Add vit_base2_patch32_256 for a model between base_patch16 and patch3…

…2 with a slightly larger img size and width

timm/models/vision_transformer.py

@@ -109,6 +109,8 @@ def _cfg(url='', **kwargs):
     'vit_giant_patch14_224': _cfg(url=''),
     'vit_gigantic_patch14_224': _cfg(url=''),
 
+    'vit_base2_patch32_256': _cfg(url='', input_size=(3, 256, 256), crop_pct=0.95),
+
     # patch models, imagenet21k (weights from official Google JAX impl)
     'vit_tiny_patch16_224_in21k': _cfg(
         url='https://storage.googleapis.com/vit_models/augreg/Ti_16-i21k-300ep-lr_0.001-aug_none-wd_0.03-do_0.0-sd_0.0.npz',
@@ -202,6 +204,7 @@ def _cfg(url='', **kwargs):
 class Attention(nn.Module):
     def __init__(self, dim, num_heads=8, qkv_bias=False, attn_drop=0., proj_drop=0.):
         super().__init__()
+        assert dim % num_heads == 0, 'dim should be divisible by num_heads'
         self.num_heads = num_heads
         head_dim = dim // num_heads
         self.scale = head_dim ** -0.5
@@ -634,6 +637,16 @@ def vit_base_patch32_224(pretrained=False, **kwargs):
     return model
 
 
+@register_model
+def vit_base2_patch32_256(pretrained=False, **kwargs):
+    """ ViT-Base (ViT-B/32)
+    # FIXME experiment
+    """
+    model_kwargs = dict(patch_size=32, embed_dim=896, depth=12, num_heads=14, **kwargs)
+    model = _create_vision_transformer('vit_base2_patch32_256', pretrained=pretrained, **model_kwargs)
+    return model
+
+
 @register_model
 def vit_base_patch32_384(pretrained=False, **kwargs):
     """ ViT-Base model (ViT-B/32) from original paper (https://arxiv.org/abs/2010.11929).