diff --git a/odoo/addons/test_new_api/tests/test_new_fields.py b/odoo/addons/test_new_api/tests/test_new_fields.py
index 805688f45ed..674dd0a029f 100644
--- a/odoo/addons/test_new_api/tests/test_new_fields.py
+++ b/odoo/addons/test_new_api/tests/test_new_fields.py
@@ -13,6 +13,7 @@ from odoo.exceptions import AccessError, UserError, ValidationError
 from odoo.tests import common
 from odoo.tools import mute_logger, float_repr
 from odoo.tools.date_utils import add, subtract, start_of, end_of
+from odoo.tools.image import image_data_uri
 
 
 class TestFields(common.TransactionCase):
@@ -1503,6 +1504,10 @@ class TestFields(common.TransactionCase):
         self.assertEqual(record_bin_size.image_512, b'1.02 Kb')
         self.assertEqual(record_bin_size.image_256, b'424.00 bytes')
 
+        # ensure image_data_uri works (value must be bytes and not string)
+        self.assertEqual(record.image_256[:8], b'iVBORw0K')
+        self.assertEqual(image_data_uri(record.image_256)[:30], 'data:image/png;base64,iVBORw0K')
+
     def test_95_binary_bin_size(self):
         binary_value = base64.b64encode(b'content')
         binary_size = b'7.00 bytes'
diff --git a/odoo/fields.py b/odoo/fields.py
index 4abdc9dcf1f..f753371719a 100644
--- a/odoo/fields.py
+++ b/odoo/fields.py
@@ -1895,7 +1895,9 @@ class Binary(Field):
             # If the client requests only the size of the field, we return that
             # instead of the content. Presumably a separate request will be done
             # to read the actual content, if necessary.
-            return human_size(value)
+            value = human_size(value)
+            # human_size can return False (-> None) or a string (-> encoded)
+            return value.encode() if value else None
         return None if value is False else value
 
     def convert_to_record(self, value, record):
@@ -2029,13 +2031,15 @@ class Image(Binary):
             # does not resize the same way as its related field
             new_value = self._image_process(value)
             new_record_values.append((record, new_value))
-            record.env.cache.update(record, self, [value if self.related else new_value] * len(record))
+            cache_value = self.convert_to_cache(value if self.related else new_value, record)
+            record.env.cache.update(record, self, [cache_value] * len(record))
         super(Image, self).create(new_record_values)
 
     def write(self, records, value):
         new_value = self._image_process(value)
         super(Image, self).write(records, new_value)
-        records.env.cache.update(records, self, [value if self.related else new_value] * len(records))
+        cache_value = self.convert_to_cache(value if self.related else new_value, records)
+        records.env.cache.update(records, self, [cache_value] * len(records))
 
     def _image_process(self, value):
         if value and (self.max_width or self.max_height):