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ppocr/modeling/heads/rec_ctc_head.py

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+# copyright (c) 2019 PaddlePaddle Authors. All Rights Reserve.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import math
+
+import paddle
+from paddle import ParamAttr, nn
+from paddle.nn import functional as F
+
+
+def get_para_bias_attr(l2_decay, k):
+    regularizer = paddle.regularizer.L2Decay(l2_decay)
+    stdv = 1.0 / math.sqrt(k * 1.0)
+    initializer = nn.initializer.Uniform(-stdv, stdv)
+    weight_attr = ParamAttr(regularizer=regularizer, initializer=initializer)
+    bias_attr = ParamAttr(regularizer=regularizer, initializer=initializer)
+    return [weight_attr, bias_attr]
+
+
+class CTCHead(nn.Layer):
+    def __init__(
+        self,
+        in_channels,
+        out_channels,
+        fc_decay=0.0004,
+        mid_channels=None,
+        return_feats=False,
+        **kwargs,
+    ):
+        super(CTCHead, self).__init__()
+        if mid_channels is None:
+            weight_attr, bias_attr = get_para_bias_attr(
+                l2_decay=fc_decay, k=in_channels
+            )
+            self.fc = nn.Linear(
+                in_channels, out_channels, weight_attr=weight_attr, bias_attr=bias_attr
+            )
+        else:
+            weight_attr1, bias_attr1 = get_para_bias_attr(
+                l2_decay=fc_decay, k=in_channels
+            )
+            self.fc1 = nn.Linear(
+                in_channels,
+                mid_channels,
+                weight_attr=weight_attr1,
+                bias_attr=bias_attr1,
+            )
+
+            weight_attr2, bias_attr2 = get_para_bias_attr(
+                l2_decay=fc_decay, k=mid_channels
+            )
+            self.fc2 = nn.Linear(
+                mid_channels,
+                out_channels,
+                weight_attr=weight_attr2,
+                bias_attr=bias_attr2,
+            )
+        self.out_channels = out_channels
+        self.mid_channels = mid_channels
+        self.return_feats = return_feats
+
+    def forward(self, x, targets=None):
+        if self.mid_channels is None:
+            predicts = self.fc(x)
+        else:
+            x = self.fc1(x)
+            predicts = self.fc2(x)
+
+        if self.return_feats:
+            result = (x, predicts)
+        else:
+            result = predicts
+        if not self.training:
+            predicts = F.softmax(predicts, axis=2)
+            result = predicts
+
+        return result