IMAGE CODER, IMAGE CODING CONTROL METHOD, AND MEDIUM STORING IMAGE CODING CONTROL PROGRAM

摘要

PROBLEM TO BE SOLVED: To use a pre-filter adaptively depending on a characteristic of an input image while conducting coding in real time. SOLUTION: A coding difficulty calculation section 42 of a coding control section 15 calculates a coding difficulty denoting degree of difficulty of image coding. A pre-filter control section 51 controls a spatial filter 52 and a time filter 53 in a pre-filter section 50 depending on a ratio of the coding difficulty to a bit rate and on a ratio of the coding difficulty of a newest bidirectional coded picture (B picture) to the coding difficulty of a newest intra coded picture (I picture).