Is it possible to recognize mouse up event by clicking anywhere on pdf .
No, only if that click is on top of a form field or link. You can create a transparent button field that covers the entire surface of a page, though...
Is to possible to assign image to form field button using hex code
Yes, but it's quite complex.
Unfortunately, the image data needed for a form field button is different from the raw hex image data used on toolbar buttons and dialogs in Acrobat. But there is a way to create custom image data for button.
See the "2D Matrix Calculator" example here: