参考:
 https://aistudio.baidu.com/projectdetail/4483048
Real-Time Scene Text Detection with Differentiable Binarization
如何读论文-by 李沐
DB (Real-Time Scene Text Detection with Differentiable Binarization)
原理
DB是一个基于分割的文本检测算法,其提出的可微分阈值,采用动态的阈值区分文本区域与背景
 
 基于分割的普通文本检测算法,流程如上图蓝色箭头所示,得到分割结果后采用固定的阈值(标准二值化不可微,导致网络无法端到端训练)得到二值化的分割图,之后采用诸如像素聚类的启发式算法得到文本区域。
DB算法的流程如图中红色箭头所示,最大的不同在于DB有一个阈值图,通过网络去预测图片每个位置处的阈值,而不是采用一个固定的值,更好的分离文本背景与前景。
优势:
 1.算法结构简单,无需繁琐的后处理
 2.开源数据上拥有良好的精度和性能
DB算法提出了可微二值化,可微二值化将标准二值化中的阶跃函数进行了近似,使用如下公式进行代替:

 
 DB算法整体结构:
 
 输入的图像经过网络Backbone和FPN提取特征,提取后的特征级联在一起,得到原图四分之一大小的特征,然后利用卷积层分别得到文本区域预测概率图和阈值图,进而通过DB的后处理得到文本包围曲线。
DB文本检测模型构建
DB文本检测模型可以分为三个部分:
Backbone网络,负责提取图像的特征
 FPN网络,特征金字塔结构增强特征
 Head网络,计算文本区域概率图
backbone网络:论文中使用了ResNet50,本节实验中,为了加快训练速度,采用MobileNetV3 large结构作为backbone。
DB的Backbone用于提取图像的多尺度特征,如下代码所示,假设输入的形状为[640, 640],backbone网络的输出有四个特征,其形状分别是 [1, 16, 160, 160],[1, 24, 80, 80], [1, 56, 40, 40],[1, 480, 20, 20]。 这些特征将输入给特征金字塔FPN网络进一步的增强特征。
import paddle 
from ppocr.modeling.backbones.det_mobilenet_v3 import MobileNetV3
fake_inputs = paddle.randn([1, 3, 640, 640], dtype="float32")
# 1. 声明Backbone
model_backbone = MobileNetV3()
model_backbone.eval()
# 2. 执行预测
outs = model_backbone(fake_inputs)
# 3. 打印网络结构
# print(model_backbone)
# 4. 打印输出特征形状
for idx, out in enumerate(outs):
    print("The index is ", idx, "and the shape of output is ", out.shape)
FPN网络
特征金字塔结构FPN是一种卷积网络来高效提取图片中各维度特征的常用方法。
 FPN网络的输入为Backbone部分的输出,输出特征图的高度和宽度为原图的四分之一。假设输入图像的形状为[1, 3, 640, 640],FPN输出特征的高度和宽度为[160, 160]
 import paddle
from paddle import nn
import paddle.nn.functional as F
from paddle import ParamAttr
class DBFPN(nn.Layer):
    def __init__(self, in_channels, out_channels, **kwargs):
        super(DBFPN, self).__init__()
        self.out_channels = out_channels
        # DBFPN详细实现参考: https://github.com/PaddlePaddle/PaddleOCRblob/release%2F2.4/ppocr/modeling/necks/db_fpn.py
    def forward(self, x):
        c2, c3, c4, c5 = x
        in5 = self.in5_conv(c5)
        in4 = self.in4_conv(c4)
        in3 = self.in3_conv(c3)
        in2 = self.in2_conv(c2)
        # 特征上采样
        out4 = in4 + F.upsample(
            in5, scale_factor=2, mode="nearest", align_mode=1)  # 1/16
        out3 = in3 + F.upsample(
            out4, scale_factor=2, mode="nearest", align_mode=1)  # 1/8
        out2 = in2 + F.upsample(
            out3, scale_factor=2, mode="nearest", align_mode=1)  # 1/4
        p5 = self.p5_conv(in5)
        p4 = self.p4_conv(out4)
        p3 = self.p3_conv(out3)
        p2 = self.p2_conv(out2)
        # 特征上采样
        p5 = F.upsample(p5, scale_factor=8, mode="nearest", align_mode=1)
        p4 = F.upsample(p4, scale_factor=4, mode="nearest", align_mode=1)
        p3 = F.upsample(p3, scale_factor=2, mode="nearest", align_mode=1)
        fuse = paddle.concat([p5, p4, p3, p2], axis=1)
        return fuse
