Change Link of html image button dynamically

Hello,
i have html image buttons in a field of a form grid. The button is linked to another application. But the button should link to different applications depending on the contents of another field. How can i do that?
Thanks for any help!
Siggi

make 2 image buttons, and play hide and seek :smiley:
i mean if you wants to display 1 button hide other one,
so set it up back n forth.

hope you got the idea.