Windows 10 comes with an image viewer app of its own which can do all the basic things that you would want from a simple image viewer. But it leaves you desiring more features such support for more image file types. There are very good image viewers and editors such as PhotoScape and Paint.NET but they may confuse the beginners. If you are looking for an image viewer that provides more features that the Photos app that comes with Windows 10 and yet is not slow or confusing, then you can try ImageGlass. It is a simple, lightweight but very fast image viewer for Windows.
ImageGlass is beautifully designed and supports themes. You can download new themes from their website and install them to change its look. It allows you to browse through your pictures stored in a folder in much the same way as Microsoft Photos app. It has a thumbnails view feature for easy browsing through your pictures. You can enable the thumbnails view in the ImageGlass layout to see thumbnails of all the images in the current working folder.
ImageGlass supports a large number of image file formats including JPG, JPE, JFIF, JPEG, PNG, GIF, ICO, BMP, DIB, TIF, TIFF, EXIF, WMF, EMF, TGA, PSD, HDR, EXR, SVG, RAW, HEIC and WEBP (non-animated). It allows you to extract the frames from GIF animation and save them as individual image files. It can be used to convert image file formats. You can right-click on the image and see advanced features such as setting that images as Windows Desktop background (wallpaper), uploading it to social networks such as Facebook or setting it as lock screen image.
ImageGlass is not an image editor, you can only view the images and save them in different image file formats. It allows you to set a third-party editor so that you can invoke this image editor from within ImageGlass.
You can download ImageGlass from https://imageglass.org/.