Head网络
计算文本区域概率图,文本区域阈值图以及文本区域二值图。
 DB Head网络会在FPN特征的基础上作上采样,将FPN特征由原图的四分之一大小映射到原图大小。
import math
import paddle
from paddle import nn
import paddle.nn.functional as F
from paddle import ParamAttr
class DBHead(nn.Layer):
    """
    Differentiable Binarization (DB) for text detection:
        see https://arxiv.org/abs/1911.08947
    args:
        params(dict): super parameters for build DB network
    """
    def __init__(self, in_channels, k=50, **kwargs):
        super(DBHead, self).__init__()
        self.k = k
        # DBHead详细实现参考 https://github.com/PaddlePaddle/PaddleOCR/blob/release%2F2.4/ppocr/modeling/heads/det_db_head.py
    def step_function(self, x, y):
        # 可微二值化实现,通过概率图和阈值图计算文本分割二值图
        return paddle.reciprocal(1 + paddle.exp(-self.k * (x - y)))
    def forward(self, x, targets=None):
        shrink_maps = self.binarize(x)
        if not self.training:
            return {'maps': shrink_maps}
        threshold_maps = self.thresh(x)
        binary_maps = self.step_function(shrink_maps, threshold_maps)
        y = paddle.concat([shrink_maps, threshold_maps, binary_maps], axis=1)
        return {'maps': y}
# 1. 从PaddleOCR中imort DBHead
from ppocr.modeling.heads.det_db_head import DBHead
import paddle 
# 2. 计算DBFPN网络输出结果
fake_inputs = paddle.randn([1, 3, 640, 640], dtype="float32")
model_backbone = MobileNetV3()
in_channles = model_backbone.out_channels
model_fpn = DBFPN(in_channels=in_channles, out_channels=256)
outs = model_backbone(fake_inputs)
fpn_outs = model_fpn(outs)
# 3. 声明Head网络
model_db_head = DBHead(in_channels=256)
# 4. 打印DBhead网络
print(model_db_head)
# 5. 计算Head网络的输出
db_head_outs = model_db_head(fpn_outs)
print(f"The shape of fpn outs {fpn_outs.shape}")
print(f"The shape of DB head outs {db_head_outs['maps'].shape}")

运行后发现报错:
 类不完整,于是重新到github paddle ocr目录下下载相应文件
 db_fpn.py
 det_db_head.py
完整代码:
# from paddle import nn
# 
# import paddle
# from paddle import nn
# import paddle.nn.functional as F
# from paddle import ParamAttr
# 
# import math
# import paddle
# from paddle import nn
# import paddle.nn.functional as F
# from paddle import ParamAttr
# 
# # import paddle
# # from ppocr.modeling.backbones.det_mobilenet_v3 import MobileNetV3
import math
import paddle
from paddle import nn
import paddle.nn.functional as F
from paddle import ParamAttr
def make_divisible(v, divisor=8, min_value=None):
    if min_value is None:
        min_value = divisor
    new_v = max(min_value, int(v + divisor / 2) // divisor * divisor)
    if new_v < 0.9 * v:
        new_v += divisor
    return new_v
class MobileNetV3(nn.Layer):
    def __init__(self,
                 in_channels=3,
                 model_name='large',
                 scale=0.5,
                 disable_se=False,
                 **kwargs):
        """
        the MobilenetV3 backbone network for detection module.
