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<br />PRELIMINARY DRAFT FOR REVIEW BY CITY OF MINNETONKA <br />Further changes are anticipated following Signage Workshop <br /> <br />**Preliminary Report is specific to City of Minnetonka issues and may not be sufficient to <br />address concerns ill other comnlunities** <br /> <br />Table A-I - Luminance Standards <br /> <br />Ambient <br />Light <br />(lux) <br />40,000 Sunlight <br />10,000 Cloudy <br />4,000 Overcast <br />400 Sunrise/Sunset <br />40 Candlelight <br />less than 4 Moonlight <br />Source: NEMA TS-4 (2005) <br /> <br />Approximate <br />Light <br /> <br />Minimum <br />Luminance <br />(nits) <br />12,400 <br />12,400 <br />2,200 <br />600 <br />250 <br />75 <br /> <br />Maximum <br />Luminance <br />(nits) <br />62,000 <br /> <br />11,000 <br />3,000 <br />1,250 <br />375 <br /> <br />Billboard Resolution <br /> <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 />L 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 /> <br />Dimming <br /> <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 /> <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 pre configured 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 /> <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 /> <br />AA7 <br />