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import itertools
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import numpy as np
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import tensorflow as tf
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import tensorflow.keras.layers as tfkl
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import deepreg.model.layer_util as layer_util
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class Norm(tf.keras.layers.Layer):
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def __init__(self, name: str = "batch_norm", axis: int = -1, **kwargs):
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"""
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Class merges batch norm and layer norm.
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:param name: str, batch_norm or layer_norm
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:param axis: int
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:param kwargs: additional arguments.
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"""
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super().__init__(**kwargs)
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if name == "batch_norm":
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self._norm = tf.keras.layers.BatchNormalization(axis=axis, **kwargs)
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elif name == "layer_norm":
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self._norm = tf.keras.layers.LayerNormalization(axis=axis)
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else:
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raise ValueError("Unknown normalization type")
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def call(self, inputs, training=None, **kwargs):
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return self._norm(inputs=inputs, training=training)
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class Deconv3d(tf.keras.layers.Layer):
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def __init__(
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self,
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filters: int,
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output_shape: (tuple, None) = None,
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kernel_size: int = 3,
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strides: int = 1,
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padding: str = "same",
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use_bias: bool = True,
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**kwargs,
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):
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"""
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Layer wraps tf.keras.layers.Conv3DTranspose
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and does not requires input shape when initializing.
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:param filters: number of channels of the output
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:param output_shape: (out_dim1, out_dim2, out_dim3)
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:param kernel_size: int or tuple of 3 ints, e.g. (3,3,3) or 3
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:param strides: int or tuple of 3 ints, e.g. (1,1,1) or 1
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:param padding: same or valid.
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:param use_bias: use bias for Conv3DTranspose or not.
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:param kwargs: additional arguments.
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"""
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super().__init__(**kwargs)
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# save parameters
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self._filters = filters
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self._output_shape = output_shape
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self._kernel_size = kernel_size
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self._strides = strides
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self._padding = padding
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self._use_bias = use_bias
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self._kwargs = kwargs
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# init layer variables
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self._output_padding = None
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self._deconv3d = None
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def build(self, input_shape):
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super().build(input_shape)
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if isinstance(self._kernel_size, int):
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self._kernel_size = [self._kernel_size] * 3
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if isinstance(self._strides, int):
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self._strides = [self._strides] * 3
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if self._output_shape is not None:
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# pylint: disable-next=line-too-long
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"""
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https://github.com/tensorflow/tensorflow/blob/1cf0898dd4331baf93fe77205550f2c2e6c90ee5/tensorflow/python/keras/utils/conv_utils.py#L139-L185
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When the output shape is defined, the padding should be calculated manually
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if padding == 'same':
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pad = filter_size // 2
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length = ((input_length - 1) * stride + filter_size
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- 2 * pad + output_padding)
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"""
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self._padding = "same"
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self._output_padding = [
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self._output_shape[i]
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- (
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(input_shape[1 + i] - 1) * self._strides[i]
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+ self._kernel_size[i]
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- 2 * (self._kernel_size[i] // 2)
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)
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for i in range(3)
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]
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self._deconv3d = tf.keras.layers.Conv3DTranspose(
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filters=self._filters,
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kernel_size=self._kernel_size,
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strides=self._strides,
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padding=self._padding,
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output_padding=self._output_padding,
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use_bias=self._use_bias,
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**self._kwargs,
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)
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def call(self, inputs, **kwargs):
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return self._deconv3d(inputs=inputs)
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class Conv3dBlock(tf.keras.layers.Layer):
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def __init__(
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self,
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filters: int,
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kernel_size: (int, tuple) = 3,
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strides: (int, tuple) = 1,
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padding: str = "same",
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activation: str = "relu",
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**kwargs,
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):
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"""
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A conv3d block having conv3d - norm - activation.
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:param filters: number of channels of the output
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:param kernel_size: int or tuple of 3 ints, e.g. (3,3,3) or 3
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:param strides: int or tuple of 3 ints, e.g. (1,1,1) or 1
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:param padding: str, same or valid
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:param activation: name of activation
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:param kwargs: additional arguments.