        Args:
            params(dict): the super parameters for build network
        """
        super(MobileNetV3, self).__init__()
        self.disable_se = disable_se
        if model_name == "large":
            cfg = [
                # k, exp, c,  se,     nl,  s,
                [3, 16, 16, False, 'relu', 1],
                [3, 64, 24, False, 'relu', 2],
                [3, 72, 24, False, 'relu', 1],
                [5, 72, 40, True, 'relu', 2],
                [5, 120, 40, True, 'relu', 1],
                [5, 120, 40, True, 'relu', 1],
                [3, 240, 80, False, 'hardswish', 2],
                [3, 200, 80, False, 'hardswish', 1],
                [3, 184, 80, False, 'hardswish', 1],
                [3, 184, 80, False, 'hardswish', 1],
                [3, 480, 112, True, 'hardswish', 1],
                [3, 672, 112, True, 'hardswish', 1],
                [5, 672, 160, True, 'hardswish', 2],
                [5, 960, 160, True, 'hardswish', 1],
                [5, 960, 160, True, 'hardswish', 1],
            ]
            cls_ch_squeeze = 960
        elif model_name == "small":
            cfg = [
                # k, exp, c,  se,     nl,  s,
                [3, 16, 16, True, 'relu', 2],
                [3, 72, 24, False, 'relu', 2],
                [3, 88, 24, False, 'relu', 1],
                [5, 96, 40, True, 'hardswish', 2],
                [5, 240, 40, True, 'hardswish', 1],
                [5, 240, 40, True, 'hardswish', 1],
                [5, 120, 48, True, 'hardswish', 1],
                [5, 144, 48, True, 'hardswish', 1],
                [5, 288, 96, True, 'hardswish', 2],
                [5, 576, 96, True, 'hardswish', 1],
                [5, 576, 96, True, 'hardswish', 1],
            ]
            cls_ch_squeeze = 576
        else:
            raise NotImplementedError("mode[" + model_name +
                                      "_model] is not implemented!")
        supported_scale = [0.35, 0.5, 0.75, 1.0, 1.25]
        assert scale in supported_scale, \
            "supported scale are {} but input scale is {}".format(supported_scale, scale)
        inplanes = 16
        # conv1
        self.conv = ConvBNLayer(
            in_channels=in_channels,
            out_channels=make_divisible(inplanes * scale),
            kernel_size=3,
            stride=2,
            padding=1,
            groups=1,
            if_act=True,
            act='hardswish')
        self.stages = []
        self.out_channels = []
        block_list = []
        i = 0
        inplanes = make_divisible(inplanes * scale)
        for (k, exp, c, se, nl, s) in cfg:
            se = se and not self.disable_se
            start_idx = 2 if model_name == 'large' else 0
            if s == 2 and i > start_idx:
                self.out_channels.append(inplanes)
                self.stages.append(nn.Sequential(*block_list))
                block_list = []
            block_list.append(
                ResidualUnit(
                    in_channels=inplanes,
                    mid_channels=make_divisible(scale * exp),
                    out_channels=make_divisible(scale * c),
                    kernel_size=k,
                    stride=s,
                    use_se=se,
                    act=nl))
            inplanes = make_divisible(scale * c)
            i += 1
        block_list.append(
            ConvBNLayer(
                in_channels=inplanes,
                out_channels=make_divisible(scale * cls_ch_squeeze),
                kernel_size=1,
                stride=1,
                padding=0,
                groups=1,
                if_act=True,
                act='hardswish'))
        self.stages.append(nn.Sequential(*block_list))
        self.out_channels.append(make_divisible(scale * cls_ch_squeeze))
        for i, stage in enumerate(self.stages):
            self.add_sublayer(sublayer=stage, name="stage{}".format(i))
    def forward(self, x):
        x = self.conv(x)
        out_list = []
        for stage in self.stages:
            x = stage(x)
            out_list.append(x)
        return out_list
class ConvBNLayer(nn.Layer):
    def __init__(self,
                 in_channels,
                 out_channels,
                 kernel_size,
                 stride,
                 padding,
                 groups=1,
                 if_act=True,
                 act=None):
        super(ConvBNLayer, self).__init__()
        self.if_act = if_act
        self.act = act
        self.conv = nn.Conv2D(
            in_channels=in_channels,
            out_channels=out_channels,
            kernel_size=kernel_size,
            stride=stride,
            padding=padding,
            groups=groups,
            bias_attr=False)
        self.bn = nn.BatchNorm(num_channels=out_channels, act=None)
    def forward(self, x):
        x = self.conv(x)
        x = self.bn(x)
        if self.if_act:
            if self.act == "relu":
                x = F.relu(x)
            elif self.act == "hardswish":
                x = F.hardswish(x)
            else:
                print("The activation function({}) is selected incorrectly.".
