桌面新建 一个文本文档，将下边复制进去，另存为命名例如为：1.reg 双击运行1.reg，点‘是’，点确认即可。
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/loren880898/p/12134029.html