将下面的代码保存为xxx.reg文件，双击注册到系统即可

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Photo Viewer\Capabilities\FileAssociations]
".tif"="PhotoViewer.FileAssoc.Tiff"
".tiff"="PhotoViewer.FileAssoc.Tiff"
".jpg"="PhotoViewer.FileAssoc.Tiff"
".png"="PhotoViewer.FileAssoc.Tiff"
".bmp"="PhotoViewer.FileAssoc.Tiff"