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Placing Shadows, 3rd Edition by Tom LeTourneau, Chuck Gloman

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Chapter 5

Video Contrast Ratios

Help, They Don’t Match!

“Contrast ratio” refers to the maximum allowable difference between the brightest area of the picture and the darkest. While film can accommodate ratios as high as 100 to 1 (i.e., the brightest object may be 100 times brighter than the darkest object), television is commonly considered to have a contrast ratio of 20 to 1. Current technology has improved this ratio to 30 to 1, and 50 to 1 in HDTV. The use of CCDs and improved circuits are the reasons for this increased range. From a practical standpoint, you should still work with the 20 to 1 ratio, however. This gives you a 5 f-stop range. If you try to use a contrast ratio higher than the standard you are working with, your images will ...

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