Starting with FormsViewer v2.2, you can build custom controls (with code) that respond to user input and read-write form data.
This How-To shows how to create a signature control for mobile devices.
Also, if you would like to upload your image to a SharePoint library, here's another How-To showing that: http://www.infopathdev.com/files/folders/formsviewer_v11/entry117152.aspx
Thanks!
Last updated: 2018-11-07