| 摘要 |
PURPOSE:To make an initial block size most suitable to every object picture element, by dividing a subject image into fine blocks, repeating more divisions only to the block containing the picture elements other than the white ground and coding the gradation information for only the block that has a 2X2 picture element size. CONSTITUTION:An original image is set at an NXN picture element size, and the gradation information per picture element is set at (a) bit. This image is divided into the blocks of 2<k>X2<k> picture element size, and the coding is performed with each bit per block to decide whether each block has the white ground or contains the picture elements (black ones) other than the white ground. Then the block containing the black picture elements is divided into minor blocks of 2<k-1>X2<k-1> picture element size. Then each minor block is coded with every bit to decide whether each minor block has the white ground or contains the black picture elements. Furthermore the minor block containing black picture elements is divided into half, and finally the gradation is coded with each picture element by the (a) bit for the block of 2X2 picture elements containing black picture elements. |
