1 files changed, 77 insertions, 0 deletions
diff --git a/text_recognizer/networks/vq_transformer.py b/text_recognizer/networks/vq_transformer.py
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+++ b/text_recognizer/networks/vq_transformer.py
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+"""Vector quantized encoder, transformer decoder."""
+import math
+from typing import Tuple
+
+from torch import nn, Tensor
+
+from text_recognizer.networks.encoders.efficientnet import EfficientNet
+from text_recognizer.networks.conv_transformer import ConvTransformer
+from text_recognizer.networks.transformer.layers import Decoder
+from text_recognizer.networks.transformer.positional_encodings import (
+    PositionalEncoding,
+    PositionalEncoding2D,
+)
+
+
+class VqTransformer(ConvTransformer):
+    """Convolutional encoder and transformer decoder network."""
+
+    def __init__(
+        self,
+        input_dims: Tuple[int, int, int],
+        hidden_dim: int,
+        dropout_rate: float,
+        num_classes: int,
+        pad_index: Tensor,
+        encoder: EfficientNet,
+        decoder: Decoder,
+    ) -> None:
+        # TODO: Load pretrained vqvae encoder.
+        super().__init__(
+            input_dims=input_dims,
+            hidden_dim=hidden_dim,
+            dropout_rate=dropout_rate,
+            num_classes=num_classes,
+            pad_index=pad_index,
+            encoder=encoder,
+            decoder=decoder,
+        )
+        # Latent projector for down sampling number of filters and 2d
+        # positional encoding.
+        self.latent_encoder = nn.Sequential(
+            nn.Conv2d(
+                in_channels=self.encoder.out_channels,
+                out_channels=self.hidden_dim,
+                kernel_size=1,
+            ),
+            PositionalEncoding2D(
+                hidden_dim=self.hidden_dim,
+                max_h=self.input_dims[1],
+                max_w=self.input_dims[2],
+            ),
+            nn.Flatten(start_dim=2),
+        )
+
+    def encode(self, x: Tensor) -> Tensor:
+        """Encodes an image into a latent feature vector.
+
+        Args:
+            x (Tensor): Image tensor.
+
+        Shape:
+            - x: :math: `(B, C, H, W)`
+            - z: :math: `(B, Sx, E)`
+
+            where Sx is the length of the flattened feature maps projected from
+            the encoder. E latent dimension for each pixel in the projected
+            feature maps.
+
+        Returns:
+            Tensor: A Latent embedding of the image.
+        """
+        z = self.encoder(x)
+        z = self.latent_encoder(z)
+
+        # Permute tensor from [B, E, Ho * Wo] to [B, Sx, E]
+        z = z.permute(0, 2, 1)
+        return z