Abstract:
A batch of credentials printed on a credential medium having a pattern of lenses (e.g., lenticular or other pattern), as well as a system and method for producing such credentials. A library of encoders is used to encode pixel locations of a plurality of view sets comprising a number of individual image frames. Each view set is associated with a distinct region on a credential having distinct polyoptic properties (e.g., orientation, frequency, shape). Encoded images produced by the library of encoders are combined (e.g., by interlacing or other encoding pattern) into a single print-ready image that is aligned (e.g., registered) with lenses of the distinct polyoptic areas on a medium on which the credential is printed. Encoding may take the form of positioning, sizing, intensifying, coloring, masking, interlacing, interleaving, scrambling, mixing, transformation, alteration, translation of pixels, or a combination thereof.

Description:
[0001]    This application claims priority to provisional application No. 60/875,547, filed Dec. 19, 2006, which is incorporated by reference herein, in its entirety, for all purposes. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a credential and, more particularly, to a credential formed on a credential medium that includes a polyoptic region, as well as a system and method to produce such credentials. 
         [0004]    2. Introduction 
         [0005]    As access to more valuable assets, information, and facilities is granted to the bearer of a personal ID credential, the importance of validating the bearer and information carried as well as securing the physical carrier of this information is dramatically increased. There are two major security questions surrounding any given credential: 1) is this person the rightful bearer of this credential, and 2) is this credential authentic. 
         [0006]    The generation of credentials that can meet security criteria such as those identified above is typically an intensive process. What is needed therefore is a credential production system and method that would enable the efficient creation of secure credentials that incorporate data that is unique to the credential or the person bearing the credential. 
       SUMMARY 
       [0007]    According to first aspect of the invention, there is provided a method of producing a credential for printing on a credential medium that includes at least one polyoptic region including a plurality of lens elements to enable viewing of respective images of a view set according to view angle. The method comprises retrieving a view set that includes at least two images; generating an encoding pattern that defines pixel characteristics of respective images of the view set; assigning pixel locations of the respective images on the credential medium according to an encoding pattern and the lens elements thereby to form an encoded image; and printing the encoded image on the medium according to assigned pixel locations thereby to enable viewing of respective images of the view set according to view angle. The credential medium may comprise a lens layer and/or one or more coating materials that carry a printed image or text. The print layer may be printed directly on the lens layer (e.g., a planar side of a polyoptic lens screen). The credential medium may also comprise print on a separate medium that is then combined with a lens layer to form a composite structure. The method may include a second or further polyoptic region and the method may further include retrieving a second view set that includes at least two images; generating a second encoding pattern that defines pixel characteristics of respective images of the second view set; assigning pixel locations of respective images of the second view set on the medium according to said second encoding pattern and the lens elements thereby to form a second encoded image; and printing the second encoded image on the medium according to assigned pixel locations to enable viewing of respective images of said second view set according to view angle. 
         [0008]    Pixel characteristics of the encoding pattern may be defined by position, size, intensity, color, masking, interlacing, interleaving, scrambling, mixing, transformation, alteration, translation of said pixels, or a combination thereof. The images may be based on biometric information or biographic text information. The polyoptic region may include a plurality of lenses that produce one of an appear/disappear, color switch, color wash, image switch, movement, moving pattern, parallax, and size change effect in response to a change in view 
         [0009]    In another aspect of the invention, there is provided a method of printing a credential on a medium that includes a polyoptic region defined by a plurality of lenses that enable viewing of respective images of a view set according to view angle. This method comprises obtaining an encoded image that embodies a view set that includes at least two images; assigning respective locations of pixels of said encoded image on the medium according to a pattern of said plurality of lenses on the medium and a desired view angle of each image of said view set; and printing said encoded image on the medium according to assigned pixel positions to enable viewing of respective images of said view set according to view angle. 
         [0010]    Another aspect of the invention comprises a method of producing a credential image for printing on a credential medium having a polyoptic region defined by a plurality of lenses that enable viewing of respective images of a view set according to view angle where the method comprises encoding pixel characteristics of a plurality of images of the view set to form an encoded image; assembling the encoded image with a non-encoded image into a credential image; and printing the credential image onto the medium, wherein the encoded image is printed onto the polyoptic region of the medium and the non-encoded image is printed onto a non-polyoptic region of the medium. 
