# Copyright (c) 2023-2024, NVIDIA CORPORATION. All rights reserved. # # NVIDIA CORPORATION and its licensors retain all intellectual property # and proprietary rights in and to this software, related documentation # and any modifications thereto. Any use, reproduction, disclosure or # distribution of this software and related documentation without an express # license agreement from NVIDIA CORPORATION is strictly prohibited. import math from typing import Union, Tuple, Optional import torch import torch.nn.functional as F from torch import nn from einops import rearrange from .cls_token import ClsToken input_dim_t = Union[int, Tuple[int, int]] try: # raise ImportError() from indirect_grid_sample import indirect_grid_sample except ImportError: indirect_grid_sample = None class ViTPatchGenerator(nn.Module): def __init__(self, patch_size: int, embed_dim: int, input_dims: input_dim_t, abs_pos: bool = True, normalize_patches: bool = False, cls_token: bool = False, max_input_dims: Optional[input_dim_t] = None, pos_dropout: float = 0.0, return_pos_enc: bool = False, num_cls_tokens: int = 1, register_multiple: int = 0, device=None, dtype=None, ): super().__init__() if isinstance(input_dims, int): input_dims = (input_dims, input_dims) if max_input_dims is None: max_input_dims = input_dims if isinstance(max_input_dims, int): max_input_dims = (max_input_dims, max_input_dims) max_input_dims = tuple( int(math.ceil(d / patch_size) * patch_size) for d in max_input_dims ) self.cpe_mode = max_input_dims != input_dims self.pos_dropout = pos_dropout self.return_pos_enc = return_pos_enc factory = dict(device=device, dtype=dtype) self.patch_size = patch_size self.abs_pos = abs_pos self.embed_dim = embed_dim self.num_rows = max_input_dims[0] // patch_size self.num_cols = max_input_dims[1] // patch_size self.input_dims = tuple(d // patch_size for d in input_dims) self.num_patches = self.num_rows * self.num_cols self.max_input_dims = max_input_dims self.im_to_patches = Im2Patches(patch_size) self.embedder = ViTPatchLinear(patch_size, embed_dim, **factory) if abs_pos: scale = embed_dim ** -0.5 self.pos_embed = nn.Parameter(torch.randn(1, self.num_patches, embed_dim, **factory) * scale) self.cls_token = ClsToken( embed_dim, num_tokens=num_cls_tokens, enabled=cls_token, register_multiple=register_multiple, ) self.patch_normalizer = nn.LayerNorm(embed_dim) if normalize_patches else nn.Identity() def forward(self, x: torch.Tensor) -> torch.Tensor: patches = self.embed_patches(x) patches, pos_enc = self.apply_pos_enc(patches, input_size=x.shape[2:]) patches = self.cls_token(patches) patches = self.patch_normalizer(patches) if self.return_pos_enc: return patches, pos_enc return patches @property def apply_cls_token(self): return self.cls_token.enabled @property def num_cls_tokens(self): return self.cls_token.num_tokens @property def num_registers(self): return self.cls_token.num_registers @property def num_skip(self): return self.num_cls_tokens + self.num_registers def no_weight_decay(self): return [ 'pos_embed', ] def _load_from_state_dict(self, state_dict, prefix, local_metadata, strict, missing_keys, unexpected_keys, error_msgs): if self.abs_pos: self._load_embed(state_dict[f'{prefix}pos_embed'], self.pos_embed) def _load_embed(self, src_embed: torch.Tensor, targ_embed: nn.Parameter): if src_embed.shape != targ_embed.shape: src_size = int(math.sqrt(src_embed.shape[1])) assert src_size ** 2 == src_embed.shape[1], 'Unable to interpolate non-square embedding' src_embed = rearrange(src_embed, 'b (h w) c -> b c h w', h=src_size, w=src_size) src_embed = F.interpolate(src_embed, size=(self.num_rows, self.num_cols), mode='bicubic', align_corners=True, antialias=False) src_embed = rearrange(src_embed, 'b c h w -> b (h w) c') targ_embed.data.copy_(src_embed) def _load_projection(self, src_proj_weight: torch.Tensor, targ_proj_weight: torch.Tensor): if src_proj_weight.shape != targ_proj_weight.shape: src_patch_size = int(math.sqrt(src_proj_weight.shape[1] // 3)) assert (src_patch_size ** 2) * 3 == src_proj_weight.shape[1], 'Unable to interpolate non-square patch size' src_proj_weight = rearrange(src_proj_weight, 'b (c h w) -> b c h w', c=3, h=src_patch_size, w=src_patch_size) src_proj_weight = F.interpolate(src_proj_weight, size=(self.patch_size, self.patch_size), mode='bicubic', align_corners=True, antialias=False) src_proj_weight = rearrange(src_proj_weight, 'b c h w -> b (c h w)') targ_proj_weight.data.copy_(src_proj_weight) def embed_patches(self, x: torch.Tensor) -> torch.Tensor: patches = self.im_to_patches(x) patches = self.embedder(patches) return patches def apply_pos_enc(self, patches: torch.Tensor, patch_idxs: Optional[torch.Tensor] = None, input_size: Optional[Tuple[int, int]] = None, ) -> torch.Tensor: if not self.abs_pos: return patches pos_enc = self.get_pos_enc(patches.shape[0], patch_idxs, input_size) if self.training and self.pos_dropout > 0: keeps = torch.rand(patches.shape[0], 1, 1, dtype=pos_enc.dtype, device=pos_enc.device) > self.pos_dropout pos_enc_drop = torch.where(keeps, pos_enc, 0) else: pos_enc_drop = pos_enc return patches + pos_enc_drop, pos_enc def get_pos_enc(self, batch_size: int, patch_idxs: Optional[torch.Tensor] = None, input_size: Optional[Tuple[int, int]] = None, ) -> torch.Tensor: if input_size is None: input_dims = self.input_dims else: input_dims = tuple(d // self.patch_size for d in input_size) pos_embed = self._get_pos_embeddings(batch_size, input_dims) if patch_idxs is None: return pos_embed exp_patch_idxs = patch_idxs.unsqueeze(-1).expand(-1, -1, pos_embed.shape[-1]) pos_embed = torch.gather(pos_embed.expand(patch_idxs.shape[0], -1, -1), dim=1, index=exp_patch_idxs) return pos_embed def _get_pos_embeddings(self, batch_size: int, input_dims: Tuple[int, int]): if (self.num_rows, self.num_cols) == input_dims: return self.pos_embed pos_embed = self.pos_embed.reshape(1, self.num_rows, self.num_cols, -1).permute(0, 3, 1, 2) def window_select(pos_embed): if input_dims[0] < pos_embed.shape[-2]: pos_embed = pos_embed[..., :input_dims[0], :] if input_dims[1] < pos_embed.shape[-1]: pos_embed = pos_embed[..., :, :input_dims[1]] return pos_embed if self.cpe_mode: if self.training: min_scale = math.sqrt(0.1) scale = torch.rand(batch_size, 1, 1, device=pos_embed.device) * (1 - min_scale) + min_scale aspect_min = math.log(3 / 4) aspect_max = -aspect_min aspect = torch.exp(torch.rand(batch_size, 1, 1, device=pos_embed.device) * (aspect_max - aspect_min) + aspect_min) scale_x = scale * aspect scale_y = scale * (1 / aspect) scale_xy = torch.stack([scale_x, scale_y], dim=-1).clamp_(0, 1) pos_xy = torch.rand(batch_size, 1, 1, 2, device=pos_embed.device) * (1 - scale_xy) lin_x = torch.linspace(0, 1, steps=input_dims[1], device=pos_embed.device)[None, None].expand(batch_size, input_dims[0], -1) lin_y = torch.linspace(0, 1, steps=input_dims[0], device=pos_embed.device)[None, :, None].expand(batch_size, -1, input_dims[1]) lin_xy = torch.stack([lin_x, lin_y], dim=-1) grid_xy = lin_xy * scale_xy + pos_xy # Convert to [-1, 1] range grid_xy.mul_(2).sub_(1) pos_embed = F.grid_sample( pos_embed.float().expand(batch_size, -1, -1, -1), grid=grid_xy, mode='bilinear', padding_mode='zeros', align_corners=True, ).to(pos_embed.dtype) else: # i_rows, i_cols = input_dims # p_rows, p_cols = pos_embed.shape[2:] # if i_rows <= p_rows and i_cols <= p_cols: # left = (p_cols - i_cols) // 2 # top = (p_rows - i_rows) // 2 # pos_embed = pos_embed[..., top:top+i_rows, left:left+i_cols] # else: max_dim = max(input_dims) pos_embed = F.interpolate(pos_embed.float(), size=(max_dim, max_dim), align_corners=True, mode='bilinear').to(pos_embed.dtype) pos_embed = window_select(pos_embed) else: pos_embed = window_select(pos_embed) if pos_embed.shape[-2:] != input_dims: pos_embed = F.interpolate(pos_embed.float(), size=input_dims, align_corners=True, mode='bilinear').to(pos_embed.dtype) pos_embed = pos_embed.flatten(2).permute(0, 2, 1) return pos_embed class Im2Patches(nn.Module): def __init__(self, patch_size: int): super().__init__() self.patch_size = patch_size def forward(self, x: torch.Tensor) -> torch.Tensor: if self.patch_size == 1: patches = x.flatten(2) patches = patches.permute(0, 2, 1) return patches py = x.shape[-2] // self.patch_size px = x.shape[-1] // self.patch_size patches = rearrange(x, 'b c (py yy) (px xx) -> b (py px) (c yy xx)', py=py, yy=self.patch_size, px=px, xx=self.patch_size, ) return patches class ViTPatchLinear(nn.Linear): def __init__(self, patch_size: int, embed_dim: int, **factory): super().__init__( 3 * (patch_size ** 2), embed_dim, bias=False, **factory ) self.patch_size = patch_size def _load_from_state_dict(self, state_dict, prefix, local_metadata, strict, missing_keys, unexpected_keys, error_msgs): if self.bias is not None: self.bias.data.copy_(state_dict[f'{prefix}bias']) chk_weight = state_dict[f'{prefix}weight'] if chk_weight.shape != self.weight.shape: src_patch_size = int(math.sqrt(chk_weight.shape[1] // 3)) assert (src_patch_size ** 2) * 3 == chk_weight.shape[1], 'Unable to interpolate non-square patch size' chk_weight = rearrange(chk_weight, 'b (c h w) -> b c h w', c=3, h=src_patch_size, w=src_patch_size) chk_weight = F.interpolate(chk_weight, size=(self.patch_size, self.patch_size), mode='bicubic', align_corners=True, antialias=False) chk_weight = rearrange(chk_weight, 'b c h w -> b (c h w)') self.weight.data.copy_(chk_weight)