Method and system for client-less viewing of scalable documents

Abstract

A method and system for viewing a document containing at least one page and at least one image, the document being located on a server computer, including sending by a client computer a page display request to the server computer creating by the server computer a layout page containing a reference to stored image data, transmitting the layout page from the server computer to the client computer, sending an image data to a remote computer according to the reference to stored image data, and transmitting requested image data from the remote computer to the client computer in response to the image data request.

Claims

What is claimed is:

1. A method for on-line accessing of client-selected scaled versions of one particular original document containing at least one page containing content other than an image and at least one high resolution raster graphics image in non-scalable PDF format, the one particular original document being located on a server computer, the method comprising the operations of:

sending by a client computer a page access request to the server computer;

creating by a rendition tool at the server computer a scalable document from an original document file located on the server computer, the original document file representing the one particular original document, the scalable viewable document containing the content other than the image and not containing the high resolution raster graphics image in non-scalable PDF format and containing a reference to stored image data;

storing the high resolution raster graphics image in non-scalable format as the stored image data, the stored image data representing the one particular original document;

transmitting the scalable viewable document from the server computer to the client computer;

sending by the client computer an image data request to the server computer to access a client-selected scaled version of the stored image data representing the one particular original document; and

transmitting the requested client-selected scaled version of the stored image data from the server computer to the client computer in response to the image data request.

2. The method as recited in claim 1, further comprising the operation of:

reversing the operations of the rendition tool to complete the accessing of the one particular original document located on the server computer, the reversing being by composing the client-selected scaled document based on the one particular original document, the composing replacing the original high resolution raster graphics image in non-scalable PDF format that was contained in the one particular original document with image data representing the client-selected scaled version in non-scalable format, the client-selected scaled version being scaled at an appropriate resolution for access by a client-selected one of a view operation, a print operation, and a save operation.

3. The method as recited in claim 1 wherein the reference to stored image data is a URL.

4. The method as recited in claim 1 wherein the image data request contains a command specifying a rectangular portion of a raster image and a display width and height.

5. The method as recited in claim 4 wherein the command specifying a rectangular portion of a raster image and a display width and height is a CVT command from an Internet Imaging Protocol.

6. The method as recited in claim 1 wherein the image data request by the client computer comprises resolution independent coordinates defining the location of a corner of a rectangle and defining the height and width of the rectangle represented as respective percentages of the respective total height and width of the original high resolution raster graphics image in non-scalable PDF format.

7. The method as recited in claim 1 wherein: the image data request further comprises an identification of any resolution that is appropriate for a client computer operation taken from the group consisting of viewing, printing, and saving the original document; and

the page access request enables the accessing at the client computer of the one particular original document having the resolution appropriate for the viewing, saving or printing of the client-selected scaled version of the one particular original document.

8. The method as recited in claim 1 wherein:

the page access request is to enable the viewing at a screen of the client computer of the one particular original document by viewing the entire high resolution raster graphics image scaled to a size of the screen, and

the image data request is defined by a continuous two-dimensional coordinate system with coordinates x and y ranging over the rectangle that is normalized as a unit, defined by 0 <x<1, 0<y<1, wherein the rectangle corresponds to the screen when x and y both equal zero and each of a height value and a width value equals 1.

9. The method as recited in claim 8 wherein:

the image data request is to view a portion of the entire high resolution raster graphics image, and the portion may be selected from any location of the screen by designating a value of each of the x and y coordinates between zero and one and designating the height value and the width value, each between zero and one.

10. The method of claim 1 wherein the image data request identifies a rectangular portion of the original high resolution raster image to be accessed and a designated resolution.

11. The method of claim 10 comprising the operations of:

repeating the sending operation to request different client-selected scaled versions of the stored image data resulting from the one particular original document, scalability of the different versions being obtained by one or both of appropriate client-initiated changes in the rectangular portion and the designated resolution.

12. The method as recited in claim 1 wherein:

the operation of transmitting the requested client-selected scaled version of the stored image data comprises producing at the server computer the client-selected scaled version of the one particular original document from the content other than an image and from the stored high resolution raster graphics image in non-scalable PDF format, and the method further comprising the operation of:

displaying the client-selected version of the one particular original document containing the content other than the image and containing the client-selected scaled version of the requested stored image data.