                      format(self.act))
                exit()
        return x
class ResidualUnit(nn.Layer):
    def __init__(self,
                 in_channels,
                 mid_channels,
                 out_channels,
                 kernel_size,
                 stride,
                 use_se,
                 act=None):
        super(ResidualUnit, self).__init__()
        self.if_shortcut = stride == 1 and in_channels == out_channels
        self.if_se = use_se
        self.expand_conv = ConvBNLayer(
            in_channels=in_channels,
            out_channels=mid_channels,
            kernel_size=1,
            stride=1,
            padding=0,
            if_act=True,
            act=act)
        self.bottleneck_conv = ConvBNLayer(
            in_channels=mid_channels,
            out_channels=mid_channels,
            kernel_size=kernel_size,
            stride=stride,
            padding=int((kernel_size - 1) // 2),
            groups=mid_channels,
            if_act=True,
            act=act)
        if self.if_se:
            self.mid_se = SEModule(mid_channels)
        self.linear_conv = ConvBNLayer(
            in_channels=mid_channels,
            out_channels=out_channels,
            kernel_size=1,
            stride=1,
            padding=0,
            if_act=False,
            act=None)
    def forward(self, inputs):
        x = self.expand_conv(inputs)
        x = self.bottleneck_conv(x)
        if self.if_se:
            x = self.mid_se(x)
        x = self.linear_conv(x)
        if self.if_shortcut:
            x = paddle.add(inputs, x)
        return x
class SEModule(nn.Layer):
    def __init__(self, in_channels, reduction=4):
        super(SEModule, self).__init__()
        self.avg_pool = nn.AdaptiveAvgPool2D(1)
        self.conv1 = nn.Conv2D(
            in_channels=in_channels,
            out_channels=in_channels // reduction,
            kernel_size=1,
            stride=1,
            padding=0)
        self.conv2 = nn.Conv2D(
            in_channels=in_channels // reduction,
            out_channels=in_channels,
            kernel_size=1,
            stride=1,
            padding=0)
    def forward(self, inputs):
        outputs = self.avg_pool(inputs)
        outputs = self.conv1(outputs)
        outputs = F.relu(outputs)
        outputs = self.conv2(outputs)
        outputs = F.hardsigmoid(outputs, slope=0.2, offset=0.5)
        return inputs * outputs
class DBFPN(nn.Layer):
    def __init__(self, in_channels, out_channels, **kwargs):
        super(DBFPN, self).__init__()
        self.out_channels = out_channels
        weight_attr = paddle.nn.initializer.KaimingUniform()
        self.in2_conv = nn.Conv2D(
            in_channels=in_channels[0],
            out_channels=self.out_channels,
            kernel_size=1,
            weight_attr=ParamAttr(initializer=weight_attr),
            bias_attr=False)
        self.in3_conv = nn.Conv2D(
            in_channels=in_channels[1],
            out_channels=self.out_channels,
            kernel_size=1,
            weight_attr=ParamAttr(initializer=weight_attr),
            bias_attr=False)
        self.in4_conv = nn.Conv2D(
            in_channels=in_channels[2],
            out_channels=self.out_channels,
            kernel_size=1,
            weight_attr=ParamAttr(initializer=weight_attr),
            bias_attr=False)
        self.in5_conv = nn.Conv2D(
            in_channels=in_channels[3],
            out_channels=self.out_channels,
            kernel_size=1,
            weight_attr=ParamAttr(initializer=weight_attr),
            bias_attr=False)
        self.p5_conv = nn.Conv2D(
            in_channels=self.out_channels,
            out_channels=self.out_channels // 4,
            kernel_size=3,
            padding=1,
            weight_attr=ParamAttr(initializer=weight_attr),
