Fixing keras.ops.image.map_coordinates Failure with uint8 Input on TensorFlow Backend"

[NebulaNerdo]

Consider the following simple example

`import keras

image = keras.ops.ones((1, 1, 3), dtype='uint8')

coordinates = keras.ops.convert_to_tensor([-1., 0., 0.])[..., None, None]
interp = keras.ops.image.map_coordinates(image, coordinates, order=1, fill_mode='constant')`

that is expected to yield [[0]]. However, with KERAS_BACKEND=tensorflow this code snippet results in

2024-12-08 16:04:24.790791: W tensorflow/core/framework/op_kernel.cc:1841] OP_REQUIRES failed at gather_nd_op.cc:65 : INVALID_ARGUMENT: indices[0,0] = [-1, 0, 0] does not index into param shape [1,1,3], node name: GatherNd 2024-12-08 16:04:24.790814: I tensorflow/core/framework/local_rendezvous.cc:405] Local rendezvous is aborting with status: INVALID_ARGUMENT: indices[0,0] = [-1, 0, 0] does not index into param shape [1,1,3], node name: GatherNd Traceback (most recent call last): File "<home>/tfmapc.py", line 11, in <module> interp = keras.ops.image.map_coordinates(image, coordinates, order=1, fill_mode='constant') ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "<home>/.env/lib/python3.12/site-packages/keras/src/ops/image.py", line 787, in map_coordinates return backend.image.map_coordinates( ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "<home>/.env/lib/python3.12/site-packages/keras/src/backend/tensorflow/image.py", line 485, in map_coordinates contribution = tf.cond(tf.reduce_all(validities), fast_path, slow_path) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "<home>/.env/lib/python3.12/site-packages/tensorflow/python/util/traceback_utils.py", line 153, in error_handler raise e.with_traceback(filtered_tb) from None File "<home>/.env/lib/python3.12/site-packages/keras/src/backend/tensorflow/image.py", line 481, in slow_path tf.transpose(tf.gather_nd(input_arr, indices)), ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ tensorflow.python.framework.errors_impl.InvalidArgumentError: {{function_node __wrapped__GatherNd_device_/job:localhost/replica:0/task:0/device:CPU:0}} indices[0,0] = [-1, 0, 0] does not index into param shape [1,1,3], node name: GatherNd [Op:GatherNd] name:

The problem does not occur if I change the dtype of image from uint8 to float32 or switch either to the jax or torch backends. Also changing the fill_mode from constant to nearest avoids the issue.

Keras version: 3.7.0

[sergiud]

Why do you plagiarize #20608?