13. A method for on-line viewing of client-selected scaled versions of one particular original document containing at least one page containing content other than an image and at least one high resolution raster graphics image in non-scalable PDF format, the one particular original document being located on a server computer, the method comprising the operations of:

sending by a client computer a page access request to the server computer;

creating by a rendition tool at the server computer a scalable viewable document from an original document file located on the server computer, the original document file representing the one particular original document, the scalable viewable document containing the content other than the image and not containing the high resolution raster graphics image in non-scalable PDF format and containing a reference to stored image data of the one particular original document;

storing the high resolution raster graphics image in non-scalable format as the stored image data of the one particular original document;

transmitting the scalable viewable document from the server computer to the client computer;

sending by the client computer an image data request to the server computer to access a client-selected scaled version of the stored image data of the one particular original document, the image data request comprising image processing commands;

processing the image data commands at the server computer to produce the client-selected scaled version of the stored image data of the one particular original document; and

transmitting the requested client-selected scaled version of the stored image data of the one particular original document from the server computer to the client computer in response to the image data request.

14. The method of claim 13, comprising the further operations of: sending by the client computer a next image data request to the server computer to access another client-selected scaled version of the stored image data of the one particular original document, the next image data request comprising next image processing commands;

processing the next image data commands at the server computer to produce a next client-selected scaled version of the stored image data of the one particular original document;

repeating the sending operation to request the next client-selected scaled version of the stored image data of the one particular original document, scalability of the next client-selected scaled version being obtained by one or both of appropriate client-initiated changes in the rectangular portion and the designated resolution.

15. The method of claim 13, comprising the further operations of:

repeating the reversing of the operations of the rendition tool to complete the accessing of the one particular original document located on the server computer by composing a next scaled viewable document based on the one particular original document, the repeated composing replacing the original high resolution raster graphics image in non-scalable PDF format that was contained in the one particular original document with the image data representing the next client-selected raster version of the graphics image in non-scalable format of the one particular original document, the next client-selected scaled version being scaled at an appropriate resolution for access by a client-selected view operation.

16. A method for viewing of a client-selected scaled version of one particular original document on a low resolution screen of a client document viewing computer in a system with a document server computer, the one particular original document containing high resolution raster graphics images in non-scalable PDF format and scalable content other than an image, the method comprising the operations of:

sending by a client computer a document viewing request to the document server computer which is storing the one particular original document to be viewed;

extracting data from the one particular original document to form a scalable document that does not contain the high resolution raster graphics image, the scalable document containing the scalable content and a reference to the high resolution raster graphics image from the one particular original document;

storing on the document server computer as stored image data, the high resolution raster graphics image in non-scalable PDF format extracted from the one particular original document;

receiving at the client computer the scalable document from the document server computer in response to the document viewing request;

sending by the client computer a client-selected image data request to the document server computer, the client-selected image data request being modeled by a continuous two-dimensional coordinate system with coordinates x and y ranging over a rectangular view region and having any value from zero to one, wherein a zero value represents an edge of the low resolution screen, wherein a one value represents a value of an entire dimension of the low resolution screen in a respective direction of the x or y coordinate, wherein a value between zero and one of each of the coordinates represents any location on the low resolution screen at which a top-left corner of the rectangular view region is located, the image data request also comprising a width value and a height value representing respective values of the size of the rectangular view region in the respective directions of the x and y coordinates referenced to the top-left corner, the client-selected image data request further comprising client-selected ones of the values for the x and y coordinates and client-selected values of the width value and the height value, the client-selected image data request further comprising a pair of discrete pixel dimensions representing the height and width of a pixel array;

receiving at the client computer image data from the image server computer in response to the client-selected image data request, the image data relating to the one particular original document and conforming to the client-selected image data request by comprising data representing the values of the x and y coordinates specifying the location of the top-left corner of the rectangular view region and representing the width value and the height value of the rectangular view region, the image data further comprising data identifying the size in pixels of the client-selected version on the low resolution screen; and

by a delivery tool substituting the image data for the reference to the high resolution raster graphics image of the one particular original document, the substituted image data converting the scalable document to the client-selected version of the one particular original document for viewing on the low resolution screen at the client computer.

Description

FIELD OF THE INVENTION

The present invention relates to electronic documents containing raster images.

BACKGROUND OF THE INVENTION

PostScript is a resolution-independent format. Fonts can be enlarged or reduced in size to accommodate any viewing resolution. When a viewer zooms in or out of a document, the text characters automatically scale accordingly. Thus it can be said that font characters are "scalable."

