深度学习,孪生网络 quick start 求助

书接上回:背景介绍,我是想做一个验证码识别,验证码的类型是点选图标,我打算分两步走,第一步使用 yolo 进行目标检测,识别出背景中的图标(big),以及要求我们点选的图标(small);第二步是使用孪生网络,比较 small 和 big 的相似性,选出最匹配的 big

现在第一步已经走完了,达到了预期期望,能正常把验证码中的图标都扣出来,并且准确率还行, 现在第二部我也是在网上找了一些孪生网络的代码,尝试在电脑上自己训练,现在的损失值已经极低了,但是识别新图片的准确率不行,我知道需要增加训练数据,当时想请大佬们帮我看看我现在的网络写的有没有问题...这个加数据真的特别难加...而且我们已经有不少数据了.. 原图长这样

用于训练孪生的长这样 现在大概 30 多个文件夹,每个文件夹里长这样

import matplotlib.pyplot as plt
import numpy as np
import random
from PIL import Image
import PIL.ImageOps

import torchvision
import torchvision.datasets as datasets
import torchvision.transforms as transforms
from torch.utils.data import DataLoader, Dataset
import torchvision.utils
import torch
from torch.autograd import Variable
import torch.nn as nn
from torch import optim
import torch.nn.functional as F

# Showing images


def imshow(img, text=None):
    npimg = img.numpy()
    plt.axis("off")
    if text:
        plt.text(75, 8, text, style='italic', fontweight='bold',
                 bbox={'facecolor': 'white', 'alpha': 0.8, 'pad': 10})

    plt.imshow(np.transpose(npimg, (1, 2, 0)))
    plt.show()

# Plotting data


def show_plot(iteration, loss):
    plt.plot(iteration, loss)
    plt.show()


class SiameseNetworkDataset(Dataset):
    def __init__(self, imageFolderDataset, transform=None):
        self.imageFolderDataset = imageFolderDataset
        self.transform = transform

    def __getitem__(self, index):
        img0_tuple = random.choice(self.imageFolderDataset.imgs)

        # We need to approximately 50% of images to be in the same class
        should_get_same_class = random.randint(0, 1)
        if should_get_same_class:
            while True:
                # Look untill the same class image is found
                img1_tuple = random.choice(self.imageFolderDataset.imgs)
                if img0_tuple[1] == img1_tuple[1]:
                    break
        else:

            while True:
                # Look untill a different class image is found
                img1_tuple = random.choice(self.imageFolderDataset.imgs)
                if img0_tuple[1] != img1_tuple[1]:
                    break

        img0 = Image.open(img0_tuple[0])
        img1 = Image.open(img1_tuple[0])

        img0 = img0.convert("L")
        img1 = img1.convert("L")

        if self.transform is not None:
            img0 = self.transform(img0)
            img1 = self.transform(img1)

        return img0, img1, torch.from_numpy(np.array([int(img1_tuple[1] != img0_tuple[1])], dtype=np.float32))

    def __len__(self):
        return len(self.imageFolderDataset.imgs)


# create the Siamese Neural Network
class SiameseNetwork(nn.Module):

    def __init__(self):
        super(SiameseNetwork, self).__init__()

        # Setting up the Sequential of CNN Layers
        self.cnn1 = nn.Sequential(
            nn.Conv2d(1, 96, kernel_size=11, stride=4),
            nn.ReLU(inplace=True),
            nn.MaxPool2d(3, stride=2),
            nn.Dropout(0.5),    # 添加 dropout

            nn.Conv2d(96, 256, kernel_size=5, stride=1),
            nn.ReLU(inplace=True),
            nn.MaxPool2d(2, stride=2),

            nn.Conv2d(256, 384, kernel_size=3, stride=1),
            nn.ReLU(inplace=True)
        )

