I can't see picture file extensions in the Open dialog box.

Extensions may be hidden in Windows Explorer   If extensions are hidden in the Microsoft Windows Explorer, you can't see them in the Open dialog box either. How to view file extensions

You may be viewing only PhotoDraw pictures with standard extensions in a folder   If PhotoDraw (*.mix) is selected in the Files of type list in the Open dialog box, other types of formats, such as Tagged Image File Format (.tif), do not appear in the file list. To view all the pictures in a folder, click All Supported Formats in the Files of type list.