Similarly, graphical objects based on vector graphics consisting of line segments and curves are also scalable. The line segments and curves can be enlarged or reduced in size by appropriately modifying the pixel coordinates of their control points.

Raster graphics, on the other hand, is not scalable. An image expressed in raster graphics is by its nature pixel resolution specific, and to enlarge or reduce the image involves digital image filtering and interpolation. Moreover, a raster image cannot be stretched beyond its original pixel resolution without introducing artificial data.

SUMMARY OF THE INVENTION

The present invention provides an electronic document, including one or more raster images, which is scalable. The raster images are referenced within the document through dynamically changing references, and it is the control of the dynamic references that provides for the scalability. The scalable document of the present invention can be enlarged or reduced to any desired resolution, making the entire document scalable--text characters, graphical objects and raster images.

Regardless of the viewing configuration, a raster image referenced within the scalable document of the present invention will automatically scale according to the viewing resolution. For example, suppose a 6".times.8" photograph is converted to a high quality digital image by scanning at 600 dots per inch (dpi). This produces a 3,600.times.4,800 pixel image, which is embedded into a page of the document.

When this page is viewed at normal size on a view monitor having 72 dpi resolution, the referenced image is scaled to 432.times.576 pixels for purposes of display. If a user zooms in by a factor of two, to see a portion of the page containing the image at higher resolution, the referenced image is scaled to 864.times.1,152 pixels. Thus the dimensions of the image referenced within the document automatically scale to twice their original values. If the document is printed on a 300 dpi color printer, the referenced image is scaled to 1,800.times.2,400 pixels in order to produce as high quality a print as possible using the color printer as an output device.

In a preferred embodiment of the present invention the referenced images are located on one or more image servers on the Internet or any other suitable computer network, and may be viewed on remote client computers. The raster images are not embedded within the scalable document, but rather are stored as separate files. The scalable document contains references to the raster images embedded therewithin, thus making the size of the scalable document relatively small. Upon display, the document will include screen-size images within it. Upon delivery or print, the document will include images scaled to the appropriate device resolution.

Each client computer preferably downloads only the portion of the image data that is necessary for satisfying a user display request, as described hereinbelow. Continuing with the example above, the 3,600.times.4,800 image uncompressed occupies a total of 51.84 MB (at 3 bytes per pixel). High fidelity compression typically reduces this by an order of magnitude, to roughly 5 MB. Rather than requiring each client to download the entire 5 MB of image data, the present invention only requires the clients to download that portion of the image data necessary to satisfy the user display request. The user display request is significantly less than the entire image size, since the maximum size image that can be viewed on a video monitor is the full video monitor pixel resolution, which may be 768.times.1,024 for example. Similarly when saving or printing the document, the user may specify a resolution less than 600 dpi for the save operation, or the printer resolution may be less than 600 dpi, in which case the client only needs to download a portion of the full image data.

The present invention also provides a rendition tool for converting standard documents with large high quality images into scalable documents, and a delivery tool for converting scalable documents into standard documents. The rendition tool is used for creating Web-Ready documents with screen-size images for interactive viewing. The delivery tool is used for saving documents containing high quality images at user specified resolutions, and for printing such documents at resolutions appropriate to specified output devices.

There is thus provided in accordance with a preferred embodiment of the present invention a method for viewing a document containing at least one page and at least one image, the document being located on a server computer, including the steps of sending by a client computer a page display request to the server computer, creating by the server computer a layout page containing a reference to stored image data, transmitting the layout page from the server computer to the client computer, sending an image data request to a remote computer according to the reference to stored image data, and transmitting requested image data from the remote computer to the client computer in response to the image data request.

There is also provided in accordance with a preferred embodiment of the present invention a system for viewing a document containing at least one page and at least one image, the document being located on a server computer, including a client computer transmitter sending a page display request to the server computer and sending an image data request to a remote computer according to a reference to stored image data, a layout page producer within the server computer creating a layout page containing the reference to stored image data, a server computer transmitter transmitting the layout page to the client computer, and a remote computer transmitter transmitting requested image data to the client computer in response to the image data request.

There is also provided in accordance with a preferred embodiment of the present invention a scalable document including at least one layout page, and at least one reference to stored image data, the at least one reference including at least one command for processing the stored image data.

