How to install Image Capture by itself?
The application resides in /Applications, the corresponding (app) bundle is called Image Capture.app, but the Finder adapts the name to your language settings (it's listed as "Digitale Bilder.app" on a (Swiss) German setting). 

One easy way to start it is to use Spotlight and search for "Image Capture". Should be one of the hits (usually the first), just press Enter to start it then.