新建一个后缀名为.reg的文件，然后将下面代码复制粘贴到文本中，保存运行即可
Windows Registry Editor Version 5.00 ; Change Extension‘s File Type [HKEY_CURRENT_USER\Software\Classes\.jpg] @="PhotoViewer.FileAssoc.Tiff" ; Change Extension‘s File Type [HKEY_CURRENT_USER\Software\Classes\.jpeg] @="PhotoViewer.FileAssoc.Tiff" ; Change Extension‘s File Type [HKEY_CURRENT_USER\Software\Classes\.gif] @="PhotoViewer.FileAssoc.Tiff" ; Change Extension‘s File Type [HKEY_CURRENT_USER\Software\Classes\.png] @="PhotoViewer.FileAssoc.Tiff" ; Change Extension‘s File Type [HKEY_CURRENT_USER\Software\Classes\.bmp] @="PhotoViewer.FileAssoc.Tiff" ; Change Extension‘s File Type [HKEY_CURRENT_USER\Software\Classes\.tiff] @="PhotoViewer.FileAssoc.Tiff" ; Change Extension‘s File Type [HKEY_CURRENT_USER\Software\Classes\.ico] @="PhotoViewer.FileAssoc.Tiff"
原文：https://www.cnblogs.com/sauronblog/p/13469063.html