YOLOv11改进-Conv篇-在线重参数化卷积OREPA助力二次创新yolov11的C3k2机制（提高推理速度加FPS）

一、本文介绍

本文给大家带来的改进机制是一种重参数化的卷积模块 OREPA ，这种重参数化模块非常适合用于二次创新，我们可以将其替换网络中的其它卷积模块可以不影响推理速度的同时让模型学习到更多的特征。 OREPA 是通过 在线卷积重参数化（Online Convolutional Re-parameterization） 来减少深度学习模型训练的成本和复杂性。这种方法主要包括 两个阶段 ：首先，利用一个特殊的线性缩放层来优化在线块的性能；其次，通过将复杂的训练时模块压缩成一个单一的卷积来减少训练开销。 欢迎大家订阅本专栏，本专栏每周更新3-5篇最新机制，更有包含我所有改进的文件和交流群提供给大家 。

欢迎大家订阅我的专栏一起学习YOLO！

二、OREPA原理

论文地址： 官方论文地址

代码地址： 官方代码地址

2.1 OREPA的基本原理

OREPA 是通过 在线卷积重参数化（Online Convolutional Re-parameterization） 来减少深度学习模型训练的成本和复杂性。这种方法主要包括 两个阶段 ：首先，利用一个特殊的线性缩放层来优化在线块的性能；其次，通过将复杂的训练时模块压缩成一个单一的卷积来减少训练开销。OREPA能够显著降低训练时的内存和计算成本，同时提高训练速度，并在标准的计算机视觉任务如图像分类、物体检测和语义分割等方面取得了更好的性能表现。

OREPA（在线卷积重参数化）的基本原理可以分为以下几点：

1. 两阶段流程： OREPA采用两个阶段来实现其目标。首先是在线优化阶段，其次是压缩训练时模块阶段。

2. 线性缩放层： 引入线性缩放层来优化在线模块，以更有效地进行训练。

3. 训练时模块压缩： 将复杂的训练时模块压缩成一个单一的卷积操作，以减少训练开销。

这张图展示了 在线卷积重参数化（OREPA）流程的具体步骤：

1. 移除（Remove）： 首先移除原型块中的非线性层，如ReLU和批量归一化（BN）。

2. 添加缩放（Add Scaling）： 引入缩放层来优化卷积层的输出。

3. 添加归一化（Add Norm）： 最后，添加归一化来进行模型的性能优化和提升。

通过这一系列步骤，OREPA方法在训练阶段有效地简化了模型的复杂性，优化了训练效率，并为高性能模型的构建提供了一种新的方法论。

2.2 两阶段流程

下面为大家展示了 在线重参数化（OREPA）的两个阶段：

1. 块线性化（Block Linearization）： 在这个阶段，原型重参数化块中的所有非线性组件被移除，只留下卷积和批量归一化（BN）层，并加入缩放层以优化性能。

2. 块挤压（Block Squeezing）： 随后，这个过程将上述线性化的块合并成一个单独的卷积层（OREPA Conv），这样可以显著减少训练成本，同时保持高性能。

2.3 线性缩放层

线性缩放层 在OREPA中是一个关键的组成部分，它允许模型在训练过程中进行更有效的权重更新。这一层的目的是在 保持训练时复杂性管理 的同时，提高模型在学习特征时的灵活性和适应性。通过对权重进行合适的缩放，这一层有助于模型在整个训练过程中维持稳定的梯度流动，这对于深度学习模型的优化至关重要。这种线性缩放层通过在训练时对卷积层的输出进行缩放，使模型可以更快地收敛，同时减少资源的消耗。

下面这张图展示了 在线卷积重参数化（OREPA）框架中提出的四个组件：

(a) 频率先验过滤器： 一个结合了1x1卷积和3x3频率先验滤波器的结构，随后是一个缩放层。
(b) 线性深度可分离卷积（Linear DW sepconv）： 包含了3x3深度可分离卷积（DW Conv），后面跟着1x1逐点卷积（PW Conv）和缩放层。
(c) 重参数1x1卷积： 由两个1x1卷积层组成，其中每个层后都接有一个缩放层，这些层被用来重参数化更大的卷积结构。

(d) 线性深层干细胞（Linear deep stem）： 由三个3x3卷积层组成，这种结构旨在处理输入数据的最初几层，以提高模型的初期特征提取能力。

2.4 训练时模块压缩

在OREPA框架中， 训练时模块压缩 指的是在训练阶段，通过 线性化处理和结构简化 将原本复杂的卷积网络块转换为一个简单的卷积层。这种方法减少了模型训练时的内存占用和计算成本。具体来说，它涉及到移除非线性激活函数、合并多个卷积层，并引入缩放层来调整卷积层权重的规模。

