| 摘要 |
PROBLEM TO BE SOLVED: To attain highly efficient coding without deteriorating image quality by using a sub band coefficient of a significant area being an area including a surrounding of an original component area and deciding the size of each surrounding part based on each band. SOLUTION: The operations of an out-area data extrapolation section 101, a sub band division section 102, a shape area coding section 106, a coefficient generating section 107, a sub band coefficient coding section 108 and a coding information synthesis section 109 are similar to those of a conventional coder/ decoder. Then a significant area decision section 103 uses a sub band shape generating section 104 to reduce each shape area in matching with a resolution of each band and applies expansion processing of the shape area of each band generated by a sub band shape expansion section 105 to decide a significant area. The significant area is decided adaptively for each band in the case of applying sub band coding to each component image and the image is coded after converting coefficients at the outside of the significant area into a prescribed value so as to attain highly efficient coding without deteriorating image quality around the component image. |