There is also provided in accordance with a preferred embodiment of the present invention a method for converting a document containing at least one image into a scalable document, including extracting at least one image from the document, storing the at least one image as stored image data, and replacing the at least one image by at least one reference to stored image data, the at least one reference containing at least one command for processing the stored image data.

There is also provided in accordance with a preferred embodiment of the present invention a system for converting a document containing at least one image into a scalable document, including an object extractor extracting at least one image from the document, a storage device for storing the at least one image as stored image data, and a reference inserter replacing the at least one image by at least one reference to the stored image data, the at least one reference containing at least one command for processing the stored image data.

There is also provided in accordance with a preferred embodiment of the present invention a method for converting a scalable document into a standard document using at least one reference to stored image data, the scalable document containing at least one layout page, and the at least one reference including at least one command for processing the stored image data, including processing the stored image data in accordance with the at least one command, producing at least one image, and positioning the at least one image within the scalable document according to positioning instructions within the layout page.

There is also provided in accordance with a preferred embodiment of the present invention a system for converting a scalable document into a standard document using at least one reference to stored image data, the scalable document containing at least one layout page, and the at least one reference including at least one command for processing the stored image data, including an image processor processing the stored image data in accordance with the at least one command, producing at least one image, and an image positioner positioning the at least one image within the scalable document according to positioning instructions within the layout page.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully understood and appreciated from the following detailed description, taken in conjunction with the drawings in which:

FIG. 1 is a simplified illustration of a network configuration for Internet publishing in which a preferred embodiment of the present invention operates;

FIG. 2 is an illustration of an image portion and its relationship to tiles in one of the resolution layers of a multi-resolution image, used in connection with a preferred embodiment of the present invention;

FIG. 3 is a simplified illustration of an Internet publishing system for publishing images over the Internet or any other suitable computer network, in accordance with a preferred embodiment of the present invention;

FIGS. 4A-4C are simplified illustrations of a page with text and images from a scalable document as seen at various display resolutions, in accordance with a preferred embodiment of the present invention;

FIG. 5 is a simplified flowchart of the operation of a document viewer in accordance with a preferred embodiment of the present invention; and

FIG. 6 is a simplified illustration of a rendition tool for converting standard documents to scalable documents, and a delivery tool for converting scalable documents to standard documents.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The present invention concerns Internet publishing, and provides the capability for storing electronic documents on a web server computer and enabling remote clients to interactively view, download and print the documents using web browsers.

Internet Publishing

A web browser is software running on a client computer that retrieves HTML pages from server computers using the HTTP protocol, and displays them. A hyper-text markup language (HTML) page is typically the basic data structure for a web page that appears on a video monitor whenever one is using the Internet. An HTML page typically contains layout instructions along with text, graphical objects, links and more. Objects referenced in an HTML page but located at remotes sites are typically referenced by a universal resource locator (URL), which contains a full IP address indicating where the object is located in addition to optional instructions for processing the object. Two well-known web browsers are Netscape Communications Corporation's Netscape.RTM. Communicator and Microsoft Corporation's Internet Explorer.RTM..

A web server is software running on a server computer that delivers requested HTML pages to web browsers using the HTTP protocol.

Documents archived on a server computer can be accessed by remote client computers by means of web browsers. If a document is not in HTML format, additional server-side or client-side processing may be necessary. Such server-side processing involves auxiliary software on the server for converting each document page requested into HTML format for viewing by the client. Client-side processing involves auxiliary software used with the browser, in the form of a plug-in, an Active-X control or a Java applet, for interpreting the non-HTML format.

There is a general disinclination on the part of users to download client software, as this interrupts the web browsing and invasively installs new software on the user's computer. For example, if a user accesses a URL that requires a plug-in while browsing the web, he must download the plug-in software, exit the browser, install the plug-in and then re-initiate the browser. When server-side processing is used in such a way that no auxiliary client software is needed other than the web browser, the application is referred to as being "client-less." Client-less applications tend to be more favorable, as they do not require the user to interrupt his web browsing or to place additional software in his computer.

The present invention, as described hereinbelow, enables client-less applications to interactively view remotely located electronic documents by scaling and moving within pages.

