web_techsystech/web_tree_image_tooltip/demo/view_res_users.xml

<?xml version="1.0" encoding="UTF-8"?>
<odoo>
    <record id="view_users_tree" model="ir.ui.view">
        <field name="model">res.users</field>
        <field name="inherit_id" ref="base.view_users_tree" />
        <field name="arch" type="xml">
            <field name="name" position="before">
                <field name="image_small" options="{'tooltip_image': 'image'}" widget="image" string="Image"/>
            </field>
        </field>
    </record>
</odoo>