According to a method and a system of the present invention, a gray-level data is generated from a binary image while reducing the vertical brightness transition, and a display with a reduced flicker is enabled in an interlaced scanning system. A filtering operation is conducted with respect to each of the pixels in a dot matrix by using the data of each pixel and the dot matrix data of the pixel adjacent to the pixel in a vertical direction, thereby generating a gray-level data and writing the data into a frame memory. A display with a reduced flicker may be conducted by transforming the gray-level data into a predetermined set of colors consisting of a foreground color, a background color, and an intermediate color thereof.