Raster scanning: The technique of reading or plotting an image by the selective identification or sampling of dots, line by line, in a series of horizontal sweeps following a raster matrix pattern or grid.

• 点线扫描:依照一个点线矩阵或格，把样本上的图像，逐点的选择和辩认，逐行逐行的横扫过去，读出或绘画该图像。