这张图展示了 不同卷积层结构在训练阶段和推理阶段的对比 ：

(a) 是一个标准的卷积层，没有重参数化（No Re-param）。
(b) 展示了一个典型的结构重参数化块（Structural Re-param）。
(c) 是论文中提出的在线重参数化块（OREPA），即在线卷积重参数化。
(d) 是部署时的结构，所有训练阶段的结构在推理时都转换为这个简单的卷积结构。

在训练阶段，OREPA的设计允许将多个卷积层和批量归一化（BN）层通过重参数化合并为一个卷积层，以减少训练时的复杂性和内存需求。在推理时，不论训练时的结构如何复杂，所有模型都被简化为单一的卷积层，这有助于提高推理速度并降低推理时的资源消耗。

下图为大家展示的是 OREPA块的设计 ，它在训练和推理过程中对应于一个 3x3的卷积 。这个设计通过将一系列卷积层、池化层和频率先验层，并带有缩放层，最终通过一个挤压操作将这些层合并成一个单独的OREPA卷积层。

三、OREPA的核心代码

代码的使用方式看章节四！

import math
import torch
import torch.nn as nn
import torch.nn.functional as F
import numpy as np
from torch.nn import init
__all__ = ['OREPA', 'C3k2_OREPA_backbone', 'C3k2_OREPA_neck']
def autopad(k, p=None, d=1):  # kernel, padding, dilation
    """Pad to 'same' shape outputs."""
    if d > 1:
        k = d * (k - 1) + 1 if isinstance(k, int) else [d * (x - 1) + 1 for x in k]  # actual kernel-size
    if p is None:
        p = k // 2 if isinstance(k, int) else [x // 2 for x in k]  # auto-pad
    return p
class Conv(nn.Module):
    """Standard convolution with args(ch_in, ch_out, kernel, stride, padding, groups, dilation, activation)."""
    default_act = nn.SiLU()  # default activation
    def __init__(self, c1, c2, k=1, s=1, p=None, g=1, d=1, act=True):
        """Initialize Conv layer with given arguments including activation."""
        super().__init__()
        self.conv = nn.Conv2d(c1, c2, k, s, autopad(k, p, d), groups=g, dilation=d, bias=False)
        self.bn = nn.BatchNorm2d(c2)
        self.act = self.default_act if act is True else act if isinstance(act, nn.Module) else nn.Identity()
    def forward(self, x):
        """Apply convolution, batch normalization and activation to input tensor."""
        return self.act(self.bn(self.conv(x)))
    def forward_fuse(self, x):
        """Perform transposed convolution of 2D data."""
        return self.act(self.conv(x))
def transI_fusebn(kernel, bn):
    gamma = bn.weight
    std = (bn.running_var + bn.eps).sqrt()
    return kernel * ((gamma / std).reshape(-1, 1, 1, 1)), bn.bias - bn.running_mean * gamma / std
def transVI_multiscale(kernel, target_kernel_size):
    H_pixels_to_pad = (target_kernel_size - kernel.size(2)) // 2
    W_pixels_to_pad = (target_kernel_size - kernel.size(3)) // 2
    return F.pad(kernel, [W_pixels_to_pad, W_pixels_to_pad, H_pixels_to_pad, H_pixels_to_pad])
class OREPA(nn.Module):
    def __init__(self,
                 in_channels,
                 out_channels,
                 kernel_size=3,
                 stride=1,
                 padding=None,
                 groups=1,
                 dilation=1,
                 act=True,
                 internal_channels_1x1_3x3=None,
                 deploy=False,
                 single_init=False,
                 weight_only=False,
                 init_hyper_para=1.0, init_hyper_gamma=1.0):
        super(OREPA, self).__init__()
        self.deploy = deploy
        self.nonlinear = Conv.default_act if act is True else act if isinstance(act, nn.Module) else nn.Identity()
        self.weight_only = weight_only
        self.kernel_size = kernel_size
        self.in_channels = in_channels
        self.out_channels = out_channels
        self.groups = groups
        self.stride = stride
        padding = autopad(kernel_size, padding, dilation)
        self.padding = padding
        self.dilation = dilation
        if deploy:
            self.orepa_reparam = nn.Conv2d(in_channels=in_channels, out_channels=out_channels, kernel_size=kernel_size,
                                           stride=stride,
                                           padding=padding, dilation=dilation, groups=groups, bias=True)
        else:
            self.branch_counter = 0
            self.weight_orepa_origin = nn.Parameter(
                torch.Tensor(out_channels, int(in_channels / self.groups), kernel_size, kernel_size))
            init.kaiming_uniform_(self.weight_orepa_origin, a=math.sqrt(0.0))
            self.branch_counter += 1
            self.weight_orepa_avg_conv = nn.Parameter(
                torch.Tensor(out_channels, int(in_channels / self.groups), 1,
                             1))
            self.weight_orepa_pfir_conv = nn.Parameter(
                torch.Tensor(out_channels, int(in_channels / self.groups), 1,
                             1))
            init.kaiming_uniform_(self.weight_orepa_avg_conv, a=0.0)
            init.kaiming_uniform_(self.weight_orepa_pfir_conv, a=0.0)
            self.register_buffer(
                'weight_orepa_avg_avg',
                torch.ones(kernel_size,
                           kernel_size).mul(1.0 / kernel_size / kernel_size))
            self.branch_counter += 1
            self.branch_counter += 1
            self.weight_orepa_1x1 = nn.Parameter(
                torch.Tensor(out_channels, int(in_channels / self.groups), 1,
                             1))
            init.kaiming_uniform_(self.weight_orepa_1x1, a=0.0)
            self.branch_counter += 1
            if internal_channels_1x1_3x3 is None:
                internal_channels_1x1_3x3 = in_channels if groups <= 4 else 2 * in_channels