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"""
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super().__init__(**kwargs)
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# init layer variables
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self._conv3d = tfkl.Conv3D(
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filters=filters,
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kernel_size=kernel_size,
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strides=strides,
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padding=padding,
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use_bias=False,
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)
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self._norm = Norm()
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self._act = tfkl.Activation(activation=activation)
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def call(self, inputs, training=None, **kwargs) -> tf.Tensor:
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"""
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:param inputs: shape = (batch, in_dim1, in_dim2, in_dim3, channels)
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:param training: training flag for normalization layers (default: None)
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:param kwargs: additional arguments.
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:return: shape = (batch, in_dim1, in_dim2, in_dim3, channels)
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"""
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output = self._conv3d(inputs=inputs)
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output = self._norm(inputs=output, training=training)
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output = self._act(output)
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return output
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class Deconv3dBlock(tf.keras.layers.Layer):
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def __init__(
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self,
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filters: int,
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output_shape: (tuple, None) = None,
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kernel_size: (int, tuple) = 3,
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strides: (int, tuple) = 1,
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padding: str = "same",
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activation: str = "relu",
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**kwargs,
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):
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"""
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A deconv3d block having deconv3d - norm - activation.
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:param filters: number of channels of the output
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:param output_shape: (out_dim1, out_dim2, out_dim3)
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:param kernel_size: int or tuple of 3 ints, e.g. (3,3,3) or 3
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:param strides: int or tuple of 3 ints, e.g. (1,1,1) or 1
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:param padding: str, same or valid
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:param activation: name of activation
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:param kwargs: additional arguments.
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"""
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super().__init__(**kwargs)
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# init layer variables
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self._deconv3d = Deconv3d(
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filters=filters,
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output_shape=output_shape,
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kernel_size=kernel_size,
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strides=strides,
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padding=padding,
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use_bias=False,
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)
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self._norm = Norm()
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self._act = tfkl.Activation(activation=activation)
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def call(self, inputs, training=None, **kwargs) -> tf.Tensor:
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"""
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:param inputs: shape = (batch, in_dim1, in_dim2, in_dim3, channels)
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:param training: training flag for normalization layers (default: None)
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:param kwargs: additional arguments.
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:return output: shape = (batch, in_dim1, in_dim2, in_dim3, channels)
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"""
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output = self._deconv3d(inputs=inputs)
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output = self._norm(inputs=output, training=training)
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output = self._act(output)
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return output
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class Residual3dBlock(tf.keras.layers.Layer):
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def __init__(
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self,
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filters: int,
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kernel_size: (int, tuple) = 3,
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strides: (int, tuple) = 1,
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activation: str = "relu",
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**kwargs,
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):
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"""
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A resnet conv3d block.
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1. conved = conv3d(conv3d_block(inputs))
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2. out = act(norm(conved) + inputs)
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:param filters: int, number of filters in the convolutional layers
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:param kernel_size: int or tuple of 3 ints, e.g. (3,3,3) or 3
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:param strides: int or tuple of 3 ints, e.g. (1,1,1) or 1
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:param activation: name of activation
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:param kwargs: additional arguments.
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"""
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super().__init__(**kwargs)
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# init layer variables
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self._conv3d_block = Conv3dBlock(
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filters=filters, kernel_size=kernel_size, strides=strides
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)
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self._conv3d = tfkl.Conv3D(
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filters=filters,
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kernel_size=kernel_size,
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strides=strides,
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padding="same",
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use_bias=False,
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)
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self._norm = Norm()
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self._act = tfkl.Activation(activation=activation)
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def call(self, inputs, training=None, **kwargs) -> tf.Tensor:
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"""
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:param inputs: shape = (batch, in_dim1, in_dim2, in_dim3, channels)
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:param training: training flag for normalization layers (default: None)
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:param kwargs: additional arguments.
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:return output: shape = (batch, in_dim1, in_dim2, in_dim3, channels)
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"""
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return self._act(
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self._norm(
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inputs=self._conv3d(inputs=self._conv3d_block(inputs)),
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training=training,
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)
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+ inputs
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)
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class DownSampleResnetBlock(tf.keras.layers.Layer):
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def __init__(
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self,
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filters: int,
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kernel_size: (int, tuple) = 3,
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pooling: bool = True,
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**kwargs,
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):
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"""
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A down-sampling resnet conv3d block, with max-pooling or conv3d.
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1. conved = conv3d_block(inputs) # adjust channel
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2. skip = residual_block(conved) # develop feature
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3. pooled = pool(skip) # down-sample
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:param filters: number of channels of the output
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:param kernel_size: int or tuple of 3 ints, e.g. (3,3,3) or 3
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:param pooling: if True, use max pooling to downsample, otherwise use conv.
