fix corner cases of static padding

Author: zylo117

efficientnet/utils_extra.py

@@ -33,13 +33,8 @@ def __init__(self, in_channels, out_channels, kernel_size, stride=1, bias=True,
     def forward(self, x):
         h, w = x.shape[-2:]
 
-        h_step = math.ceil(w / self.stride[1])
-        v_step = math.ceil(h / self.stride[0])
-        h_cover_len = self.stride[1] * (h_step - 1) + 1 + (self.kernel_size[1] - 1)
-        v_cover_len = self.stride[0] * (v_step - 1) + 1 + (self.kernel_size[0] - 1)
-
-        extra_h = h_cover_len - w
-        extra_v = v_cover_len - h
+        extra_h = (w - 1) * self.stride[1] - w + self.kernel_size[1]
+        extra_v = (h - 1) * self.stride[0] - h + self.kernel_size[0]
 
         left = extra_h // 2
         right = extra_h - left
@@ -77,13 +72,8 @@ def __init__(self, *args, **kwargs):
     def forward(self, x):
         h, w = x.shape[-2:]
 
-        h_step = math.ceil(w / self.stride[1])
-        v_step = math.ceil(h / self.stride[0])
-        h_cover_len = self.stride[1] * (h_step - 1) + 1 + (self.kernel_size[1] - 1)
-        v_cover_len = self.stride[0] * (v_step - 1) + 1 + (self.kernel_size[0] - 1)
-
-        extra_h = h_cover_len - w
-        extra_v = v_cover_len - h
+        extra_h = (w - 1) * self.stride[1] - w + self.kernel_size[1]
+        extra_v = (h - 1) * self.stride[0] - h + self.kernel_size[0]
 
         left = extra_h // 2
         right = extra_h - left