            if internal_channels_1x1_3x3 == in_channels:
                self.weight_orepa_1x1_kxk_idconv1 = nn.Parameter(
                    torch.zeros(in_channels, int(in_channels / self.groups), 1, 1))
                id_value = np.zeros(
                    (in_channels, int(in_channels / self.groups), 1, 1))
                for i in range(in_channels):
                    id_value[i, i % int(in_channels / self.groups), 0, 0] = 1
                id_tensor = torch.from_numpy(id_value).type_as(
                    self.weight_orepa_1x1_kxk_idconv1)
                self.register_buffer('id_tensor', id_tensor)
            else:
                self.weight_orepa_1x1_kxk_idconv1 = nn.Parameter(
                    torch.zeros(internal_channels_1x1_3x3,
                                int(in_channels / self.groups), 1, 1))
                id_value = np.zeros(
                    (internal_channels_1x1_3x3, int(in_channels / self.groups), 1, 1))
                for i in range(internal_channels_1x1_3x3):
                    id_value[i, i % int(in_channels / self.groups), 0, 0] = 1
                id_tensor = torch.from_numpy(id_value).type_as(
                    self.weight_orepa_1x1_kxk_idconv1)
                self.register_buffer('id_tensor', id_tensor)
                # init.kaiming_uniform_(
                # self.weight_orepa_1x1_kxk_conv1, a=math.sqrt(0.0))
            self.weight_orepa_1x1_kxk_conv2 = nn.Parameter(
                torch.Tensor(out_channels,
                             int(internal_channels_1x1_3x3 / self.groups),
                             kernel_size, kernel_size))
            init.kaiming_uniform_(self.weight_orepa_1x1_kxk_conv2, a=math.sqrt(0.0))
            self.branch_counter += 1
            expand_ratio = 8
            self.weight_orepa_gconv_dw = nn.Parameter(
                torch.Tensor(in_channels * expand_ratio, 1, kernel_size,
                             kernel_size))
            self.weight_orepa_gconv_pw = nn.Parameter(
                torch.Tensor(out_channels, int(in_channels * expand_ratio / self.groups), 1, 1))
            init.kaiming_uniform_(self.weight_orepa_gconv_dw, a=math.sqrt(0.0))
            init.kaiming_uniform_(self.weight_orepa_gconv_pw, a=math.sqrt(0.0))
            self.branch_counter += 1
            self.vector = nn.Parameter(torch.Tensor(self.branch_counter, self.out_channels))
            if weight_only is False:
                self.bn = nn.BatchNorm2d(self.out_channels)
            self.fre_init()
            init.constant_(self.vector[0, :], 0.25 * math.sqrt(init_hyper_gamma))  # origin
            init.constant_(self.vector[1, :], 0.25 * math.sqrt(init_hyper_gamma))  # avg
            init.constant_(self.vector[2, :], 0.0 * math.sqrt(init_hyper_gamma))  # prior
            init.constant_(self.vector[3, :], 0.5 * math.sqrt(init_hyper_gamma))  # 1x1_kxk
            init.constant_(self.vector[4, :], 1.0 * math.sqrt(init_hyper_gamma))  # 1x1
            init.constant_(self.vector[5, :], 0.5 * math.sqrt(init_hyper_gamma))  # dws_conv
            self.weight_orepa_1x1.data = self.weight_orepa_1x1.mul(init_hyper_para)
            self.weight_orepa_origin.data = self.weight_orepa_origin.mul(init_hyper_para)
            self.weight_orepa_1x1_kxk_conv2.data = self.weight_orepa_1x1_kxk_conv2.mul(init_hyper_para)
            self.weight_orepa_avg_conv.data = self.weight_orepa_avg_conv.mul(init_hyper_para)
            self.weight_orepa_pfir_conv.data = self.weight_orepa_pfir_conv.mul(init_hyper_para)
            self.weight_orepa_gconv_dw.data = self.weight_orepa_gconv_dw.mul(math.sqrt(init_hyper_para))
            self.weight_orepa_gconv_pw.data = self.weight_orepa_gconv_pw.mul(math.sqrt(init_hyper_para))
            if single_init:
                #   Initialize the vector.weight of origin as 1 and others as 0. This is not the default setting.
                self.single_init()
    def fre_init(self):
        prior_tensor = torch.Tensor(self.out_channels, self.kernel_size,
                                    self.kernel_size)
        half_fg = self.out_channels / 2
        for i in range(self.out_channels):
            for h in range(3):
                for w in range(3):
                    if i < half_fg:
                        prior_tensor[i, h, w] = math.cos(math.pi * (h + 0.5) *
                                                         (i + 1) / 3)
                    else:
                        prior_tensor[i, h, w] = math.cos(math.pi * (w + 0.5) *
                                                         (i + 1 - half_fg) / 3)
        self.register_buffer('weight_orepa_prior', prior_tensor)
    def weight_gen(self):
        weight_orepa_origin = torch.einsum('oihw,o->oihw',
                                           self.weight_orepa_origin,
                                           self.vector[0, :])
        weight_orepa_avg = torch.einsum('oihw,hw->oihw', self.weight_orepa_avg_conv, self.weight_orepa_avg_avg)
        weight_orepa_avg = torch.einsum(
            'oihw,o->oihw',
            torch.einsum('oi,hw->oihw', self.weight_orepa_avg_conv.squeeze(3).squeeze(2),