Reference is now made to FIG. 1 which is a simplified illustration of a network configuration for Internet publishing in which a preferred embodiment of the present invention operates. A server computer 110 stores documents and HTML pages for remote access by multiple client computers 120. Server computer 110 contains a web server 130 for serving files 150 and HTML pages 160 to client computers 120 in response to requests 170. Client computers 120 typically contain web browsers 140 for displaying HTML pages 160, and typically use the links in HTML pages 160 to request documents and other HTML pages from server computer 110.

In a preferred embodiment of the present invention, the HTML pages 160 contain links 180 to objects 190, such as raster images, stored on remote computers 200 connected to the Internet.

Web browsers 140 typically can display only a limited number of different page formats, such as HTML. In order for a web browser to display a document that is not in one of the supported formats, auxiliary client software 210 may be needed to supplement the web browser so that it can interpret the document format. Alternatively, server software 220 can be used to convert the document into HTML format, so that it is ready for display by the web browser when the document arrives at the client computer. In this latter case there is no need for client software 210, and the application is client-less.

Resolution Independence

The present invention uses resolution independent image data requests to achieve scalability of raster images referenced within documents. Resolution independence is a technique for processing large digital images based on the tenet that an image can be considered as a continuum of color values distributed over a rectangular spatial region. That is, an image can be considered as a two-dimensional continuous spatial signal, analogous to a one-dimensional continuous time signal. Carrying this analogy further, a continuous "resolution-independent" image can be converted to a discrete spatial array by sampling at appropriate frequencies in each dimension, just as a continuous time signal can be converted to a discrete time signal by sampling at an appropriate rate.

Resolution independent images are modeled by a continuous two-dimensional coordinate system with coordinates x and y ranging over a rectangular region that can be normalized as the unit square, 0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1. Specifically, a resolution independent image is determined by a vector-valued function .function.(x, y), with .function.(x, y) indicating the color value at location (x, y) as x and y range over the unit square. Color is typically prescribed by multiple values within a standard color space, such as RGB or CMYK.

In distributed imaging systems, one of the most common user requests is for access to a rectangular portion of an image. A rectangular portion can be described by a set of four values (t, l, h, w), where (t, l) are the coordinates of the top-left corner of the portion, h is the height of the portion and w is the width of the portion--all four numbers being relative to the normalized unit square. Thus, for example, the portion (0.25, 0.35, 0.15, 0.3) denotes the rectangle extending from top-left corner (0.25, 0.35) to bottom right corner (0.4, 0.65). The height of this rectangle is 15% of the total height of the image, and its width is 30% of the total width of the image.

Any digital image, no matter how large, does not contain more information than the sum total of its color values. Thus, considering a digital image to be a continuum of color values is an idealization. The extent to which this idealization applies is up to the point where the pixel dimension of the original image is exceeded. For large digital images, this leaves enough room to make the idealization a practical one. This idealization is analogous to the applicability of continuum mechanics to physical bodies up to the point where the atomic level is reached.

Discretization

The present invention involves three types of client requests for documents: (i) interactively displaying and navigating through the document on a video monitor, (ii) printing the document on a local or network printer, and (ii) delivering the document to the client computer; i.e. downloading the document, such as by means of a "Save As" operation. In order to display, print or save a resolution-independent image included within a document, the image must first be converted to a pixel array, which is a raster array of discrete pixel values. The required dimensions of the pixel array determine the sampling frequencies, and as long as these frequencies are each greater than or equal to one, the conversion can be accomplished without introducing artificial data. Every request for displaying, printing or saving a portion or all of an image can be described by a rectangle in resolution-independent coordinates, as described hereinabove, together with a pair of discrete pixel dimensions representing the width and height of the pixel array. The pixel array can represent a view window for display, a dot array for printing or a raster array for saving a raster image.

Consider, for example, a 6".times.8" photograph that is converted to a high quality digital color image by scanning at 600 dots per inch (dpi). This produces a 3,600.times.4,800 pixel digital image. In order to view this entire image on a video monitor having 72 dpi resolution, the image has to be scaled to 432.times.576 pixels, which amounts to a reduction in size of the original image by a factor of 25/3=8.33 in each dimension; that is, the sampling frequency is 8.33 in each dimension. Using the resolution independent paradigm, the digital image is idealized as a resolution independent image, the rectangular portion designating the entire image is (0, 0, 1, 1) and the required view window size is 432.times.576 pixels.

