| 摘要 |
PURPOSE:To reduce a memory capacity, and to execute the rewrite of luminance information at a picture element string having an optional length starting form an optional address without extending a write time, by always filling in advance a high- ordered bit at a frame buffer at every regulated number of picture elements. CONSTITUTION:The picture element string arranged in a scanning direction is divided into, for example, plural number of blocks consisting of four picture elements, and the high-ordered bit and a low-ordered bit (only the high-ordered bit is permitted) is always stored in advance at a forefront picture element of each block. The first block in a buffer memory is read out for the rewrite picture elements of addresses 2 and 3, and the second block is read out from the buffer memory for the rewrite picture elements of addresses 4 and 5. Since the high-ordered bits are stored at the forefront picture elements of read first and second blocks, they are referred, and are compared with a high-ordered bit U included in the luminance information for a rewrite picture element string, and it is decided whether they are same or different. Thus, a picture element is traced to go back to the preceding, and the first high- ordered bit can be found.
|