            bias_attr=False)
        self.p4_conv = nn.Conv2D(
            in_channels=self.out_channels,
            out_channels=self.out_channels // 4,
            kernel_size=3,
            padding=1,
            weight_attr=ParamAttr(initializer=weight_attr),
            bias_attr=False)
        self.p3_conv = nn.Conv2D(
            in_channels=self.out_channels,
            out_channels=self.out_channels // 4,
            kernel_size=3,
            padding=1,
            weight_attr=ParamAttr(initializer=weight_attr),
            bias_attr=False)
        self.p2_conv = nn.Conv2D(
            in_channels=self.out_channels,
            out_channels=self.out_channels // 4,
            kernel_size=3,
            padding=1,
            weight_attr=ParamAttr(initializer=weight_attr),
            bias_attr=False)
    def forward(self, x):
        c2, c3, c4, c5 = x
        in5 = self.in5_conv(c5)
        in4 = self.in4_conv(c4)
        in3 = self.in3_conv(c3)
        in2 = self.in2_conv(c2)
        out4 = in4 + F.upsample(
            in5, scale_factor=2, mode="nearest", align_mode=1)  # 1/16
        out3 = in3 + F.upsample(
            out4, scale_factor=2, mode="nearest", align_mode=1)  # 1/8
        out2 = in2 + F.upsample(
            out3, scale_factor=2, mode="nearest", align_mode=1)  # 1/4
        p5 = self.p5_conv(in5)
        p4 = self.p4_conv(out4)
        p3 = self.p3_conv(out3)
        p2 = self.p2_conv(out2)
        p5 = F.upsample(p5, scale_factor=8, mode="nearest", align_mode=1)
        p4 = F.upsample(p4, scale_factor=4, mode="nearest", align_mode=1)
        p3 = F.upsample(p3, scale_factor=2, mode="nearest", align_mode=1)
        fuse = paddle.concat([p5, p4, p3, p2], axis=1)
        return fuse
# class DBFPN(nn.Layer):
#     def __init__(self, in_channels, out_channels, **kwargs):
#         super(DBFPN, self).__init__()
#         self.out_channels = out_channels
#
#         # DBFPN详细实现参考: https://github.com/PaddlePaddle/PaddleOCRblob/release%2F2.4/ppocr/modeling/necks/db_fpn.py
#
#     def forward(self, x):
#         c2, c3, c4, c5 = x
#
#         in5 = self.in5_conv(c5)
#         in4 = self.in4_conv(c4)
#         in3 = self.in3_conv(c3)
#         in2 = self.in2_conv(c2)
#
#         # 特征上采样
#         out4 = in4 + F.upsample(
#             in5, scale_factor=2, mode="nearest", align_mode=1)  # 1/16
#         out3 = in3 + F.upsample(
#             out4, scale_factor=2, mode="nearest", align_mode=1)  # 1/8
#         out2 = in2 + F.upsample(
#             out3, scale_factor=2, mode="nearest", align_mode=1)  # 1/4
#
#         p5 = self.p5_conv(in5)
#         p4 = self.p4_conv(out4)
#         p3 = self.p3_conv(out3)
#         p2 = self.p2_conv(out2)
#
#         # 特征上采样
#         p5 = F.upsample(p5, scale_factor=8, mode="nearest", align_mode=1)
#         p4 = F.upsample(p4, scale_factor=4, mode="nearest", align_mode=1)
#         p3 = F.upsample(p3, scale_factor=2, mode="nearest", align_mode=1)
#
#         fuse = paddle.concat([p5, p4, p3, p2], axis=1)
#         return fuse
def get_bias_attr(k):
    stdv = 1.0 / math.sqrt(k * 1.0)
    initializer = paddle.nn.initializer.Uniform(-stdv, stdv)
    bias_attr = ParamAttr(initializer=initializer)
    return bias_attr
class Head(nn.Layer):
    def __init__(self, in_channels, name_list):
        super(Head, self).__init__()
        self.conv1 = nn.Conv2D(
            in_channels=in_channels,
            out_channels=in_channels // 4,
            kernel_size=3,
            padding=1,
            weight_attr=ParamAttr(),
            bias_attr=False)
        self.conv_bn1 = nn.BatchNorm(
            num_channels=in_channels // 4,
            param_attr=ParamAttr(
                initializer=paddle.nn.initializer.Constant(value=1.0)),
            bias_attr=ParamAttr(
                initializer=paddle.nn.initializer.Constant(value=1e-4)),
