diff --git a/README.md b/README.md index 87de09d..d98f999 100644 --- a/README.md +++ b/README.md @@ -24,6 +24,7 @@ - [Simple Masked Image Modeling](#simple-masked-image-modeling) - [Masked Patch Prediction](#masked-patch-prediction) - [Adaptive Token Sampling](#adaptive-token-sampling) +- [Vision Transformer for Small Datasets](#vision-transformer-for-small-datasets) - [Dino](#dino) - [Accessing Attention](#accessing-attention) - [Research Ideas](#research-ideas) @@ -739,6 +740,52 @@ preds = v(img) # (1, 1000) preds, token_ids = v(img, return_sampled_token_ids = True) # (1, 1000), (1, <=8) ``` +## Vision Transformer for Small Datasets + + + +This paper proposes a new image to patch function that incorporates shifts of the image, before normalizing and dividing the image into patches. I have found shifting to be extremely helpful in some other transformers work, so decided to include this for further explorations. It also includes the `LRA` with the learned temperature and masking out of token attention to itself. + +You can use as follows: + +```python +import torch +from vit_pytorch.vit_for_small_dataset import ViT + +v = ViT( + image_size = 256, + patch_size = 16, + num_classes = 1000, + dim = 1024, + depth = 6, + heads = 16, + mlp_dim = 2048, + dropout = 0.1, + emb_dropout = 0.1 +) + +img = torch.randn(4, 3, 256, 256) + +preds = v(img) # (1, 1000) +``` + +You can also use the `SPT` from this paper as a standalone module + +```python +import torch +from vit_pytorch.vit_for_small_dataset import SPT + +spt = SPT( + dim = 1024, + patch_size = 16, + channels = 3 +) + +img = torch.randn(4, 3, 256, 256) + +tokens = spt(img) # (4, 256, 1024) +``` + ## Dino @@ -1236,6 +1283,17 @@ Coming from computer vision and new to transformers? Here are some resources tha } ``` +```bibtex +@misc{lee2021vision, + title = {Vision Transformer for Small-Size Datasets}, + author = {Seung Hoon Lee and Seunghyun Lee and Byung Cheol Song}, + year = {2021}, + eprint = {2112.13492}, + archivePrefix = {arXiv}, + primaryClass = {cs.CV} +} +``` + ```bibtex @misc{vaswani2017attention, title = {Attention Is All You Need}, diff --git a/images/vit_for_small_datasets.png b/images/vit_for_small_datasets.png new file mode 100644 index 0000000..c52b83d Binary files /dev/null and b/images/vit_for_small_datasets.png differ diff --git a/setup.py b/setup.py index ae59572..d9583ae 100644 --- a/setup.py +++ b/setup.py @@ -3,7 +3,7 @@ from setuptools import setup, find_packages setup( name = 'vit-pytorch', packages = find_packages(exclude=['examples']), - version = '0.25.6', + version = '0.26.0', license='MIT', description = 'Vision Transformer (ViT) - Pytorch', author = 'Phil Wang', diff --git a/vit_pytorch/extractor.py b/vit_pytorch/extractor.py index 54fc05e..297c577 100644 --- a/vit_pytorch/extractor.py +++ b/vit_pytorch/extractor.py @@ -10,6 +10,7 @@ class Extractor(nn.Module): vit, device = None, layer_name = 'transformer', + layer_save_input = False, return_embeddings_only = False ): super().__init__() @@ -23,10 +24,12 @@ class Extractor(nn.Module): self.device = device self.layer_name = layer_name + self.layer_save_input = layer_save_input # whether to save input or output of layer self.return_embeddings_only = return_embeddings_only - def _hook(self, _, input, output): - self.latents = output.clone().detach() + def _hook(self, _, inputs, output): + tensor_to_save = inputs if self.layer_save_input else output + self.latents = tensor_to_save.clone().detach() def _register_hook(self): assert hasattr(self.vit, self.layer_name), 'layer whose output to take as embedding not found in vision transformer' diff --git a/vit_pytorch/vit_for_small_dataset.py b/vit_pytorch/vit_for_small_dataset.py new file mode 100644 index 0000000..0e223ce --- /dev/null +++ b/vit_pytorch/vit_for_small_dataset.py @@ -0,0 +1,142 @@ +from math import sqrt +import torch +import torch.nn.functional as F +from torch import nn + +from einops import rearrange, repeat +from einops.layers.torch import Rearrange + +# helpers + +def pair(t): + return t if isinstance(t, tuple) else (t, t) + +# classes + +class PreNorm(nn.Module): + def __init__(self, dim, fn): + super().