         [0011]    Another aspect of the invention comprises a method of producing a group of encoded credential images for printing on a credential medium having at least one polyoptic region where the method comprises retrieving a dynamic image layer that includes an encoded image formed of a plurality of images having encoded pixels wherein at least one of said plurality of images is unique to a first credential; retrieving a static background layer that is not unique to the first credential; assembling the dynamic image layer and the static background layer into a first credential image; repeating the retrieving step to assemble a second credential image; and printing the first credential image and a second credential image together onto a unitary medium wherein the dynamic layers are printed in respective polyoptic regions of the medium and the static background layers are printed in non-polyoptic regions. The unitary medium may comprise a single lens layer sheet having a print enhancement coating (e.g., Topaz) printed on one side thereof and one or more further layers of printing or other coatings, or a composite structure that comprises multiple layers of printing, coating or material on one or more separate components along with a lens layer. 
         [0012]    Another aspect of the invention comprises a system to generate an encoded credential image for printing on a credential medium. Such a system comprises an encoder that encodes a characteristic of pixels of a plurality of images of a view set to form an encoded image to permit viewing of respective images of said view set according to view angle where the encoded image has a printing size that is less than an area defined for a printed credential; an assembler that combines the encoded image with a non-encoded image into a credential image, and a printer to print the assembled image on the medium. 
         [0013]    A further aspect of the invention comprises a batch of credentials produced during a production run that includes a credential medium on which each credential is placed. The medium includes a print medium and a polyoptic lens layer having a pattern of lens elements; and at least two credentials of the batch includes unique encoded images embodying pixels of at least two images having pixels encoded on the medium relative to the lens elements to enable, for each credential, a separate viewing of a distinct image according to a view angle. The pattern of lens elements may be rows of generally convex lenses. In addition, the pitch or frequency of the rows may vary within a polyoptic region. 
         [0014]    A further aspect of the invention comprises a batch of credentials printed on a credential medium that includes at least one polyoptic lens layer having a plurality of lenses to enable viewing of respective images of a view set according to a view angle where the batch of credentials is produced by retrieving a view set that includes at least two images; providing an encoding scheme that defines a characteristic of pixels of respective images of said view set; assigning the characteristic to pixels of respective images thereby to form an encoded image; and printing the encoded image on the polyoptic lens layer of the medium according to the characteristic thereby to produce the batch of credentials each enabling viewing of respective images of their own view set according to a view angle. 
         [0015]    A yet further aspect of the invention comprises a group of credentials printed on a credential medium that includes at least one polyoptic lens layer having a plurality of lenses to enable viewing of respective images of a view set according to a view angle. Such a group of credentials may be produced by obtaining an encoded image that embodies a view set of at least two images; assigning respective locations of pixels of the encoded image on the medium according to a pattern of the plurality of lenses and a view angle of each image of the view set; and for each credential of the group, printing the encoded image on the medium according to assigned pixel positions. 
         [0016]    Another aspect of the invention comprises a set of credentials each being printed on a credential medium that includes at least one polyoptic lens layer having a plurality of lenses to enable viewing of respective images of a view set according to a view angle where the set of credentials is produced by, for at least two credentials of the set, encoding pixels of a plurality of images of a view set to form an encoded image; assembling the encoded image with a non-encoded image into a credential image; and printing the credential image onto the medium wherein the encoded image is printed onto a polyoptic area of the medium and the non-encoded image is printed onto a non-polyoptic area of the medium. 
         [0017]    In yet another aspect of the invention, there is provided a plurality of credentials each being printed on a credential medium that includes at least one polyoptic lens layer having a plurality of lenses to enable viewing of respective images of a view set according to a view angle where each credential is produced by retrieving a dynamic image layer that includes an encoded image formed of a plurality of images having an encoded pixel characteristic wherein at least one of the plurality of images is unique to a first credential; retrieving a static background layer that is not unique to the first credential; assembling the dynamic image layer and the static background layer into a first credential image; and printing the first credential image and a second credential image together onto a single medium wherein said dynamic layers are printed in respective polyoptic areas of the medium. 
         [0018]    A credential medium is disclosed as well as a system and method to generate an image for printing onto a medium, substantially as shown in and/or described in connection with at least one of the figures, and as set forth in the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0019]    In order to describe the manner in which the above-recited and other advantages and features of the invention can be obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
           [0020]      FIG. 1  illustrates an embodiment of a credential production process. 
