My RAW images have 12 or 14 bits depth (depending on camera settings). After I open them in Adobe Camera Raw, adjust exposure and other things, and then send to Photoshop, is the image reduced to 8-bit, or does it still have all 12/14 bits of information?
In other words, would it make sense to open image in PS, duplicate layers, edit them both and use selective transparency mask, or should I rather adjust my image twice in ACR, and later compose those two copies in PS?
You have the option to open the image either as 8-bit or 16-bit (in any appropriate colour space) in Photoshop. Getting to the option isn't always clear; click on the blue text at the bottom of the ACR window to get to the workflow options.
Just be aware that many of the tools in Photoshop are significantly slower when working in 16-bit. If you don't anticipate making any major tonal adjustments, working in 8-bit will probably not have any deleterious effect. (It is highly probable that your final image output will be 8-bit in any case. Keeping the working file -- the PSD -- in 16-bit is only a problem in that it increases the necessary storage space.)
