Image encoding system, image decoding system and methods therefor

An image decoding system comprising:

• a code input part which inputs an encoded signal;
• a second decoder which decodes the encoded signal inputted from the code input part to generate a second prediction value;
• a second inverse predictive converter which inversely converts the second prediction value generated by the second decoder to generate intermediate data;
• a first decoder which decodes the intermediate data generated by the second inverse predictive converter to generate a first prediction value;
• and
• a first inverse predictive converter which inversely converts the first prediction value decoded by the first decoder to generate a pixel value of a target pixel.

An image encoding method comprising the steps of:

• inputting an image signal;
• converting relation between the pixel value of a target pixel in the image signal and that of another pixel into a first prediction value;
• encoding the first prediction value to generate intermediate data;
• converting relation between a target symbol among symbols making up the intermediate data and another symbol into a second prediction value;
• and
• encoding the second prediction value to generate an encoded signal.

An image decoding method comprising the steps of:

• inputting an encoded signal;
• decoding the encoded signal to generate a second prediction value;
• inversely converting the second prediction value to generate intermediate data;
• decoding the intermediate data to generate a first prediction value;
• and
• inversely converting the first prediction value to generate a pixel value of a target pixel.