           [0021]      FIG. 2  illustrates an example of a credential medium and various image frames viewable upon a change of view angle. 
           [0022]      FIG. 3  illustrates a flowchart of a process of generating credential image components based on credential data in a remotely or locally accessed database. 
           [0023]      FIG. 4  illustrates an example of data elements that may be incorporated into a credential. 
           [0024]      FIG. 5  illustrates an example of a credential that uses a credential medium comprising a number of polyoptic or lens regions overlying a sheet medium. 
           [0025]      FIG. 6  illustrates an example of layers incorporated into a finished credential formed on a portion of print grid. 
           [0026]      FIG. 7  illustrates an example of interlaced image frames viewable in accordance with placement of pixel elements of respective image frames on a medium. 
           [0027]      FIG. 8  illustrates an example of view sets (e.g., sets of image frames) viewable on respective regions of a credential medium in accordance with a change in view angle or viewing position. 
           [0028]      FIG. 9  illustrates an example of encoding or pixel interlacing to create an underlying combined or interlaced image embodying respective image frames the become separately viewable in response to a change in viewing angle or position. 
           [0029]      FIG. 10  illustrates an example of assembling multiple polyoptic regions to produce a credential. 
           [0030]      FIG. 11  illustrates an example of tiling multiple credentials on a sheet medium. 
           [0031]      FIG. 12  shows a variable lens pitch or frequency, which may be formed in polyoptic regions. 
           [0032]      FIG. 13  shows different shaped lenses in a variable lens configuration that may be incorporated in a polyoptic region of an encoded credential. 
           [0033]      FIG. 14  shows an arrangement of horizontal and vertical rows of lens that may be incorporated in a polyoptic region. 
           [0034]      FIG. 15  shows a variable pitch lens that may be incorporated into a lens arrangement similar to that shown in  FIG. 14 . 
       
    
    
     DETAILED DESCRIPTION  
       [0035]    Various embodiments of the invention are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the invention. 
         [0036]    The teachings of the present invention enable the creation of a tamper-proof, tamper-evident, anti-counterfeiting credential management system and method. In general, a credential can represent any printed item utilized to identify and/or authenticate an individual, item, or representation of an individual or item. Examples of a credential include identity cards, citizen cards, driver&#39;s licenses, passports, work permits, breeder documents (e.g., social security card, birth certificates), social/medical benefits cards (e.g., health, dental, prescription, vision, unemployment, etc), tickets, labels, seals, tags, packaging, certificates of authenticity, container seals, etc. As such, the principles of the present invention can be applied in various industries or markets such as advertising, promotions, software, pharmaceuticals, tobacco, spirits, replacement parts, luxury goods, banknotes, IDs, packaged entertainment, ticketing, etc. 
         [0037]      FIG. 1  illustrates an embodiment of a credential production process. To facilitate the construction of credentials, the credential production process can be described as a system that mimics an assembly line, wherein raw biometric and biographic data of an individual is used to create a finished credential. 
         [0038]    The credentials produced by the credential production process are created using polyoptically-encoded images. In general, a polyoptically-encoded image is formed using a printed image and a polyoptic lens layer through which the printed image is viewed.  FIG. 2  illustrates an example of a credential medium comprising a lens layer and print layer. In one embodiment, the credential medium includes a polyoptic lens layer in the form of a sheet of plastic screen on which a series of convex or parabolic lenses are molded in parallel rib-like rows. A print enhancement coating to enable adherence of printing ink, such as a coating commercially known as Topaz, is placed on a back side of the polyoptic lens layer and an image is printed onto the coating, or directly onto the lens layer. In this case, each of the individual polyoptic lenses magnifies a small portion (e.g., a few pixels wide) of the image that is printed on the coating underlying the polyoptic lens layer. Instead of rib-like rows, the lenses may be molded in other patterns. Alternatively, instead of a coating, the lens layer and a separate print medium may also be laminated or otherwise combined together or combined with other layers to form a polyoptic print medium. As illustrated, three strips taken from respective images A, B, and C are printed behind respective rows of the polyoptic lens layer. In this arrangement, as the viewer changes the angle of view, the strip that is being magnified by the polyoptic lens layer also changes. The resulting change between images A, B, and C in association with the change in angle of view produces an animation effect between images A, B, and C. Although only three image strips are shown, the number of image strips and rows of the polyoptic print medium may vary from a lower or higher number, e.g., ten or more—being limited only by the printing and registration accuracy. 
