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# coding=utf-8 |
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from typing import List, Tuple, Union |
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import tensorflow as tf |
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import tensorflow.keras.layers as tfkl |
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from tensorflow.python.keras.utils import conv_utils |
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from deepreg.model import layer, layer_util |
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from deepreg.model.backbone.interface import Backbone |
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from deepreg.registry import REGISTRY |
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class AdditiveUpsampling(tfkl.Layer): |
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def __init__( |
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self, |
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filters: int, |
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output_padding: int, |
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kernel_size: int, |
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padding: str, |
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strides: int, |
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output_shape: tuple, |
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name: str = "AdditiveUpsampling", |
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): |
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""" |
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Addictive up-sampling layer. |
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:param filters: number of channels for output |
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:param output_padding: padding for output |
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:param kernel_size: arg for deconv3d |
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:param padding: arg for deconv3d |
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:param strides: arg for deconv3d |
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:param output_shape: shape of the output tensor |
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:param name: name of the layer. |
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""" |
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super().__init__(name=name) |
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self.deconv3d = layer.Deconv3dBlock( |
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filters=filters, |
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output_padding=output_padding, |
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kernel_size=kernel_size, |
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strides=strides, |
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padding=padding, |
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) |
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self.resize = layer.Resize3d(shape=output_shape) |
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def call(self, inputs, **kwargs): |
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deconved = self.deconv3d(inputs) |
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resized = self.resize(inputs) |
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resized = tf.add_n(tf.split(resized, num_or_size_splits=2, axis=4)) |
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return deconved + resized |
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class Extraction(tfkl.Layer): |
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def __init__( |
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self, |
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image_size: Tuple[int], |
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extract_levels: List[int], |
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out_channels: int, |
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out_kernel_initializer: str, |
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out_activation: str, |
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name: str = "Extraction", |
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): |
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""" |
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:param image_size: such as (dim1, dim2, dim3) |
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:param extract_levels: number of extraction levels. |
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:param out_channels: number of channels for the extractions |
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:param out_kernel_initializer: initializer to use for kernels. |
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:param out_activation: activation to use at end layer. |
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:param name: name of the layer |
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""" |
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super().__init__(name=name) |
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self.extract_levels = extract_levels |
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self.max_level = max(extract_levels) |
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self.layers = [ |
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tf.keras.Sequential( |
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[ |
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tfkl.Conv3D( |
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filters=out_channels, |
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kernel_size=3, |
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strides=1, |
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padding="same", |
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kernel_initializer=out_kernel_initializer, |
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activation=out_activation, |
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), |
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layer.Resize3d(shape=image_size), |
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] |
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) |
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for _ in extract_levels |
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] |
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def call(self, inputs: List[tf.Tensor], **kwargs) -> tf.Tensor: |
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""" |
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:param inputs: a list of tensors |
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:param kwargs: |
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:return: |
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""" |
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return tf.add_n( |
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[ |
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self.layers[idx](inputs=inputs[self.max_level - level]) |
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for idx, level in enumerate(self.extract_levels) |
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] |
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) / len(self.extract_levels) |
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@REGISTRY.register_backbone(name="local") |
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class LocalNet(Backbone): |
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""" |
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Build LocalNet for image registration. |
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Reference: |
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- Hu, Yipeng, et al. |
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"Weakly-supervised convolutional neural networks |
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for multimodal image registration." |
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Medical image analysis 49 (2018): 1-13. |
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https://doi.org/10.1016/j.media.2018.07.002 |
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- Hu, Yipeng, et al. |
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"Label-driven weakly-supervised learning |
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for multimodal deformable image registration," |
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https://arxiv.org/abs/1711.01666 |
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""" |
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def __init__( |
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self, |