                         self.weight_orepa_avg_avg), self.vector[1, :])
        weight_orepa_pfir = torch.einsum(
            'oihw,o->oihw',
            torch.einsum('oi,ohw->oihw', self.weight_orepa_pfir_conv.squeeze(3).squeeze(2),
                         self.weight_orepa_prior), self.vector[2, :])
        weight_orepa_1x1_kxk_conv1 = None
        if hasattr(self, 'weight_orepa_1x1_kxk_idconv1'):
            weight_orepa_1x1_kxk_conv1 = (self.weight_orepa_1x1_kxk_idconv1 +
                                          self.id_tensor).squeeze(3).squeeze(2)
        elif hasattr(self, 'weight_orepa_1x1_kxk_conv1'):
            weight_orepa_1x1_kxk_conv1 = self.weight_orepa_1x1_kxk_conv1.squeeze(3).squeeze(2)
        else:
            raise NotImplementedError
        weight_orepa_1x1_kxk_conv2 = self.weight_orepa_1x1_kxk_conv2
        if self.groups > 1:
            g = self.groups
            t, ig = weight_orepa_1x1_kxk_conv1.size()
            o, tg, h, w = weight_orepa_1x1_kxk_conv2.size()
            weight_orepa_1x1_kxk_conv1 = weight_orepa_1x1_kxk_conv1.view(
                g, int(t / g), ig)
            weight_orepa_1x1_kxk_conv2 = weight_orepa_1x1_kxk_conv2.view(
                g, int(o / g), tg, h, w)
            weight_orepa_1x1_kxk = torch.einsum('gti,gothw->goihw',
                                                weight_orepa_1x1_kxk_conv1,
                                                weight_orepa_1x1_kxk_conv2).reshape(
                o, ig, h, w)
        else:
            weight_orepa_1x1_kxk = torch.einsum('ti,othw->oihw',
                                                weight_orepa_1x1_kxk_conv1,
                                                weight_orepa_1x1_kxk_conv2)
        weight_orepa_1x1_kxk = torch.einsum('oihw,o->oihw', weight_orepa_1x1_kxk, self.vector[3, :])
        weight_orepa_1x1 = 0
        if hasattr(self, 'weight_orepa_1x1'):
            weight_orepa_1x1 = transVI_multiscale(self.weight_orepa_1x1,
                                                  self.kernel_size)
            weight_orepa_1x1 = torch.einsum('oihw,o->oihw', weight_orepa_1x1,
                                            self.vector[4, :])
        weight_orepa_gconv = self.dwsc2full(self.weight_orepa_gconv_dw,
                                            self.weight_orepa_gconv_pw,
                                            self.in_channels, self.groups)
        weight_orepa_gconv = torch.einsum('oihw,o->oihw', weight_orepa_gconv,
                                          self.vector[5, :])
        weight = weight_orepa_origin + weight_orepa_avg + weight_orepa_1x1 + weight_orepa_1x1_kxk + weight_orepa_pfir + weight_orepa_gconv
        return weight
    def dwsc2full(self, weight_dw, weight_pw, groups, groups_conv=1):
        t, ig, h, w = weight_dw.size()
        o, _, _, _ = weight_pw.size()
        tg = int(t / groups)
        i = int(ig * groups)
        ogc = int(o / groups_conv)
        groups_gc = int(groups / groups_conv)
        weight_dw = weight_dw.view(groups_conv, groups_gc, tg, ig, h, w)
        weight_pw = weight_pw.squeeze().view(ogc, groups_conv, groups_gc, tg)
        weight_dsc = torch.einsum('cgtihw,ocgt->cogihw', weight_dw, weight_pw)
        return weight_dsc.reshape(o, int(i / groups_conv), h, w)
    def forward(self, inputs=None):
        if hasattr(self, 'orepa_reparam'):
            return self.nonlinear(self.orepa_reparam(inputs))
        weight = self.weight_gen()
        if self.weight_only is True:
            return weight
        out = F.conv2d(
            inputs,
            weight,
            bias=None,
            stride=self.stride,
            padding=self.padding,
            dilation=self.dilation,
            groups=self.groups)
        return self.nonlinear(self.bn(out))
    def get_equivalent_kernel_bias(self):
        return transI_fusebn(self.weight_gen(), self.bn)
    def switch_to_deploy(self):
        if hasattr(self, 'or1x1_reparam'):
            return
        kernel, bias = self.get_equivalent_kernel_bias()
        self.orepa_reparam = nn.Conv2d(in_channels=self.in_channels, out_channels=self.out_channels,
                                       kernel_size=self.kernel_size, stride=self.stride,
                                       padding=self.padding, dilation=self.dilation, groups=self.groups, bias=True)
        self.orepa_reparam.weight.data = kernel
        self.orepa_reparam.bias.data = bias
        for para in self.parameters():
            para.detach_()
        self.__delattr__('weight_orepa_origin')
        self.__delattr__('weight_orepa_1x1')
        self.__delattr__('weight_orepa_1x1_kxk_conv2')
        if hasattr(self, 'weight_orepa_1x1_kxk_idconv1'):
            self.__delattr__('id_tensor')
            self.__delattr__('weight_orepa_1x1_kxk_idconv1')
        elif hasattr(self, 'weight_orepa_1x1_kxk_conv1'):
            self.__delattr__('weight_orepa_1x1_kxk_conv1')
        else:
            raise NotImplementedError
        self.__delattr__('weight_orepa_avg_avg')
        self.__delattr__('weight_orepa_avg_conv')
        self.__delattr__('weight_orepa_pfir_conv')