         [0039]    As illustrated, the credentials move through six different stages of processing, starting with raw data and ending with a finished physical credential. The stages are illustrated as follows: retrieval stage  102 , which includes data element  104  retrieval from the database; converting stage  106 , which includes conversion of the raw data into graphical elements; encoding stage  110 , which includes encoding of the graphical elements for viewing through the polyoptic lens layer; a RIP&#39;ing stage  114  which includes converting the image to a print-ready format; tiling stage  118 , which includes consolidation of multiple credentials onto a single sheet  120  for printing, and printing stage  122 , which includes physical printing of the credentials and/or assembly of the separate layers, if appropriate. 
         [0040]    These six stages are processed, in order, for each credential. In various scenarios, there may be dependencies between the different stages depending on the complexity of the credential, such as data characteristics, polyoptically based effects, printing hardware, etc. In certain cases, the order of processing may vary and certain steps may be omitted. Additional steps may also be incorporated. 
         [0041]    As illustrated, stages produce artifacts that are described herein as products. These products represent partially finished components of the final credential. For example, the first product is produced by retrieval stage  102 , which product is consumed by converting stage  106 . Each stage may produce more than one of these products. In the embodiment of  FIG. 1 , the five illustrated products include the following: element product  104 , which includes the raw data (biometric, biographic, or any unique identifying information such as a bar code, serial number, product tag, etc.) of the credential; view product  108   a,    108   b,  etc., which includes a subset of a polyoptic view of the credential, layer product  112   a,    112   b,  etc., which includes a single image layer of the credential, credential product  116 , which includes a print-ready representation of the credential, and sheet product  120 , which includes a print-ready layout of a plurality of credentials. The final result of the process is the finished, printed credential, which is produced by printing stage  122 . 
         [0042]    Retrieval stage  102  is the first stage and includes basic setup and packaging of data. The input to retrieval stage  102  is the credential&#39;s ID that is used to universally describe a single credential throughout its entire lifetime. 
         [0043]    A primary purpose of retrieval stage  102  is to take a credential ID and retrieve all relevant data. In one embodiment, retrieval stage  102  would retrieve biographic text data, biometric graphic data, and template data that will be used in constructing the credential. In one embodiment, the template data defines what data is to be included in the credential, where data is to be placed (layout), and any dynamic data relationships. This retrieved data is packed into an element product, which would then be consumed or used by the subsequent converting stage  108 . 
         [0044]    As noted, retrieval stage  102  can be designed to retrieve personal information such as biometric text data (e.g., name, address, security level, seat number, etc.) and biometric graphic data (e.g., picture, fingerprint, or any other unique identifying formation such as a bar code, SKU number, etc.). In one embodiment, retrieval stage  102  can also be designed to determine and retrieve personalized data relationships. In general, the appearance of any element or set of elements may be modified based on information derived through dynamic data relationships defined in a credential template. For example, a dynamic data relationship can be defined that would optically generate a certain advertisement on an admission ticket based on a row number for the ticket. As would be appreciated, the dynamic data relationship can be driven by any piece of data that is associated with a given credential. 
         [0045]    In one embodiment, defining a template involves two separate processes: 1) identifying the personal data elements and specifying where on a credential medium these elements are to be placed, and 2) specifying any relationship(s) between personalized elements such that a specific value of element one determines the value of element two. For example, an employee type element (contractor, full-time, part-time) could determine the color of the frame around the employee&#39;s portrait when placed on the medium. 
         [0046]      FIGS. 3 and 4  illustrate an example of a positional relation between retrieved data and a credential printed or placed on a credential medium  400 . In this example, three types of data are retrieved by retrieval stage  102  ( FIG. 1 ). This may include biometric text data  310   a,    310   b,    310   c,  biometric graphic data  320   a,    320   b,    320   c,  and template data  330 . Polyoptic medium  400  has a variable lens layer structure that provides a plurality of regions  410 ,  420 ,  430 . Each region generates a different visual effect when visually examined by a user. In the illustrate example, region  410  has lenses arranged in vertical rows, thereby providing a first animated effect when the angle of view is swept horizontally. Region  420 , on the other hand, has lenses arranged in horizontal rows, thereby producing a second animated effect when the angle of view is swept vertically. Finally, region  430  is designed to produce no animated visual effect when changing the angle of view. It should be noted that in this example, different regions of the polyoptic medium  400  are produced using different orientations of lenses. In other embodiments, different regions of a polyoptic medium can be produced by sets of lenses having different planar configurations, lens shapes or properties, focal points, frequencies or row periodicity, and/or orientations. Thus, a variety of visual effects of a credential may be generated upon changing the angle of view of the medium. 
