Merge pull request #2111 from jamesljlster/enhance_vit_get_intermediate_layers

Vision Transformer (ViT) get_intermediate_layers: enhanced to support dynamic image size and saved computational costs from unused blocks

Author: rwightman

timm/models/vision_transformer.py

@@ -635,13 +635,14 @@ def _intermediate_layers(
     ) -> List[torch.Tensor]:
         outputs, num_blocks = [], len(self.blocks)
         take_indices = set(range(num_blocks - n, num_blocks) if isinstance(n, int) else n)
+        last_index_to_take = max(take_indices)
 
         # forward pass
         x = self.patch_embed(x)
         x = self._pos_embed(x)
         x = self.patch_drop(x)
         x = self.norm_pre(x)
-        for i, blk in enumerate(self.blocks):
+        for i, blk in enumerate(self.blocks[: last_index_to_take + 1]):
             x = blk(x)
             if i in take_indices:
                 outputs.append(x)
@@ -667,9 +668,12 @@ def get_intermediate_layers(
         outputs = [out[:, self.num_prefix_tokens:] for out in outputs]
 
         if reshape:
-            grid_size = self.patch_embed.grid_size
+            patch_size = self.patch_embed.patch_size
+            batch, _, height, width = x.size()
             outputs = [
-                out.reshape(x.shape[0], grid_size[0], grid_size[1], -1).permute(0, 3, 1, 2).contiguous()
+                out.reshape(batch, int(math.ceil(height / patch_size[0])), int(math.ceil(width / patch_size[1])), -1)
+                .permute(0, 3, 1, 2)
+                .contiguous()
                 for out in outputs
             ]