新建txt,复制下面内容，保存。
修改文件扩展名txt为reg,然后导入之

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Photo Viewer\Capabilities\FileAssociations]

".bmp"="PhotoViewer.FileAssoc.Tiff""

".gif"="PhotoViewer.FileAssoc.Tiff"

".jpg"="PhotoViewer.FileAssoc.Tiff"

".jpeg"="PhotoViewer.FileAssoc.Tiff"

".png"="PhotoViewer.FileAssoc.Tiff"

".tif"="PhotoViewer.FileAssoc.Tiff"

".tiff""="PhotoViewer.FileAssoc.Tiff"

".ico"="PhotoViewer.FileAssoc.Tiff"

注：必须双引号