Revert "Revert "new arch for densenet: less pooling for height axis""

This reverts commit 8f41bdc4.

cnocr/symbols/densenet.py

@@ -140,8 +140,15 @@ class DenseNet(HybridBlock):
             # self.output = nn.Dense(classes)
 
     def hybrid_forward(self, F, x):
-        x = self.features(x)
-        # x = self.output(x)
+        """
+
+        :param F:
+        :param x: with shape (batch_size, channels, img_height, img_width)
+        :return: with shape (batch_size, embed_size, 1, img_width // 4)
+        """
+        x = self.features(x)  # res: (batch_size, embed_size, 2, img_width // 4)
+        x = F.reshape(x, (0, -3, 0))  # res: (batch_size, embed_size * 2, img_width // 4)
+        x = F.expand_dims(x, axis=2)  # res: (batch_size, embed_size * 2, 1, img_width // 4)
         return x
 
 
@@ -213,7 +220,10 @@ def _make_final_stage_net(stage_index, out_channels):
         features.add(nn.Conv2D(out_channels // 4, kernel_size=1, use_bias=False))
         features.add(nn.BatchNorm())
         features.add(nn.Activation('relu'))
-        features.add(nn.Conv2D(out_channels, kernel_size=(4, 1), use_bias=False))
+        features.add(
+            nn.Conv2D(out_channels, kernel_size=(2, 1), strides=(2, 1), use_bias=False)
+        )
         features.add(nn.BatchNorm())
         features.add(nn.Activation('relu'))
+        # features.add(nn.MaxPool2D(pool_size=(2, 1), strides=(2, 1)))
     return features