Windows Photo Viewer, a built-in picture viewing program in Windows, is not only very slow to open large pictures, but also very laborious to view large-sized pictures (you need to reach the top with great effort, and then drag and drop pictures with great effort). In order to obtain a faster, more efficient, and better image viewing experience, we often need to use a third-party image viewer.

nomacs is a free, open-source and cross-platform universal image viewer & simple editor from Austria. If you have many photos to view, edit or manage, this software will be a very convenient choice. In addition to the common image formats, it also supports some proprietary image file formats such like RAW and PSD.

P3dO Explorer (AKA: Photo 3D Explorer) is an inconceivable 2D, 3D and other files universal viewer and manager. Especially, it almost supports any kind of image formats - 45+ popular image types, 60+ 3D Mesh types, 25 + Texture / Material / Shader file formats, 19+ motion files and 18 other file formats.

As for a good third-party image viewer to choose, before, I used to find XnView better than ACDSee, this is true, and i keep my point.But today i just found a better one than XnView - FastStone Image Viewer. If I could evaluate XnView with stars, I will give FastStone Image Viewer 4.5 or 5. Because it has a faster image reading speed than most of the image viewers (including XnView and ACDSee).