        self.__delattr__('weight_orepa_prior')
        self.__delattr__('weight_orepa_gconv_dw')
        self.__delattr__('weight_orepa_gconv_pw')
        self.__delattr__('bn')
        self.__delattr__('vector')
    def init_gamma(self, gamma_value):
        init.constant_(self.vector, gamma_value)
    def single_init(self):
        self.init_gamma(0.0)
        init.constant_(self.vector[0, :], 1.0)
class Bottleneck_DBB(nn.Module):
    # Standard bottleneck with DCN
    def __init__(self, c1, c2, shortcut=True, g=1, k=(3, 3), e=0.5):  # ch_in, ch_out, shortcut, groups, kernels, expand
        super().__init__()
        c_ = int(c2 * e)  # hidden channels
        self.cv1 = Conv(c1, c_, k[0], 1)
        self.cv2 = OREPA(c_, c2, 3, stride=1, groups=g)
        self.add = shortcut and c1 == c2
    def forward(self, x):
        return x + self.cv2(self.cv1(x)) if self.add else self.cv2(self.cv1(x))
class Bottleneck(nn.Module):
    """Standard bottleneck."""
    def __init__(self, c1, c2, shortcut=True, g=1, k=(3, 3), e=0.5):
        """Initializes a standard bottleneck module with optional shortcut connection and configurable parameters."""
        super().__init__()
        c_ = int(c2 * e)  # hidden channels
        self.cv1 = Conv(c1, c_, k[0], 1)
        self.cv2 = Conv(c_, c2, k[1], 1, g=g)
        self.add = shortcut and c1 == c2
    def forward(self, x):
        """Applies the YOLO FPN to input data."""
        return x + self.cv2(self.cv1(x)) if self.add else self.cv2(self.cv1(x))
class C2f(nn.Module):
    """Faster Implementation of CSP Bottleneck with 2 convolutions."""
    def __init__(self, c1, c2, n=1, shortcut=False, g=1, e=0.5):
        """Initializes a CSP bottleneck with 2 convolutions and n Bottleneck blocks for faster processing."""
        super().__init__()
        self.c = int(c2 * e)  # hidden channels
        self.cv1 = Conv(c1, 2 * self.c, 1, 1)
        self.cv2 = Conv((2 + n) * self.c, c2, 1)  # optional act=FReLU(c2)
        self.m = nn.ModuleList(Bottleneck(self.c, self.c, shortcut, g, k=((3, 3), (3, 3)), e=1.0) for _ in range(n))
    def forward(self, x):
        """Forward pass through C2f layer."""
        y = list(self.cv1(x).chunk(2, 1))
        y.extend(m(y[-1]) for m in self.m)
        return self.cv2(torch.cat(y, 1))
    def forward_split(self, x):
        """Forward pass using split() instead of chunk()."""
        y = list(self.cv1(x).split((self.c, self.c), 1))
        y.extend(m(y[-1]) for m in self.m)
        return self.cv2(torch.cat(y, 1))
class C3(nn.Module):
    """CSP Bottleneck with 3 convolutions."""
    def __init__(self, c1, c2, n=1, shortcut=True, g=1, e=0.5):
        """Initialize the CSP Bottleneck with given channels, number, shortcut, groups, and expansion values."""
        super().__init__()
        c_ = int(c2 * e)  # hidden channels
        self.cv1 = Conv(c1, c_, 1, 1)
        self.cv2 = Conv(c1, c_, 1, 1)
        self.cv3 = Conv(2 * c_, c2, 1)  # optional act=FReLU(c2)
        self.m = nn.Sequential(*(Bottleneck(c_, c_, shortcut, g, k=((1, 1), (3, 3)), e=1.0) for _ in range(n)))
    def forward(self, x):
        """Forward pass through the CSP bottleneck with 2 convolutions."""
        return self.cv3(torch.cat((self.m(self.cv1(x)), self.cv2(x)), 1))
class C3k(C3):
    """C3k is a CSP bottleneck module with customizable kernel sizes for feature extraction in neural networks."""
    def __init__(self, c1, c2, n=1, shortcut=True, g=1, e=0.5, k=3):
        """Initializes the C3k module with specified channels, number of layers, and configurations."""
        super().__init__(c1, c2, n, shortcut, g, e)
        c_ = int(c2 * e)  # hidden channels
        # self.m = nn.Sequential(*(RepBottleneck(c_, c_, shortcut, g, k=(k, k), e=1.0) for _ in range(n)))
        self.m = nn.Sequential(*(Bottleneck_DBB(c_, c_, shortcut, g, k=(k, k), e=1.0) for _ in range(n)))
class C3k2_OREPA_backbone(C2f):
    """Faster Implementation of CSP Bottleneck with 2 convolutions."""
    def __init__(self, c1, c2, n=1, c3k=False, e=0.5, g=1, shortcut=True):
        """Initializes the C3k2 module, a faster CSP Bottleneck with 2 convolutions and optional C3k blocks."""
        super().__init__(c1, c2, n, shortcut, g, e)
        self.m = nn.ModuleList(
            C3k(self.c, self.c, 2, shortcut, g) if c3k else Bottleneck_DBB(self.c, self.c, shortcut, g) for _ in range(n)
        )
class C3k2_OREPA_neck(C2f):
    """Faster Implementation of CSP Bottleneck with 2 convolutions."""
    def __init__(self, c1, c2, n=1, c3k=False, e=0.5, g=1, shortcut=True):
        """Initializes the C3k2 module, a faster CSP Bottleneck with 2 convolutions and optional C3k blocks."""
        super().__init__(c1, c2, n, shortcut, g, e)
        self.m = nn.ModuleList(
            C3k(self.c, self.c, 2, shortcut, g) if c3k else Bottleneck(self.c, self.c, shortcut, g) for _ in range(n)
        )
if __name__ == "__main__":
    # Generating Sample image
    image_size = (1, 64, 224, 224)
    image = torch.rand(*image_size)
    # Model
    model = C3k2_OREPA_backbone(64, 64)
    out = model(image)
    print(out.size())

