Adjust value_range for random_contrast and random_hue (#20671)

* Adjust value_range for random_contrast and random_hue

* Add value_range description

* Correct failed test cases

Author: shashaka

keras/src/layers/preprocessing/image_preprocessing/random_contrast.py

@@ -40,14 +40,19 @@ class RandomContrast(BaseImagePreprocessingLayer):
             `[1.0 - lower, 1.0 + upper]`. For any pixel x in the channel,
             the output will be `(x - mean) * factor + mean`
             where `mean` is the mean value of the channel.
+        value_range: the range of values the incoming images will have.
+            Represented as a two-number tuple written `[low, high]`. This is
+            typically either `[0, 1]` or `[0, 255]` depending on how your
+            preprocessing pipeline is set up.
         seed: Integer. Used to create a random seed.
     """
 
     _FACTOR_BOUNDS = (0, 1)
 
-    def __init__(self, factor, seed=None, **kwargs):
+    def __init__(self, factor, value_range=(0, 255), seed=None, **kwargs):
         super().__init__(**kwargs)
         self._set_factor(factor)
+        self.value_range = value_range
         self.seed = seed
         self.generator = SeedGenerator(seed)
 
@@ -89,7 +94,9 @@ def transform_images(self, images, transformation, training=True):
         if training:
             constrast_factor = transformation["contrast_factor"]
             outputs = self._adjust_constrast(images, constrast_factor)
-            outputs = self.backend.numpy.clip(outputs, 0, 255)
+            outputs = self.backend.numpy.clip(
+                outputs, self.value_range[0], self.value_range[1]
+            )
             self.backend.numpy.reshape(outputs, self.backend.shape(images))
             return outputs
         return images
@@ -135,6 +142,7 @@ def compute_output_shape(self, input_shape):
     def get_config(self):
         config = {
             "factor": self.factor,
+            "value_range": self.value_range,
             "seed": self.seed,
         }
         base_config = super().get_config()

keras/src/layers/preprocessing/image_preprocessing/random_contrast_test.py

@@ -14,6 +14,7 @@ def test_layer(self):
             layers.RandomContrast,
             init_kwargs={
                 "factor": 0.75,
+                "value_range": (0, 255),
                 "seed": 1,
             },
             input_shape=(8, 3, 4, 3),
@@ -24,6 +25,7 @@ def test_layer(self):
             layers.RandomContrast,
             init_kwargs={
                 "factor": 0.75,
+                "value_range": (0, 255),
                 "seed": 1,
                 "data_format": "channels_first",
             },
@@ -32,21 +34,67 @@ def test_layer(self):
             expected_output_shape=(8, 3, 4, 4),
         )
 
-    def test_random_contrast(self):
+    def test_random_contrast_with_value_range_0_to_255(self):
         seed = 9809
         np.random.seed(seed)
-        inputs = np.random.random((12, 8, 16, 3))
-        layer = layers.RandomContrast(factor=0.5, seed=seed)
-        outputs = layer(inputs)
+
+        data_format = backend.config.image_data_format()
+        if data_format == "channels_last":
+            inputs = np.random.random((12, 8, 16, 3))
+            height_axis = -3
+            width_axis = -2
+        else:
+            inputs = np.random.random((12, 3, 8, 16))
+            height_axis = -2
+            width_axis = -1
+
+        inputs = backend.convert_to_tensor(inputs, dtype="float32")
+        layer = layers.RandomContrast(
+            factor=0.5, value_range=(0, 255), seed=seed
+        )
+        transformation = layer.get_random_transformation(inputs, training=True)
+        outputs = layer.transform_images(inputs, transformation, training=True)
+
+        # Actual contrast arithmetic
+        np.random.seed(seed)
+        factor = backend.convert_to_numpy(transformation["contrast_factor"])
+        inputs = backend.convert_to_numpy(inputs)
+        inp_mean = np.mean(inputs, axis=height_axis, keepdims=True)
+        inp_mean = np.mean(inp_mean, axis=width_axis, keepdims=True)
+        actual_outputs = (inputs - inp_mean) * factor + inp_mean
+        outputs = backend.convert_to_numpy(outputs)
+        actual_outputs = np.clip(actual_outputs, 0, 255)
+
+        self.assertAllClose(outputs, actual_outputs)
+
+    def test_random_contrast_with_value_range_0_to_1(self):
+        seed = 9809
+        np.random.seed(seed)
+
+        data_format = backend.config.image_data_format()
+        if data_format == "channels_last":
+            inputs = np.random.random((12, 8, 16, 3))
+            height_axis = -3
+            width_axis = -2
+        else:
+            inputs = np.random.random((12, 3, 8, 16))
+            height_axis = -2
+            width_axis = -1
+
+        inputs = backend.convert_to_tensor(inputs, dtype="float32")
+        layer = layers.RandomContrast(factor=0.5, value_range=(0, 1), seed=seed)
+        transformation = layer.get_random_transformation(inputs, training=True)
+        outputs = layer.transform_images(inputs, transformation, training=True)
 
