[Note: The Online Photographer's M.C., majordomo, and Chief Bottlewasher, Mike J., just had his eye operated on and is recuperating. Big rule during recovery: no screens, no reading, lie flat and stare at the ceiling. He got an Echo and is listening to Audible books! Meanwhile, for your amusement and edification, a few bon mots from other writers and photographers. One will be published every day while Mike’s away.]
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"What is bit depth? Before we compare the various options, lets first discuss what the naming means. A 'bit' is a computer’s way of storing information as a 1 or 0. A single bit isn’t really good for anything beyond 'yes' or 'no' because it can only have two values. If it was a pixel, it would be pure black or pure white. Not very useful.
"To describe something complex, we can combine multiple bits. Every time we add another bit, the number of potential combinations doubles. A single bit has two possible values, 0 or 1. When you combine two bits, then you can have four possible values (00, 01, 10, and 11). When you combine three bits, you can have eight possible values (000, 001, 010, 011, 100, 101, 110, and 111). And so on. In general, the number of possible choices is 2 raised to the number of bits. So '8-bit' = 28 = 256 possible integer values. In Photoshop, this is represented as integers 0–255 (internally, this is binary 00000000-11111111 to the computer).
"So 'bit-depth' determines the smallest changes you can make, relative to some range of values."
—Greg Benz, from a very useful primer-type article called "8, 12, 14 vs 16-Bit Depth: What Do You Really Need?!" (quoted with permission)
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(Sorry! There are no comments this week—the moderator is also stuck supine staring at the ceiling.)
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