四、手把手教你添加OREPA模块

这个添加方式和之前的变了一下，以后的添加方法都按照这个来了，是为了和群内的文件适配。

4.1 修改一

第一还是建立文件，我们找到如下 ultralytics /nn文件夹下建立一个目录名字呢就是'Addmodules'文件夹( 用群内的文件的话已经有了无需新建) ！然后在其内部建立一个新的py文件将核心代码复制粘贴进去即可。

4.2 修改二

第二步我们在该目录下创建一个新的py文件名字为'__init__.py'( 用群内的文件的话已经有了无需新建) ，然后在其内部导入我们的检测头如下图所示。

4.3 修改三

第三步我门中到如下文件'ultralytics/nn/tasks.py'进行导入和注册我们的模块( 用群内的文件的话已经有了无需重新导入直接开始第四步即可) ！

从今天开始以后的教程就都统一成这个样子了，因为我默认大家用了我群内的文件来进行修改！！

4.4 修改四

按照我的添加在parse_model里添加即可。

到此就修改完成了，大家可以复制下面的yaml文件运行。

五、OREPA的yaml文件和运行记录

5.1 OREPA的yaml文件一

此版本的训练信息：YOLO11-C3k2-OREPA-backbone summary: 309 layers, 3,119,167 parameters, 3,119,151 gradients, 6.0 GFLOPs