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:param kwargs: additional arguments.
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"""
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super().__init__(**kwargs)
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# save parameters
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self._pooling = pooling
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# init layer variables
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self._conv3d_block = Conv3dBlock(filters=filters, kernel_size=kernel_size)
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self._residual_block = Residual3dBlock(filters=filters, kernel_size=kernel_size)
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self._max_pool3d = (
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tfkl.MaxPool3D(pool_size=(2, 2, 2), strides=(2, 2, 2), padding="same")
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if pooling
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else None
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)
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self._conv3d_block3 = (
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None
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if pooling
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else Conv3dBlock(filters=filters, kernel_size=kernel_size, strides=2)
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)
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def call(self, inputs, training=None, **kwargs) -> (tf.Tensor, tf.Tensor):
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"""
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:param inputs: shape = (batch, in_dim1, in_dim2, in_dim3, channels)
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:param training: training flag for normalization layers (default: None)
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:param kwargs: additional arguments.
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:return: (pooled, skip)
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- downsampled, shape = (batch, in_dim1//2, in_dim2//2, in_dim3//2, channels)
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- skipped, shape = (batch, in_dim1, in_dim2, in_dim3, channels)
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"""
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conved = self._conv3d_block(inputs=inputs, training=training) # adjust channel
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skip = self._residual_block(inputs=conved, training=training) # develop feature
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pooled = (
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self._max_pool3d(inputs=skip)
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if self._pooling
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else self._conv3d_block3(inputs=skip, training=training)
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) # downsample
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return pooled, skip
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class UpSampleResnetBlock(tf.keras.layers.Layer):
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312
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def __init__(self, filters, kernel_size=3, concat=False, **kwargs):
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"""
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314
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An up-sampling resnet conv3d block, with deconv3d.
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:param filters: number of channels of the output
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:param kernel_size: int or tuple of 3 ints, e.g. (3,3,3) or 3
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:param concat: bool,specify how to combine input and skip connection images.
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If True, use concatenation, otherwise use sum (default=False).
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:param kwargs: additional arguments.
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"""
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super().__init__(**kwargs)
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# save parameters
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self._filters = filters
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self._concat = concat
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# init layer variables
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self._deconv3d_block = None
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self._conv3d_block = Conv3dBlock(filters=filters, kernel_size=kernel_size)
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self._residual_block = Residual3dBlock(filters=filters, kernel_size=kernel_size)
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def build(self, input_shape):
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"""
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:param input_shape: tuple, (downsampled_image_shape, skip_image_shape)
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"""
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super().build(input_shape)
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skip_shape = input_shape[1][1:4]
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self._deconv3d_block = Deconv3dBlock(
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filters=self._filters, output_shape=skip_shape, strides=2
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)
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def call(self, inputs, training=None, **kwargs) -> tf.Tensor:
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r"""
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:param inputs: tuple
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- down-sampled
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- skipped
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:param training: training flag for normalization layers (default: None)
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:param kwargs: additional arguments.
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:return: shape = (batch, \*skip_connection_image_shape, filters]
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"""
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up_sampled, skip = inputs[0], inputs[1]
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up_sampled = self._deconv3d_block(
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inputs=up_sampled, training=training
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) # up sample and change channel
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up_sampled = (
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tf.concat([up_sampled, skip], axis=4) if self._concat else up_sampled + skip
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) # combine
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up_sampled = self._conv3d_block(
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inputs=up_sampled, training=training
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) # adjust channel
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up_sampled = self._residual_block(inputs=up_sampled, training=training) # conv
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return up_sampled
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class Conv3dWithResize(tf.keras.layers.Layer):
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367
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def __init__(
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self,
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output_shape: tuple,
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filters: int,
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kernel_initializer: str = "glorot_uniform",
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activation: (str, None) = None,
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**kwargs,
|
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):
|
375
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"""
|
376
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A layer contains conv3d - resize3d.
|
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|
378
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:param output_shape: tuple, (out_dim1, out_dim2, out_dim3)
|
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:param filters: int, number of channels of the output
|
380
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:param kernel_initializer: str, defines the initialization method
|
381
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:param activation: str, defines the activation function
|
382
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:param kwargs: additional arguments.