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image_size: tuple, |
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num_channel_initial: int, |
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extract_levels: List[int], |
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out_kernel_initializer: str, |
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out_activation: str, |
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out_channels: int, |
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use_additive_upsampling: bool = True, |
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name: str = "LocalNet", |
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**kwargs, |
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): |
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""" |
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Init. |
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Image is encoded gradually, i from level 0 to D, |
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then it is decoded gradually, j from level D to 0. |
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Some of the decoded levels are used for generating extractions. |
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So, extract_levels are between [0, D]. |
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:param image_size: such as (dim1, dim2, dim3) |
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:param out_channels: number of channels for the extractions |
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:param num_channel_initial: number of initial channels. |
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:param extract_levels: number of extraction levels. |
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:param out_kernel_initializer: initializer to use for kernels. |
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:param out_activation: activation to use at end layer. |
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:param use_additive_upsampling: whether use additive up-sampling. |
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:param name: name of the backbone. |
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:param kwargs: additional arguments. |
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""" |
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super().__init__( |
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image_size=image_size, |
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out_channels=out_channels, |
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num_channel_initial=num_channel_initial, |
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out_kernel_initializer=out_kernel_initializer, |
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out_activation=out_activation, |
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name=name, |
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**kwargs, |
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) |
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# save parameters |
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self._extract_levels = extract_levels |
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self._use_additive_upsampling = use_additive_upsampling |
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self._depth = max(self._extract_levels) # D |
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# init layers |
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# all lists start with d = 0 |
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self._downsample_convs = None |
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self._downsample_pools = None |
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self._bottom_block = None |
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self._upsample_deconvs = None |
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self._upsample_convs = None |
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self._output_block = None |
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# build layers |
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self.build_layers( |
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image_size=image_size, |
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num_channel_initial=num_channel_initial, |
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depth=self._depth, |
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extract_levels=self._extract_levels, |
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downsample_kernel_sizes=[7] + [3] * self._depth, |
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upsample_kernel_sizes=3, |
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strides=2, |
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padding="same", |
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out_kernel_initializer=out_kernel_initializer, |
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out_activation=out_activation, |
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out_channels=out_channels, |
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) |
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def build_layers( |
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self, |
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image_size: tuple, |
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num_channel_initial: int, |
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depth: int, |
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extract_levels: List[int], |
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downsample_kernel_sizes: Union[int, List[int]], |
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upsample_kernel_sizes: Union[int, List[int]], |
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strides: int, |
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padding: str, |
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out_kernel_initializer: str, |
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out_activation: str, |
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out_channels: int, |
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): |
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""" |
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Build layers that will be used in call. |
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:param image_size: (dim1, dim2, dim3). |
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:param num_channel_initial: number of initial channels. |
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:param depth: network starts with d = 0, and the bottom has d = depth. |
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:param extract_levels: from which depths the output will be built. |
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:param downsample_kernel_sizes: kernel size for down-sampling |
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:param upsample_kernel_sizes: kernel size for up-sampling |
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:param strides: strides for down-sampling |
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:param padding: padding mode for all conv layers |
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:param out_kernel_initializer: initializer to use for kernels. |
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:param out_activation: activation to use at end layer. |
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:param out_channels: number of channels for the extractions |
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""" |
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# init params |
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min_extract_level = min(extract_levels) |
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num_channels = [num_channel_initial * (2 ** d) for d in range(depth + 1)] |
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if isinstance(downsample_kernel_sizes, int): |
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downsample_kernel_sizes = [downsample_kernel_sizes] * (depth + 1) |
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assert len(downsample_kernel_sizes) == depth + 1 |
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if isinstance(upsample_kernel_sizes, int): |
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upsample_kernel_sizes = [upsample_kernel_sizes] * depth |
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assert len(upsample_kernel_sizes) == depth |
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# down-sampling |
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self._downsample_convs = [] |
