RGB to Grayscale

.github/CODEOWNERS

@@ -64,6 +64,8 @@
 /tensorflow_addons/image/tests/interpolate_spline_test.py
 /tensorflow_addons/image/resampler_ops.py @autoih
 /tensorflow_addons/image/tests/resampler_ops_test.py @autoih
+/tensorflow_addons/image/rgb_to_grayscale_op.py @ghosalsattam
+/tensorflow_addons/image/tests/rgb_to_grayscale_op_test.py @ghosalsattam
 /tensorflow_addons/image/sparse_image_warp.py
 /tensorflow_addons/image/tests/sparse_image_warp_test.py
 /tensorflow_addons/image/transform_ops.py @mels630

tensorflow_addons/image/__init__.py

@@ -29,6 +29,7 @@
 from tensorflow_addons.image.cutout_ops import random_cutout
 from tensorflow_addons.image.distort_image_ops import random_hsv_in_yiq
 from tensorflow_addons.image.resampler_ops import resampler
+from tensorflow_addons.image.rgb_to_grayscale_op import rgb_to_grayscale
 from tensorflow_addons.image.transform_ops import rotate
 from tensorflow_addons.image.transform_ops import shear_x
 from tensorflow_addons.image.transform_ops import shear_y

tensorflow_addons/image/rgb_to_grayscale_op.py

@@ -0,0 +1,45 @@
+# Copyright 2019 The TensorFlow Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"RGB to Grayscale op"
+
+from tensorflow_addons.utils.types import FloatTensorLike
+from tensorflow_addons.image import utils as img_utils
+import tensorflow as tf
+
+from typing import Optional
+
+
+def rgb_to_grayscale(
+    image: FloatTensorLike, name: Optional[str] = None,
+) -> FloatTensorLike:
+    """Perform RGB to Grayscale conversion of image(s).
+
+    Args:
+      image: A 3-D `Tensor` of shape `[height, width, channels]`,
+        or a 4-D `Tensor` of shape `[batch_size, height, width, channels]`.
+        The number of channels must be equal to 3.
+      name: A name for this operation (optional).
+    """
+
+    with tf.name_scope(name or "rgb_to_grayscale"):
+        image = tf.cast(image, tf.float32)
+        original_ndims = img_utils.get_ndims(image)
+        image = img_utils.to_4D_image(image)
+        channels = tf.shape(image)[3]
+        if channels != 3:
+            raise ValueError("The image must be in RGB format")
+        grayscale_output = tf.image.rgb_to_grayscale(image)
+        grayscale_output = img_utils.from_4D_image(grayscale_output, original_ndims)
+        return grayscale_output

tensorflow_addons/image/tests/rgb_to_grayscale_op_test.py

@@ -0,0 +1,89 @@
+# Copyright 2019 The TensorFlow Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"rgb to grayscale op test"
+
+
+import numpy as np
+import tensorflow as tf
+from tensorflow_addons.image.rgb_to_grayscale_op import rgb_to_grayscale
+import pytest
+
+
+@pytest.mark.usefixtures("maybe_run_functions_eagerly")
+def test_rgb_to_grayscale_op():
+    img = tf.constant(
+        [
+            [
+                [
+                    [0.0, 0.0, 0.0],
+                    [2.0, 2.0, 2.0],
+                    [4.0, 4.0, 4.0],
+                    [6.0, 6.0, 6.0],
+                    [8.0, 8.0, 8.0],
+                ],
+                [
+                    [10.0, 10.0, 10.0],
+                    [12.0, 12.0, 12.0],
+                    [14.0, 14.0, 14.0],
+                    [16.0, 16.0, 16.0],
+                    [18.0, 18.0, 18.0],
+                ],
+                [
+                    [20.0, 20.0, 20.0],
+                    [22.0, 22.0, 22.0],
+                    [24.0, 24.0, 24.0],
+                    [26.0, 26.0, 26.0],
+                    [28.0, 28.0, 28.0],
+                ],
+                [
+                    [30.0, 30.0, 30.0],
+                    [32.0, 32.0, 32.0],
+                    [34.0, 34.0, 34.0],
+                    [36.0, 36.0, 36.0],
+                    [38.0, 38.0, 38.0],
+                ],
+                [
+                    [40.0, 40.0, 40.0],
+                    [42.0, 42.0, 42.0],
+                    [44.0, 44.0, 44.0],
+                    [46.0, 46.0, 46.0],
+                    [48.0, 48.0, 48.0],
+                ],
+            ]
+        ],
+        dtype=tf.float32,
+    )
+    r = np.arange(0, 50, 2)
+    count = 0
+    exp_plane = np.ones([5, 5, 1])
+    for i in range(5):
+        for j in range(5):
+            exp_plane[i][j][0] = (
+                0.2989 * r[count] + 0.5870 * r[count] + 0.1140 * r[count]
+            )
+            count += 1
+    grayscale_tfa = rgb_to_grayscale(img)
+    grayscale_tfa = grayscale_tfa.numpy()
+    grayscale_tfa = np.resize(grayscale_tfa, (5, 5))
+    exp_plane = np.resize(exp_plane, (5, 5))
+    np.testing.assert_allclose(grayscale_tfa, exp_plane, 0.06)
+
+
+@pytest.mark.usefixtures("maybe_run_functions_eagerly")
+def test_rgb_to_grayscale_op_random_image():
+    img = tf.random.uniform([2, 40, 40, 3], minval=0, maxval=255, dtype=tf.float32)
+    exp_plane = tf.image.rgb_to_grayscale(img)
+    grayscale_tfa = tf.image.rgb_to_grayscale(img)
+    np.testing.assert_allclose(grayscale_tfa, exp_plane, 0.06)