|
383
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"""
|
384
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super().__init__(**kwargs)
|
385
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# save parameters
|
386
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self._output_shape = output_shape
|
387
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# init layer variables
|
388
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self._conv3d = tfkl.Conv3D(
|
389
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filters=filters,
|
390
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kernel_size=3,
|
391
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strides=1,
|
392
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padding="same",
|
393
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kernel_initializer=kernel_initializer,
|
394
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activation=activation,
|
395
|
|
|
) # if not zero, with init NN, ddf may be too large
|
396
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|
397
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def call(self, inputs, **kwargs) -> tf.Tensor:
|
|
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|
|
398
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|
"""
|
399
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|
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:param inputs: shape = (batch, dim1, dim2, dim3, channels)
|
400
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|
:param kwargs: additional arguments.
|
401
|
|
|
:return: shape = (batch, out_dim1, out_dim2, out_dim3, channels)
|
402
|
|
|
"""
|
403
|
|
|
output = self._conv3d(inputs=inputs)
|
404
|
|
|
output = layer_util.resize3d(image=output, size=self._output_shape)
|
405
|
|
|
return output
|
406
|
|
|
|
407
|
|
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|
408
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|
class Warping(tf.keras.layers.Layer):
|
|
|
|
|
409
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def __init__(self, fixed_image_size: tuple, **kwargs):
|
410
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|
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"""
|
411
|
|
|
A layer warps an image using DDF.
|
412
|
|
|
|
413
|
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|
Reference:
|
414
|
|
|
|
415
|
|
|
- transform of neuron
|
416
|
|
|
https://github.com/adalca/neurite/blob/legacy/neuron/utils.py
|
417
|
|
|
|
418
|
|
|
where vol = image, loc_shift = ddf
|
419
|
|
|
|
420
|
|
|
:param fixed_image_size: shape = (f_dim1, f_dim2, f_dim3)
|
421
|
|
|
or (f_dim1, f_dim2, f_dim3, ch) with the last channel for features
|
422
|
|
|
:param kwargs: additional arguments.
|
423
|
|
|
"""
|
424
|
|
|
super().__init__(**kwargs)
|
425
|
|
|
self.grid_ref = tf.expand_dims(
|
426
|
|
|
layer_util.get_reference_grid(grid_size=fixed_image_size), axis=0
|
427
|
|
|
) # shape = (1, f_dim1, f_dim2, f_dim3, 3)
|
428
|
|
|
|
429
|
|
|
def call(self, inputs, **kwargs) -> tf.Tensor:
|
|
|
|
|
430
|
|
|
"""
|
431
|
|
|
:param inputs: (ddf, image)
|
432
|
|
|
|
433
|
|
|
- ddf, shape = (batch, f_dim1, f_dim2, f_dim3, 3), dtype = float32
|
434
|
|
|
- image, shape = (batch, m_dim1, m_dim2, m_dim3), dtype = float32
|
435
|
|
|
:param kwargs: additional arguments.
|
436
|
|
|
:return: shape = (batch, f_dim1, f_dim2, f_dim3)
|
437
|
|
|
"""
|
438
|
|
|
return layer_util.warp_image_ddf(
|
439
|
|
|
image=inputs[1], ddf=inputs[0], grid_ref=self.grid_ref
|
440
|
|
|
)
|
441
|
|
|
|
442
|
|
|
|
443
|
|
|
class IntDVF(tf.keras.layers.Layer):
|
|
|
|
|
444
|
|
|
def __init__(self, fixed_image_size: tuple, num_steps: int = 7, **kwargs):
|
445
|
|
|
"""
|
446
|
|
|
Layer calculates DVF from DDF.
|
447
|
|
|
|
448
|
|
|
Reference:
|
449
|
|
|
|
450
|
|
|
- integrate_vec of neuron
|
451
|
|
|
https://github.com/adalca/neurite/blob/legacy/neuron/utils.py
|
452
|
|
|
|
453
|
|
|
:param fixed_image_size: tuple, (f_dim1, f_dim2, f_dim3)
|
454
|
|
|
:param num_steps: int, number of steps for integration
|
455
|
|
|
:param kwargs: additional arguments.
