TWAIN is supported by photoshop, as well as many other applications. The plug-in would work with Photoshop and any other application that supports Photoshop Plugins.
For the trial, either would work. I prefer TWAIN myself, as it has a more universal application base. Others may prefer plugs, as they sometimes offer more power.
Shel Belinkoff wrote:
I was about to download a trial version of Silverfast and discovered that I
don't know which to DL. One version sets up a Photoshop plug-in, the other
is for "Twain." So, what's Twain? Why would I want a plug-in as opposed
to Twain, or vice-versa? I couldn't find an explanation on the site that
defined the differences or why one option should be chosen over another. Is anyone using SF with PS CS on Win XP? How's it working out for you?
Shel

