► Keras 2 API documentation / Layers API / Convolution layers / Conv2DTranspose layer

Conv2DTranspose layer

[source]

Conv2DTranspose class

tf_keras.layers.Conv2DTranspose(
    filters,
    kernel_size,
    strides=(1, 1),
    padding="valid",
    output_padding=None,
    data_format=None,
    dilation_rate=(1, 1),
    activation=None,
    use_bias=True,
    kernel_initializer="glorot_uniform",
    bias_initializer="zeros",
    kernel_regularizer=None,
    bias_regularizer=None,
    activity_regularizer=None,
    kernel_constraint=None,
    bias_constraint=None,
    **kwargs
)

Transposed convolution layer (sometimes called Deconvolution).

The need for transposed convolutions generally arises from the desire to use a transformation going in the opposite direction of a normal convolution, i.e., from something that has the shape of the output of some convolution to something that has the shape of its input while maintaining a connectivity pattern that is compatible with said convolution.

When using this layer as the first layer in a model, provide the keyword argument input_shape (tuple of integers or None, does not include the sample axis), e.g. input_shape=(128, 128, 3) for 128x128 RGB pictures in data_format="channels_last".

Arguments

  • filters: Integer, the dimensionality of the output space (i.e. the number of output filters in the convolution).
  • kernel_size: An integer or tuple/list of 2 integers, specifying the height and width of the 2D convolution window. Can be a single integer to specify the same value for all spatial dimensions.
  • strides: An integer or tuple/list of 2 integers, specifying the strides of the convolution along the height and width. Can be a single integer to specify the same value for all spatial dimensions. Specifying any stride value != 1 is incompatible with specifying any dilation_rate value != 1.
  • padding: one of "valid" or "same" (case-insensitive). "valid" means no padding. "same" results in padding with zeros evenly to the left/right or up/down of the input such that output has the same height/width dimension as the input.
  • output_padding: An integer or tuple/list of 2 integers, specifying the amount of padding along the height and width of the output tensor. Can be a single integer to specify the same value for all spatial dimensions. The amount of output padding along a given dimension must be lower than the stride along that same dimension. If set to None (default), the output shape is inferred.
  • data_format: A string, one of channels_last (default) or channels_first. The ordering of the dimensions in the inputs. channels_last corresponds to inputs with shape (batch_size, height, width, channels) while channels_first corresponds to inputs with shape (batch_size, channels, height, width). When unspecified, uses image_data_format value found in your Keras config file at ~/.keras/keras.json (if exists) else 'channels_last'. Defaults to "channels_last".
  • dilation_rate: an integer, specifying the dilation rate for all spatial dimensions for dilated convolution. Specifying different dilation rates for different dimensions is not supported. Currently, specifying any dilation_rate value != 1 is incompatible with specifying any stride value != 1.
  • activation: Activation function to use. If you don't specify anything, no activation is applied (see keras.activations).
  • use_bias: Boolean, whether the layer uses a bias vector.
  • kernel_initializer: Initializer for the kernel weights matrix (see keras.initializers). Defaults to 'glorot_uniform'.
  • bias_initializer: Initializer for the bias vector (see keras.initializers). Defaults to 'zeros'.
  • kernel_regularizer: Regularizer function applied to the kernel weights matrix (see keras.regularizers).
  • bias_regularizer: Regularizer function applied to the bias vector (see keras.regularizers).
  • activity_regularizer: Regularizer function applied to the output of the layer (its "activation") (see keras.regularizers).
  • kernel_constraint: Constraint function applied to the kernel matrix (see keras.constraints).
  • bias_constraint: Constraint function applied to the bias vector (see keras.constraints).

Input shape

4D tensor with shape: (batch_size, channels, rows, cols) if data_format='channels_first' or 4D tensor with shape: (batch_size, rows, cols, channels) if data_format='channels_last'.

Output shape

4D tensor with shape: (batch_size, filters, new_rows, new_cols) if data_format='channels_first' or 4D tensor with shape: (batch_size, new_rows, new_cols, filters) if data_format='channels_last'. rows and cols values might have changed due to padding. If output_padding is specified:

new_rows = ((rows - 1) * strides[0] + kernel_size[0] - 2 * padding[0] +
output_padding[0])
new_cols = ((cols - 1) * strides[1] + kernel_size[1] - 2 * padding[1] +
output_padding[1])

Returns

A tensor of rank 4 representing activation(conv2dtranspose(inputs, kernel) + bias).

Raises

  • ValueError: if padding is "causal".
  • ValueError: when both strides > 1 and dilation_rate > 1.

References

Conv2DTranspose layer
Conv2DTranspose class