I'm trying to add o image widget in odoo screeen,

I have used the field as below ,

  image = fields.Binary("Image", attachment=True,
                          help="This field holds the image used as avatar for \
        this contact, limited to 1024x1024px",)

XML :

<field name="image" widget='image' class="oe_avatar"/>

The uploaded image has white space around image, how to upload image as it is , without adding white space around image ?