|
456
|
|
|
"""
|
457
|
|
|
super().__init__(**kwargs)
|
458
|
|
|
self._warping = Warping(fixed_image_size=fixed_image_size)
|
459
|
|
|
self._num_steps = num_steps
|
460
|
|
|
|
461
|
|
|
def call(self, inputs, **kwargs) -> tf.Tensor:
|
|
|
|
|
462
|
|
|
"""
|
463
|
|
|
:param inputs: dvf, shape = (batch, f_dim1, f_dim2, f_dim3, 3), type = float32
|
464
|
|
|
:param kwargs: additional arguments.
|
465
|
|
|
:return: ddf, shape = (batch, f_dim1, f_dim2, f_dim3, 3)
|
466
|
|
|
"""
|
467
|
|
|
ddf = inputs / (2 ** self._num_steps)
|
468
|
|
|
for _ in range(self._num_steps):
|
469
|
|
|
ddf += self._warping(inputs=[ddf, ddf])
|
470
|
|
|
return ddf
|
471
|
|
|
|
472
|
|
|
|
473
|
|
|
class AdditiveUpSampling(tf.keras.layers.Layer):
|
|
|
|
|
474
|
|
|
def __init__(self, output_shape: tuple, stride: (int, list) = 2, **kwargs):
|
475
|
|
|
"""
|
476
|
|
|
Layer up-samples 3d tensor and reduce channels using split and sum.
|
477
|
|
|
|
478
|
|
|
:param output_shape: (out_dim1, out_dim2, out_dim3)
|
479
|
|
|
:param stride: int, 1-D Tensor or list
|
480
|
|
|
:param kwargs: additional arguments.
|
481
|
|
|
"""
|
482
|
|
|
super().__init__(**kwargs)
|
483
|
|
|
# save parameters
|
484
|
|
|
self._stride = stride
|
485
|
|
|
self._output_shape = output_shape
|
486
|
|
|
|
487
|
|
|
def call(self, inputs, **kwargs) -> tf.Tensor:
|
|
|
|
|
488
|
|
|
"""
|
489
|
|
|
:param inputs: shape = (batch, dim1, dim2, dim3, channels)
|
490
|
|
|
:param kwargs: additional arguments.
|
491
|
|
|
:return: shape = (batch, out_dim1, out_dim2, out_dim3, channels//stride]
|
492
|
|
|
"""
|
493
|
|
|
if inputs.shape[4] % self._stride != 0:
|
494
|
|
|
raise ValueError("The channel dimension can not be divided by the stride")
|
495
|
|
|
output = layer_util.resize3d(image=inputs, size=self._output_shape)
|
496
|
|
|
# a list of (batch, out_dim1, out_dim2, out_dim3, channels//stride)
|
497
|
|
|
output = tf.split(output, num_or_size_splits=self._stride, axis=4)
|
|
|
|
|
498
|
|
|
# (batch, out_dim1, out_dim2, out_dim3, channels//stride)
|
499
|
|
|
output = tf.reduce_sum(tf.stack(output, axis=5), axis=5)
|
500
|
|
|
return output
|
501
|
|
|
|
502
|
|
|
|
503
|
|
|
class LocalNetResidual3dBlock(tf.keras.layers.Layer):
|
|
|
|
|
504
|
|
|
def __init__(
|
505
|
|
|
self,
|
506
|
|
|
filters: int,
|
507
|
|
|
kernel_size: (int, tuple) = 3,
|
508
|
|
|
strides: (int, tuple) = 1,
|
509
|
|
|
activation: str = "relu",
|
510
|
|
|
**kwargs,
|
511
|
|
|
):
|
512
|
|
|
"""
|
513
|
|
|
A resnet conv3d block, simpler than Residual3dBlock.
|
514
|
|
|
|
515
|
|
|
1. conved = conv3d(inputs)
|
516
|
|
|
2. out = act(norm(conved) + inputs)
|
517
|
|
|
|
518
|
|
|
:param filters: number of channels of the output
|
519
|
|
|
:param kernel_size: int or tuple of 3 ints, e.g. (3,3,3) or 3
|
520
|
|
|
:param strides: int or tuple of 3 ints, e.g. (1,1,1) or 1
|
521
|
|
|
:param activation: name of activation
|
522
|
|
|
:param kwargs: additional arguments.
