All Posts by Date or last 15, 30, 90 or 180 days.
also by Lloyd: photography and
Thank you for purchasing through links and ads on this site.
diglloyd Deal Finder...
Buy other stuff at
Speed To Create, Capacity To Dream
Storage Wishlist…

Whither 16-bit in Photoshop?

Pure white is 32768 = 15-bits + 1

What does it mean to have a 16-bit image file when the maximum value in Photoshop CS5 is 32678, not 65535?

A 16-bit range is 0..65535. Furthermore, a 15-bit range is 0..32767, not 32768. So what’s up with Photoshop going one value beyond that which is possible with 15 bits? This situation has existed for as long as I know.

Readers sent me a couple of links, it’s apparently a deliberate design limitation of Photoshop (a bug). Bottom line is that it’s 15-bit mode, not 16-bit mode. Or more precisely, 15-bit + 1 value = 0..32768 mode, a quite irrelevant distinction in terms of precision. See this link and this link and this link.

In short, a 16-bit RGB image has one bit thrown away by Photoshop since Photoshop operates in quasi 15-bit mode. Which means that a camera like the Nikon D3x with its 14-bit images is only 1 bit short of what’s possible to edit in Photoshop (setting 32 bit mode aside, which hs poor support).

Medium format 16-bit images? Well, they might start out that way, but as soon as Photoshop whacks them down to 15-bits they’re not 16-bit any more. Important? No.

The reason that this 32768 trick is done (0..32768 = 32769 values) is so that there is an easy midpoint value of 16384 which does not require a divide operation; all the other boundaries are also thus neatly powers of two.

ThunderBay 4 - The Speed To Create. The Capacity To Dream.
B&H Deal ZoneDeals by Brand/Category/Savings
Deals expire in 3 hours unless noted. Certain deals may last longer.
$2699 SAVE $300 = 10.0% Canon 11-24mm f/4 EF L USM in Lenses: DSLR
$3299 SAVE $200 = 5.0% Canon EOS 5D Mark IV DSLR in Cameras: DSLR
$1497 SAVE $500 = 25.0% Nikon D750 DSLR in Cameras: DSLR
$2497 SAVE $500 = 16.0% Nikon D810 DSLR in Cameras: DSLR | Terms of Use | PRIVACY POLICY
Contact | About Lloyd Chambers | Consulting | Photo Tours
Mailing Lists | RSS Feeds | Twitter
Copyright © 2008-2017 diglloyd Inc, all rights reserved.
Display info: __RETINA_INFO_STATUS__