Re: Can I use Nik software on its own? Or does it need some other software to run?
Thank you for contacting Nik Software. Yes, HDR Efex Pro is the only one of our software that will run as a standalone product.
Hmm; interesting..... I have them all (the Nik versions on my Mac) and I think they *all* work as standalone if you drag a (JPEG or TIFF) file or files onto their OS icons to open it/them.
HDR Efex is the only one which has a file open menu though; so maybe that is why Nik speak specifically of it working standalone.
As far as I can tell (and I am pretty confident in what I say, certainly under OS X), the Lightroom and Aperture versions are actually standalone. They do not really run inside Lightroom or Aperture. Those "host" programs merely export a processed TIFF to the Nik program, and then after the Nik program is closed with a save, the result is imported back to Lightrrom or Aperture. The plug-in part is really just that export/import interface.
When used with Photoshop, then they are much more true plug-ins and work actually inside Photoshop. They still have the same user-interface as per the standalone Lightroom/Aperture implementation, but they just are running as a filter within Photoshop. That gives you also the power of smart-objects and smart-filters and with that an ability to go back and re-adjust.
The only issue you may get without a host is a Nik installer warning saying that it cannot identify a host program (I do not know because I have all of Lightroom, Aperture and Photoshop on my machine). Maybe the Nik installer for everything except HDR Efex does not let you install without host. The way round that would be to download Lightroom as free 30-day trail and install that first. Then install the Nik applications.
Obviously I do not work for Nik/Google, and above is just my own observations with the current Nik versions. I did not install the Google branded ones yet as I did not get my e-mail to do so. It's also of course possible that the functionality would change in later versions, but above is certainly my observation with current and previous versions. I suggest you download all that interest you and try for yourself at your risk.