|
523
|
|
|
"""
|
524
|
|
|
super().__init__(**kwargs)
|
525
|
|
|
# init layer variables
|
526
|
|
|
self._conv3d = tfkl.Conv3D(
|
527
|
|
|
filters=filters,
|
528
|
|
|
kernel_size=kernel_size,
|
529
|
|
|
strides=strides,
|
530
|
|
|
padding="same",
|
531
|
|
|
use_bias=False,
|
532
|
|
|
)
|
533
|
|
|
self._norm = Norm()
|
534
|
|
|
self._act = tfkl.Activation(activation=activation)
|
535
|
|
|
|
536
|
|
|
def call(self, inputs, training=None, **kwargs) -> tf.Tensor:
|
|
|
|
|
537
|
|
|
return self._act(
|
538
|
|
|
self._norm(inputs=self._conv3d(inputs=inputs[0]), training=training)
|
539
|
|
|
+ inputs[1]
|
540
|
|
|
)
|
541
|
|
|
|
542
|
|
|
|
543
|
|
|
class LocalNetUpSampleResnetBlock(tf.keras.layers.Layer):
|
|
|
|
|
544
|
|
|
def __init__(self, filters: int, use_additive_upsampling: bool = True, **kwargs):
|
545
|
|
|
"""
|
546
|
|
|
Layer up-samples tensor with two inputs (skipped and down-sampled).
|
547
|
|
|
|
548
|
|
|
:param filters: int, number of output channels
|
549
|
|
|
:param use_additive_upsampling: bool to used additive upsampling
|
550
|
|
|
:param kwargs: additional arguments.
|
551
|
|
|
"""
|
552
|
|
|
super().__init__(**kwargs)
|
553
|
|
|
# save parameters
|
554
|
|
|
self._filters = filters
|
555
|
|
|
self._use_additive_upsampling = use_additive_upsampling
|
556
|
|
|
# init layer variables
|
557
|
|
|
self._deconv3d_block = None
|
558
|
|
|
self._additive_upsampling = None
|
559
|
|
|
self._conv3d_block = Conv3dBlock(filters=filters)
|
560
|
|
|
self._residual_block = LocalNetResidual3dBlock(filters=filters, strides=1)
|
561
|
|
|
|
562
|
|
|
def build(self, input_shape):
|
|
|
|
|
563
|
|
|
"""
|
564
|
|
|
:param input_shape: tuple (nonskip_tensor_shape, skip_tensor_shape)
|
565
|
|
|
"""
|
566
|
|
|
super().build(input_shape)
|
567
|
|
|
|
568
|
|
|
output_shape = input_shape[1][1:4]
|
569
|
|
|
self._deconv3d_block = Deconv3dBlock(
|
570
|
|
|
filters=self._filters, output_shape=output_shape, strides=2
|
571
|
|
|
)
|
572
|
|
|
if self._use_additive_upsampling:
|
573
|
|
|
self._additive_upsampling = AdditiveUpSampling(output_shape=output_shape)
|
574
|
|
|
|
575
|
|
|
def call(self, inputs, training=None, **kwargs) -> tf.Tensor:
|
|
|
|
|
576
|
|
|
"""
|
577
|
|
|
:param inputs: list = [inputs_nonskip, inputs_skip]
|
578
|
|
|
:param training: training flag for normalization layers (default: None)
|
579
|
|
|
:param kwargs: additional arguments.
|
580
|
|
|
:return:
|
581
|
|
|
"""
|
582
|
|
|
inputs_nonskip, inputs_skip = inputs[0], inputs[1]
|
583
|
|
|
h0 = self._deconv3d_block(inputs=inputs_nonskip, training=training)
|
584
|
|
|
if self._use_additive_upsampling:
|
585
|
|
|
h0 += self._additive_upsampling(inputs=inputs_nonskip)
|
586
|
|
|
r1 = h0 + inputs_skip
|
587
|
|
|
r2 = self._conv3d_block(inputs=h0, training=training)
|
588
|
|
|
h1 = self._residual_block(inputs=[r2, r1], training=training)
|
589
|
|
|
return h1
|
590
|
|
|
|
591
|
|
|
|
592
|
|
|
class ResizeCPTransform(tf.keras.layers.Layer):
|
593
|
|
|
"""
|
594
|
|
|
Layer for getting the control points from the output of a image-to-image network.
|
595
|
|
|
It uses an anti-aliasing Gaussian filter before downsampling.
|
596
|
|
|
"""
|
597
|
|
|
|
598
|
|
|
def __init__(self, control_point_spacing: (list, tuple, int), **kwargs):
|
599
|
|
|
"""
|
600
|
|
|
:param control_point_spacing: list or int
|
601
|
|
|
:param kwargs: additional arguments.