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self._downsample_pools = [] |
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tensor_shape = image_size |
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tensor_shapes = [tensor_shape] |
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for d in range(depth): |
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downsample_conv = self.build_conv_block( |
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filters=num_channels[d], |
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kernel_size=downsample_kernel_sizes[d], |
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padding=padding, |
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) |
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downsample_pool = self.build_down_sampling_block( |
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kernel_size=strides, strides=strides, padding=padding |
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) |
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tensor_shape = tuple( |
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conv_utils.conv_output_length( |
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input_length=x, |
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filter_size=strides, |
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padding=padding, |
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stride=strides, |
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dilation=1, |
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) |
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for x in tensor_shape |
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) |
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self._downsample_convs.append(downsample_conv) |
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self._downsample_pools.append(downsample_pool) |
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tensor_shapes.append(tensor_shape) |
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# bottom layer |
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self._bottom_block = self.build_bottom_block( |
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filters=num_channels[depth], |
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kernel_size=downsample_kernel_sizes[depth], |
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padding=padding, |
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) |
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# up-sampling |
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self._upsample_deconvs = [] |
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self._upsample_convs = [] |
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for d in range(depth - 1, min_extract_level - 1, -1): |
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kernel_size = upsample_kernel_sizes[d] |
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output_padding = layer_util.deconv_output_padding( |
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input_shape=tensor_shapes[d + 1], |
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output_shape=tensor_shapes[d], |
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kernel_size=kernel_size, |
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stride=strides, |
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padding=padding, |
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) |
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upsample_deconv = self.build_up_sampling_block( |
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filters=num_channels[d], |
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output_padding=output_padding, |
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kernel_size=kernel_size, |
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strides=strides, |
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padding=padding, |
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output_shape=tensor_shapes[d], |
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) |
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upsample_conv = self.build_conv_block( |
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filters=num_channels[d], kernel_size=kernel_size, padding=padding |
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) |
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self._upsample_deconvs = [upsample_deconv] + self._upsample_deconvs |
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self._upsample_convs = [upsample_conv] + self._upsample_convs |
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if min_extract_level > 0: |
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# add Nones to make lists have length depth - 1 |
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self._upsample_deconvs = [None] * min_extract_level + self._upsample_deconvs |
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self._upsample_convs = [None] * min_extract_level + self._upsample_convs |
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# extraction |
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self._output_block = self.build_output_block( |
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image_size=image_size, |
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extract_levels=extract_levels, |
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out_channels=out_channels, |
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out_kernel_initializer=out_kernel_initializer, |
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out_activation=out_activation, |
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) |
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def build_conv_block( |
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self, filters: int, kernel_size: int, padding: str |
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) -> Union[tf.keras.Model, tfkl.Layer]: |
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""" |
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Build a conv block for down-sampling or up-sampling. |
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This block do not change the tensor shape (width, height, depth), |
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316
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it only changes the number of channels. |
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317
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318
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:param filters: number of channels for output |
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:param kernel_size: arg for conv3d |
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320
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:param padding: arg for conv3d |
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321
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:return: a block consists of one or multiple layers |
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""" |
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323
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return tf.keras.Sequential( |
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324
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[ |
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325
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layer.Conv3dBlock( |
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326
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filters=filters, |
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327
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kernel_size=kernel_size, |
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328
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padding=padding, |
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329
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), |
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330
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layer.ResidualConv3dBlock( |
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331
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filters=filters, |
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332
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kernel_size=kernel_size, |
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333
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padding=padding, |
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334
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), |
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335
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] |
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336
