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10,000 Cloudy 12,400 - <br />4,000 Overcast 2,200 11,000 <br />400 Sunrise/Sunset 600 3,000 <br />40 Candlelight 250 1,250 <br />less than 4 Moonlight 75 375 <br />Source: NEMA TS-4 (2005) <br />Billboard Resolution <br />Billboards require far less resolution than print advertisements. For example, Clear <br />Channel's LED "Digital Outdoor Network" LED bulletin -size (14' x 48') billboards require <br />dimensions of only 208 pixels high by 720 pixels wide. If this image were to be printed at <br />300 dots per inch (dpi), a typical print resolution, the entire image would be less than <br />1.7 square inches. Therefore, it is ideal to keep the message on these signs simple and clear <br />because they do not currently allow resolutions similar to printed images. <br />Dimming <br />To maintain readability, the brightness of a sign must be adjusted to match ambient light <br />conditions. If this is not done, the image will appear too bright and can even degrade the <br />image quality through a phenomenon called "blooming." If the image blooms, the brightest <br />areas of the image bleed over into darker parts and the image clarity is degraded. <br />Dimming is typically controlled by a photocell, which measures the ambient light conditions <br />and varies the light output of the sign based on preconfigured settings. As ambient light <br />conditions darken, the photocell senses the decrease and lowers the light output of the sign. <br />Some sign manufacturers do not incorporate photocells in their electronic signs. <br />Electronic billboard dimming can also be controlled by scheduled dimming according to time <br />of day or manual dimming. On -premise signs may use any of these methods, but most, if not <br />all, off -premise standard size electronic billboards are auto dimmed by photocell. Some <br />signs include user -defined dimming curve capability allowing total control over sign <br />brightness and adjustability to accommodate local brightness ordinances. <br />B-2 <br />