         [0047]    In the example of  FIG. 4 , biometric text data  310   a,    310   b,    310   c  are mapped to region  410 , biometric graphic data  320   a,    320   b,    320   c  are mapped to region  420 , and data identified by template  330  is mapped to region  430 . In this arrangement, the credential produced by polyoptic medium  400  would produce a first animation in region  410  when the credential is moved in relation to the eye horizontally and a second animation in region  420  when the credential is moved in relation to the eye vertically. In general, one or more effects can be obtained by moving the credential or angle of view in any direction relative to the eye, which change would create a view of different image data printed behind respective lenses of the polyoptic medium. 
         [0048]    Converting stage  106  ( FIG. 1 ) operates on or transforms element product  104  obtained by retrieval stage  102 . Here, all of the text data in element product  104  is extracted and rendered as graphical elements and all of the graphic data (including any rendered text) are scaled and processed to match the template&#39;s specifications. 
         [0049]      FIG. 5  illustrates an embodiment of a conversion process based on a template defining a plurality of layers. In the example of  FIG. 5 , the template defines three layers: top layer  510 , dynamic layer  520 , and background layer  530 . Both top layer  510  and background layer  530  may comprise static images that are defined components of the design template. Dynamic layer  520 , on the other hand, incorporates dynamic data elements such as personal information and personalized data of an individual. As illustrated in  FIG. 5 , dynamic layer  520  is designed to incorporate two views (i.e., source images) that are auto-generated from SVG templates and personalized data elements that are generated based on pre-defined dynamic data relationships. 
         [0050]    The three layers  510 ,  520 , and  530  are combined into a single composite image for a single credential  540  in a print-ready grid. Here, it should be noted that each credential in the print-ready grid would have data that is generated by its own respective dynamic layer. Accordingly, each credential in the print-ready grid would be distinct since it is based on a unique set of data. 
         [0051]    The print-ready grid that is ultimately generated is designed to be applied to a polyoptic medium that defines a plurality of regions for each credential. Each of the plurality of regions for a credential can produce a different polyoptic effect for the underlying set of source images. Each individual source image is called a view, and a set of source images is called a view set. As the credential is moved relative to the eye, a different view in a view set will be visible. In this way, a view is similar to a single frame of an animation. Rather than the views changing over time, the views change depending on the orientation of the credential. The views are grouped together in a view set based on the template specifications. 
         [0052]      FIG. 6  illustrates the relation between frames and a view set. As illustrated, printed behind a lens element  610  of the medium is a set of addressable frames  1 - 8  that are visible behind lens  610  depending on the view angle. In one example, these eight addressable frames would result when an 800 dpi printer is used with a polyoptic area having a periodicity, pitch or frequency of 100 lenses/inch (lpi). 
         [0053]    Each view in a view set is assigned to one or more frames. In the example of  FIG. 6 , views V 1 , V 2 , and V 3  are assigned to frames  1 - 8 . As illustrated, view V 1  is assigned to frames  1 - 3 , view V 2  is assigned to frames  4 - 6 , and view V 3  is assigned to frames  7 - 8 . In this assignment, the animation of views V 1 , V 2 , V 3  in the view set would be seen as lens  610  sequentially brings the data in frames  1 - 8  into view. 
         [0054]    For example, if an effect is desired wherein all the text images are to move from red to blue to green, then the following three template files are defined: one that specifies the text elements as red, one that specifies the text elements as blue, and one that specifies the text elements as green. Here, each SVG element defines a view of the data that will be encoded with all the other views to create the dynamic layer of the credential. 