            act='relu')
        self.conv2 = nn.Conv2DTranspose(
            in_channels=in_channels // 4,
            out_channels=in_channels // 4,
            kernel_size=2,
            stride=2,
            weight_attr=ParamAttr(
                initializer=paddle.nn.initializer.KaimingUniform()),
            bias_attr=get_bias_attr(in_channels // 4))
        self.conv_bn2 = nn.BatchNorm(
            num_channels=in_channels // 4,
            param_attr=ParamAttr(
                initializer=paddle.nn.initializer.Constant(value=1.0)),
            bias_attr=ParamAttr(
                initializer=paddle.nn.initializer.Constant(value=1e-4)),
            act="relu")
        self.conv3 = nn.Conv2DTranspose(
            in_channels=in_channels // 4,
            out_channels=1,
            kernel_size=2,
            stride=2,
            weight_attr=ParamAttr(
                initializer=paddle.nn.initializer.KaimingUniform()),
            bias_attr=get_bias_attr(in_channels // 4), )
    def forward(self, x):
        x = self.conv1(x)
        x = self.conv_bn1(x)
        x = self.conv2(x)
        x = self.conv_bn2(x)
        x = self.conv3(x)
        x = F.sigmoid(x)
        return x
class DBHead(nn.Layer):
    """
    Differentiable Binarization (DB) for text detection:
        see https://arxiv.org/abs/1911.08947
    args:
        params(dict): super parameters for build DB network
    """
    def __init__(self, in_channels, k=50, **kwargs):
        super(DBHead, self).__init__()
        self.k = k
        binarize_name_list = [
            'conv2d_56', 'batch_norm_47', 'conv2d_transpose_0', 'batch_norm_48',
            'conv2d_transpose_1', 'binarize'
        ]
        thresh_name_list = [
            'conv2d_57', 'batch_norm_49', 'conv2d_transpose_2', 'batch_norm_50',
            'conv2d_transpose_3', 'thresh'
        ]
        self.binarize = Head(in_channels, binarize_name_list)
        self.thresh = Head(in_channels, thresh_name_list)
    def step_function(self, x, y):
        return paddle.reciprocal(1 + paddle.exp(-self.k * (x - y)))
    def forward(self, x, targets=None):
        shrink_maps = self.binarize(x)
        if not self.training:
            return {'maps': shrink_maps}
        threshold_maps = self.thresh(x)
        binary_maps = self.step_function(shrink_maps, threshold_maps)
        y = paddle.concat([shrink_maps, threshold_maps, binary_maps], axis=1)
        return {'maps': y}
# class DBHead(nn.Layer):
#     """
#     Differentiable Binarization (DB) for text detection:
#         see https://arxiv.org/abs/1911.08947
#     args:
#         params(dict): super parameters for build DB network
#     """
#
#     def __init__(self, in_channels, k=50, **kwargs):
#         super(DBHead, self).__init__()
#         self.k = k
#
#         # DBHead详细实现参考 https://github.com/PaddlePaddle/PaddleOCR/blob/release%2F2.4/ppocr/modeling/heads/det_db_head.py
#
#     def step_function(self, x, y):
#         # 可微二值化实现,通过概率图和阈值图计算文本分割二值图
#         return paddle.reciprocal(1 + paddle.exp(-self.k * (x - y)))
#
#     def forward(self, x, targets=None):
#         shrink_maps = self.binarize(x)
#         if not self.training:
#             return {'maps': shrink_maps}
#
#         threshold_maps = self.thresh(x)
#         binary_maps = self.step_function(shrink_maps, threshold_maps)
#         y = paddle.concat([shrink_maps, threshold_maps, binary_maps], axis=1)
#         return {'maps': y}
if __name__=='__main__':
    fake_inputs = paddle.randn([1, 3, 640, 640], dtype="float32")
    #   声明Backbone
    model_backbone = MobileNetV3()
    # model_backbone.eval()
    # # 2. 执行预测
    # outs = model_backbone(fake_inputs)
    # # 3. 打印网络结构
    # # print(model_backbone)
    #
    # # 4. 打印输出特征形状
    # for idx, out in enumerate(outs):
    #     print("The index is ", idx, "and the shape of output is ", out.shape)
