火狐 | FireFox14.0.1
+++++++++++++++++++++++++++++++++++++++
后缀名 | MIME
+++++++++++++++++++++++++++++++++++++++
bmp | image/bmp
jpg | image/jpeg
jpeg | image/jpeg
png | image/png
gif | image/gif
=======================================
IE8
+++++++++++++++++++++++++++++++++++++++
后缀名 | MIME
+++++++++++++++++++++++++++++++++++++++
bmp | image/bmp
jpg | image/pjpeg
jpeg | image/pjpeg
png | image/x-png
gif | image/gif