tf.keras.layers.DepthwiseConv2D

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2D depthwise convolution layer.

tf.keras.layers.DepthwiseConv2D(
    kernel_size,
    strides=(1, 1),
    padding='valid',
    depth_multiplier=1,
    data_format=None,
    dilation_rate=(1, 1),
    activation=None,
    use_bias=True,
    depthwise_initializer='glorot_uniform',
    bias_initializer='zeros',
    depthwise_regularizer=None,
    bias_regularizer=None,
    activity_regularizer=None,
    depthwise_constraint=None,
    bias_constraint=None,
    **kwargs
)

Used in the notebooks

Used in the guide
Pruning for on-device inference w/ XNNPACK

Depthwise convolution is a type of convolution in which each input channel is convolved with a different kernel (called a depthwise kernel). You can understand depthwise convolution as the first step in a depthwise separable convolution.

It is implemented via the following steps:

Split the input into individual channels.
Convolve each channel with an individual depthwise kernel withdepth_multiplier output channels.
Concatenate the convolved outputs along the channels axis.

Unlike a regular 2D convolution, depthwise convolution does not mix information across different input channels.

The depth_multiplier argument determines how many filters are applied to one input channel. As such, it controls the amount of output channels that are generated per input channel in the depthwise step.

Args
kernel_size	int or tuple/list of 2 integer, specifying the size of the depthwise convolution window.
strides	int or tuple/list of 2 integer, specifying the stride length of the depthwise convolution. strides > 1 is incompatible withdilation_rate > 1.
padding	string, either "valid" or "same" (case-insensitive)."valid" means no padding. "same" results in padding evenly to the left/right or up/down of the input. When padding="same" andstrides=1, the output has the same size as the input.
depth_multiplier	The number of depthwise convolution output channels for each input channel. The total number of depthwise convolution output channels will be equal to input_channel * depth_multiplier.
data_format	string, either "channels_last" or "channels_first". The ordering of the dimensions in the inputs. "channels_last"corresponds to inputs with shape (batch, height, width, channels)while "channels_first" corresponds to inputs with shape(batch, channels, height, width). It defaults to theimage_data_format value found in your Keras config file at ~/.keras/keras.json. If you never set it, then it will be "channels_last".
dilation_rate	int or tuple/list of 2 integers, specifying the dilation rate to use for dilated convolution.
activation	Activation function. If None, no activation is applied.
use_bias	bool, if True, bias will be added to the output.
depthwise_initializer	Initializer for the convolution kernel. If None, the default initializer ("glorot_uniform") will be used.
bias_initializer	Initializer for the bias vector. If None, the default initializer ("zeros") will be used.
depthwise_regularizer	Optional regularizer for the convolution kernel.
bias_regularizer	Optional regularizer for the bias vector.
activity_regularizer	Optional regularizer function for the output.
depthwise_constraint	Optional projection function to be applied to the kernel after being updated by an Optimizer (e.g. used to implement norm constraints or value constraints for layer weights). The function must take as input the unprojected variable and must return the projected variable (which must have the same shape). Constraints are not safe to use when doing asynchronous distributed training.
bias_constraint	Optional projection function to be applied to the bias after being updated by an Optimizer.

Input shape:

If data_format="channels_last": A 4D tensor with shape: (batch_size, height, width, channels)
If data_format="channels_first": A 4D tensor with shape: (batch_size, channels, height, width)

Output shape:

If data_format="channels_last": A 4D tensor with shape:(batch_size, new_height, new_width, channels * depth_multiplier)
If data_format="channels_first": A 4D tensor with shape:(batch_size, channels * depth_multiplier, new_height, new_width)

Returns
A 4D tensor representingactivation(depthwise_conv2d(inputs, kernel) + bias).

Raises
ValueError	when both strides > 1 and dilation_rate > 1.

Example:

x = np.random.rand(4, 10, 10, 12) y = keras.layers.DepthwiseConv2D(3, 3, activation='relu')(x) print(y.shape) (4, 8, 8, 36)

Attributes
input	Retrieves the input tensor(s) of a symbolic operation.Only returns the tensor(s) corresponding to the _first time_the operation was called.
output	Retrieves the output tensor(s) of a layer.Only returns the tensor(s) corresponding to the _first time_the operation was called.

Methods

`from_config`

View source

@classmethod from_config( config )

Creates a layer from its config.

This method is the reverse of get_config, capable of instantiating the same layer from the config dictionary. It does not handle layer connectivity (handled by Network), nor weights (handled by set_weights).

Args
config	A Python dictionary, typically the output of get_config.

Returns
A layer instance.

`symbolic_call`