1、WINDOWS+R输入regedit
2、第一种方法：
找到以下位置——计算机\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Photo Viewer\Capabilities\FileAssociations
3、第二种方法：
复制以下代码按图行事
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"
".tga"="PhotoViewer.FileAssoc.Tiff"
".bmp"="PhotoViewer.FileAssoc.Tiff"
".jpeg"="PhotoViewer.FileAssoc.Tiff"
