An LED sign can meet its brightness specification and still lose legibility at midday. Sunlight reflects off the display face, so the dark areas of the image stop looking black and the contrast a viewer sees drops. Four decisions control the result: how much brightness the site needs, how the content is drawn for the native pixel matrix, how the display is dimmed after sunset, and how the finished installation is checked under real light. Introduction A display that reads cleanly at 8 a.m. can look flat and gray at 4 p.m. on the same day, at the same brightness…