""" Res2Net and Res2NeXt Adapted from Official Pytorch impl at: https://github.com/gasvn/Res2Net/ Paper: `Res2Net: A New Multi-scale Backbone Architecture` - https://arxiv.org/abs/1904.01169 """ import math import torch import torch.nn as nn from timm.data import IMAGENET_DEFAULT_MEAN, IMAGENET_DEFAULT_STD from ._builder import build_model_with_cfg from ._registry import register_model from .resnet import ResNet __all__ = [] def _cfg(url='', **kwargs): return { 'url': url, 'num_classes': 1000, 'input_size': (3, 224, 224), 'pool_size': (7, 7), 'crop_pct': 0.875, 'interpolation': 'bilinear', 'mean': IMAGENET_DEFAULT_MEAN, 'std': IMAGENET_DEFAULT_STD, 'first_conv': 'conv1', 'classifier': 'fc', **kwargs } default_cfgs = { 'res2net50_26w_4s': _cfg( url='https://github.com/rwightman/pytorch-image-models/releases/download/v0.1-res2net/res2net50_26w_4s-06e79181.pth'), 'res2net50_48w_2s': _cfg( url='https://github.com/rwightman/pytorch-image-models/releases/download/v0.1-res2net/res2net50_48w_2s-afed724a.pth'), 'res2net50_14w_8s': _cfg( url='https://github.com/rwightman/pytorch-image-models/releases/download/v0.1-res2net/res2net50_14w_8s-6527dddc.pth'), 'res2net50_26w_6s': _cfg( url='https://github.com/rwightman/pytorch-image-models/releases/download/v0.1-res2net/res2net50_26w_6s-19041792.pth'), 'res2net50_26w_8s': _cfg( url='https://github.com/rwightman/pytorch-image-models/releases/download/v0.1-res2net/res2net50_26w_8s-2c7c9f12.pth'), 'res2net101_26w_4s': _cfg( url='https://github.com/rwightman/pytorch-image-models/releases/download/v0.1-res2net/res2net101_26w_4s-02a759a1.pth'), 'res2next50': _cfg( url='https://github.com/rwightman/pytorch-image-models/releases/download/v0.1-res2net/res2next50_4s-6ef7e7bf.pth'), } class Bottle2neck(nn.Module): """ Res2Net/Res2NeXT Bottleneck Adapted from https://github.com/gasvn/Res2Net/blob/master/res2net.py """ expansion = 4 def __init__( self, inplanes, planes, stride=1, downsample=None, cardinality=1, base_width=26, scale=4, dilation=1, first_dilation=None, act_layer=nn.ReLU, norm_layer=None, attn_layer=None, **_, ): super(Bottle2neck, self).__init__() self.scale = scale self.is_first = stride > 1 or downsample is not None self.num_scales = max(1, scale - 1) width = int(math.floor(planes * (base_width / 64.0))) * cardinality self.width = width outplanes = planes * self.expansion first_dilation = first_dilation or dilation self.conv1 = nn.Conv2d(inplanes, width * scale, kernel_size=1, bias=False) self.bn1 = norm_layer(width * scale) convs = [] bns = [] for i in range(self.num_scales): convs.append(nn.Conv2d( width, width, kernel_size=3, stride=stride, padding=first_dilation, dilation=first_dilation, groups=cardinality, bias=False)) bns.append(norm_layer(width)) self.convs = nn.ModuleList(convs) self.bns = nn.ModuleList(bns) if self.is_first: # FIXME this should probably have count_include_pad=False, but hurts original weights self.pool = nn.AvgPool2d(kernel_size=3, stride=stride, padding=1) else: self.pool = None self.conv3 = nn.Conv2d(width * scale, outplanes, kernel_size=1, bias=False) self.bn3 = norm_layer(outplanes) self.se = attn_layer(outplanes) if attn_layer is not None else None self.relu = act_layer(inplace=True) self.downsample = downsample def zero_init_last(self): if getattr(self.bn3, 'weight', None) is not None: nn.init.zeros_(self.bn3.weight) def forward(self, x): shortcut = x out = self.conv1(x) out = self.bn1(out) out = self.relu(out) spx = torch.split(out, self.width, 1) spo = [] sp = spx[0] # redundant, for torchscript for i, (conv, bn) in enumerate(zip(self.convs, self.bns)): if i == 0 or self.is_first: sp = spx[i] else: sp = sp + spx[i] sp = conv(sp) sp = bn(sp) sp = self.relu(sp) spo.append(sp) if self.scale > 1: if self.pool is not None: # self.is_first == True, None check for torchscript spo.append(self.pool(spx[-1])) else: spo.append(spx[-1]) out = torch.cat(spo, 1) out = self.conv3(out) out = self.bn3(out) if self.se is not None: out = self.se(out) if self.downsample is not None: shortcut = self.downsample(x) out += shortcut out = self.relu(out) return out def _create_res2net(variant, pretrained=False, **kwargs): return build_model_with_cfg(ResNet, variant, pretrained, **kwargs) @register_model def res2net50_26w_4s(pretrained=False, **kwargs): """Constructs a Res2Net-50 26w4s model. Args: pretrained (bool): If True, returns a model pre-trained on ImageNet """ model_args = dict( block=Bottle2neck, layers=[3, 4, 6, 3], base_width=26, block_args=dict(scale=4)) return _create_res2net('res2net50_26w_4s', pretrained, **dict(model_args, **kwargs)) @register_model def res2net101_26w_4s(pretrained=False, **kwargs): """Constructs a Res2Net-101 26w4s model. Args: pretrained (bool): If True, returns a model pre-trained on ImageNet """ model_args = dict( block=Bottle2neck, layers=[3, 4, 23, 3], base_width=26, block_args=dict(scale=4)) return _create_res2net('res2net101_26w_4s', pretrained, **dict(model_args, **kwargs)) @register_model def res2net50_26w_6s(pretrained=False, **kwargs): """Constructs a Res2Net-50 26w6s model. Args: pretrained (bool): If True, returns a model pre-trained on ImageNet """ model_args = dict( block=Bottle2neck, layers=[3, 4, 6, 3], base_width=26, block_args=dict(scale=6)) return _create_res2net('res2net50_26w_6s', pretrained, **dict(model_args, **kwargs)) @register_model def res2net50_26w_8s(pretrained=False, **kwargs): """Constructs a Res2Net-50 26w8s model. Args: pretrained (bool): If True, returns a model pre-trained on ImageNet """ model_args = dict( block=Bottle2neck, layers=[3, 4, 6, 3], base_width=26, block_args=dict(scale=8)) return _create_res2net('res2net50_26w_8s', pretrained, **dict(model_args, **kwargs)) @register_model def res2net50_48w_2s(pretrained=False, **kwargs): """Constructs a Res2Net-50 48w2s model. Args: pretrained (bool): If True, returns a model pre-trained on ImageNet """ model_args = dict( block=Bottle2neck, layers=[3, 4, 6, 3], base_width=48, block_args=dict(scale=2)) return _create_res2net('res2net50_48w_2s', pretrained, **dict(model_args, **kwargs)) @register_model def res2net50_14w_8s(pretrained=False, **kwargs): """Constructs a Res2Net-50 14w8s model. Args: pretrained (bool): If True, returns a model pre-trained on ImageNet """ model_args = dict( block=Bottle2neck, layers=[3, 4, 6, 3], base_width=14, block_args=dict(scale=8)) return _create_res2net('res2net50_14w_8s', pretrained, **dict(model_args, **kwargs)) @register_model def res2next50(pretrained=False, **kwargs): """Construct Res2NeXt-50 4s Args: pretrained (bool): If True, returns a model pre-trained on ImageNet """ model_args = dict( block=Bottle2neck, layers=[3, 4, 6, 3], base_width=4, cardinality=8, block_args=dict(scale=4)) return _create_res2net('res2next50', pretrained, **dict(model_args, **kwargs))