| 摘要 |
PURPOSE:To obtain a natural gradation expression by performing gradation interpolation of adjacent blocks in accordance with a gradation correcting pattern based on an average gradation value of each block of image information and gradation values of blocks vertically and horizontally adjacent to this block. CONSTITUTION:Data read out from a RAM 11 is sent to a comparator 23 directly and through a latch circuit 22. Data of an object block is compared with data of blocks vertically and horizontally adjacent to this block, and a ternary code indicating comparison results is latched in latch circuits 27a-27d. The gradation correcting pattern of (3 bits)X16 stored in a designated address of a ROM 28 is read out by this latched data. This gradation correcting pattern is read into a shift register 29 by the timing signal from a timing generator 14. Correcting data successively read out from the shift register 29 is sent to an adder 25 and is added to the 6-bit gradation value held in a latch circuit 22 to obtain a decoded pattern of (6 bits)X16. |
