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authoraktersnurra <gustaf.rydholm@gmail.com>2020-11-12 23:42:03 +0100
committeraktersnurra <gustaf.rydholm@gmail.com>2020-11-12 23:42:03 +0100
commit8fdb6435e15703fa5b76df19728d905650ee1aef (patch)
treebe3bec9e5cab4ef7f9d94528d102e57ce9b16c3f /src/text_recognizer/networks/vision_transformer.py
parentdc28cbe2b4ed77be92ee8b2b69a20689c3bf02a4 (diff)
parent6cb08a110620ee09fe9d8a5d008197a801d025df (diff)
Working cnn transformer.
Diffstat (limited to 'src/text_recognizer/networks/vision_transformer.py')
-rw-r--r--src/text_recognizer/networks/vision_transformer.py159
1 files changed, 0 insertions, 159 deletions
diff --git a/src/text_recognizer/networks/vision_transformer.py b/src/text_recognizer/networks/vision_transformer.py
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--- a/src/text_recognizer/networks/vision_transformer.py
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-"""VisionTransformer module.
-
-Splits each image into patches and feeds them to a transformer.
-
-"""
-
-from typing import Dict, Optional, Tuple, Type
-
-from einops import rearrange, reduce
-from einops.layers.torch import Rearrange
-from loguru import logger
-import torch
-from torch import nn
-from torch import Tensor
-
-from text_recognizer.networks.transformer import PositionalEncoding, Transformer
-from text_recognizer.networks.util import configure_backbone
-
-
-class VisionTransformer(nn.Module):
- """Linear projection+Transfomer for image to sequence prediction, sort of based on the ideas from ViT."""
-
- def __init__(
- self,
- num_encoder_layers: int,
- num_decoder_layers: int,
- hidden_dim: int,
- vocab_size: int,
- num_heads: int,
- max_len: int,
- expansion_dim: int,
- dropout_rate: float,
- trg_pad_index: int,
- mlp_dim: Optional[int] = None,
- patch_size: Tuple[int, int] = (28, 28),
- stride: Tuple[int, int] = (1, 14),
- activation: str = "gelu",
- backbone: Optional[str] = None,
- backbone_args: Optional[Dict] = None,
- ) -> None:
- super().__init__()
-
- self.patch_size = patch_size
- self.stride = stride
- self.trg_pad_index = trg_pad_index
- self.slidning_window = self._configure_sliding_window()
- self.character_embedding = nn.Embedding(vocab_size, hidden_dim)
- self.position_encoding = PositionalEncoding(hidden_dim, dropout_rate, max_len)
- self.mlp_dim = mlp_dim
-
- self.use_backbone = False
- if backbone is None:
- self.linear_projection = nn.Linear(
- self.patch_size[0] * self.patch_size[1], hidden_dim
- )
- else:
- self.backbone = configure_backbone(backbone, backbone_args)
- if mlp_dim:
- self.mlp = nn.Linear(mlp_dim, hidden_dim)
- self.use_backbone = True
-
- self.transformer = Transformer(
- num_encoder_layers,
- num_decoder_layers,
- hidden_dim,
- num_heads,
- expansion_dim,
- dropout_rate,
- activation,
- )
-
- self.head = nn.Sequential(nn.Linear(hidden_dim, vocab_size),)
-
- def _configure_sliding_window(self) -> nn.Sequential:
- return nn.Sequential(
- nn.Unfold(kernel_size=self.patch_size, stride=self.stride),
- Rearrange(
- "b (c h w) t -> b t c h w",
- h=self.patch_size[0],
- w=self.patch_size[1],
- c=1,
- ),
- )
-
- def _create_trg_mask(self, trg: Tensor) -> Tensor:
- # Move this outside the transformer.
- trg_pad_mask = (trg != self.trg_pad_index)[:, None, None]
- trg_len = trg.shape[1]
- trg_sub_mask = torch.tril(
- torch.ones((trg_len, trg_len), device=trg.device)
- ).bool()
- trg_mask = trg_pad_mask & trg_sub_mask
- return trg_mask
-
- def encoder(self, src: Tensor) -> Tensor:
- """Forward pass with the encoder of the transformer."""
- return self.transformer.encoder(src)
-
- def decoder(self, trg: Tensor, memory: Tensor, trg_mask: Tensor) -> Tensor:
- """Forward pass with the decoder of the transformer + classification head."""
- return self.head(
- self.transformer.decoder(trg=trg, memory=memory, trg_mask=trg_mask)
- )
-
- def _backbone(self, x: Tensor) -> Tensor:
- b, t = x.shape[:2]
- if self.use_backbone:
- x = rearrange(x, "b t c h w -> (b t) c h w", b=b, t=t)
- x = self.backbone(x)
- if self.mlp_dim:
- x = rearrange(x, "(b t) c h w -> b t (c h w)", b=b, t=t)
- x = self.mlp(x)
- else:
- x = rearrange(x, "(b t) h -> b t h", b=b, t=t)
- else:
- x = rearrange(x, "b t c h w -> b t (c h w)", b=b, t=t)
- x = self.linear_projection(x)
- return x
-
- def preprocess_input(self, src: Tensor) -> Tensor:
- """Encodes src with a backbone network and a positional encoding.
-
- Args:
- src (Tensor): Input tensor.
-
- Returns:
- Tensor: A input src to the transformer.
-
- """
- # If batch dimenstion is missing, it needs to be added.
- if len(src.shape) < 4:
- src = src[(None,) * (4 - len(src.shape))]
- src = self.slidning_window(src) # .squeeze(-2)
- src = self._backbone(src)
- src = self.position_encoding(src)
- return src
-
- def preprocess_target(self, trg: Tensor) -> Tuple[Tensor, Tensor]:
- """Encodes target tensor with embedding and postion.
-
- Args:
- trg (Tensor): Target tensor.
-
- Returns:
- Tuple[Tensor, Tensor]: Encoded target tensor and target mask.
-
- """
- trg_mask = self._create_trg_mask(trg)
- trg = self.character_embedding(trg.long())
- trg = self.position_encoding(trg)
- return trg, trg_mask
-
- def forward(self, x: Tensor, trg: Tensor) -> Tensor:
- """Forward pass with vision transfomer."""
- src = self.preprocess_input(x)
- trg, trg_mask = self.preprocess_target(trg)
- out = self.transformer(src, trg, trg_mask=trg_mask)
- logits = self.head(out)
- return logits