         [0055]    Each of these views is then assigned to some set of underlying frames. If eight frames exist and a smooth color change is desired, then the first view can be assigned to frames  1 - 3 , the second view assigned to frames  4 - 6 , and the third view assigned to frames  7 - 8 . This view to frame assignment can be handled by mask parameters defined in the template. For example, each view element can have a plurality of values that specifies the view number and the number of frames on which that view will appear. In the above example the polyoptic mask would look as follows: View( 1 , 3 ); View( 2 , 3 ); View( 3 , 2 ). Here, there are three views. View  1  is placed on the first three frames, view  2  is placed on the next three frames and view  3  is placed on the last 2 frames. The result of looking at this encoded image would then be a transition of the font color from red to blue to green as the credential was moved relative to the eye. 
         [0056]      FIG. 7  illustrates the relation between view sets and regions on a polyoptic medium. As illustrated, polyoptic medium  700  includes regions  710 ,  720 , and  730 . Region  710  defines a field providing a vertical polyoptic effect and has view set A assigned to it. View set A consists of three individual views. Region  720 , on the other hand, defines a field providing horizontal polyoptic effect and has view set B assigned to it. View Set B also consists of three individual views. Lastly, Region  730  defines a no effect region and has view set C assigned to it. View set C consists of a single view. 
         [0057]    As illustrated, each of view sets A, B, and C span single regions on the polyoptic medium. It should be noted, however, that it is possible for a single graphic (or text) to span more than one region on the medium. In this case, the source images may be altered, cropped, or combined to create the appropriate views for a particular region. 
         [0058]    In encoding stage  110  ( FIG. 1 ), views created by converting stage  106  are encoded to create a single image. An encoded image is designed to be viewed under a polyoptic lens layer and is specially formatted to display a single view depending on the angle of view of the image. As noted above, the encoded image produced by encoding stage  110  is a layer, such as dynamic layer  112   a.    
         [0059]    Different types of polyoptic material can create different effects. It therefore follows that for each polyoptic effect a different encoding process can be used to encode the views. In one embodiment, there is a library of encoders, each one containing a distinct encoding process. By way of example, polyoptic materials include plastics commercial known as PET, PETG, PVC, PBT, Lenstar, etc. 
         [0060]    Each view set for a particular region on the polyoptic medium is encoded by a single encoder to create a single layer. Since there can be multiple effect types per credential, there can be multiple encoders in use at a single time, each one processing a different view set and creating a different layer. For example, visual or polyoptic effects such as appear/disappear, color switch, color wash, image switch, animation, movement, moving pattern, parallax, size change, etc. can be implemented. A combination of these effects may also be implemented. In any given field or region on the medium, the lens pitch or frequency may also vary to provide additional effects from, for example, from one hundred to three hundred lenses per inch, more or less with a corresponding variation in printing density (e.g., dpi) or resolution to accommodate frame assignments. 
         [0061]      FIG. 8  illustrates an example illustration of encoding stage  110 , which process will be described with reference to the flowchart of  FIG. 9 . As illustrated in the flowchart of  FIG. 9 , the encoding process begins at step  902  where a view set is retrieved. This view set is illustrated in the example of  FIG. 8  as containing views (or images)  812 ,  814 ,  816 . Each of views  812 ,  814 ,  816  represents a distinct image that will be in view when the credential is held at a certain viewing angle. When viewed sequentially, views  812 ,  814 ,  816  would then provide a certain polyoptic effect. 
         [0062]    For example, views  812 ,  814 , and  816  can contain an object at three different positions, wherein the sequential viewing of those three object positions would produce an animation effect. In another example, views  812 ,  814 , and  816  can contain three different images (e.g., picture, fingerprint, and company logo) that would alternatively appear in a single region on the credential depending on the angle of view. As would be appreciated, the content and relation between the various views would be dependent on the type of polyoptic effect desired in that region of the credential. 
         [0063]    In the example of  FIG. 8 , the encoding process is designed to generate a print-ready image that can be applied to a region of polyoptic medium that has vertically-aligned lenses designed to produce a horizontal polyoptic effect. The generation of the print-ready image that can be applied to that region of polyoptic medium is the responsibility of encoder  820 . As would be appreciated, encoder  820  is specifically designed to produce a print-ready image for a defined polyoptic region. 
         [0064]    It is a feature of the present invention that a single credential can have multiple regions with distinct polyoptic properties. For example, a single credential can have a first region with vertically-aligned lenses designed to produce a horizontal polyoptic effect, and a second region with horizontally-aligned lenses designed to produce a vertical polyoptic effect. This example illustrates regions that have a different orientation property. In another example, a first region can have 100 lenses/inch, while a second region can have 50 lenses/inch. This example illustrates regions that have a different lens frequency property. In general, the various distinct polyoptic regions defined for a credential can differ in one or more of the size, occurrence, direction, orientation, frequency, or lens shape properties. 
