Converting pdf to eps

Although pdf is better than eps format, some journals still insist the figure files in eps format. There are many possible option to convert the pdf files to eps files, although none of them is perfect.

Using Adobe Reader

Open the pdf file with adobe reader.

Print it to ps file. Make sure that the box "Choose paper source by paper size" is unchecked. 

Use the command ps2eps filename.ps to convert the ps file to eps file.

Open the eps file in a text editor and modify the BoundingBox parameters. The bounding box can be obtained by
gs -dNOPAUSE -dBATCH -q -sDEVICE=bbox

Using command line:

acroread -toPostScript input.pdf

ps2eps -f -l -B -s b0 -F input.ps
or

ps2eps -f -B -s b0 -F input.ps

Using pdftops

pdftops -eps filename.pdf
will convert it to eps file. One can also use ps2eps to generate the bounding-box.