# Ultralytics YOLO 🚀, AGPL-3.0 license
# YOLO11 object detection model with P3-P5 outputs. For Usage examples see https://docs.ultralytics.com/tasks/detect
# Parameters
nc: 80 # number of classes
scales: # model compound scaling constants, i.e. 'model=yolo11n.yaml' will call yolo11.yaml with scale 'n'
  # [depth, width, max_channels]
  n: [0.50, 0.25, 1024] # summary: 319 layers, 2624080 parameters, 2624064 gradients, 6.6 GFLOPs
  s: [0.50, 0.50, 1024] # summary: 319 layers, 9458752 parameters, 9458736 gradients, 21.7 GFLOPs
  m: [0.50, 1.00, 512] # summary: 409 layers, 20114688 parameters, 20114672 gradients, 68.5 GFLOPs
  l: [1.00, 1.00, 512] # summary: 631 layers, 25372160 parameters, 25372144 gradients, 87.6 GFLOPs
  x: [1.00, 1.50, 512] # summary: 631 layers, 56966176 parameters, 56966160 gradients, 196.0 GFLOPs
# YOLO11n backbone
backbone:
  # [from, repeats, module, args]
  - [-1, 1, Conv, [64, 3, 2]] # 0-P1/2
  - [-1, 1, Conv, [128, 3, 2]] # 1-P2/4
  - [-1, 2, C3k2_OREPA_backbone, [256, False, 0.25]]
  - [-1, 1, Conv, [256, 3, 2]] # 3-P3/8
  - [-1, 2, C3k2_OREPA_backbone, [512, False, 0.25]]
  - [-1, 1, Conv, [512, 3, 2]] # 5-P4/16
  - [-1, 2, C3k2_OREPA_backbone, [512, True]]
  - [-1, 1, Conv, [1024, 3, 2]] # 7-P5/32
  - [-1, 2, C3k2_OREPA_backbone, [1024, True]]
  - [-1, 1, SPPF, [1024, 5]] # 9
  - [-1, 2, C2PSA, [1024]] # 10
# YOLO11n head
head:
  - [-1, 1, nn.Upsample, [None, 2, "nearest"]]
  - [[-1, 6], 1, Concat, [1]] # cat backbone P4
  - [-1, 2, C3k2_OREPA_backbone, [512, False]] # 13
  - [-1, 1, nn.Upsample, [None, 2, "nearest"]]
  - [[-1, 4], 1, Concat, [1]] # cat backbone P3
  - [-1, 2, C3k2_OREPA_backbone, [256, False]] # 16 (P3/8-small)
  - [-1, 1, Conv, [256, 3, 2]]
  - [[-1, 13], 1, Concat, [1]] # cat head P4
  - [-1, 2, C3k2_OREPA_backbone, [512, False]] # 19 (P4/16-medium)
  - [-1, 1, Conv, [512, 3, 2]]
  - [[-1, 10], 1, Concat, [1]] # cat head P5
  - [-1, 2, C3k2_OREPA_backbone, [1024, True]] # 22 (P5/32-large)
  - [[16, 19, 22], 1, Detect, [nc]] # Detect(P3, P4, P5)

5.2 OREPA的yaml文件二

此版本的训练信息：YOLO11-C3k2-OREPA-neck summary: 314 layers, 3,002,847 parameters, 3,002,831 gradients, 6.3 GFLOPs

# Ultralytics YOLO 🚀, AGPL-3.0 license
# YOLO11 object detection model with P3-P5 outputs. For Usage examples see https://docs.ultralytics.com/tasks/detect
# Parameters
nc: 80 # number of classes
scales: # model compound scaling constants, i.e. 'model=yolo11n.yaml' will call yolo11.yaml with scale 'n'
  # [depth, width, max_channels]
  n: [0.50, 0.25, 1024] # summary: 319 layers, 2624080 parameters, 2624064 gradients, 6.6 GFLOPs
  s: [0.50, 0.50, 1024] # summary: 319 layers, 9458752 parameters, 9458736 gradients, 21.7 GFLOPs
  m: [0.50, 1.00, 512] # summary: 409 layers, 20114688 parameters, 20114672 gradients, 68.5 GFLOPs
  l: [1.00, 1.00, 512] # summary: 631 layers, 25372160 parameters, 25372144 gradients, 87.6 GFLOPs
  x: [1.00, 1.50, 512] # summary: 631 layers, 56966176 parameters, 56966160 gradients, 196.0 GFLOPs
# YOLO11n backbone
backbone:
  # [from, repeats, module, args]
  - [-1, 1, Conv, [64, 3, 2]] # 0-P1/2
  - [-1, 1, Conv, [128, 3, 2]] # 1-P2/4
  - [-1, 2, C3k2_OREPA_neck, [256, False, 0.25]]
  - [-1, 1, Conv, [256, 3, 2]] # 3-P3/8
  - [-1, 2, C3k2_OREPA_neck, [512, False, 0.25]]
  - [-1, 1, Conv, [512, 3, 2]] # 5-P4/16
  - [-1, 2, C3k2_OREPA_neck, [512, True]]
  - [-1, 1, Conv, [1024, 3, 2]] # 7-P5/32
  - [-1, 2, C3k2_OREPA_neck, [1024, True]]
  - [-1, 1, SPPF, [1024, 5]] # 9
  - [-1, 2, C2PSA, [1024]] # 10
# YOLO11n head
head:
  - [-1, 1, nn.Upsample, [None, 2, "nearest"]]
  - [[-1, 6], 1, Concat, [1]] # cat backbone P4
  - [-1, 2, C3k2_OREPA_neck, [512, False]] # 13
  - [-1, 1, nn.Upsample, [None, 2, "nearest"]]
  - [[-1, 4], 1, Concat, [1]] # cat backbone P3
  - [-1, 2, C3k2_OREPA_neck, [256, False]] # 16 (P3/8-small)
  - [-1, 1, Conv, [256, 3, 2]]
  - [[-1, 13], 1, Concat, [1]] # cat head P4
  - [-1, 2, C3k2_OREPA_neck, [512, False]] # 19 (P4/16-medium)
  - [-1, 1, Conv, [512, 3, 2]]
  - [[-1, 10], 1, Concat, [1]] # cat head P5
  - [-1, 2, C3k2_OREPA_neck, [1024, True]] # 22 (P5/32-large)
  - [[16, 19, 22], 1, Detect, [nc]] # Detect(P3, P4, P5)

