基於SRGAN的圖像超分辨率重建
本文偏新手項,因此只是作爲定性學習使用,因此不涉及最後的定量評估環節
1 簡要介紹
SRGAN的原論文發表於CVPR2017,即《Photo-Realistic Single Image Super-Resolution Using a Generative Adversarial Network》
SRGAN使用了生成對抗的方式來進行圖像的超分辨率重建,同時提出了一個由Adversarial Loss和Content Loss組成的損失函數。
更詳細的介紹可以去看看這篇文章 傳送門
2 代碼實現
2.1 開發環境
pytorch == '1.7.0+cu101'
numpy == '1.19.4'
PIL == '8.0.1'
tqdm == '4.52.0'
matplotlib == '3.3.3'
對於開發文件的路徑爲
/root
- /Urban100
- img_001.png
- img_002.png
···
- img_100.png
- /Img
- /model
- /result
- main.py #主代碼應該放在這裏
2.2 主要流程
這次代碼的主要流程爲
構 建 數 據 集 → 構 建 生 成 模 型 → 構 建 辨 別 模 型 → 構 建 迭 代 器 → 構 建 訓 練 循 環 構建數據集\rightarrow 構建生成模型\rightarrow 構建辨別模型\rightarrow 構建迭代器\rightarrow 構建訓練循環 構建數據集→構建生成模型→構建辨別模型→構建迭代器→構建訓練循環
2.3 構建數據集
這次的數據集用的是Urban100數據集,當然使用其他數據集也沒有太大的問題(不建議使用帶有灰度圖的數據集,會報錯)
在這裏使用的構造方法和我的上一篇博客相同 傳送門
首先我們先把數據集預處理類構建好
import torchvision.transforms as transforms
import torch
from torch.utils.data import Dataset
import numpy as np
import os
from PIL import Image
#圖像處理操作,包括隨機裁剪,轉換張量
transform = transforms.Compose([transforms.RandomCrop(96),
transforms.ToTensor()])
class PreprocessDataset(Dataset):
"""預處理數據集類"""
def __init__(self,imgPath = path,transforms = transform, ex = 10):
"""初始化預處理數據集類"""
self.transforms = transform
for _,_,files in os.walk(imgPath):
self.imgs = [imgPath + file for file in files] * ex
np.random.shuffle(self.imgs) #隨機打亂
def __len__(self):
"""獲取數據長度"""
return len(self.imgs)
def __getitem__(self,index):
"""獲取數據"""
tempImg = self.imgs[index]
tempImg = Image.open(tempImg)
sourceImg = self.transforms(tempImg) #對原始圖像進行處理
cropImg = torch.nn.MaxPool2d(4,stride=4)(sourceImg)
return cropImg,sourceImg
隨後,我們只需要構造一個DataLoader就可以在後續訓練中使用到我們的模型了
path = './Urban100/'
device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")
BATCH = 32
EPOCHS = 100
#構建數據集
processDataset = PreprocessDataset(imgPath = path)
trainData = DataLoader(processDataset,batch_size=BATCH)
#構造迭代器並取出其中一個樣本
dataiter = iter(trainData)
testImgs,_ = dataiter.next()
testImgs = testImgs.to(device) #testImgs的用處是爲了可視化生成對抗的結果
2.4 構建生成模型(Generator)
在文章中的生成模型即爲SRResNet,下圖爲他的網絡結構圖
該模型是可以單獨用於進行超分辨率訓練的,詳情請看 → \rightarrow → 傳送門
模型的構造代碼如下
import torch.nn as nn
import torch.nn.functional as F
class ResBlock(nn.Module):
"""殘差模塊"""
def __init__(self,inChannals,outChannals):
"""初始化殘差模塊"""
super(ResBlock,self).__init__()
self.conv1 = nn.Conv2d(inChannals,outChannals,kernel_size=1,bias=False)
self.bn1 = nn.BatchNorm2d(outChannals)
self.conv2 = nn.Conv2d(outChannals,outChannals,kernel_size=3,stride=1,padding=1,bias=False)
self.bn2 = nn.BatchNorm2d(outChannals)
self.conv3 = nn.Conv2d(outChannals,outChannals,kernel_size=1,bias=False)
self.relu = nn.PReLU()
def forward(self,x):
"""前向傳播過程"""
resudial = x
out = self.conv1(x)
out = self.bn1(out)
out = self.relu(out)
out = self.conv2(x)
out = self.bn2(out)
out = self.relu(out)
out = self.conv3(x)
out += resudial
out = self.relu(out)
return out
class Generator(nn.Module):
"""生成模型(4x)"""
def __init__(self):
"""初始化模型配置"""
super(Generator,self).__init__()