    # The index is  0 and the shape of output is  [1, 16, 160, 160]
    # The index is  1 and the shape of output is  [1, 24, 80, 80]
    # The index is  2 and the shape of output is  [1, 56, 40, 40]
    # The index is  3 and the shape of output is  [1, 480, 20, 20]
    in_channles = model_backbone.out_channels
    # 声明FPN网络
    model_fpn = DBFPN(in_channels=in_channles, out_channels=256)
    #  打印FPN网络
    print(model_fpn)
    # DBFPN(
    #   (in2_conv): Conv2D(16, 256, kernel_size=[1, 1], data_format=NCHW)
    #   (in3_conv): Conv2D(24, 256, kernel_size=[1, 1], data_format=NCHW)
    #   (in4_conv): Conv2D(56, 256, kernel_size=[1, 1], data_format=NCHW)
    #   (in5_conv): Conv2D(480, 256, kernel_size=[1, 1], data_format=NCHW)
    #   (p5_conv): Conv2D(256, 64, kernel_size=[3, 3], padding=1, data_format=NCHW)
    #   (p4_conv): Conv2D(256, 64, kernel_size=[3, 3], padding=1, data_format=NCHW)
    #   (p3_conv): Conv2D(256, 64, kernel_size=[3, 3], padding=1, data_format=NCHW)
    #   (p2_conv): Conv2D(256, 64, kernel_size=[3, 3], padding=1, data_format=NCHW)
    # )
    # 5. 计算得到FPN结果输出
    outs = model_backbone(fake_inputs)
    fpn_outs = model_fpn(outs)
    # The shape of fpn outs [1, 256, 160, 160]
    # 3. 声明Head网络
    model_db_head = DBHead(in_channels=256)
    # 4. 打印DBhead网络
    print(model_db_head)
    # DBHead(
    #   (binarize): Head(
    #     (conv1): Conv2D(256, 64, kernel_size=[3, 3], padding=1, data_format=NCHW)
    #     (conv_bn1): BatchNorm()
    #     (conv2): Conv2DTranspose(64, 64, kernel_size=[2, 2], stride=[2, 2], data_format=NCHW)
    #     (conv_bn2): BatchNorm()
    #     (conv3): Conv2DTranspose(64, 1, kernel_size=[2, 2], stride=[2, 2], data_format=NCHW)
    #   )
    #   (thresh): Head(
    #     (conv1): Conv2D(256, 64, kernel_size=[3, 3], padding=1, data_format=NCHW)
    #     (conv_bn1): BatchNorm()
    #     (conv2): Conv2DTranspose(64, 64, kernel_size=[2, 2], stride=[2, 2], data_format=NCHW)
    #     (conv_bn2): BatchNorm()
    #     (conv3): Conv2DTranspose(64, 1, kernel_size=[2, 2], stride=[2, 2], data_format=NCHW)
    #   )
    # )
    # 5. 计算Head网络的输出
    db_head_outs = model_db_head(fpn_outs)
    print(f"The shape of fpn outs {fpn_outs.shape}")
    # The shape of fpn outs [1, 256, 160, 160]
    print(f"The shape of DB head outs {db_head_outs['maps'].shape}")
    # The shape of DB head outs [1, 3, 640, 640]
结果:
DBFPN(
  (in2_conv): Conv2D(16, 256, kernel_size=[1, 1], data_format=NCHW)
  (in3_conv): Conv2D(24, 256, kernel_size=[1, 1], data_format=NCHW)
  (in4_conv): Conv2D(56, 256, kernel_size=[1, 1], data_format=NCHW)
  (in5_conv): Conv2D(480, 256, kernel_size=[1, 1], data_format=NCHW)
  (p5_conv): Conv2D(256, 64, kernel_size=[3, 3], padding=1, data_format=NCHW)
  (p4_conv): Conv2D(256, 64, kernel_size=[3, 3], padding=1, data_format=NCHW)
  (p3_conv): Conv2D(256, 64, kernel_size=[3, 3], padding=1, data_format=NCHW)
  (p2_conv): Conv2D(256, 64, kernel_size=[3, 3], padding=1, data_format=NCHW)
)
DBHead(
  (binarize): Head(
    (conv1): Conv2D(256, 64, kernel_size=[3, 3], padding=1, data_format=NCHW)
    (conv_bn1): BatchNorm()
    (conv2): Conv2DTranspose(64, 64, kernel_size=[2, 2], stride=[2, 2], data_format=NCHW)
    (conv_bn2): BatchNorm()
    (conv3): Conv2DTranspose(64, 1, kernel_size=[2, 2], stride=[2, 2], data_format=NCHW)
  )
  (thresh): Head(
    (conv1): Conv2D(256, 64, kernel_size=[3, 3], padding=1, data_format=NCHW)
    (conv_bn1): BatchNorm()
    (conv2): Conv2DTranspose(64, 64, kernel_size=[2, 2], stride=[2, 2], data_format=NCHW)
    (conv_bn2): BatchNorm()
    (conv3): Conv2DTranspose(64, 1, kernel_size=[2, 2], stride=[2, 2], data_format=NCHW)
  )
)
The shape of fpn outs [1, 256, 160, 160]
The shape of DB head outs [1, 3, 640, 640]
DB算法优点:(有监督,backbone选ResNet50效果更好)
- 精度更高、快
- 弯曲文本
- 多方向文本
- 多语言



















