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Introduction to Writing Windows CE Display Drivers(2) 
Because most monitors cannot maintain the display image on their own, the display must be continuously refreshed. For the standard non-interlaced display, this is done one line at a time in sequence. Interlaced displays, such as televisions, refresh all the even lines first, then all the odd lines, sometimes resulting in display flicker. The time after one display line is completed and before the next one is started is called the horizontal blanking period. The time after a complete display refresh is done and until the next display refresh is started is called the vertical blanking period. These blanking periods are the result of monitor technology requirements. Cathode ray tubes, or CRTs, used in monitors direct a beam along the face of the tube. This beam causes phosphors on the tube to emit light, which you see as the display. After the beam traces a line across the tube, it needs to retrace to the beginning of the next line. While it is retracing, the beam is shut off, or blanked. The same applies for a complete display with vertical retracing and blanking.
The display itself is organized in rows and columns. Each element, or pixel, in the display is stored in the frame buffer, where between one and thirty-two bits are used per pixel. The color of a pixel is represented by the intensity of each of the red, green, and blue color channels. These intensities are represented directly by the pixel data in modes where a pixel is 16 bits or more. When a pixel is 8 bits or less, the pixel data usually represents an index into a color look-up table. This look-up table stores the red, green, and blue intensities for each index in the palette of currently available colors. In this case, the look-up table values are passed to the DAC.
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