If this same digital image is to be printed on a 300 dpi resolution color printer, then the relevant rectangular portion is (0, 0, 1, 1) and the required dot array size is 1,800.times.2,400 pixels. This corresponds to a sampling frequency of 2 in each dimension.

If a user wishes to display the top left quadrant of the image in a 450.times.600 view window, then the relevant resolution independent portion of the image is (0, 0, 0.5, 0.5) and the required view window size is 450.times.600 pixels. This corresponds to a sampling frequency of 4 in each dimension. On the other hand, if the user had wanted to save the top left quadrant of the image as a 2,400.times.3,200 pixel array, this would correspond to a sampling frequency of 2/3 in each dimension. In this latter case, the limits of the resolution independent idealization are exceeded.

Image distribution systems that accommodate interactive display, printing and saving (i.e. downloading) can operate by (i) storing large digital images on server computers, (ii) accepting user requests for image data from remote client computers, each request being determined by a resolution independent rectangular portion and a pixel array size, and (iii) responding to such requests by transmitting appropriate image data from a server to a remote client. The Flashpix image format and the Internet Imaging Protocol, as described hereinbelow, were designed to make Internet image distribution systems as efficient as possible, by administering a "just enough data" policy and transmitting only the minimal amount of image data necessary to satisfy a client request.

Referring back to the abovementioned example, the 3,600.times.4,800 original image occupies a total of 3.times.3,600.times.4,800=51.84 MB uncompressed, at a pixel depth of 3 bytes per pixel. High fidelity compression such as JPEG typically reduces this by an order of magnitude to roughly 5 MB. In the first scenario above, where the user requests the entire image to be displayed at 432.times.576 pixel resolution, the image to be displayed occupies only 3.times.432.times.576=746,496 bytes uncompressed, which corresponds to approximately 75 KB compressed. Rather than transmit the entire 5 MB of image data from the server to the client, an efficient image distribution system transmits only the 75 MB of data, or slightly more as described below in reference to caching, necessary to render the desired display image.

Flashpix Image Format

Multi-resolution tiled (MRT) image formats are particularly well-suited for storing resolution independent images in such a way that specified rectangular portions of such an image can be efficiently generated at specified pixel resolutions. An MRT format stores the original image together with the successively reduced versions of the image. Moreover the image data for the original image and for each reduced version thereof is partitioned into blocks called tiles. As such, an MRT format is redundant in that the reduced versions of the image can be generated form the original image data but are nevertheless stored in the file. However, the advantage of the MRT format is that lower resolution image data is readily available, and the tile structure makes it simple to access rectangular portions of the image.

FLASHPIX, a trademark of the Digital Imaging Group (DIG), is an example of an MRT image format. A Flashpix image is generated by starting with an original image and recursively subsampling it at half of the previous resolution. The recursion continues until the final sub-sampled image is reduced to a size of 64 pixels or less in each dimension. Each resolution level is partitioned into image tiles that are 64.times.64 pixels in size, and the individual tiles can be stored as uncompressed of JPEG compressed image data. A reference for Flashpix is the document "Flashpix Format Specification," .COPYRGT. 1996, 1997, Eastman Kodak Company, the contents of which are hereby incorporated by reference.

Referring back to the abovementioned example, the 3,600.times.4,800 pixel image would be stored as a Flashpix image with eight resolution layers as follows:

                Layer #7:          3,600 .times. 4,800
                Layer #6:          1,800 .times. 2,400
                Layer #5:           900 .times. 1,200
                Layer #4:            450 .times. 600
                Layer #3:            225 .times. 300
                Layer #2:            113 .times. 150
                Layer #1:             57 .times. 75
                Layer #0:             29 .times. 38

• Inventors
  Blumberg, Robert;
• Assignee
  Canon Kabushiki Kaisha (Tokyo, JP)
• Published
  Mar-29-2005
• Current US Classes:
  382/148
  382/299
  382/305
  709/203
  715/513
  715/907
  715/908
• Application #
  191867
• International Classes
  G06F 017//24; G06K 009//00
• Field of Search
  709/201 709/203 709/217 709/218 709/219 715/510 715/511 715/512 715/513 715/522 715/907 715/708 382/148 382/299 382/302 382/303 382/304 382/305
• Examiner
  Thompson; Marc D.
• Agent
  Fitzpatrick, Cella, Harper & Scinto
• US Patent References:
  6167442
  6199082
  6205452