that clients have no software installed other than JavaScript™ when browsing a given website. 
     The layering method described above may be considered as a client-side method for generating detail-in-context lens presentations. The software for implementing the method may be client-side software. However, this layering method may be limited due to current browser JavaScript™ capabilities. For example, the lenses generated may be restricted to simple truncated pyramid shapes (or similar shapes) and the quality of rendering of the lens&#39; shoulder region  630  may be restricted by the number of layers  631 ,  632 ,  633 ,  634  used to build the pyramid shape. As described above, improved visual quality of the shoulder region  630  may be achieved by increasing the number of layers in the shoulder region and decreasing the size of each layer. 
     According to one embodiment there is provided a method for generating detail-in-context lens presentations in client/server systems (e.g., in performance-constrained online environments). This method can be used in conjunction with the above-described layering method (and potentially with other client-side lens generation methods) to improve the quality of detail-in-context lens presentations and to support the generation of new lens shapes. The method minimizes the demands on servers to perform server-side rendering yet preserves some lens generation functionality at the client in the event that website traffic or network or server limitations make server-side lens generation unavailable. 
     Now, during periods when a user is actively moving a lens  610  (i.e., a presentation of the lens) across an original image  640  on the display screen  340 , the user is less sensitive to the quality of rendering of the shoulder or shoulder region  630  of the lens  610 . Hence, the rendering quality may be decreased for the shoulder region  630  during periods of lens movement. According to one embodiment, during periods of lens movement initiated by the user (or otherwise), the operations required to generate a presentation of the lens  610  are performed by the client using, for example, the layering method described above. According to this embodiment, when the user stops moving the lens  610  about the original image  640  (e.g., if the user selects a particular location for the lens  610  in the original image  640 , if a predetermined period of time expires, etc.), rendering of a presentation of the lens  610  is performed by the server and the rendered presentation of the lens  610  is then downloaded to the client for display of the client&#39;s display screen  340 . Advantageously, since the server typically does not have the rendering limitations of the client, this method allows higher quality lens shoulders to be rendered by the server (e.g., by the displacement followed by perspective projection method, by the pre-calculated texel coverages method, by the stretch bit-block transfer method, etc.). 
     According to one embodiment, the layering method may be performed by the client during periods when the server or network is heavily loaded or is otherwise performing slowly. 
     According to one embodiment, the server may be used to render lens shapes other than simple truncated pyramids. For example, lenses with rounded shoulders, etc., may be generated by the server. Furthermore, the server can provide additional server-side rendering of new information or blending of new information layers. 
     According to one embodiment, the rendering or occasional rendering of lenses by the server can also be used to temporarily present content such as advertising to the client browser for presentation to the user on the display screen  340 . 
     According to one embodiment, the higher quality rendering (e.g., by the displacement followed by perspective projection method, by the pre-calculated texel coverages method, by the stretch bit-block transfer method, etc.) may be provided by a separate lens rendering server or proxy server or by a lens rendering module downloaded to the client. 
     Advantageously, the above embodiments address the problem of a server not being able to keep up with the rendering demands of a large number of client users. In this case, client-side lens generation is maintained and the user is provided with useful detail-in-context presentations, albeit presentations that may have lens images  620 ,  630  or at least shoulder images  630  that are rendered at a lower quality. 
     The above described method may be summarized with the aid of a flowchart.  FIG. 8  is a flow chart illustrating operations  800  of modules  331  within the memory  330  of a data processing system  300  for generating a presentation of a region-of-interest in an original image  640  for display on a display screen  340 , the data processing system  300  coupled over a network to a server, in accordance with an embodiment. 
     At step  801 , the operations  800  start. 
     At step  802 , a lens  610  having a focal region  620  for the region-of-interest at least partially surrounded by a shoulder region  630  is established (e.g., by user selection, etc). 
     At step  803 , if the lens  610  is in transit between first and second locations for the region-of-interest in the original image  640 , the lens  610  is applied to the original image  640  by a first method to generate the presentation. 
     At step  804 , if the lens  610  is stationary in the original image  640 , the presentation is received from the server, the server having applied the lens  610  to the original image  640  by a second method to generate the presentation. 
     At step  805 , the operations  800  end. 
     In the above method, the first method may require less resources (e.g., processing power, rendering functionality, etc.) than the second method. The lens  610  may have a shape and the second method may more accurately reflect the shape of the lens in the presentation than the first method. The shoulder region  630  may have a shape and the second method may more accurately reflect the shape of the shoulder region in the presentation than the first method. The second method may include displacing the original image  640  onto the lens  610  to produce a displaced image and projecting the displaced image onto a plane  201  in a direction  231  aligned with a viewpoint  240  for the region-of-interest  233 . The first method may include: creating a focal region image for the focal region  620  by scaling the original image  640  within the focal region  620  by a focal region magnification; creating a shoulder region image for the shoulder region  630  by scaling the original image  640  within the shoulder region  630  by a shoulder region magnification, the shoulder region magnification being less than the focal region magnification; and, overlaying the focal region image and the shoulder region image on the original image  640 . The method may further include receiving a signal indicating the transit between the first and second locations from a graphical user interface (“GUI”)  400  displayed over the lens  610  on the display screen  340 . The method may further include, if the lens  610  is stationary in the original image  640 , sending a signal from the system  300  to the server requesting the presentation. The method may further include, if the lens  610  is stationary in the original image  640  and if the server is unavailable, applying the lens  610  to the original image  640  by the first method to generate the presentation within the system  300 . And, the method may further include displaying the presentation on the display screen  340 . 
     According to one embodiment, the above method may be implemented by the server rather than, or in addition to, the client. 
     While this discussion is primarily discussed as a method, a person of ordinary skill in the art will understand that the apparatus discussed above with reference to a data processing system  300 , may be programmed to enable the practice of the method. Moreover, an article of manufacture for use with a data processing system  300 , such as a pre-recorded storage device or other similar computer readable medium including program instructions recorded thereon, may direct the data processing system  300  to facilitate the practice of the method. It is understood that such apparatus and articles of manufacture also come within the scope. 
     In particular, the sequences of instructions which when executed cause the method described herein to be performed by the data processing system  300  can be contained in a data carrier product according to one embodiment. This data carrier product can be loaded into and run by the data processing system  300 . In addition, the sequences of instructions which when executed cause the method described herein to be performed by the data processing system  300  can be contained in a computer software product according to one embodiment. This computer software product can be loaded into and run by the data processing system  300 . Moreover, the sequences of instructions which when executed cause the method described herein to be performed by the data processing system  300  can be contained in an integrated circuit product (e.g., a hardware module or modules) which may include a coprocessor or memory according to one embodiment. This integrated circuit product can be installed in the data processing system  300 . 
     The embodiments described above are intended to be exemplary only. Those skilled in the art will understand that various modifications of detail may be made to these embodiments, all of which come within the scope.