Patent Publication Number: US-2005129269-A1

Title: Context watermark for digital contents

Description:
TECHNICAL FIELD  
      This invention relates in general to the field of electronics and more specifically to context watermarking of digital contents.  
     BACKGROUND  
      As more electronic devices like radio communication devices (e.g., cellular telephones) become capable of digital content capturing (e.g., recording voice notes, taking still images using a built-in camera or attachable camera, collecting video clips, etc.) it would be beneficial if context information like location, time and other environmental information of the digital capture is recorded along with the content information that is captured. Context information (e.g., location of captured content) is sometimes valuable to those recording a digital content like a still image, since the context information may add extra sentimental or other value to the person capturing the content.  
      Collecting context information along with the captured content requires a way of retaining the context information and help facilitate its processing as the contents get transferred and stored. It would also be beneficial if the way of retaining the context information provides privacy and security protection to prevent any non-authorized use of tampering of the context invention. Given this, a need exists in the art for a context watermarking technique and apparatus that can help address some of the problems mentioned above. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The invention may best be understood by reference to the following description, taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which:  
       FIG. 1  shows a flow diagram showing how capturing and context watermarking is performed in accordance with one embodiment of the invention.  
       FIG. 2  shows how context separation and content playback is performed in accordance with an embodiment of the invention.  
       FIG. 3  illustrates how streaming context watermarking is performed in accordance with an embodiment of the invention.  
       FIG. 4  shows how streaming content and context playback is performed in accordance with an embodiment of the invention.  
       FIG. 5  shows a flowchart highlighting some of the steps performed for context watermark insertion without encryption is performed in accordance with an embodiment of the invention.  
       FIG. 6  shows a flowchart highlighting how context watermarking with encryption is performed in accordance with an embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      While the specification concludes with claims defining the features of the invention that are regarded as novel, it is believed that the invention will be better understood from a consideration of the following description in conjunction with the drawing figures.  
      Referring now to  FIG. 1 , there is shown a flow diagram  100  showing how digital content capturing and context watermarking is performed in accordance with one embodiment of the invention. The present invention integrates digital watermark technology with content and context capturing mechanisms which can be located on an electronic device. The captured information can be encrypted for further security and also capturing can be preformed in either a still mode or a streaming mode.  
      Possible digital contents can include but are not limited to still images, video clips, voice recording, screen capturing or any other data capturing that can be digitized. Content capturing device A  102  and content capturing device B  104  can comprise but are not limited to digital camera, video recorder, microphone, etc.  
      Context capturing device A  106  and context capturing device B  108  collect context information that can include but is not limited to GPS location, time, capturing device characteristics, and other environmental variables such as lighting levels, temperature, etc. Some context capturing devices can include GPS receivers, temperature detectors, light meters, clocks, etc.  
      Coupled to the content capturing devices  102  and  104  is a digital content capturing interface  110  whose design will depend on the particular content capturing devices being utilized in a particular electronic device. The digital content capturing interface will provide any necessary hardware and/or software interface required to convert the captured content information into acceptable digital data which is stored in block  114 .  
      The context capturing devices  106  and  108  will also have a context capturing interface  112  whose design will also depend on the type of context that is being captured. The context information such as location, time, etc. is stored in block  116 . In block  118 , the context watermark is inserted with the digital content  122  and context information  124  being stored in a combined format as well be explained below in block  120 .  
      Referring now to  FIG. 5 , there is shown a flowchart on how the context watermark insertion of block  118  is performed in accordance with an embodiment of the invention. In step  502 , a Hash function (referred to as “D”) of the digital content is calculated. In step  504 , a Hash function (referred to as “C”) of the context information is calculated. In step  506 , the Hash function “D” is appended to the context information, while in step  508 , the Hash function “C” is appended to the digital content information. The augmented content and context are packaged together in step  510  (see block  118  in  FIG. 1 ) and in step  512  (see block  120  in FIG.  1 ), the Hash function values “D” and “C” bind the content and context information together.  
      It should be noted that although Hash functions are used in the described embodiment, other techniques such as using Discrete Wavelet Transforms (DWTs) or fractional-based transforms may also be used. These are ideally suited for video and audio respectively.  