#卷積模塊1
self.conv1 = nn.Conv2d(3,64,kernel_size=9,padding=4,padding_mode='reflect',stride=1)
self.relu = nn.PReLU()
#殘差模塊
self.resBlock = self._makeLayer_(ResBlock,64,64,5)
#卷積模塊2
self.conv2 = nn.Conv2d(64,64,kernel_size=1,stride=1)
self.bn2 = nn.BatchNorm2d(64)
self.relu2 = nn.PReLU()
#子像素卷積
self.convPos1 = nn.Conv2d(64,256,kernel_size=3,stride=1,padding=2,padding_mode='reflect')
self.pixelShuffler1 = nn.PixelShuffle(2)
self.reluPos1 = nn.PReLU()
self.convPos2 = nn.Conv2d(64,256,kernel_size=3,stride=1,padding=1,padding_mode='reflect')
self.pixelShuffler2 = nn.PixelShuffle(2)
self.reluPos2 = nn.PReLU()
self.finConv = nn.Conv2d(64,3,kernel_size=9,stride=1)
def _makeLayer_(self,block,inChannals,outChannals,blocks):
"""構建殘差層"""
layers = []
layers.append(block(inChannals,outChannals))
for i in range(1,blocks):
layers.append(block(outChannals,outChannals))
return nn.Sequential(*layers)
def forward(self,x):
"""前向傳播過程"""
x = self.conv1(x)
x = self.relu(x)
residual = x
out = self.resBlock(x)
out = self.conv2(out)
out = self.bn2(out)
out += residual
out = self.convPos1(out)
out = self.pixelShuffler1(out)
out = self.reluPos1(out)
out = self.convPos2(out)
out = self.pixelShuffler2(out)
out = self.reluPos2(out)
out = self.finConv(out)
return out
2.5 構建辨別模型(Discriminator)
辨別器採用了類似於VGG結構的模型,因此在實現上也沒有很大難度
class ConvBlock(nn.Module):
"""殘差模塊"""
def __init__(self,inChannals,outChannals,stride = 1):
"""初始化殘差模塊"""
super(ConvBlock,self).__init__()
self.conv = nn.Conv2d(inChannals,outChannals,kernel_size=3,stride = stride,padding=1,padding_mode='reflect',bias=False)
self.bn = nn.BatchNorm2d(outChannals)
self.relu = nn.LeakyReLU()
def forward(self,x):
"""前向傳播過程"""
out = self.conv(x)
out = self.bn(out)
out = self.relu(out)
return out
class Discriminator(nn.Module):
def __init__(self):
super(Discriminator,self).__init__()
self.conv1 = nn.Conv2d(3,64,kernel_size=3,stride=1,padding=1,padding_mode='reflect')
self.relu1 = nn.LeakyReLU()
self.convBlock1 = ConvBlock(64,64,stride = 2)
self.convBlock2 = ConvBlock(64,128,stride = 1)
self.convBlock3 = ConvBlock(128,128,stride = 2)
self.convBlock4 = ConvBlock(128,256,stride = 1)
self.convBlock5 = ConvBlock(256,256,stride = 2)
self.convBlock6 = ConvBlock(256,512,stride = 1)
self.convBlock7 = ConvBlock(512,512,stride = 2)
self.avePool = nn.AdaptiveAvgPool2d(1)
self.conv2 = nn.Conv2d(512,1024,kernel_size=1)
self.relu2 = nn.LeakyReLU()
self.conv3 = nn.Conv2d(1024,1,kernel_size=1)
self.sigmoid = nn.Sigmoid()
def forward(self,x):
x = self.conv1(x)
x = self.relu1(x)
x = self.convBlock1(x)
x = self.convBlock2(x)
x = self.convBlock3(x)
x = self.convBlock4(x)
x = self.convBlock5(x)
x = self.convBlock6(x)
x = self.convBlock7(x)
x = self.avePool(x)
x = self.conv2(x)
x = self.relu2(x)
x = self.conv3(x)
x = self.sigmoid(x)
return x
(原諒我醜的一批的代碼…)
2.6 初始化訓練迭代器
在構建完數據集和兩個網絡之後,我們需要構造訓練所需要的模型實例,損失函數,迭代器等。
這裏迭代器使用的是Adam,兩個網絡的迭代器是互不相同的,爲了保證網絡之間對抗的穩定性,這裏設置了兩個模型的學習率相同。
SRGAN中使用了基於VGG提取的高級特徵作爲損失函數,因此需要使用到VGG預訓練模型。
