Improve vision models (#17731)

* Improve vision models

* Add a lot of improvements

* Remove to_2tuple from swin tests

* Fix TF Swin

* Fix more tests

* Fix copies

* Improve more models

* Fix ViTMAE test

* Add channel check for TF models

* Add proper channel check for TF models

* Apply suggestion from code review

* Apply suggestions from code review

* Add channel check for Flax models, apply suggestion

* Fix bug

* Add tests for greyscale images

* Add test for interpolation of pos encodigns

Co-authored-by: Niels Rogge <nielsrogge@Nielss-MacBook-Pro.local>

src/transformers/testing_utils.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import collections
 import contextlib
 import inspect
 import logging
@@ -1534,3 +1535,9 @@ def check_json_file_has_correct_format(file_path):
                 left_indent = len(lines[1]) - len(lines[1].lstrip())
                 assert left_indent == 2
             assert lines[-1].strip() == "}"
+
+
+def to_2tuple(x):
+    if isinstance(x, collections.abc.Iterable):
+        return x
+    return (x, x)