|
| 1 | +from enum import Enum |
| 2 | + |
| 3 | +import torch |
| 4 | +from torch import nn |
| 5 | +from torchvision.models import resnet18, resnet50, swin_s, swin_t |
| 6 | + |
| 7 | +from ddlitlab2024.ml.model.encoder.base import BaseEncoder |
| 8 | + |
| 9 | + |
| 10 | +class ImageEncoderType(Enum): |
| 11 | + """ |
| 12 | + Enum class for the image encoder types. |
| 13 | + """ |
| 14 | + |
| 15 | + RESNET18 = "resnet18" |
| 16 | + RESNET50 = "resnet50" |
| 17 | + SWIN_TRANSFORMER_TINY = "swin_transformer_tiny" |
| 18 | + SWIN_TRANSFORMER_SMALL = "swin_transformer_small" |
| 19 | + |
| 20 | + |
| 21 | +class SequenceEncoderType(Enum): |
| 22 | + """ |
| 23 | + Enum class for the sequence encoder types. |
| 24 | + """ |
| 25 | + |
| 26 | + TRANSFORMER = "transformer" |
| 27 | + NONE = "none" |
| 28 | + |
| 29 | + |
| 30 | +class AbstractImageEncoder(nn.Module): |
| 31 | + """ |
| 32 | + Abstract class for image encoders. |
| 33 | + """ |
| 34 | + |
| 35 | + encoder: nn.Module |
| 36 | + |
| 37 | + def forward(self, x: torch.Tensor) -> torch.Tensor: |
| 38 | + """ |
| 39 | + Forward pass of the image encoder. |
| 40 | +
|
| 41 | + :param x: A sequence of images. |
| 42 | + :return: A sequence of encoded images. |
| 43 | + """ |
| 44 | + # Squash the sequence dimension together with the batch dimension |
| 45 | + images = x.view(-1, *x.shape[2:]) |
| 46 | + |
| 47 | + # Encode the images into tokens |
| 48 | + tokens = self.encoder(images) |
| 49 | + |
| 50 | + # Restore the original sequence dimension |
| 51 | + return tokens.view(x.shape[0], x.shape[1], -1) |
| 52 | + |
| 53 | + |
| 54 | +class ResNetImageEncoder(AbstractImageEncoder): |
| 55 | + """ |
| 56 | + ResNet image encoder. |
| 57 | + """ |
| 58 | + |
| 59 | + def __init__(self, resnet_type: ImageEncoderType, hidden_dim: int): |
| 60 | + super().__init__() |
| 61 | + match resnet_type: |
| 62 | + case ImageEncoderType.RESNET18: |
| 63 | + self.encoder = resnet18(pretrained=True) |
| 64 | + case ImageEncoderType.RESNET50: |
| 65 | + self.encoder = resnet50(pretrained=True) |
| 66 | + case _: |
| 67 | + raise ValueError(f"Invalid ResNet type: {resnet_type}") |
| 68 | + # TODO check for softmax layer etc. |
| 69 | + self.encoder.fc = nn.Linear(self.encoder.fc.in_features, hidden_dim) |
| 70 | + |
| 71 | + |
| 72 | +class SwinTransformerImageEncoder(AbstractImageEncoder): |
| 73 | + """ |
| 74 | + Swin Transformer image encoder. |
| 75 | + """ |
| 76 | + |
| 77 | + def __init__(self, swin_type: ImageEncoderType, hidden_dim: int): |
| 78 | + super().__init__() |
| 79 | + match swin_type: |
| 80 | + case ImageEncoderType.SWIN_TRANSFORMER_TINY: |
| 81 | + self.encoder = swin_t() |
| 82 | + case ImageEncoderType.SWIN_TRANSFORMER_SMALL: |
| 83 | + self.encoder = swin_s() |
| 84 | + case _: |
| 85 | + raise ValueError(f"Invalid Swin Transformer type: {swin_type}") |
| 86 | + self.encoder.head = nn.Linear(self.encoder.head.in_features, hidden_dim) |
| 87 | + |
| 88 | + |
| 89 | +class TransformerImageSequenceEncoder(nn.Module): |
| 90 | + """ |
| 91 | + Transformer image sequence encoder. |
| 92 | + """ |
| 93 | + |
| 94 | + def __init__(self, image_encoder: AbstractImageEncoder, hidden_dim: int, num_layers: int, max_seq_len: int): |
| 95 | + super().__init__() |
| 96 | + self.image_encoder = image_encoder |
| 97 | + self.transformer_encoder = BaseEncoder( |
| 98 | + input_dim=hidden_dim, hidden_dim=hidden_dim, num_layers=num_layers, num_heads=8, max_seq_len=max_seq_len |
| 99 | + ) |
| 100 | + |
| 101 | + def forward(self, x: torch.Tensor) -> torch.Tensor: |
| 102 | + return self.transformer_encoder(self.image_encoder(x)) |
| 103 | + |
| 104 | + |
| 105 | +def image_encoder_factory(encoder_type: ImageEncoderType, hidden_dim: int) -> AbstractImageEncoder: |
| 106 | + """ |
| 107 | + Factory function for creating image encoders. |
| 108 | +
|
| 109 | + :param encoder_type: The type of the image encoder. |
| 110 | + :return: The image encoder. |
| 111 | + """ |
| 112 | + if encoder_type in [ImageEncoderType.RESNET18, ImageEncoderType.RESNET50]: |
| 113 | + return ResNetImageEncoder(encoder_type, hidden_dim) |
| 114 | + if encoder_type in [ImageEncoderType.SWIN_TRANSFORMER_TINY, ImageEncoderType.SWIN_TRANSFORMER_SMALL]: |
| 115 | + return SwinTransformerImageEncoder(encoder_type, hidden_dim) |
| 116 | + else: |
| 117 | + raise ValueError(f"Invalid image encoder type: {encoder_type}") |
| 118 | + |
| 119 | + |
| 120 | +def image_sequence_encoder_factory( |
| 121 | + encoder_type: SequenceEncoderType, |
| 122 | + image_encoder_type: ImageEncoderType, |
| 123 | + hidden_dim: int, |
| 124 | + num_layers: int, |
| 125 | + max_seq_len: int, |
| 126 | +): |
| 127 | + """ |
| 128 | + Factory function for creating image sequence encoders. |
| 129 | +
|
| 130 | + :param encoder_type: The type of the sequence encoder that allows communication between different images. |
| 131 | + If no sequence encoder is needed, the image encoder is returned. |
| 132 | + :param image_encoder_type: The type of the image encoder. |
| 133 | + :return: The image sequence encoder. |
| 134 | + """ |
| 135 | + image_encoder = image_encoder_factory(image_encoder_type, hidden_dim) |
| 136 | + |
| 137 | + match encoder_type: |
| 138 | + case SequenceEncoderType.TRANSFORMER: |
| 139 | + return TransformerImageSequenceEncoder(image_encoder, hidden_dim, num_layers, max_seq_len) |
| 140 | + case SequenceEncoderType.NONE: |
| 141 | + return image_encoder |
| 142 | + case _: |
| 143 | + raise ValueError(f"Invalid sequence encoder type: {encoder_type}") |
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