remove patch size from T2TViT

README.md

@@ -130,7 +130,6 @@ from vit_pytorch.t2t import T2TViT
 v = T2TViT(
     dim = 512,
     image_size = 224,
-    patch_size = 16,
     depth = 5,
     heads = 8,
     mlp_dim = 512,

setup.py

@@ -3,7 +3,7 @@
 setup(
   name = 'vit-pytorch',
   packages = find_packages(exclude=['examples']),
-  version = '0.7.1',
+  version = '0.7.2',
   license='MIT',
   description = 'Vision Transformer (ViT) - Pytorch',
   author = 'Phil Wang',

vit_pytorch/t2t.py

@@ -9,6 +9,9 @@
 
 # classes
 
+def conv_output_size(image_size, kernel_size, stride, padding):
+    return int(((image_size - kernel_size + (2 * padding)) / stride) + 1)
+
 class RearrangeImage(nn.Module):
     def forward(self, x):
         return rearrange(x, 'b (h w) c -> b c h w', h = int(math.sqrt(x.shape[1])))
@@ -17,19 +20,18 @@ def forward(self, x):
 
 class T2TViT(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., t2t_layers = ((7, 4), (3, 2), (3, 2))):
+        self, *, image_size, num_classes, dim, depth, heads, mlp_dim, pool = 'cls', channels = 3, dim_head = 64, dropout = 0., emb_dropout = 0., t2t_layers = ((7, 4), (3, 2), (3, 2))):
         super().__init__()
-        assert image_size % patch_size == 0, 'Image dimensions must be divisible by the patch size.'
-        num_patches = (image_size // patch_size) ** 2
-        patch_dim = channels * patch_size ** 2
         assert pool in {'cls', 'mean'}, 'pool type must be either cls (cls token) or mean (mean pooling)'
 
         layers = []
         layer_dim = channels
+        output_image_size = image_size
 
         for i, (kernel_size, stride) in enumerate(t2t_layers):
             layer_dim *= kernel_size ** 2
             is_first = i == 0
+            output_image_size = conv_output_size(output_image_size, kernel_size, stride, stride // 2)
 
             layers.extend([
                 RearrangeImage() if not is_first else nn.Identity(),
@@ -41,7 +43,7 @@ def __init__(
         layers.append(nn.Linear(layer_dim, dim))
         self.to_patch_embedding = nn.Sequential(*layers)
 
-        self.pos_embedding = nn.Parameter(torch.randn(1, num_patches + 1, dim))
+        self.pos_embedding = nn.Parameter(torch.randn(1, output_image_size ** 2 + 1, dim))
         self.cls_token = nn.Parameter(torch.randn(1, 1, dim))
         self.dropout = nn.Dropout(emb_dropout)
 
@@ -61,7 +63,7 @@ def forward(self, img):
 
         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.pos_embedding
         x = self.dropout(x)
 
         x = self.transformer(x)