NX Studio is described as 'computer software that allows users to enjoy the viewing, processing, and editing of still images and video, and provides more intuitive operation' and is an app in the Photos & Graphics category. There are more than 100 alternatives to NX Studio for a variety of platforms, including Windows, Mac, Linux, Online / Web-based and Xfce. The best alternative is IrfanView. It's not free, so if you're looking for a free alternative, you could try nomacs or ImageGlass. Other great apps like NX Studio are XnView MP (Free Personal), FastStone Image Viewer (Free Personal), XnView (Free Personal) and JPEGView (Free, Open Source).
nomacs is a small, fast image viewer able to handle the most common image formats including RAW images. Additionally it is possible to synchronize multiple viewers. A synchronization of viewers running on the same computer or via LAN is possible.
ImageGlass is a simple picture viewer with which you will be able to display your image collection in a very similar way to the one that Windows provides by default, but with some additional functions.
FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor. It has a nice array of features that include image viewing, management, comparison, red-eye removal, emailing, resizing, cropping and color adjustments.
HoneyView is a fast image viewer that supports archived image files for comics/manga/photos. Its design is light and the interface skin can be changed. You can set HoneyView as your default image viewer and also add a shell context menu.