         [0065]    To generate a print-ready image for a distinct region having defined polyoptic properties, a specific encoder is used. The specific encoder for the distinct region is selected at step  904 . This selected encoder is designed to generate an image (from the retrieved view set) that corresponds to the individual lens areas within the distinct region. As multiple regions with distinct polyoptic properties can be defined for a single credential, multiple encoders, or multiple configurations of an encoder, can be used. 
         [0066]    After the particular encoder is selected, the view images in the retrieved view set are encoded at step  906  into, for example, an assigned frame. In one embodiment, a bitmask encoder is used that is designed to encode a series of input images together to form a final, polyoptic-oriented image using pre-determined, and cached, bitmasks (or polyoptic screen filters). For each input image, a bitmask is created that represents which pixels should, or should not be included in the final encoded image. Which pixels are filtered out is governed by the desired polyoptic medium configuration. This configuration could relate to different lens sizes, occurrences, directions, orientations, frequencies, or shapes. In one embodiment, these bitmasks are represented as a series of high (white) and low (black) pixels that mean include-this-pixel and do-not-include-this-pixel, respectively. After creation, the bitmasks are cached in memory where they can be used again and again. 
         [0067]    During processing, each input image has its corresponding bitmask applied to it using a bitwise AND operation (e.g., any pixel which is non-black in both the input image and the bitmask is kept). Once each of the input images has been filtered, they are combined into a final, encoded image using a bitwise OR operation (e.g., keep any pixel which is non-black in any of the images). 
         [0068]    In the example of  FIG. 8 , encoder  820  encodes bitmask segments  812   a,    814   a,  and  816   a  (taken from views  812 ,  814 , and  816 , respectively) into an area  832  of layer  830 . Area  832  is the area defined for a single lens in a polyoptic region. As illustrated, a second set of bitmask segments (also taken from views  812 ,  814 , and  816 , respectively) would be encoded into the next lens-defined area  834  of layer  830 . This process would be repeated to cover the entire layer  830 . 
         [0069]    At step  908 , the resulting encoded image is included in the dynamic layer. At step  910 , it is then determined whether there are any additional view sets to be processed. As noted, these additional view sets can be assigned to other regions of the credential that have different polyoptic properties. If there are additional view sets to be processed, then the process would return to step  902 , where the additional view set is retrieved for processing. Here, it should be noted that while the example flowchart of  FIG. 9  illustrates sequential processing of view sets, actual implementations can choose to process the view sets in parallel. Once a credential is complete it may then be converted to a print ready format through the RIPing stage. 
         [0070]    If, at step  910 , it is determined that there are no more view sets to process, then the process continues at step  912 , where the various layers (e.g., top, dynamic, background) are assembled. In general, the layers that were generated by encoding stage  110  are each pieces of the final credential, much like pieces of a puzzle. These layers are assembled by assembling stage  114  to create a single credential image  116  that can be used at a later stage for printing. 
         [0071]    As noted, assembling stage  114  can also merge static (possibly non-encoded or pre-encoded) layers together with the encoded layers. A single layer may not need to be encoded and can be merged with the final credential image without any additional processing. This layer can be merged over or under the encoded layers, as a background or foreground.  FIG. 10  illustrates an example of the assembly process, wherein encoded layers  1020 ,  1030  and static layer  1040  are merged together into a single credential image defined by template  1010 . 
         [0072]    Depending on the printer hardware it may be possible to fit more than one credential on a single sheet of polyoptic material, thereby allowing multiple credentials  116  to be printed at once. Tiling stage  118  creates a blank canvas, called a sheet, and then arranges one or more credentials  116  on sheet  120 . Once sheet  120  is full, or there are no more credentials  116  to print, sheet  120  is sent to printing stage  122 .  FIG. 10  illustrates an example of the tiling process, where credential  1110  is added to sheet  1100 . 
         [0073]    Printing stage  122  is the final stage in creating a credential. Here, sheet  120 , which contains a plurality of credentials, is printed to the polyoptic material. Printing stage  122  manages the printer hardware and delivers sheet  120  to the printer. 
