Image coding method and apparatus and image decoding method and apparatus

Abstract

An image coding and decoding technology for digital movie or video that provides for error checking within the digital video files. The digital video is coded in a data stream that includes key frames and correspondence data between key frames as well as additional correspondence data between somewhat separated key frames. During decoding, an intermediate image generator generates an intermediate frame or frames by interpolation, based on key frame data and correspondence data file between key frames. If an error detector detects an error in an input coded data stream, an error controller instructs the intermediate image generator to perform an error avoidance processing which may include substituting another key frame for an error-containing key frame or use of the additional correspondence data to create the intermediate key frame or frames for an error-containing correspondence data file, and so forth.

1 . An image decoding apparatus comprising: 
 a data stream receiver that receives a data stream comprising a plurality of key frames and correspondence data files therebetween;    an error detector that detects errors in the data stream;    an intermediate image generator that generates intermediate images based on the data stream; and    an error controller that, on detection of an error by the error detector, controls said intermediate image generator in a manner such that an error avoidance processing is performed in said intermediate image generator.    
   
   
       2 . An image decoding apparatus according to  claim 1 , wherein, said error controller determines if the seriousness of the error is above a predetermined level before controlling said intermediate image generator to include error avoidance processing.  
   
   
       3 . An image decoding apparatus according to  claim 1 , wherein said correspondence data files have been computed using a matching between critical points detected through a two-dimensional search respectively conducted on two key frames.  
   
   
       4 . An image decoding method, comprising: 
 acquiring a data stream that includes a plurality of key frames and a correspondence data file therebetween;    monitoring for an error in the data stream; and    generating an intermediate frame between the key frames, from the data stream,    wherein, when an error is detected, an error avoidance processing is performed at the time of said generating the intermediate frame.    
   
   
       5 . An image decoding method according to  claim 4 , wherein, when an error is detected in data of a key frame, the error avoidance processing is performed in a manner such that the intermediate frame is generated from data of another key frame, which is substituted for data of the error-containing key frame.  
   
   
       6 . An image decoding method according to  claim 4 , wherein, when an error is detected in data of a key frame, the error avoidance processing is performed in a manner such that the intermediate frame is generated based on data of another key frame and a correspondence data file relating thereto.  
   
   
       7 . An image decoding method according to  claim 4 , wherein, said error avoidance processing is abandoned in the event that it is judged that seriousness of the error is below a predetermined level.  
   
   
       8 . An image coding method, comprising: 
 first generating, based on data of two adjacent key frames, correspondence data therebetween;    second generating, based on data of two non-adjacent key frames, correspondence data therebetween; and    generating a data stream in a manner such that the correspondence data generated in said first generating serve as main data and the correspondence data generated in said second generating serve as spare data.    
   
   
       9 . An image coding method according to  claim 8 , wherein said second generating is performed with lower frequency than said first generating.  
   
   
       10 . An image coding method according to  claim 8 , wherein the correspondence data are generated in a manner such that data for checking for an error are embedded in the correspondence data.  
   
   
       11 . A computer program executable by a computer, the program comprising the functions of: 
 acquiring a data stream that includes a plurality of key frames and a correspondence data file therebetween;    generating an intermediate frame between the key frames, from the data stream;    monitoring for an error in the data stream; and    performing, upon detecting an error, an error avoidance processing at the time of said generating the intermediate frame.