5.3 OREPA的yaml文件三

此版本训练信息：YOLO11-OREPA summary: 314 layers, 4,175,263 parameters, 4,175,247 gradients, 4.8 GFLOPs

# Ultralytics YOLO 🚀, AGPL-3.0 license
# YOLO11 object detection model with P3-P5 outputs. For Usage examples see https://docs.ultralytics.com/tasks/detect
# Parameters
nc: 80 # number of classes
scales: # model compound scaling constants, i.e. 'model=yolo11n.yaml' will call yolo11.yaml with scale 'n'
  # [depth, width, max_channels]
  n: [0.50, 0.25, 1024] # summary: 319 layers, 2624080 parameters, 2624064 gradients, 6.6 GFLOPs
  s: [0.50, 0.50, 1024] # summary: 319 layers, 9458752 parameters, 9458736 gradients, 21.7 GFLOPs
  m: [0.50, 1.00, 512] # summary: 409 layers, 20114688 parameters, 20114672 gradients, 68.5 GFLOPs
  l: [1.00, 1.00, 512] # summary: 631 layers, 25372160 parameters, 25372144 gradients, 87.6 GFLOPs
  x: [1.00, 1.50, 512] # summary: 631 layers, 56966176 parameters, 56966160 gradients, 196.0 GFLOPs
# YOLO11n backbone
backbone:
  # [from, repeats, module, args]
  - [-1, 1, Conv, [64, 3, 2]] # 0-P1/2
  - [-1, 1, OREPA, [128, 3, 2]] # 1-P2/4
  - [-1, 2, C3k2, [256, False, 0.25]]
  - [-1, 1, OREPA, [256, 3, 2]] # 3-P3/8
  - [-1, 2, C3k2, [512, False, 0.25]]
  - [-1, 1, OREPA, [512, 3, 2]] # 5-P4/16
  - [-1, 2, C3k2, [512, True]]
  - [-1, 1, OREPA, [1024, 3, 2]] # 7-P5/32
  - [-1, 2, C3k2, [1024, True]]
  - [-1, 1, SPPF, [1024, 5]] # 9
  - [-1, 2, C2PSA, [1024]] # 10
# YOLO11n head
head:
  - [-1, 1, nn.Upsample, [None, 2, "nearest"]]
  - [[-1, 6], 1, Concat, [1]] # cat backbone P4
  - [-1, 2, C3k2, [512, False]] # 13
  - [-1, 1, nn.Upsample, [None, 2, "nearest"]]
  - [[-1, 4], 1, Concat, [1]] # cat backbone P3
  - [-1, 2, C3k2, [256, False]] # 16 (P3/8-small)
  - [-1, 1, OREPA, [256, 3, 2]]
  - [[-1, 13], 1, Concat, [1]] # cat head P4
  - [-1, 2, C3k2, [512, False]] # 19 (P4/16-medium)
  - [-1, 1, OREPA, [512, 3, 2]]
  - [[-1, 10], 1, Concat, [1]] # cat head P5
  - [-1, 2, C3k2, [1024, True]] # 22 (P5/32-large)
  - [[16, 19, 22], 1, Detect, [nc]] # Detect(P3, P4, P5)

5.3 OREPA的训练过程截图

五、本文总结

到此本文的正式分享内容就结束了，在这里给大家推荐我的YOLOv11改进有效涨点专栏，本专栏目前为新开的平均质量分98分，后期我会根据各种最新的前沿顶会进行论文复现，也会对一些老的改进机制进行补充，如果大家觉得本文帮助到你了，订阅本专栏，关注后续更多的更新~