      Referring now to  FIG. 2 , a simplified flow diagram  200  of how the context separation and content playback is performed is shown. The digital content  204  and context information that had been combined in block  202  as content with context watermark is sent to a context separator  208  which separates the context information  210  and the digital content information  212 . The context separator  208  parses the combined package  202  of digital content  204  and context watermark information  206 . For stationary digital content, the output is the digital content  212  and a separate context information watermark  210 .  
      In  FIG. 3 , there is shown a block diagram highlighting the use of the context watermarking technique of the present invention in a streaming context environment. When digital contents are captured continuously the context information may change continuously as well. The context watermarking scheme is illustrated for a single unit but can be extended for continuous media types. Content capturing devices A  302  and B  304  are coupled to a digital content capturing interface  310 , while context capturing devices A  306  and B  308  are coupled to a context capturing interface  312 . Stored content fragments  314  and stored context information  316  are then combined in the context watermarking insertion block  318 .  
      A dynamic capture period control block  320  provides information to the context watermarking block  318  regarding the desired capture period length. The context watermarking period can be predefined or adjusted dynamically based on how fast the context changes by the dynamic capture period control block  320 . The combined digital content fragments  324  and the context information  326  stored in block  322  can be output as a string of fragments  328 . The period determined by the dynamic capture period control block  320  in another embodiment can be determined solely based on how fast the the content changes or based on the streaming rate of the electronic device (i.e., vocoder rate that breaks the down the stream into logical blocks of data, etc.).  
      The playback for the streaming content and context is shown in  FIG. 4 . The fragments  402  are received and the digital content fragments  406  and the context information  408  are assembled in block  404 . The context separator  410  outputs digital content fragment stream  412  and context information watermark stream  414 .  
      The two streams  412  and  414  are separated by the context separator  410  while synchronized in playback.  
      A further enhancement to the present invention is the ability to encrypt the content and/or the context information independently. When encryption is required due to the nature of the information, the content and/or the context is encrypted with a randomly generated key. The secret encryption key is encrypted using PKI technology and packaged with the content and/or context. After encryption, the context watermark insertion can proceed as previously described above. In  FIG. 6 , there is shown a flowchart highlighting the steps when performing encryption. In step  602 , the content and/or context are encrypted independently using a randomly generated secret key. After encryption the context watermark insertion is performed in step  606  following the steps shown in the flowchart of  FIG. 5 . Although the above flowchart has shown the step of encrypting prior to watermarking, the steps can be reversed with the same security level being accomplished.  
      Referring now to  FIG. 7 , there is shown a block diagram of an electronic device such as a radio communication device  700  (e.g., cellular telephone) that can take advantage of the context watermarking of the present invention. Cellular telephone  700  includes an antenna  718  which is selectively coupled to a conventional receiver  704  and transmitter  706  sections. A controller, such as a microprocessor and/or Digital Signal Processor (DSP), provides the overall control for telephone  700 . Memory  714  coupled to the controller  702  such as Random Access Memory (RAM), Read-Only Memory (ROM), FLASH, etc. stored all of the algorithms and variables needed by cellular telephone  700 . A display  716  provides visual information to the cellular telephone user. An audio processing block  708  which can include a vocoder and Analog-to-Digital (A/D) and Digital-to-Analog (D/A) block provides all the necessary audio processing for both incoming and outgoing voice traffic. Coupled to the audio processing block  708  is a speaker  712  and microphone  710 .  
      One or more content capturing devices  720  and one or more context capturing devices  722  are coupled to controller  702 . Controller  702  performs all of the necessary steps previously described in order to provide the context watermark insertion and separation required by the present invention as well as any required encryption. Memory  714  stores all of the context and content information that has been received and processed.  
      The above described context watermarking technique provides for a simple way of retaining context information and facilitates its processing while the contents get transferred and stored. Added features include the ability to provide for streaming situations where the digital contents are captured continuously with the context information changing continuously by providing for a predefined or adjustable context watermarking period as provided by the dynamic capture period control  320 . Extra security can also be provided by encrypting the content and/or context information.  
      While the preferred embodiments of the invention have been illustrated and described, it will be clear that the invention is not so limited. Numerous modifications, changes, variations, substitutions and equivalents will occur to those skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims.