add basic code for MAE

main.py

@@ -1,9 +1,11 @@
 import pyjson5 as json
 from self_supervised.mocov2 import builder
+from self_supervised.mae import mae_model
 from utilities.utils import prepare_configuration
-from training import train_ssl, train_supervised
+from training import train_contrastive, train_supervised
 import argparse
 import pprint
+import os
 
 if __name__ == "__main__":
     parser = argparse.ArgumentParser()
@@ -39,7 +41,10 @@
                 config["moco_t"],
                 config["mlp"],
             )
+        elif config['method'] == "mae":
+            raise NotImplementedError(f'{config["method"]} is not supported.')
+
         else:
             raise NotImplementedError(f'{config["method"]} is not supported.')
 
-        train_ssl.exec_model(model, config)
+        train_contrastive.exec_model(model, config)

self_supervised/mae/mae_model.py

@@ -0,0 +1,332 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+
+# This source code is licensed under the license found in the
+# LICENSE file in the root directory of this source tree.
+# --------------------------------------------------------
+# References:
+# timm: https://github.com/rwightman/pytorch-image-models/tree/master/timm
+# DeiT: https://github.com/facebookresearch/deit
+# --------------------------------------------------------
+
+from functools import partial
+
+import torch
+import torch.nn as nn
+
+from timm.models.vision_transformer import PatchEmbed, Block
+
+# --------------------------------------------------------
+# 2D sine-cosine position embedding
+# References:
+# Transformer: https://github.com/tensorflow/models/blob/master/official/nlp/transformer/model_utils.py
+# MoCo v3: https://github.com/facebookresearch/moco-v3
+# --------------------------------------------------------
+def get_2d_sincos_pos_embed(embed_dim, grid_size, cls_token=False):
+    """
+    grid_size: int of the grid height and width
+    return:
+    pos_embed: [grid_size*grid_size, embed_dim] or [1+grid_size*grid_size, embed_dim] (w/ or w/o cls_token)
+    """
+    grid_h = np.arange(grid_size, dtype=np.float32)
+    grid_w = np.arange(grid_size, dtype=np.float32)
+    grid = np.meshgrid(grid_w, grid_h)  # here w goes first
+    grid = np.stack(grid, axis=0)
+
+    grid = grid.reshape([2, 1, grid_size, grid_size])
+    pos_embed = get_2d_sincos_pos_embed_from_grid(embed_dim, grid)
+    if cls_token:
+        pos_embed = np.concatenate([np.zeros([1, embed_dim]), pos_embed], axis=0)
+    return pos_embed
+
+
+def get_2d_sincos_pos_embed_from_grid(embed_dim, grid):
+    assert embed_dim % 2 == 0
+
+    # use half of dimensions to encode grid_h
+    emb_h = get_1d_sincos_pos_embed_from_grid(embed_dim // 2, grid[0])  # (H*W, D/2)
+    emb_w = get_1d_sincos_pos_embed_from_grid(embed_dim // 2, grid[1])  # (H*W, D/2)
+
+    emb = np.concatenate([emb_h, emb_w], axis=1) # (H*W, D)
+    return emb
+
+
+def get_1d_sincos_pos_embed_from_grid(embed_dim, pos):
+    """
+    embed_dim: output dimension for each position
+    pos: a list of positions to be encoded: size (M,)
+    out: (M, D)
+    """
+    assert embed_dim % 2 == 0
+    omega = np.arange(embed_dim // 2, dtype=np.float)
+    omega /= embed_dim / 2.
+    omega = 1. / 10000**omega  # (D/2,)
+
+    pos = pos.reshape(-1)  # (M,)
+    out = np.einsum('m,d->md', pos, omega)  # (M, D/2), outer product
+
+    emb_sin = np.sin(out) # (M, D/2)
+    emb_cos = np.cos(out) # (M, D/2)
+
+    emb = np.concatenate([emb_sin, emb_cos], axis=1)  # (M, D)
+    return emb
+
+
+# --------------------------------------------------------
+# Interpolate position embeddings for high-resolution
+# References:
+# DeiT: https://github.com/facebookresearch/deit
+# --------------------------------------------------------