|
602
|
|
|
"""
|
603
|
|
|
super().__init__(**kwargs)
|
604
|
|
|
|
605
|
|
|
if isinstance(control_point_spacing, int):
|
606
|
|
|
control_point_spacing = [control_point_spacing] * 3
|
607
|
|
|
|
608
|
|
|
self.kernel_sigma = [
|
609
|
|
|
0.44 * cp for cp in control_point_spacing
|
610
|
|
|
] # 0.44 = ln(4)/pi
|
611
|
|
|
self.cp_spacing = control_point_spacing
|
612
|
|
|
self.kernel = None
|
613
|
|
|
self._output_shape = None
|
614
|
|
|
|
615
|
|
|
def build(self, input_shape):
|
616
|
|
|
super().build(input_shape=input_shape)
|
617
|
|
|
|
618
|
|
|
self.kernel = layer_util.gaussian_filter_3d(self.kernel_sigma)
|
619
|
|
|
output_shape = [
|
620
|
|
|
tf.cast(tf.math.ceil(v / c) + 3, tf.int32)
|
621
|
|
|
for v, c in zip(input_shape[1:-1], self.cp_spacing)
|
622
|
|
|
]
|
623
|
|
|
self._output_shape = output_shape
|
624
|
|
|
|
625
|
|
|
def call(self, inputs, **kwargs) -> tf.Tensor:
|
626
|
|
|
output = tf.nn.conv3d(
|
627
|
|
|
inputs, self.kernel, strides=(1, 1, 1, 1, 1), padding="SAME"
|
628
|
|
|
)
|
629
|
|
|
return layer_util.resize3d(image=output, size=self._output_shape)
|
630
|
|
|
|
631
|
|
|
|
632
|
|
|
class BSplines3DTransform(tf.keras.layers.Layer):
|
633
|
|
|
"""
|
634
|
|
|
Layer for BSplines interpolation with precomputed cubic spline filters.
|
635
|
|
|
It assumes a full sized image from which:
|
636
|
|
|
1. it compute the contol points values by downsampling the initial image
|
637
|
|
|
2. performs the interpolation
|
638
|
|
|
3. crops the image around the valid values.
|
639
|
|
|
|
640
|
|
|
:param cp_spacing: int or tuple of three ints specifying the spacing (in pixels)
|
641
|
|
|
in each dimension. When a single int is used,
|
642
|
|
|
the same spacing to all dimensions is used
|
643
|
|
|
:param output_shape: (batch_size, dim0, dim1, dim2, 3) of the high resolution
|
644
|
|
|
deformation fields.
|
645
|
|
|
:param kwargs: additional arguments.
|
646
|
|
|
"""
|
647
|
|
|
|
648
|
|
|
def __init__(self, cp_spacing: (int, tuple), output_shape: tuple, **kwargs):
|
649
|
|
|
|
650
|
|
|
super().__init__(**kwargs)
|
651
|
|
|
|
652
|
|
|
self.filters = []
|
653
|
|
|
self._output_shape = output_shape
|
654
|
|
|
|
655
|
|
|
if isinstance(cp_spacing, int):
|
656
|
|
|
self.cp_spacing = (cp_spacing, cp_spacing, cp_spacing)
|
657
|
|
|
else:
|
658
|
|
|
self.cp_spacing = cp_spacing
|
659
|
|
|
|
660
|
|
|
def build(self, input_shape: tuple):
|
|
|
|
|
661
|
|
|
"""
|
662
|
|
|
:param input_shape: tuple with the input shape
|
663
|
|
|
:return: None
|
664
|
|
|
"""
|
665
|
|
|
|
666
|
|
|
super().build(input_shape=input_shape)
|
667
|
|
|
|
668
|
|
|
b = {
|
669
|
|
|
0: lambda u: np.float64((1 - u) ** 3 / 6),
|
670
|
|
|
1: lambda u: np.float64((3 * (u ** 3) - 6 * (u ** 2) + 4) / 6),
|
671
|
|
|
2: lambda u: np.float64((-3 * (u ** 3) + 3 * (u ** 2) + 3 * u + 1) / 6),
