Fix dynamic_resize for deit models (distilled or no_embed_cls) and vit w/o class tokens

Author: rwightman

timm/models/deit.py

@@ -73,45 +73,36 @@ def reset_classifier(self, num_classes, global_pool=None):
     def set_distilled_training(self, enable=True):
         self.distilled_training = enable
 
-    def _intermediate_layers(
-            self,
-            x: torch.Tensor,
-            n: Union[int, Sequence] = 1,
-    ):
-        outputs, num_blocks = [], len(self.blocks)
-        take_indices = set(range(num_blocks - n, num_blocks) if isinstance(n, int) else n)
-
-        # forward pass
-        x = self.patch_embed(x)
-        x = torch.cat((
-            self.cls_token.expand(x.shape[0], -1, -1),
-            self.dist_token.expand(x.shape[0], -1, -1),
-            x),
-            dim=1)
-        x = self.pos_drop(x + self.pos_embed)
-        x = self.patch_drop(x)
-        x = self.norm_pre(x)
-        for i, blk in enumerate(self.blocks):
-            x = blk(x)
-            if i in take_indices:
-                outputs.append(x)
-
-        return outputs
-
-    def forward_features(self, x) -> torch.Tensor:
-        x = self.patch_embed(x)
-        x = torch.cat((
-            self.cls_token.expand(x.shape[0], -1, -1),
-            self.dist_token.expand(x.shape[0], -1, -1),
-            x),
-            dim=1)
-        x = self.pos_drop(x + self.pos_embed)
-        if self.grad_checkpointing and not torch.jit.is_scripting():
-            x = checkpoint_seq(self.blocks, x)
+    def _pos_embed(self, x):
+        if self.dynamic_size:
+            B, H, W, C = x.shape
+            pos_embed = resample_abs_pos_embed(
+                self.pos_embed,
+                (H, W),
+                num_prefix_tokens=0 if self.no_embed_class else self.num_prefix_tokens,
+            )
+            x = x.view(B, -1, C)
         else:
-            x = self.blocks(x)
-        x = self.norm(x)
-        return x
+            pos_embed = self.pos_embed
+        if self.no_embed_class:
+            # deit-3, updated JAX (big vision)
+            # position embedding does not overlap with class token, add then concat
+            x = x + pos_embed
+            x = torch.cat((
+                self.cls_token.expand(x.shape[0], -1, -1),
+                self.dist_token.expand(x.shape[0], -1, -1),
+                x),
+                dim=1)
+        else:
+            # original timm, JAX, and deit vit impl
+            # pos_embed has entry for class token, concat then add
+            x = torch.cat((
+                self.cls_token.expand(x.shape[0], -1, -1),
+                self.dist_token.expand(x.shape[0], -1, -1),
+                x),
+                dim=1)
+            x = x + pos_embed
+        return self.pos_drop(x)
 
     def forward_head(self, x, pre_logits: bool = False) -> torch.Tensor:
         x, x_dist = x[:, 0], x[:, 1]

timm/models/vision_transformer.py

@@ -459,11 +459,8 @@ def __init__(
 
         embed_args = {}
         if dynamic_size:
-            embed_args.update(dict(
-                strict_img_size=False,
-                flatten=False,  # flatten deferred until after pos embed
-                output_fmt='NHWC',
-            ))
+            # flatten deferred until after pos embed
+            embed_args.update(dict(strict_img_size=False, output_fmt='NHWC'))
         self.patch_embed = embed_layer(
             img_size=img_size,
             patch_size=patch_size,
@@ -559,7 +556,11 @@ def reset_classifier(self, num_classes: int, global_pool=None):
     def _pos_embed(self, x):
         if self.dynamic_size:
             B, H, W, C = x.shape
-            pos_embed = resample_abs_pos_embed(self.pos_embed, (H, W))
+            pos_embed = resample_abs_pos_embed(
+                self.pos_embed,
+                (H, W),
+                num_prefix_tokens=0 if self.no_embed_class else self.num_prefix_tokens,
+            )
             x = x.view(B, -1, C)
         else:
             pos_embed = self.pos_embed