+def interpolate_pos_embed(model, checkpoint_model):
+    if 'pos_embed' in checkpoint_model:
+        pos_embed_checkpoint = checkpoint_model['pos_embed']
+        embedding_size = pos_embed_checkpoint.shape[-1]
+        num_patches = model.patch_embed.num_patches
+        num_extra_tokens = model.pos_embed.shape[-2] - num_patches
+        # height (== width) for the checkpoint position embedding
+        orig_size = int((pos_embed_checkpoint.shape[-2] - num_extra_tokens) ** 0.5)
+        # height (== width) for the new position embedding
+        new_size = int(num_patches ** 0.5)
+        # class_token and dist_token are kept unchanged
+        if orig_size != new_size:
+            print("Position interpolate from %dx%d to %dx%d" % (orig_size, orig_size, new_size, new_size))
+            extra_tokens = pos_embed_checkpoint[:, :num_extra_tokens]
+            # only the position tokens are interpolated
+            pos_tokens = pos_embed_checkpoint[:, num_extra_tokens:]
+            pos_tokens = pos_tokens.reshape(-1, orig_size, orig_size, embedding_size).permute(0, 3, 1, 2)
+            pos_tokens = torch.nn.functional.interpolate(
+                pos_tokens, size=(new_size, new_size), mode='bicubic', align_corners=False)
+            pos_tokens = pos_tokens.permute(0, 2, 3, 1).flatten(1, 2)
+            new_pos_embed = torch.cat((extra_tokens, pos_tokens), dim=1)
+            checkpoint_model['pos_embed'] = new_pos_embed
+
+
+class MaskedAutoencoderViT(nn.Module):
+    """ Masked Autoencoder with VisionTransformer backbone
+    """
+    def __init__(self, img_size=224, patch_size=16, in_chans=3,
+                 embed_dim=1024, depth=24, num_heads=16,
+                 decoder_embed_dim=512, decoder_depth=8, decoder_num_heads=16,
+                 mlp_ratio=4., norm_layer=nn.LayerNorm, norm_pix_loss=False):
+        super().__init__()
+
+        # --------------------------------------------------------------------------
+        # MAE encoder specifics
+        self.patch_embed = PatchEmbed(img_size, patch_size, in_chans, embed_dim)
+        num_patches = self.patch_embed.num_patches
+
+        self.cls_token = nn.Parameter(torch.zeros(1, 1, embed_dim))
+        self.pos_embed = nn.Parameter(torch.zeros(1, num_patches + 1, embed_dim), requires_grad=False)  # fixed sin-cos embedding
+
+        self.blocks = nn.ModuleList([
+            Block(embed_dim, num_heads, mlp_ratio, qkv_bias=True, qk_scale=None, norm_layer=norm_layer)
+            for i in range(depth)])
+        self.norm = norm_layer(embed_dim)
+        # --------------------------------------------------------------------------
+
+        # --------------------------------------------------------------------------
+        # MAE decoder specifics
+        self.decoder_embed = nn.Linear(embed_dim, decoder_embed_dim, bias=True)
+
+        self.mask_token = nn.Parameter(torch.zeros(1, 1, decoder_embed_dim))
+
+        self.decoder_pos_embed = nn.Parameter(torch.zeros(1, num_patches + 1, decoder_embed_dim), requires_grad=False)  # fixed sin-cos embedding
+
+        self.decoder_blocks = nn.ModuleList([
+            Block(decoder_embed_dim, decoder_num_heads, mlp_ratio, qkv_bias=True, qk_scale=None, norm_layer=norm_layer)
+            for i in range(decoder_depth)])
+
+        self.decoder_norm = norm_layer(decoder_embed_dim)
+        self.decoder_pred = nn.Linear(decoder_embed_dim, patch_size**2 * in_chans, bias=True) # decoder to patch
+        # --------------------------------------------------------------------------
+
+        self.norm_pix_loss = norm_pix_loss
+
+        self.initialize_weights()
+
+    def initialize_weights(self):
+        # initialization
+        # initialize (and freeze) pos_embed by sin-cos embedding
+        pos_embed = get_2d_sincos_pos_embed(self.pos_embed.shape[-1], int(self.patch_embed.num_patches**.5), cls_token=True)
+        self.pos_embed.data.copy_(torch.from_numpy(pos_embed).float().unsqueeze(0))
+
+        decoder_pos_embed = get_2d_sincos_pos_embed(self.decoder_pos_embed.shape[-1], int(self.patch_embed.num_patches**.5), cls_token=True)
+        self.decoder_pos_embed.data.copy_(torch.from_numpy(decoder_pos_embed).float().unsqueeze(0))
+
+        # initialize patch_embed like nn.Linear (instead of nn.Conv2d)
+        w = self.patch_embed.proj.weight.data
+        torch.nn.init.xavier_uniform_(w.view([w.shape[0], -1]))
+
+        # timm's trunc_normal_(std=.02) is effectively normal_(std=0.02) as cutoff is too big (2.)
+        torch.nn.init.normal_(self.cls_token, std=.02)
+        torch.nn.init.normal_(self.mask_token, std=.02)
+
+        # initialize nn.Linear and nn.LayerNorm
+        self.apply(self._init_weights)
+
+    def _init_weights(self, m):
+        if isinstance(m, nn.Linear):
+            # we use xavier_uniform following official JAX ViT:
+            torch.nn.init.xavier_uniform_(m.weight)
+            if isinstance(m, nn.Linear) and m.bias is not None:
+                nn.init.constant_(m.bias, 0)
+        elif isinstance(m, nn.LayerNorm):
+            nn.init.constant_(m.bias, 0)
+            nn.init.constant_(m.weight, 1.0)
+
+    def patchify(self, imgs):
+        """
+        imgs: (N, 3, H, W)
+        x: (N, L, patch_size**2 *3)
+        """
+        p = self.patch_embed.patch_size[0]
+        assert imgs.shape[2] == imgs.shape[3] and imgs.shape[2] % p == 0
+
+        h = w = imgs.shape[2] // p
+        x = imgs.reshape(shape=(imgs.shape[0], 3, h, p, w, p))
+        x = torch.einsum('nchpwq->nhwpqc', x)
+        x = x.reshape(shape=(imgs.shape[0], h * w, p**2 * 3))
+        return x
+
+    def unpatchify(self, x):
+        """
+        x: (N, L, patch_size**2 *3)
+        imgs: (N, 3, H, W)
+        """
+        p = self.patch_embed.patch_size[0]
+        h = w = int(x.shape[1]**.5)
+        assert h * w == x.shape[1]
+
+        x = x.reshape(shape=(x.shape[0], h, w, p, p, 3))
+        x = torch.einsum('nhwpqc->nchpwq', x)
+        imgs = x.reshape(shape=(x.shape[0], 3, h * p, h * p))
+        return imgs
+
+    def random_masking(self, x, mask_ratio):
+        """
+        Perform per-sample random masking by per-sample shuffling.
+        Per-sample shuffling is done by argsort random noise.
+        x: [N, L, D], sequence
+        """
+        N, L, D = x.shape  # batch, length, dim
+        len_keep = int(L * (1 - mask_ratio))
+
+        noise = torch.rand(N, L, device=x.device)  # noise in [0, 1]
+
+        # sort noise for each sample
+        ids_shuffle = torch.argsort(noise, dim=1)  # ascend: small is keep, large is remove
+        ids_restore = torch.argsort(ids_shuffle, dim=1)
+
+        # keep the first subset
+        ids_keep = ids_shuffle[:, :len_keep]
+        x_masked = torch.gather(x, dim=1, index=ids_keep.unsqueeze(-1).repeat(1, 1, D))
+
+        # generate the binary mask: 0 is keep, 1 is remove
+        mask = torch.ones([N, L], device=x.device)
+        mask[:, :len_keep] = 0
+        # unshuffle to get the binary mask
+        mask = torch.gather(mask, dim=1, index=ids_restore)
+
+        return x_masked, mask, ids_restore
+
+    def forward_encoder(self, x, mask_ratio):
+        # embed patches
+        x = self.patch_embed(x)
+
+        # add pos embed w/o cls token
+        x = x + self.pos_embed[:, 1:, :]
+
+        # masking: length -> length * mask_ratio
+        x, mask, ids_restore = self.random_masking(x, mask_ratio)
+
+        # append cls token
+        cls_token = self.cls_token + self.pos_embed[:, :1, :]
+        cls_tokens = cls_token.expand(x.shape[0], -1, -1)
+        x = torch.cat((cls_tokens, x), dim=1)
+