         [0074]    Depending on the printer hardware and configuration, this may be a direct request to the printer, the sheet file may be placed into some sort of “hot folder”, or some other mechanism may be used to print sheet  120 . In one embodiment, printing stage  122  is hardware dependent to enable it to take full advantage of the hardware being used. 
         [0075]    As sheet  120  includes a plurality of credentials, the image file produced by tiling stage  118  can be quite large. In one example, sheet  120  is embodied as a TIFF file that can be larger than 500 MB though the system may be configured to write out files with compressed formats specific to individual printers. 
         [0076]    In one embodiment, a streaming TIFF encoder is used to accommodate the large TIFF file sizes. This streaming TIFF encoder is a means by which exceptionally large TIFF files (e.g., 500 MB or higher) can be created and managed in such a way that only a fraction of the image remains in memory at any one time. 
         [0077]    To create such an image, certain predefined data is known up front. These data include, but are not necessarily limited to: the final image dimensions, the color depth (e.g., 3-byte RGB, 4-byte CMYK, etc.), and individual tile dimensions. To construct the image, smaller “tiles” are created that represent smaller, isolated areas of the full image. Upon creation, a blank TIFF file is written piece-meal, wherein a standard TIFF header is written, followed by a section of small (1 to 4 bytes, generally), repeating picture elements representing a white (or some other solid color) field. Then, as each individual tile of the output image is generated, it is written to a specific section of the file so that it will appear in the correct location of the final, composite image. 
         [0078]      FIG. 11  illustrates an example of tiling multiple credentials on a sheet medium prior to being scored and/or cut from a sheet. 
         [0079]      FIG. 12  shows a variable lens pitch or frequency, which may be formed in polyoptic regions. Pixel locations of printed images of a view set may be arranged (i.e., encoded) to accommodate the respective pitches of the lenses to produce a unique effect in each of the variable pitch regions. This way, encoding techniques may be expanded beyond a single-pitch arrangement. 
         [0080]      FIG. 13  shows different shaped lenses in a variable lens configuration that may be incorporated in a polyoptic region of an encoded credential, which generated yet further unique visual effects in response to a changing view angle. 
         [0081]      FIG. 14  shows an arrangement of horizontal and vertical rows of lens that may be incorporated in a polyoptic region. In this arrangement, separate and distinct visual effects are generated differently for vertical and horizontal sweeps in view angel. 
         [0082]      FIG. 15  shows a variable pitch lens that may be incorporated into a lens arrangement similar to that shown in  FIG. 14 , but produces in further distinct visual effects. 
         [0083]    As apparent, encoding of images according to numerous combinations of lens structures and arrangements may be incorporated on a credential to achieve security, unique and varied visual effects, anti-counterfeit or other measures. In addition, the lens layer may be formed to include non-polyoptic regions that produce no visual effect upon the underlying image. Instead of having lens formations, these regions may simply be planar or a complete absence of material in regions in which no visual effect is desired. 
         [0084]    These and other aspects of the present invention will become apparent to those skilled in the art by a review of the preceding detailed description. Although a number of salient features of the present invention have been described above, the invention is capable of other embodiments and of being practiced and carried out in various ways that would be apparent to one of ordinary skill in the art after reading the disclosed invention, therefore the above description should not be considered to be exclusive of these other embodiments. For example, although the illustrated polyoptic material is characterized by rows of lenticular lenses, a matrix or other pattern of lens elements may also be provided to generate polyoptic effects. An encoded image that makes up a view set may be interlaced, interleaved, combined or mixed by other patterns. Phraseology and terminology employed herein are for the purposes of description and should not be regarded as limiting. A database or data store may be a digital data stored in a memory device or a physical list of information (manually or automatically generated) from which data is obtained or retrieved manually. A lens may comprise any light-bending, frequency-shifting, or focusing medium of any shape. A polyoptic effect includes a change in visual effect in response to a change in view angle, whether in color, picture, motion, animation, visual effect, or any other visual phenomenon. Retrieval may be accomplished manually or electronically by a computer device. A medium or sheet on which an image is printed may comprise any natural or synthetic material that carries a printing substance, e.g., ink. Thus, the invention defined by the appended claims is not limited by the specific illustrations described above. Different embodiments can be formed by different combinations of the features described herein. It is intended that polyoptic and non-polyoptic regions can be placed on one or both sides of the credential medium.