|
672
|
|
|
3: lambda u: np.float64(u ** 3 / 6),
|
673
|
|
|
}
|
674
|
|
|
|
675
|
|
|
filters = np.zeros(
|
676
|
|
|
(
|
677
|
|
|
4 * self.cp_spacing[0],
|
678
|
|
|
4 * self.cp_spacing[1],
|
679
|
|
|
4 * self.cp_spacing[2],
|
680
|
|
|
3,
|
681
|
|
|
3,
|
682
|
|
|
),
|
683
|
|
|
dtype=np.float32,
|
684
|
|
|
)
|
685
|
|
|
|
686
|
|
|
u_arange = 1 - np.arange(
|
687
|
|
|
1 / (2 * self.cp_spacing[0]), 1, 1 / self.cp_spacing[0]
|
688
|
|
|
)
|
689
|
|
|
v_arange = 1 - np.arange(
|
690
|
|
|
1 / (2 * self.cp_spacing[1]), 1, 1 / self.cp_spacing[1]
|
691
|
|
|
)
|
692
|
|
|
w_arange = 1 - np.arange(
|
693
|
|
|
1 / (2 * self.cp_spacing[2]), 1, 1 / self.cp_spacing[2]
|
694
|
|
|
)
|
695
|
|
|
|
696
|
|
|
filter_idx = [[0, 1, 2, 3] for _ in range(3)]
|
697
|
|
|
filter_coord = list(itertools.product(*filter_idx))
|
698
|
|
|
|
699
|
|
|
for f_idx in filter_coord:
|
700
|
|
|
for it_dim in range(3):
|
701
|
|
|
filters[
|
702
|
|
|
f_idx[0] * self.cp_spacing[0] : (f_idx[0] + 1) * self.cp_spacing[0],
|
703
|
|
|
f_idx[1] * self.cp_spacing[1] : (f_idx[1] + 1) * self.cp_spacing[1],
|
704
|
|
|
f_idx[2] * self.cp_spacing[2] : (f_idx[2] + 1) * self.cp_spacing[2],
|
705
|
|
|
it_dim,
|
706
|
|
|
it_dim,
|
707
|
|
|
] = (
|
708
|
|
|
b[f_idx[0]](u_arange)[:, None, None]
|
709
|
|
|
* b[f_idx[1]](v_arange)[None, :, None]
|
710
|
|
|
* b[f_idx[2]](w_arange)[None, None, :]
|
711
|
|
|
)
|
712
|
|
|
|
713
|
|
|
self.filter = tf.convert_to_tensor(filters)
|
714
|
|
|
|
715
|
|
|
def interpolate(self, field) -> tf.Tensor:
|
|
|
|
|
716
|
|
|
"""
|
717
|
|
|
:param field: tf.Tensor with shape=number_of_control_points_per_dim
|
718
|
|
|
:return: interpolated_field: tf.Tensor
|
719
|
|
|
"""
|
720
|
|
|
|
721
|
|
|
image_shape = tuple(
|
722
|
|
|
[(a - 1) * b + 4 * b for a, b in zip(field.shape[1:-1], self.cp_spacing)]
|
723
|
|
|
)
|
724
|
|
|
|
725
|
|
|
output_shape = (field.shape[0],) + image_shape + (3,)
|
726
|
|
|
return tf.nn.conv3d_transpose(
|
727
|
|
|
field,
|
728
|
|
|
self.filter,
|
729
|
|
|
output_shape=output_shape,
|
730
|
|
|
strides=self.cp_spacing,
|
731
|
|
|
padding="VALID",
|
732
|
|
|
)
|
733
|
|
|
|
734
|
|
|
def call(self, inputs, **kwargs) -> tf.Tensor:
|
|
|
|
|
735
|
|
|
"""
|
736
|
|
|
:param inputs: tf.Tensor defining a low resolution free-form deformation field
|
737
|
|
|
:param kwargs: additional arguments.
|
738
|
|
|
:return: interpolated_field: tf.Tensor of shape=self.input_shape
|
739
|
|
|
"""
|
740
|
|
|
high_res_field = self.interpolate(inputs)
|
741
|
|
|
|
742
|
|
|
index = [int(3 * c) for c in self.cp_spacing]
|
743
|
|
|
return high_res_field[
|
744
|
|
|
:,
|
745
|
|
|
index[0] : index[0] + self._output_shape[0],
|
746
|
|
|
index[1] : index[1] + self._output_shape[1],
|
747
|
|
|
index[2] : index[2] + self._output_shape[2],
|
748
|
|
|
]
|
749
|
|
|
|