Image coding method and apparatus and image decoding method and apparatus

An image coding apparatus in which, for nonnegative integers i and j, data of an i-th key frame and a j-th key frame are defined as KFi and KFj, respectively, and a correspondence data file between the i-th key frame and the j-th key frame is defined as Ci,j, the apparatus comprising:

• an image input unit which receives data for key frames;
• a correspondence data generator which generates Ci,i+1 by utilizing KFi and KFi+1, and generates Ci,j by utilizing KFi and KFj, j>i+1, among the input key frame data;
• and
• a stream generator which generates a data stream including data generated by said correspondence data generator.

An image decoding method, comprising:

• 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;
• and
• monitoring for an error in the data stream,
• wherein, when an error is detected, an error avoidance processing is performed at the time of said generating the intermediate frame.

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 key frames disposed at an interval, 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.

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.