一、GAN
1.介绍
生成对抗网络(Generative Adversarial Networks, 简称GAN)是当前人工智能学界最为重要的研究热点之一。其突出的生成能力不仅可用于生成各类图像和自然语言数据,还启发和推动了各类半监督学习和无监督学习任务的发展。主要包含生成模型( Generative Model)和判别模型(Discriminative Model)。判别模型需要输入变量 ,通过某种模型来预测 。生成模型是给定某种隐含信息,来随机产生观测数据。
2.模型结构
import torch
import torch.nn as nn
import torch.nn.functional as F
from torchvision import transforms, datasets, utils
import matplotlib.pyplot as plt
import numpy as np
import torch.optim as optim
from torchvision.datasets import ImageFolder
from tqdm import tqdm
ROOT_TRAIN = r'D:\cnn\data1\train'
train_transform = transforms.Compose([transforms.ToTensor(),
transforms.Normalize((0.5, 0.5, 0.5), (0.5, 0.5, 0.5))])
train_dataset = ImageFolder(ROOT_TRAIN, transform=train_transform) # 加载训练集
dataloader = torch.utils.data.DataLoader(train_dataset,
batch_size=4,
shuffle=True,
num_workers=0)
# 定义生成器,输入是长度为100的噪声(正态分布随机数)
# 输出为3*224*224的图片(tensor)
class Generator(nn.Module):
def __init__(self):
super(Generator, self).__init__()
self.main = nn.Sequential(
nn.Linear(100, 256),
nn.ReLU(),
nn.Linear(256, 1024),
nn.ReLU(),
nn.Linear(1024, 3*224*224),
nn.Tanh(),
)
def forward(self, x): #x为噪声输入
img = self.main(x)
img = img.view(-1, 3, 224, 224)
return img
# 定义判别器,输入为3*224*224的图片,输出为二分类概率值
class Discriminator(nn.Module):
def __init__(self):
super(Discriminator, self).__init__()
self.main = nn.Sequential(
nn.Linear(3*224*224, 1024),
nn.LeakyReLU(),
nn.Linear(1024, 256),
nn.LeakyReLU(),
nn.Linear(256, 1),
nn.Sigmoid(),
)
def forward(self, x):
x = x.view(-1, 3*224*224)
x = self.main(x)
return x
device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")
gen = Generator().to(device)
dis = Discriminator().to(device)
# 判别器优化器
d_optim = torch.optim.Adam(dis.parameters(), lr=0.0001)
# 生成器优化器
g_optim = torch.optim.Adam(gen.parameters(), lr=0.001)
loss_fn = torch.nn.BCELoss() # 二元交叉熵损失
# 绘图函数,将每一个epoch中生成器生成的图片绘制
def gen_img_plot(model, epoch, test_input): # model为Generator,test_input代表生成器输入的随机数
# prediction = np.squeeze(model(test_input).detach().cpu().numpy()) #squeeze为去掉通道维度
prediction = model(test_input).permute(0, 2, 3, 1).cpu().numpy() #将通道维度放在最后
plt.figure(figsize=(10, 10))
for i in range(prediction.shape[0]): #prediction.shape[0]=test_input的batchsize
plt.subplot(2, 2, i + 1)
plt.imshow((prediction[i]+1)/2) #从-1~1 --> 0~1
plt.axis('off')
plt.savefig('./data/GANimage_at_{}.png'.format(epoch)) #把每一轮生成的图片保存到文件夹data中
test_input = torch.randn(4, 100, device=device) # 16个长度为100的随机数
# GAN训练
D_loss = []
G_loss = []
for epoch in range(20):
d_epoch_loss = 0 #判别器损失
g_epoch_loss = 0 #生成器损失
count = len(dataloader) #len(dataloader)返回批次数
count1 = len(train_dataset) #len(train_dataset)返回样本数
for step, (img, _) in enumerate(dataloader):
img = img.to(device)
size = img.size(0) #该批次包含多少张图片
random_noise = torch.randn(size, 100, device=device) #创建生成器的输入
d_optim.zero_grad() #判别器梯度清0
real_output = dis(img) #将真实图像放到判别器上进行判断,得到对真实图像的预测结果
d_real_loss = loss_fn(real_output, torch.ones_like(real_output)) #得到判别器在真实图像上的损失
d_real_loss.backward() #计算梯度
gen_img = gen(random_noise) #得到生成图像
fake_output = dis(gen_img.detach()) #将生成图像放到判别器上进行判断,得到对生成图像的预测结果,detach()为截断梯度
d_fake_loss = loss_fn(fake_output, torch.zeros_like(fake_output)) #得到判别器在生成图像上的损失
d_fake_loss.backward() # 计算梯度
d_loss = d_real_loss + d_fake_loss #判别器的损失包含两部分
d_optim.step() #判别器优化
# 生成器
g_optim.zero_grad() #生成器梯度清零
fake_output = dis(gen_img) #将生成图像放到判别器上进行判断
g_loss = loss_fn(fake_output, torch.ones_like(fake_output)) #此处希望生成的图像能被判定为1
g_loss.backward() # 计算梯度
g_optim.step() #生成器优化
with torch.no_grad(): # loss累加的过程不需要计算梯度
d_epoch_loss += d_loss.item() #将每一个批次的损失累加
g_epoch_loss += g_loss.item() #将每一个批次的损失累加
with torch.no_grad(): # loss累加的过程不需要计算梯度
g_epoch_loss /= count
d_epoch_loss /= count
D_loss.append(d_epoch_loss) #保存每一个epoch的平均loss
G_loss.append(g_epoch_loss) #保存每一个epoch的平均loss
print('Epoch:', epoch)
gen_img_plot(gen, epoch, test_input) #每个epoch会生成一张图
二、图片reshape
1.直接进行resize
# -*- coding: utf-8 -*-
from PIL import Image
import os
def image_resize(image_path, new_path):
for img_name in os.listdir(image_path):
img_path = image_path + "/" + img_name # 获取该图片全称
image = Image.open(img_path) # 打开图片
width = image.size[0] #宽
high = image.size[1] #高
mask = Image.new('RGB', (width, high)) # 新建一个正方形mask,RGB代表3*8位像素
mask.paste(image, (0, 0))
mask = mask.resize((224, 224))
mask.save(new_path + '/' + img_name)
if __name__ == '__main__':
ori_path = r"D:\cnn\All Classfication\AlexNet\data\train\Cat" # 输入图片的文件夹路径
new_path = 'D:\cnn\All Classfication\AlexNet\data1/train\Cat' # resize之后的文件夹路径
image_resize(ori_path, new_path)
2.不失真的resize
# -*- coding: utf-8 -*-
from PIL import Image
import os
def image_resize(image_path, new_path):
for img_name in os.listdir(image_path):
img_path = image_path + "/" + img_name
image = Image.open(img_path) # 打开一张图片
temp = max(image.size)
mask = Image.new('RGB', (temp, temp), (255, 255, 255)) # 新建一个正方形mask,RGB代表3*8位像素,255为填充白色
mask.paste(image, (0, 0))
mask = mask.resize((224, 224))
mask.save(new_path + '/' + img_name)
if __name__ == '__main__':
ori_path = r"D:\cnn\All Classfication\AlexNet\data\train\Cat" # 输入图片的文件夹路径
new_path = 'D:\cnn\All Classfication\AlexNet\data1/train\Cat' # resize之后的文件夹路径
image_resize(ori_path, new_path)