feat(mge/funcitonal): add cvt_color opr python interface

GitOrigin-RevId: 29e069fb2334a20545021f37a7133f7bfdbafd0b

imperative/python/megengine/functional/__init__.py

@@ -8,6 +8,7 @@
 # "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # pylint: disable=redefined-builtin
 from .elemwise import *
+from .img_proc import *
 from .math import *
 from .nn import *
 from .tensor import *

imperative/python/megengine/functional/img_proc.py

+# -*- coding: utf-8 -*-
+# MegEngine is Licensed under the Apache License, Version 2.0 (the "License")
+#
+# Copyright (c) 2014-2021 Megvii Inc. All rights reserved.
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+from ..core._imperative_rt.core2 import apply
+from ..core.ops import builtin
+from ..tensor import Tensor
+
+__all__ = [
+    "cvt_color",
+]
+
+
+def cvt_color(inp: Tensor, mode: str = ""):
+    r"""
+    Convert images from one format to another
+
+    :param inp: input images.
+    :param mode: format mode.
+    :return: convert result.
+
+    Examples:
+
+    .. testcode::
+
+        import numpy as np
+        import megengine as mge
+        import megengine.functional as F
+
+        x = mge.tensor(np.array([[[[-0.58675045, 1.7526233, 0.10702174]]]]).astype(np.float32))
+        y = F.img_proc.cvt_color(x, mode="RGB2GRAY")
+        print(y.numpy())
+
+    Outputs:
+
+    .. testoutput::
+
+        [[[[0.86555195]]]]
+
+    """
+    assert mode in builtin.CvtColor.Mode.__dict__, "unspport mode for cvt_color"
+    mode = getattr(builtin.CvtColor.Mode, mode)
+    assert isinstance(mode, builtin.CvtColor.Mode)
+    op = builtin.CvtColor(mode=mode)
+    (out,) = apply(op, inp)
+    return out

imperative/python/test/unit/functional/test_functional.py

@@ -704,3 +704,14 @@ def test_argmxx_on_inf():
 
     assert all(run_argmax() >= 0)
     assert all(run_argmin() >= 0)
+
+
+def test_cvt_color():
+    def rgb2gray(rgb):
+        return np.dot(rgb[..., :3], [0.299, 0.587, 0.114])
+
+    inp = np.random.randn(3, 3, 3, 3).astype(np.float32)
+    out = np.expand_dims(rgb2gray(inp), 3).astype(np.float32)
+    x = tensor(inp)
+    y = F.img_proc.cvt_color(x, mode="RGB2GRAY")
+    np.testing.assert_allclose(y.numpy(), out, atol=1e-5)

imperative/src/impl/ops/img_proc.cpp

+/**
+ * \file imperative/src/impl/ops/img_proc.cpp
+ * MegEngine is Licensed under the Apache License, Version 2.0 (the "License")
+ *
+ * Copyright (c) 2014-2021 Megvii Inc. All rights reserved.
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ */
+
+#include "megbrain/imperative/ops/autogen.h"
+#include "megbrain/opr/imgproc.h"
+
+#include "../op_trait.h"
+
+namespace mgb {
+namespace imperative {
+
+namespace {
+auto apply_on_var_node(
+        const OpDef& def,
+        const VarNodeArray& inputs) {
+    auto&& op = static_cast<const CvtColor&>(def);
+    mgb_assert(inputs.size() == 1);
+    return opr::CvtColor::make(inputs[0], op.param());
+}
+OP_TRAIT_REG(CvtColor, CvtColor)
+    .apply_on_var_node(apply_on_var_node)
+    .fallback();
+}
+}
+}
\ No newline at end of file

src/core/include/megbrain/ir/ops.td

@@ -254,4 +254,6 @@ def TensorRTRuntime: MgbHashableOp<"TensorRTRuntime"> {
   );
 }
 
+def CvtColor: MgbHashableOp<"CvtColor", [CvtColorParam]>;
+
 #endif // MGB_OPS