        # Setting up the Fully Connected Layers
        self.fc1 = nn.Sequential(
            nn.Linear(384, 1024),
            nn.ReLU(inplace=True),

            nn.Linear(1024, 256),
            nn.ReLU(inplace=True),

            nn.Linear(256, 2)
        )

    def forward_once(self, x):
        # This function will be called for both images
        # Its output is used to determine the similiarity
        output = self.cnn1(x)
        output = output.view(x.size()[0], 384)
        output = self.fc1(output)
        return output

    def forward(self, input1, input2):
        # In this function we pass in both images and obtain both vectors
        # which are returned
        output1 = self.forward_once(input1)
        output2 = self.forward_once(input2)

        return output1, output2


# Define the Contrastive Loss Function
class ContrastiveLoss(torch.nn.Module):
    def __init__(self, margin=2.0):
        super(ContrastiveLoss, self).__init__()
        self.margin = margin

    def forward(self, output1, output2, label):
        # Calculate the euclidean distance and calculate the contrastive loss
        euclidean_distance = F.pairwise_distance(
            output1, output2, keepdim=True)

        loss_contrastive = torch.mean((1-label) * torch.pow(euclidean_distance, 2) +
                                      (label) * torch.pow(torch.clamp(self.margin - euclidean_distance, min=0.0), 2))

        return loss_contrastive


def build(epochs, model_path, old_model_path):
    # Load the training dataset
    # folder_dataset = datasets.ImageFolder(root="./data/faces/training/")
    folder_dataset = datasets.ImageFolder(root="/Users/yangyuhan/temp/")

    # # Resize the images and transform to tensors
    transformation = transforms.Compose([transforms.Resize((100, 100)),
                                         transforms.RandomHorizontalFlip(),
                                         transforms.RandomRotation(10),
                                         transforms.ColorJitter(
                                             brightness=0.1, contrast=0.1, saturation=0.1),
                                        transforms.ToTensor()
                                         ])
    # Initialize the network
    siamese_dataset = SiameseNetworkDataset(imageFolderDataset=folder_dataset,
                                            transform=transformation)

    # Load the training dataset
    train_dataloader = DataLoader(siamese_dataset,
                                  shuffle=True,
                                  num_workers=6,
                                  batch_size=64)

    # net = SiameseNetwork().cuda()
    net = SiameseNetwork()
    net.load_state_dict(torch.load(old_model_path))
    # Set the model in training mode
    net.train()
    criterion = ContrastiveLoss()
    optimizer = optim.Adam(net.parameters(), lr=0.0005)

    counter = []
    loss_history = []
    iteration_number = 0

    # Iterate throught the epochs
    for epoch in range(epochs):

        # Iterate over batches
        for i, (img0, img1, label) in enumerate(train_dataloader, 0):

            # Send the images and labels to CUDA
            # img0, img1, label = img0.cuda(), img1.cuda(), label.cuda()

            # Zero the gradients
            optimizer.zero_grad()

            # Pass in the two images into the network and obtain two outputs
            output1, output2 = net(img0, img1)

            # Pass the outputs of the networks and label into the loss function
            loss_contrastive = criterion(output1, output2, label)

            # Calculate the backpropagation
            loss_contrastive.backward()

            # Optimize
            optimizer.step()

            # Every 10 batches print out the loss
            if i % 10 == 0:
                print(
                    f"Epoch number {epoch}\n Current loss {loss_contrastive.item()}\n")
                iteration_number += 10

                counter.append(iteration_number)
                loss_history.append(loss_contrastive.item())

    show_plot(counter, loss_history)
    torch.save(net.state_dict(), model_path)



if __name__ == '__main__':
    old_model_path = '/Users/yangyuhan/model/captcha_618_200.pth'
    model_path = '/Users/yangyuhan/model/captcha_618_500.pth'
    # test(model_path)
    build(200, model_path, old_model_path)

我的代码合源码的区别是 output = output.view(x.size()[0], 384) 这行 他原本应该是 output = output.view(output.size()[0], -1) 我不知道这个会不会对训练有啥影响,因为我直接用它的代码这里是报错的,后来在 gpt 上找的答案,告诉我这里改成 384 就可以了.

请大佬们帮我看看网络结构有没有什么问题 现在我训练的数据是统一类别的图片放在同一个文件夹下边的 Current loss 已经是 0.004438498988747597 是不是我训练的 太狠了?会不会让他的 loss 保持在 0.1 附近效果比较好? 之类的... 可以给点建议吗

由于我的网络返回的是相似性,越接近 0 越相似,所以我最后测试的时候使用 3 长小图每张都去和每张大图比较,取各自最相似的一张作为结果.