         # Actual contrast arithmetic
         np.random.seed(seed)
-        factor = np.random.uniform(0.5, 1.5)
-        inp_mean = np.mean(inputs, axis=-3, keepdims=True)
-        inp_mean = np.mean(inp_mean, axis=-2, keepdims=True)
+        factor = backend.convert_to_numpy(transformation["contrast_factor"])
+        inputs = backend.convert_to_numpy(inputs)
+        inp_mean = np.mean(inputs, axis=height_axis, keepdims=True)
+        inp_mean = np.mean(inp_mean, axis=width_axis, keepdims=True)
         actual_outputs = (inputs - inp_mean) * factor + inp_mean
         outputs = backend.convert_to_numpy(outputs)
-        actual_outputs = np.clip(outputs, 0, 255)
+        actual_outputs = np.clip(actual_outputs, 0, 1)
 
         self.assertAllClose(outputs, actual_outputs)
 

keras/src/layers/preprocessing/image_preprocessing/random_hue.py

@@ -44,7 +44,12 @@ class RandomHue(BaseImagePreprocessingLayer):
     _FACTOR_BOUNDS = (0, 1)
 
     def __init__(
-        self, factor, value_range, data_format=None, seed=None, **kwargs
+        self,
+        factor,
+        value_range=(0, 255),
+        data_format=None,
+        seed=None,
+        **kwargs,
     ):
         super().__init__(data_format=data_format, **kwargs)
         self._set_factor(factor)

keras/src/layers/preprocessing/image_preprocessing/random_hue_test.py

@@ -31,15 +31,24 @@ def test_random_hue_inference(self):
         output = layer(inputs, training=False)
         self.assertAllClose(inputs, output)
 
-    def test_random_hue_value_range(self):
+    def test_random_hue_value_range_0_to_1(self):
         image = keras.random.uniform(shape=(3, 3, 3), minval=0, maxval=1)
 
-        layer = layers.RandomHue(0.2, (0, 255))
+        layer = layers.RandomHue(0.2, (0, 1))
         adjusted_image = layer(image)
 
         self.assertTrue(keras.ops.numpy.all(adjusted_image >= 0))
         self.assertTrue(keras.ops.numpy.all(adjusted_image <= 1))
 
+    def test_random_hue_value_range_0_to_255(self):
+        image = keras.random.uniform(shape=(3, 3, 3), minval=0, maxval=255)
+
+        layer = layers.RandomHue(0.2, (0, 255))
+        adjusted_image = layer(image)
+
+        self.assertTrue(keras.ops.numpy.all(adjusted_image >= 0))
+        self.assertTrue(keras.ops.numpy.all(adjusted_image <= 255))
+
     def test_random_hue_no_change_with_zero_factor(self):
         data_format = backend.config.image_data_format()
         if data_format == "channels_last":