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) |
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338
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def build_down_sampling_block( |
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339
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self, kernel_size: int, padding: str, strides: int |
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340
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) -> Union[tf.keras.Model, tfkl.Layer]: |
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""" |
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342
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Build a block for down-sampling. |
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344
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This block changes the tensor shape (width, height, depth), |
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345
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but it does not changes the number of channels. |
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346
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347
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:param kernel_size: arg for pool3d |
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348
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:param padding: arg for pool3d |
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349
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:param strides: arg for pool3d |
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350
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:return: a block consists of one or multiple layers |
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351
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""" |
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352
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return tfkl.MaxPool3D(pool_size=kernel_size, strides=strides, padding=padding) |
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353
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354
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def build_bottom_block( |
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355
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self, filters: int, kernel_size: int, padding: str |
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356
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) -> Union[tf.keras.Model, tfkl.Layer]: |
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357
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""" |
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358
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|
Build a block for bottom layer. |
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359
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|
360
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This block do not change the tensor shape (width, height, depth), |
|
361
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it only changes the number of channels. |
|
362
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|
363
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|
:param filters: number of channels for output |
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364
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:param kernel_size: arg for conv3d |
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365
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|
:param padding: arg for conv3d |
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366
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|
|
:return: a block consists of one or multiple layers |
|
367
|
|
|
""" |
|
368
|
|
|
return layer.Conv3dBlock( |
|
369
|
|
|
filters=filters, kernel_size=kernel_size, padding=padding |
|
370
|
|
|
) |
|
371
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|
|
372
|
|
|
def build_up_sampling_block( |
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373
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|
|
self, |
|
374
|
|
|
filters: int, |
|
375
|
|
|
output_padding: int, |
|
376
|
|
|
kernel_size: int, |
|
377
|
|
|
padding: str, |
|
378
|
|
|
strides: int, |
|
379
|
|
|
output_shape: tuple, |
|
380
|
|
|
) -> Union[tf.keras.Model, tfkl.Layer]: |
|
381
|
|
|
""" |
|
382
|
|
|
Build a block for up-sampling. |
|
383
|
|
|
|
|
384
|
|
|
This block changes the tensor shape (width, height, depth), |
|
385
|
|
|
but it does not changes the number of channels. |
|
386
|
|
|
|
|
387
|
|
|
:param filters: number of channels for output |
|
388
|
|
|
:param output_padding: padding for output |
|
389
|
|
|
:param kernel_size: arg for deconv3d |
|
390
|
|
|
:param padding: arg for deconv3d |
|
391
|
|
|
:param strides: arg for deconv3d |
|
392
|
|
|
:param output_shape: shape of the output tensor |
|
393
|
|
|
:return: a block consists of one or multiple layers |
|
394
|
|
|
""" |
|
395
|
|
|
|
|
396
|
|
|
if self._use_additive_upsampling: |
|
397
|
|
|
return AdditiveUpsampling( |
|
398
|
|
|
filters=filters, |
|
399
|
|
|
output_padding=output_padding, |
|
400
|
|
|
kernel_size=kernel_size, |
|
401
|
|
|
strides=strides, |
|
402
|
|
|
padding=padding, |
|
403
|
|
|
output_shape=output_shape, |
|
404
|
|
|
) |
|
405
|
|
|
|
|
406
|
|
|
return layer.Deconv3dBlock( |
|
407
|
|
|
filters=filters, |
|
408
|
|
|
output_padding=output_padding, |
|
409
|
|
|
kernel_size=kernel_size, |
|
410
|
|
|
strides=strides, |
|
411
|
|
|
padding=padding, |
|
412
|
|
|
) |
|
413
|
|
|
|
|
414
|
|
|
def build_skip_block(self) -> Union[tf.keras.Model, tfkl.Layer]: |
|
415
|
|
|
""" |
|
416
|
|
|
Build a block for combining skipped tensor and up-sampled one. |
|
417
|
|
|
|
|
418
|
|
|
This block do not change the tensor shape (width, height, depth), |
|
419
|
|
|
it only changes the number of channels. |
|
420
|
|
|
|
|
421
|
|
|
The input to this block is a list of tensors. |
|
422
|
|
|
|
|
423
|
|
|
:return: a block consists of one or multiple layers |
|
424
|
|
|
""" |
|
425
|
|
|
return tfkl.Add() |
|
426
|
|
|
|
|
427
|
|
|
def build_output_block( |
|
428
|
|
|
self, |
|
429
|
|
|
image_size: Tuple[int], |
|
430
|
|
|
extract_levels: List[int], |
|
431
|
|
|
out_channels: int, |
|
432
|
|
|
out_kernel_initializer: str, |
|
433
|
|
|
out_activation: str, |
|
434
|
|
|
) -> Union[tf.keras.Model, tfkl.Layer]: |
|
435
|
|
|
""" |
|
436
|
|
|
Build a block for output. |
|
437
|
|
|
|
|
438
|
|
|
The input to this block is a list of tensors. |
|
439
|
|
|
|
|
440
|
|
|
:param image_size: such as (dim1, dim2, dim3) |
|
441
|
|
|
:param extract_levels: number of extraction levels. |
|
442
|
|
|
:param out_channels: number of channels for the extractions |
|
443
|
|
|
:param out_kernel_initializer: initializer to use for kernels. |
|
444
|
|
|
:param out_activation: activation to use at end layer. |
|
445
|
|
|
:return: a block consists of one or multiple layers |
|
446
|
|
|
""" |
|
447
|
|
|
return Extraction( |
|
448
|
|
|
image_size=image_size, |
|
449
|
|
|
extract_levels=extract_levels, |
|
450
|
|
|
out_channels=out_channels, |
|
451
|
|
|
out_kernel_initializer=out_kernel_initializer, |
|
452
|
|
|
out_activation=out_activation, |
|
453
|
|
|
) |
|
454
|
|
|
|
|
455
|
|
|
def call(self, inputs: tf.Tensor, training=None, mask=None) -> tf.Tensor: |
|
|
|
|
|
|
456
|
|
|
""" |
|
457
|
|
|
Build LocalNet graph based on built layers. |
|
458
|
|
|
|
|
459
|
|
|
:param inputs: image batch, shape = (batch, f_dim1, f_dim2, f_dim3, ch) |
|
460
|
|
|
:param training: None or bool. |
|
461
|
|
|
:param mask: None or tf.Tensor. |
|
462
|
|
|
:return: shape = (batch, f_dim1, f_dim2, f_dim3, out_channels) |
|
463
|
|
|
""" |
|
464
|
|
|
|
|
465
|
|
|
# down-sampling |
|
466
|
|
|
skips = [] |
|
467
|
|
|
down_sampled = inputs |
|
468
|
|
|
for d in range(self._depth): |
|
469
|
|
|
skip = self._downsample_convs[d](inputs=down_sampled, training=training) |
|
470
|
|
|
down_sampled = self._downsample_pools[d](inputs=skip, training=training) |
|
471
|
|
|
skips.append(skip) |
|
472
|
|
|
|
|
473
|
|
|
# bottom |
|
474
|
|
|
up_sampled = self._bottom_block(inputs=down_sampled, training=training) |
|
475
|
|
|
|
|
476
|
|
|
# up-sampling |
|
477
|
|
|
outs = [up_sampled] |
|
478
|
|
|
for d in range(self._depth - 1, min(self._extract_levels) - 1, -1): |
|
479
|
|
|
up_sampled = self._upsample_deconvs[d](inputs=up_sampled, training=training) |
|
480
|
|
|
up_sampled = self.build_skip_block()([up_sampled, skips[d]]) |
|
481
|
|
|
up_sampled = self._upsample_convs[d](inputs=up_sampled, training=training) |
|
482
|
|
|
outs.append(up_sampled) |
|
483
|
|
|
|
|
484
|
|
|
# output |
|
485
|
|
|
output = self._output_block(outs) |
|
486
|
|
|
|
|
487
|
|
|
return output |
|
488
|
|
|
|