__init__() + self.norm = nn.LayerNorm(dim) + self.fn = fn + def forward(self, x, **kwargs): + return self.fn(self.norm(x), **kwargs) + +class FeedForward(nn.Module): + def __init__(self, dim, hidden_dim, dropout = 0.): + super().__init__() + self.net = nn.Sequential( + nn.Linear(dim, hidden_dim), + nn.GELU(), + nn.Dropout(dropout), + nn.Linear(hidden_dim, dim), + nn.Dropout(dropout) + ) + def forward(self, x): + return self.net(x) + +class LSA(nn.Module): + def __init__(self, dim, heads = 8, dim_head = 64, dropout = 0.): + super().__init__() + inner_dim = dim_head * heads + self.heads = heads + self.temperature = nn.Parameter(torch.log(torch.tensor(dim_head ** -0.5))) + + self.attend = nn.Softmax(dim = -1) + self.to_qkv = nn.Linear(dim, inner_dim * 3, bias = False) + + self.to_out = nn.Sequential( + nn.Linear(inner_dim, dim), + nn.Dropout(dropout) + ) + + def forward(self, x): + qkv = self.to_qkv(x).chunk(3, dim = -1) + q, k, v = map(lambda t: rearrange(t, 'b n (h d) -> b h n d', h = self.heads), qkv) + + dots = torch.matmul(q, k.transpose(-1, -2)) * self.temperature.exp() + + mask = torch.eye(dots.shape[-1], device = dots.device, dtype = torch.bool) + mask_value = -torch.finfo(dots.dtype).max + dots = dots.masked_fill(mask, mask_value) + + attn = self.attend(dots) + + out = torch.matmul(attn, v) + out = rearrange(out, 'b h n d -> b n (h d)') + return self.to_out(out) + +class Transformer(nn.Module): + def __init__(self, dim, depth, heads, dim_head, mlp_dim, dropout = 0.): + super().__init__() + self.layers = nn.ModuleList([]) + for _ in range(depth): + self.layers.append(nn.ModuleList([ + PreNorm(dim, LSA(dim, heads = heads, dim_head = dim_head, dropout = dropout)), + PreNorm(dim, FeedForward(dim, mlp_dim, dropout = dropout)) + ])) + def forward(self, x): + for attn, ff in self.layers: + x = attn(x) + x + x = ff(x) + x + return x + +class SPT(nn.Module): + def __init__(self, *, dim, patch_size, channels = 3): + super().__init__() + patch_dim = patch_size * patch_size * 5 * channels + + self.to_patch_tokens = nn.Sequential( + Rearrange('b c (h p1) (w p2) -> b (h w) (p1 p2 c)', p1 = patch_size, p2 = patch_size), + nn.LayerNorm(patch_dim), + nn.Linear(patch_dim, dim) + ) + + def forward(self, x): + shifts = ((1, -1, 0, 0), (-1, 1, 0, 0), (0, 0, 1, -1), (0, 0, -1, 1)) + shifted_x = list(map(lambda shift: F.pad(x, shift), shifts)) + x_with_shifts = torch.cat((x, *shifted_x), dim = 1) + return self.to_patch_tokens(x_with_shifts) + +class ViT(nn.Module): + def __init__(self, *, image_size, patch_size, num_classes, dim, depth, heads, mlp_dim, pool = 'cls', channels = 3, dim_head = 64, dropout = 0., emb_dropout = 0.): + super().__init__() + image_height, image_width = pair(image_size) + patch_height, patch_width = pair(patch_size) + + assert image_height % patch_height == 0 and image_width % patch_width == 0, 'Image dimensions must be divisible by the patch size.' + + num_patches = (image_height // patch_height) * (image_width // patch_width) + patch_dim = channels * patch_height * patch_width + assert pool in {'cls', 'mean'}, 'pool type must be either cls (cls token) or mean (mean pooling)' + + self.to_patch_embedding = SPT(dim = dim, patch_size = patch_size, channels = channels) + + self.pos_embedding = nn.Parameter(torch.randn(1, num_patches + 1, dim)) + self.cls_token = nn.Parameter(torch.randn(1, 1, dim)) + self.dropout = nn.Dropout(emb_dropout) + + self.transformer = Transformer(dim, depth, heads, dim_head, mlp_dim, dropout) + + self.pool = pool + self.to_latent = nn.Identity() + + self.mlp_head = nn.Sequential( + nn.LayerNorm(dim), + nn.Linear(dim, num_classes) + ) + + def forward(self, img): + x = self.to_patch_embedding(img) + b, n, _ = x.shape + + cls_tokens = repeat(self.cls_token, '() n d -> b n d', b = b) + x = torch.cat((cls_tokens, x), dim=1) + x += self.pos_embedding[:, :(n + 1)] + x = self.dropout(x) + + x = self.transformer(x) + + x = x.mean(dim = 1) if self.pool == 'mean' else x[:, 0] + + x = self.to_latent(x) + return self.mlp_head(x)