| 摘要 |
PURPOSE: To adaptively compress/restore video data to obtain an aliasing prevention mode by checking (n×n)-picture element blocks of picture element data to judge which compression system should be used, for every block. CONSTITUTION: Video data is divided into blocks of n×n picture elements, for example, 4x4 picture elements, and different colors are settled for them. That is, they are obtained by averaging colors whose luminances are higher and lower than the average luminance of blocks. Generally, two different colors are calculated in an RGB space. The difference between these two colors is checked; and if this difference is larger than a first threshold, at least two colors and an n×n-bit map are stored to store the picture element data block. When it is smaller than the first threshold, the picture element data block is stored as a single color without a bit map. At the time of decoding, two colors are obtained by calculation, and bit map data is used to select one of four colors for every picture element. |
