Resize produces incorrect results

[electriclilies]

The relay reshape function produces incorrect results. For scale factors other than 2, the output of relay.resize does not match the testing function.

The test I changed:

--- a/tests/python/relay/test_op_level5.py
+++ b/tests/python/relay/test_op_level5.py
@@ -66,7 +66,7 @@ def test_resize():
tvm.testing.assert_allclose(op_res.asnumpy(), ref_res, rtol=1e-4, atol=1e-6)
for method in ["bilinear", "nearest_neighbor"]:
for layout in ["NHWC", "NCHW"]:
- verify_resize((1, 4, 4, 4), 2, method, layout)
+ verify_resize((1, 4, 4, 4), 7, method, layout)

In this particular case, we get this error:

   AssertionError: 
   Not equal to tolerance rtol=0.0001, atol=1e-06
   
   Mismatched elements: 832 / 3136 (26.5%)
   Max absolute difference: 0.8489792
   Max relative difference: 711.5619
    x: array([[[[0.507647, 0.792792, 0.245963, 0.439271],
            [0.507647, 0.792792, 0.245963, 0.439271],
            [0.507647, 0.792792, 0.245963, 0.439271],...
    y: array([[[[0.507647, 0.792792, 0.245963, 0.439271],
            [0.507647, 0.792792, 0.245963, 0.439271],
            [0.507647, 0.792792, 0.245963, 0.439271],...

cc @mbrookhart

[mbrookhart]

It looks like it's failing with NHWC nearest_neighbor. Looking at git blame, it seems @masahi worked on the test utility and @yongwww worked on the topi op. Could one or both of you take a look at this?

[masahi]

Using align_corner option with nearest is a mistake: https://github.com/apache/incubator-tvm/blob/master/tests/python/relay/test_op_level5.py#L56

For nearest, I think the coordinate transform option should always be assymetric. The following should fix the test. The same fix should be applied to the dynamic one added in #6198.

coord_trans = "asymmetric" if method == "nearest_neighbor" else "align_corners"
z = relay.image.resize(x, size, layout, method,
                       coordinate_transformation_mode=coord_trans)

@electriclilies A PR welcome, or you can add the fix above to one of your on going PRs.

[electriclilies]

Proposed fix is in #6298