thank you!
The icon is a gif file.In Infopath form, I created a field data type is 'Picture or File Attachment'. and Specify the icon.gif file as the field's default picture. (it should embedded in the form, right? because the icon can show up if insert the field picture to the form)
then in the page setup/ Print Settings/ footer: Print form with this footer: insert AutoText :I inserted the picture field.
If save the form and print preview from the Infopath designer the footerIcon will show up the field path: {/my:Fiels/my:footerIcon}
If publish the form and printpreview fromInfopath filler the footerIcon will show up like: ROIGODIHmGcANuAAAAAP///zsOzkge0uGODIHmGc3ANu5AAPzsOzkge0u....
do you understand what I mean?