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Minimizing Moiré

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Back when I worked in broadcast television, the first thing they told the on-camera newscaster was “never wear striped.” But a striped shirt is only one of many potential causes of the visual distortion known as Moiré. In the years before progressive scan HD, the NTSC standard ruled the land — and it’s still broadcast today. The NTSC system uses 525 horizontal scan lines to create video frames. When these parallel scan lines encounter another set of parallel lines (for example, on the newscaster’s shirt) via the video camera, visual havoc results. The same problem emerges when LED panels get in the shot at sports events and concerts. Aside from simply avoiding the LED walls, you can turn down video camera “contour” controls to soften the image and keep the problem at bay. Also, avoid leaving the camera in auto-focus mode. If you manually focus on the talent, the LED panels will be in soft focus mode, minimizing the problem. By opening up the camera’s iris (aperture) and adjusting the depth of field, you can optimize this strategy.

—From “Video World” by Paul Berliner, PLSN, Nov. 2013