src/models/patch_embedding.py

import torch
import torch.nn as nn


class PatchEmbed(nn.Module):
    """Image to Patch Embedding"""
    def __init__(
        self,
        img_size: int = 224,
        patch_size: int = 14,
        in_chans: int = 3,
        embed_dim: int = 768,
    ):
        super().__init__()
        self.img_size = img_size
        self.patch_size = patch_size
        self.grid_size = img_size // patch_size
        self.num_patches = self.grid_size ** 2

        self.proj = nn.Conv2d(
            in_chans,
            embed_dim,
            kernel_size=patch_size,
            stride=patch_size
        )

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        x = self.proj(x)
        x = x.flatten(2)
        x = x.transpose(1, 2)
        return x