| 主权项 |
1. A method for changing an image raster direction from an application raster direction to a screen raster direction which is perpendicular to the application raster direction, in-flight, while pixel values of an image are being transferred successively from an application output memory to a display unit, the image being divided into parallel image strips successively transferred, each image strip having a length direction perpendicular to the application raster direction, a strip length and a strip width expressed in pixel numbers, and each image strip being read from the application output memory according to the application raster direction and loaded into a buffer memory, and then transferred from said buffer memory to the display unit according to the screen raster direction, wherein a writing order is used for selecting cells of the buffer memory where the pixel values pertaining to a same image strip are written successively, and a reading order is used for selecting the cells of the buffer memory where the pixel values pertaining to a same image strip are read successively, said writing order and reading order being varied between two image strips transferred successively, the method comprising:
using a memory cell array as the buffer memory, with a buffer width at least equal to the strip width, and a buffer length at least equal to the strip length and to a multiple of the strip width; and using only two writing orders different from each other, and only two reading orders different from each other, the two writing orders being combined one-to-one and fixedly with the two reading orders for processing the image strips individually, and each of the two writing orders combined with the corresponding reading order being used in turn for image strips transferred successively. |
