# copyright (c) 2022 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. # # Code was heavily based on https://github.com/Robert-JunWang/PeleeNet # reference: https://arxiv.org/pdf/1804.06882.pdf import math import paddle import paddle.nn as nn import paddle.nn.functional as F from paddle.nn.initializer import Normal, Constant from ....utils.save_load import load_dygraph_pretrain, load_dygraph_pretrain_from_url MODEL_URLS = { "PeleeNet": "" # TODO } __all__ = MODEL_URLS.keys() normal_ = lambda x, mean=0, std=1: Normal(mean, std)(x) constant_ = lambda x, value=0: Constant(value)(x) zeros_ = Constant(value=0.) ones_ = Constant(value=1.) class _DenseLayer(nn.Layer): def __init__(self, num_input_features, growth_rate, bottleneck_width, drop_rate): super(_DenseLayer, self).__init__() growth_rate = int(growth_rate / 2) inter_channel = int(growth_rate * bottleneck_width / 4) * 4 if inter_channel > num_input_features / 2: inter_channel = int(num_input_features / 8) * 4 print('adjust inter_channel to ', inter_channel) self.branch1a = BasicConv2D( num_input_features, inter_channel, kernel_size=1) self.branch1b = BasicConv2D( inter_channel, growth_rate, kernel_size=3, padding=1) self.branch2a = BasicConv2D( num_input_features, inter_channel, kernel_size=1) self.branch2b = BasicConv2D( inter_channel, growth_rate, kernel_size=3, padding=1) self.branch2c = BasicConv2D( growth_rate, growth_rate, kernel_size=3, padding=1) def forward(self, x): branch1 = self.branch1a(x) branch1 = self.branch1b(branch1) branch2 = self.branch2a(x) branch2 = self.branch2b(branch2) branch2 = self.branch2c(branch2) return paddle.concat([x, branch1, branch2], 1) class _DenseBlock(nn.Sequential): def __init__(self, num_layers, num_input_features, bn_size, growth_rate, drop_rate): super(_DenseBlock, self).__init__() for i in range(num_layers): layer = _DenseLayer(num_input_features + i * growth_rate, growth_rate, bn_size, drop_rate) setattr(self, 'denselayer%d' % (i + 1), layer) class _StemBlock(nn.Layer): def __init__(self, num_input_channels, num_init_features): super(_StemBlock, self).__init__() num_stem_features = int(num_init_features / 2) self.stem1 = BasicConv2D( num_input_channels, num_init_features, kernel_size=3, stride=2, padding=1) self.stem2a = BasicConv2D( num_init_features, num_stem_features, kernel_size=1, stride=1, padding=0) self.stem2b = BasicConv2D( num_stem_features, num_init_features, kernel_size=3, stride=2, padding=1) self.stem3 = BasicConv2D( 2 * num_init_features, num_init_features, kernel_size=1, stride=1, padding=0) self.pool = nn.MaxPool2D(kernel_size=2, stride=2) def forward(self, x): out = self.stem1(x) branch2 = self.stem2a(out) branch2 = self.stem2b(branch2) branch1 = self.pool(out) out = paddle.concat([branch1, branch2], 1) out = self.stem3(out) return out class BasicConv2D(nn.Layer): def __init__(self, in_channels, out_channels, activation=True, **kwargs): super(BasicConv2D, self).__init__() self.conv = nn.Conv2D( in_channels, out_channels, bias_attr=False, **kwargs) self.norm = nn.BatchNorm2D(out_channels) self.activation = activation def forward(self, x): x = self.conv(x) x = self.norm(x) if self.activation: return F.relu(x) else: return x class PeleeNetDY(nn.Layer): r"""PeleeNet model class, based on `"Densely Connected Convolutional Networks" and "Pelee: A Real-Time Object Detection System on Mobile Devices" ` Args: growth_rate (int or list of 4 ints) - how many filters to add each layer (`k` in paper) block_config (list of 4 ints) - how many layers in each pooling block num_init_features (int) - the number of filters to learn in the first convolution layer bottleneck_width (int or list of 4 ints) - multiplicative factor for number of bottle neck layers (i.e. bn_size * k features in the bottleneck layer) drop_rate (float) - dropout rate after each dense layer class_num (int) - number of classification classes """ def __init__(self, growth_rate=32, block_config=[3, 4, 8, 6], num_init_features=32, bottleneck_width=[1, 2, 4, 4], drop_rate=0.05, class_num=1000): super(PeleeNetDY, self).__init__() self.features = nn.Sequential(* [('stemblock', _StemBlock( 3, num_init_features)), ]) if type(growth_rate) is list: growth_rates = growth_rate assert len(growth_rates) == 4, \ 'The growth rate must be the list and the size must be 4' else: growth_rates = [growth_rate] * 4 if type(bottleneck_width) is list: bottleneck_widths = bottleneck_width assert len(bottleneck_widths) == 4, \ 'The bottleneck width must be the list and the size must be 4' else: bottleneck_widths = [bottleneck_width] * 4 # Each denseblock num_features = num_init_features for i, num_layers in enumerate(block_config): block = _DenseBlock( num_layers=num_layers, num_input_features=num_features, bn_size=bottleneck_widths[i], growth_rate=growth_rates[i], drop_rate=drop_rate) setattr(self.features, 'denseblock%d' % (i + 1), block) num_features = num_features + num_layers * growth_rates[i] setattr( self.features, 'transition%d' % (i + 1), BasicConv2D( num_features, num_features, kernel_size=1, stride=1, padding=0)) if i != len(block_config) - 1: setattr( self.features, 'transition%d_pool' % (i + 1), nn.AvgPool2D( kernel_size=2, stride=2)) num_features = num_features # Linear layer self.classifier = nn.Linear(num_features, class_num) self.drop_rate = drop_rate self.apply(self._initialize_weights) def forward(self, x): features = self.features(x) out = F.avg_pool2d( features, kernel_size=features.shape[2:4]).flatten(1) if self.drop_rate > 0: out = F.dropout(out, p=self.drop_rate, training=self.training) out = self.classifier(out) return out def _initialize_weights(self, m): if isinstance(m, nn.Conv2D): n = m._kernel_size[0] * m._kernel_size[1] * m._out_channels normal_(m.weight, std=math.sqrt(2. / n)) if m.bias is not None: zeros_(m.bias) elif isinstance(m, nn.BatchNorm2D): ones_(m.weight) zeros_(m.bias) elif isinstance(m, nn.Linear): normal_(m.weight, std=0.01) zeros_(m.bias) def _load_pretrained(pretrained, model, model_url, use_ssld): if pretrained is False: pass elif pretrained is True: load_dygraph_pretrain_from_url(model, model_url, use_ssld=use_ssld) elif isinstance(pretrained, str): load_dygraph_pretrain(model, pretrained) else: raise RuntimeError( "pretrained type is not available. Please use `string` or `boolean` type." ) def PeleeNet(pretrained=False, use_ssld=False, **kwargs): model = PeleeNetDY(**kwargs) _load_pretrained(pretrained, model, MODEL_URLS["PeleeNet"], use_ssld) return model