Image Assistant is a browser addon, which opens images in any external viewer (having saved them on local disk), thus providing zooming, rotating, & other rich functionality not available by default (including any editing features supported by the viewer). Or 1-click-save without opening...
At present you can download Saving Launcher, which is a native application that Image Assistant depends on, from the following links: Windows (64-bit), (32-bit); Linux 64-bit.
Nothing special to note about this approach.
If you encounter an issue, you can log it here.