1 files changed, 38 insertions, 0 deletions
diff --git a/text_recognizer/networks/coat/patch_embedding.py b/text_recognizer/networks/coat/patch_embedding.py
new file mode 100644
index 0000000..3b7b76a
--- /dev/null
+++ b/text_recognizer/networks/coat/patch_embedding.py
@@ -0,0 +1,38 @@
+"""Patch embedding for images and feature maps."""
+from typing import Sequence, Tuple
+
+from einops import rearrange
+from loguru import logger
+from torch import nn
+from torch import Tensor
+
+
+class PatchEmbedding(nn.Module):
+    """Patch embedding of images."""
+
+    def __init__(
+        self,
+        image_shape: Sequence[int],
+        patch_size: int = 16,
+        in_channels: int = 1,
+        embedding_dim: int = 512,
+    ) -> None:
+        if image_shape[0] % patch_size == 0 and image_shape[1] % patch_size == 0:
+            logger.error(
+                f"Image shape {image_shape} not divisable by patch size {patch_size}"
+            )
+
+        self.patch_size = patch_size
+        self.embedding = nn.Conv2d(
+            in_channels, embedding_dim, kernel_size=patch_size, stride=patch_size
+        )
+        self.norm = nn.LayerNorm(embedding_dim)
+
+    def forward(self, x: Tensor) -> Tuple[Tensor, Tuple[int, int]]:
+        """Embeds image or feature maps with patch embedding."""
+        _, _, h, w = x.shape
+        h_out, w_out = h // self.patch_size, w // self.patch_size
+        x = self.embedding(x)
+        x = rearrange(x, "b c h w -> b (h w) c")
+        x = self.norm(x)
+        return x, (h_out, w_out)