web/web_digital_sign/users_view.xml

<?xml version="1.0" ?>
<openerp>
	<data>

		<record id="inherited_res_users_form" model="ir.ui.view">
            <field name="name">inherited.res.users.form</field>
            <field name="model">res.users</field>
            <field name="inherit_id" ref="base.view_users_form"/>
            <field name="arch" type="xml">
            	<xpath expr="//field[@name='signature']" position="replace">
					<label for="signature_image" class="oe_edit_only"/>
					<h2><field name="signature_image" widget="signature"/></h2>
				</xpath>
            </field>
        </record>

	</data>
</openerp>