I'm watching a Lynda.com course named "Scanning Techniques for Photography, Art, and Design" (https://www.lynda.com/Design-Digital-Illustration-tutorials/Scanning-Techniques-for-Photography-Art-and-Design/84091-2.html). In it, the presenter repeatedly mentions the benefits of using a higher bit depth (such as 16-bit grayscale, or 48-bit color), but then chooses a scan option which itself reduces the bit depth (such as 16-bit to 8-bit grayscale).
Although he does explain why one would scan at a higher bit depth, he does not explain why one would scan at a higher bit depth but then convert to a lower bit depth, so I'm wondering under what circumstances someone would do that. I've thought of two options:
- Space: more bit-depth = more bits = more space taken up by an individual scan. But since I have plenty of space, this isn't really a concern for me
- Processing speed: more bit-depth = more bits = more bits to process when trying to manipulate the image. However, more bits (generally) means more information, and therefore you'd get a better result at the cost of that increased time spent processing. That makes the argument for deciding between 16-bit or 8-bit, but not for why someone would use a "16->8 Bit" option.