module updates

models/common.py

 # This file contains modules common to various models
 
-
 from utils.utils import *
 
 
+def autopad(k):
+    # Pad to 'same'
+    return k // 2 if isinstance(k, int) else [x // 2 for x in k]  # auto-pad
+
+
 def DWConv(c1, c2, k=1, s=1, act=True):
     # Depthwise convolution
     return Conv(c1, c2, k, s, g=math.gcd(c1, c2), act=act)
@@ -11,10 +15,9 @@ def DWConv(c1, c2, k=1, s=1, act=True):
 
 class Conv(nn.Module):
     # Standard convolution
-    def __init__(self, c1, c2, k=1, s=1, g=1, act=True):  # ch_in, ch_out, kernel, stride, groups
+    def __init__(self, c1, c2, k=1, s=1, p=None, g=1, act=True):  # ch_in, ch_out, kernel, stride, padding, groups
         super(Conv, self).__init__()
-        p = k // 2 if isinstance(k, int) else [x // 2 for x in k]  # padding
-        self.conv = nn.Conv2d(c1, c2, k, s, p, groups=g, bias=False)
+        self.conv = nn.Conv2d(c1, c2, k, s, p or autopad(k), groups=g, bias=False)
         self.bn = nn.BatchNorm2d(c2)
         self.act = nn.LeakyReLU(0.1, inplace=True) if act else nn.Identity()
 
@@ -46,7 +49,7 @@ class BottleneckCSP(nn.Module):
         self.cv1 = Conv(c1, c_, 1, 1)
         self.cv2 = nn.Conv2d(c1, c_, 1, 1, bias=False)
         self.cv3 = nn.Conv2d(c_, c_, 1, 1, bias=False)
-        self.cv4 = Conv(c2, c2, 1, 1)
+        self.cv4 = Conv(2 * c_, c2, 1, 1)
         self.bn = nn.BatchNorm2d(2 * c_)  # applied to cat(cv2, cv3)
         self.act = nn.LeakyReLU(0.1, inplace=True)
         self.m = nn.Sequential(*[Bottleneck(c_, c_, shortcut, g, e=1.0) for _ in range(n)])
@@ -79,9 +82,9 @@ class Flatten(nn.Module):
 
 class Focus(nn.Module):
     # Focus wh information into c-space
-    def __init__(self, c1, c2, k=1):
+    def __init__(self, c1, c2, k=1, s=1, p=None, g=1, act=True):  # ch_in, ch_out, kernel, stride, padding, groups
         super(Focus, self).__init__()
-        self.conv = Conv(c1 * 4, c2, k, 1)
+        self.conv = Conv(c1 * 4, c2, k, s, p, g, act)
 
     def forward(self, x):  # x(b,c,w,h) -> y(b,4c,w/2,h/2)
         return self.conv(torch.cat([x[..., ::2, ::2], x[..., 1::2, ::2], x[..., ::2, 1::2], x[..., 1::2, 1::2]], 1))

models/experimental.py

+# This file contains experimental modules
+
 from models.common import *
 
 
+class CrossConv(nn.Module):
+    # Cross Convolution
+    def __init__(self, c1, c2, shortcut=True, g=1, e=0.5):  # ch_in, ch_out, shortcut, groups, expansion
+        super(CrossConv, self).__init__()
+        c_ = int(c2 * e)  # hidden channels
+        self.cv1 = Conv(c1, c_, (1, 3), 1)
+        self.cv2 = Conv(c_, c2, (3, 1), 1, g=g)
+        self.add = shortcut and c1 == c2
+
+    def forward(self, x):
+        return x + self.cv2(self.cv1(x)) if self.add else self.cv2(self.cv1(x))
+
+
+class C3(nn.Module):
+    # Cross Convolution CSP
+    def __init__(self, c1, c2, n=1, shortcut=True, g=1, e=0.5):  # ch_in, ch_out, number, shortcut, groups, expansion
+        super(C3, self).__init__()
+        c_ = int(c2 * e)  # hidden channels
+        self.cv1 = Conv(c1, c_, 1, 1)
+        self.cv2 = nn.Conv2d(c1, c_, 1, 1, bias=False)
+        self.cv3 = nn.Conv2d(c_, c_, 1, 1, bias=False)
+        self.cv4 = Conv(2 * c_, c2, 1, 1)
+        self.bn = nn.BatchNorm2d(2 * c_)  # applied to cat(cv2, cv3)
+        self.act = nn.LeakyReLU(0.1, inplace=True)
+        self.m = nn.Sequential(*[CrossConv(c_, c_, shortcut, g, e=1.0) for _ in range(n)])
+
+    def forward(self, x):
+        y1 = self.cv3(self.m(self.cv1(x)))
+        y2 = self.cv2(x)
+        return self.cv4(self.act(self.bn(torch.cat((y1, y2), dim=1))))
+
+
 class Sum(nn.Module):
     # Weighted sum of 2 or more layers https://arxiv.org/abs/1911.09070
     def __init__(self, n, weight=False):  # n: number of inputs