tf.keras.ops.image.rgb_to_grayscale

Convert RGB images to grayscale.

tf.keras.ops.image.rgb_to_grayscale(
    image, data_format='channels_last'
)

This function converts RGB images to grayscale images. It supports both 3D and 4D tensors, where the last dimension represents channels.

image Input RGB image or batch of RGB images. Must be a 3D tensor with shape (height, width, channels) or a 4D tensor with shape (batch, height, width, channels).
data_format A string specifying the data format of the input tensor. It can be either "channels_last" or "channels_first". "channels_last" corresponds to inputs with shape (batch, height, width, channels), while "channels_first" corresponds to inputs with shape (batch, channels, height, width). Defaults to "channels_last".

Grayscale image or batch of grayscale images.

Examples:

import numpy as np
from keras.src import ops
x = np.random.random((2, 4, 4, 3))
y = ops.image.rgb_to_grayscale(x)
y.shape
(2, 4, 4, 1)

x = np.random.random((4, 4, 3)) # Single RGB image
y = ops.image.rgb_to_grayscale(x)
y.shape
(4, 4, 1)

x = np.random.random((2, 3, 4, 4))
y = ops.image.rgb_to_grayscale(x, data_format="channels_first")
y.shape
(2, 1, 4, 4)