+        # apply Transformer blocks
+        for blk in self.blocks:
+            x = blk(x)
+        x = self.norm(x)
+
+        return x, mask, ids_restore
+
+    def forward_decoder(self, x, ids_restore):
+        # embed tokens
+        x = self.decoder_embed(x)
+
+        # append mask tokens to sequence
+        mask_tokens = self.mask_token.repeat(x.shape[0], ids_restore.shape[1] + 1 - x.shape[1], 1)
+        x_ = torch.cat([x[:, 1:, :], mask_tokens], dim=1)  # no cls token
+        x_ = torch.gather(x_, dim=1, index=ids_restore.unsqueeze(-1).repeat(1, 1, x.shape[2]))  # unshuffle
+        x = torch.cat([x[:, :1, :], x_], dim=1)  # append cls token
+
+        # add pos embed
+        x = x + self.decoder_pos_embed
+
+        # apply Transformer blocks
+        for blk in self.decoder_blocks:
+            x = blk(x)
+        x = self.decoder_norm(x)
+
+        # predictor projection
+        x = self.decoder_pred(x)
+
+        # remove cls token
+        x = x[:, 1:, :]
+
+        return x
+
+    def forward_loss(self, imgs, pred, mask):
+        """
+        imgs: [N, 3, H, W]
+        pred: [N, L, p*p*3]
+        mask: [N, L], 0 is keep, 1 is remove, 
+        """
+        target = self.patchify(imgs)
+        if self.norm_pix_loss:
+            mean = target.mean(dim=-1, keepdim=True)
+            var = target.var(dim=-1, keepdim=True)
+            target = (target - mean) / (var + 1.e-6)**.5
+
+        loss = (pred - target) ** 2
+        loss = loss.mean(dim=-1)  # [N, L], mean loss per patch
+
+        loss = (loss * mask).sum() / mask.sum()  # mean loss on removed patches
+        return loss
+
+    def forward(self, imgs, mask_ratio=0.75):
+        latent, mask, ids_restore = self.forward_encoder(imgs, mask_ratio)
+        pred = self.forward_decoder(latent, ids_restore)  # [N, L, p*p*3]
+        loss = self.forward_loss(imgs, pred, mask)
+        return loss, pred, mask
+
+
+def mae_vit_base_patch16_dec512d8b(**kwargs):
+    model = MaskedAutoencoderViT(
+        patch_size=16, embed_dim=768, depth=12, num_heads=12,
+        decoder_embed_dim=512, decoder_depth=8, decoder_num_heads=16,
+        mlp_ratio=4, norm_layer=partial(nn.LayerNorm, eps=1e-6), **kwargs)
+    return model
+
+
+def mae_vit_large_patch16_dec512d8b(**kwargs):
+    model = MaskedAutoencoderViT(
+        patch_size=16, embed_dim=1024, depth=24, num_heads=16,
+        decoder_embed_dim=512, decoder_depth=8, decoder_num_heads=16,
+        mlp_ratio=4, norm_layer=partial(nn.LayerNorm, eps=1e-6), **kwargs)
+    return model
+
+
+def mae_vit_huge_patch14_dec512d8b(**kwargs):
+    model = MaskedAutoencoderViT(
+        patch_size=14, embed_dim=1280, depth=32, num_heads=16,
+        decoder_embed_dim=512, decoder_depth=8, decoder_num_heads=16,
+        mlp_ratio=4, norm_layer=partial(nn.LayerNorm, eps=1e-6), **kwargs)
+    return model
+
+
+# set recommended archs
+mae_vit_base_patch16 = mae_vit_base_patch16_dec512d8b  # decoder: 512 dim, 8 blocks
+mae_vit_large_patch16 = mae_vit_large_patch16_dec512d8b  # decoder: 512 dim, 8 blocks
+mae_vit_huge_patch14 = mae_vit_huge_patch14_dec512d8b  # decoder: 512 dim, 8 blocks

self_supervised/mae/mae_scheduler.py

@@ -0,0 +1,15 @@
+import math
+
+def adjust_learning_rate(optimizer, epoch, args):
+    """Decay the learning rate with half-cycle cosine after warmup"""
+    if epoch < args.warmup_epochs:
+        lr = args.lr * epoch / args.warmup_epochs 
+    else:
+        lr = args.min_lr + (args.lr - args.min_lr) * 0.5 * \
+            (1. + math.cos(math.pi * (epoch - args.warmup_epochs) / (args.epochs - args.warmup_epochs)))
+    for param_group in optimizer.param_groups:
+        if "lr_scale" in param_group:
+            param_group["lr"] = lr * param_group["lr_scale"]
+        else:
+            param_group["lr"] = lr
+    return lr