DMD display device

Barco projectors uses a DMD device from Texas Instruments to display the image. A DMD device displays the intensity of a pixel by time multiplexing the time it is on over the frame time. If one pixel is 50% grey, it is on for 50% of the time for that frame. Since we also change the color of the light during the same frame period, all the DMD mirrors (pixels) must be displayed synchronously. This is done by dividing the image into bitplanes and sending the bitplanes one by one to all the mirrors simultaneously. As a simplistic explanation, consider an 8-bit pr. pixel image. First the LSB bitplane is loaded. All the pixels that has the LSB bit set, has the corresponding DMD mirror turned on for a short time. Next, the second to last bitplane is loaded, and all the DMD mirrors where this bit is set are displayed for twice as long. This continues until the MSB (bitiplane 8) is loaded and displayed.

Because of dividing the image into bitplanes, all pixels of an image must be loaded to the DMD before it can start to display any of the pixels.