diff --git a/addons/sale/models/sale.py b/addons/sale/models/sale.py
index 6b61f3b32da..002762fb84f 100644
--- a/addons/sale/models/sale.py
+++ b/addons/sale/models/sale.py
@@ -208,7 +208,7 @@ class SaleOrder(models.Model):
         change_default=True, default=_get_default_team, check_company=True,  # Unrequired company
         domain="['|', ('company_id', '=', False), ('company_id', '=', company_id)]")
 
-    signature = fields.Binary('Signature', help='Signature received through the portal.', copy=False, attachment=True)
+    signature = fields.Image('Signature', help='Signature received through the portal.', copy=False, attachment=True, max_width=1024, max_height=1024)
     signed_by = fields.Char('Signed By', help='Name of the person that signed the SO.', copy=False)
     signed_on = fields.Datetime('Signed On', help='Date of the signature.', copy=False)