import torch.optim as optim
from torchvision.models.vgg import vgg16
#構造模型
netD = Discriminator()
netG = Generator()
netD.to(device)
netG.to(device)
#構造迭代器
optimizerG = optim.Adam(netG.parameters())
optimizerD = optim.Adam(netD.parameters())
#構造損失函數
lossF = nn.MSELoss().to(device)
#構造VGG損失中的網絡模型
vgg = vgg16(pretrained=True).to(device)
lossNetwork = nn.Sequential(*list(vgg.features)[:31]).eval()
for param in lossNetwork.parameters():
param.requires_grad = False #讓VGG停止學習
2.7 構造訓練循環
訓練的循環如下
from tqdm import tqdm
import torchvision.utils as vutils
import matplotlib.pyplot as plt
for epoch in range(EPOCHS):
netD.train()
netG.train()
processBar = tqdm(enumerate(trainData,1))
for i,(cropImg,sourceImg) in processBar:
cropImg,sourceImg = cropImg.to(device),sourceImg.to(device)
fakeImg = netG(cropImg).to(device)
#迭代辨別器網絡
netD.zero_grad()
realOut = netD(sourceImg).mean()
fakeOut = netD(fakeImg).mean()
dLoss = 1 - realOut + fakeOut
dLoss.backward(retain_graph=True)
#迭代生成器網絡
netG.zero_grad()
gLossSR = lossF(fakeImg,sourceImg)
gLossGAN = 0.001 * torch.mean(1 - fakeOut)
gLossVGG = 0.006 * lossF(lossNetwork(fakeImg),lossNetwork(sourceImg))
gLoss = gLossSR + gLossGAN + gLossVGG
gLoss.backward()
optimizerD.step()
optimizerG.step()
#數據可視化
processBar.set_description(desc='[%d/%d] Loss_D: %.4f Loss_G: %.4f D(x): %.4f D(G(z)): %.4f' % (
epoch, EPOCHS, dLoss.item(),gLoss.item(),realOut.item(),fakeOut.item()))
#將文件輸出到目錄中
with torch.no_grad():
fig = plt.figure(figsize=(10,10))
plt.axis("off")
fakeImgs = netG(testImgs).detach().cpu()
plt.imshow(np.transpose(vutils.make_grid(fakeImgs,padding=2,normalize=True),(1,2,0)), animated=True)
plt.savefig('./Img/Result_epoch % 05d.jpg' % epoch, bbox_inches='tight', pad_inches = 0)
print('[INFO] Image saved successfully!')
#保存模型路徑文件
torch.save(netG.state_dict(), 'model/netG_epoch_%d_%d.pth' % (4, epoch))
torch.save(netD.state_dict(), 'model/netD_epoch_%d_%d.pth' % (4, epoch))
[0/100] Loss_D: 1.0737 Loss_G: 0.0360 D(x): 0.1035 D(G(z)): 0.1772: : 33it [00:32, 1.02it/s]
0it [00:00, ?it/s]
[INFO] Image saved successfully!
[1/100] Loss_D: 0.8497 Loss_G: 0.0216 D(x): 0.6464 D(G(z)): 0.4960: : 33it [00:31, 1.04it/s]
0it [00:00, ?it/s]
[INFO] Image saved successfully!
[2/100] Loss_D: 0.9925 Loss_G: 0.0235 D(x): 0.5062 D(G(z)): 0.4987: : 33it [00:31, 1.05it/s]
0it [00:00, ?it/s]
[INFO] Image saved successfully!
[3/100] Loss_D: 0.9907 Loss_G: 0.0277 D(x): 0.4948 D(G(z)): 0.4856: : 33it [00:31, 1.06it/s]
0it [00:00, ?it/s]
[INFO] Image saved successfully!
[4/100] Loss_D: 0.9936 Loss_G: 0.0180 D(x): 0.0127 D(G(z)): 0.0062: : 33it [00:31, 1.06it/s]
0it [00:00, ?it/s]
[INFO] Image saved successfully!
[5/100] Loss_D: 1.0636 Loss_G: 0.0300 D(x): 0.2553 D(G(z)): 0.3188: : 33it [00:31, 1.06it/s]
0it [00:00, ?it/s]
[INFO] Image saved successfully!
[6/100] Loss_D: 1.0000 Loss_G: 0.0132 D(x): 0.1667 D(G(z)): 0.1667: : 33it [00:31, 1.06it/s]
0it [00:00, ?it/s]
[INFO] Image saved successfully!
[7/100] Loss_D: 1.1650 Loss_G: 0.0227 D(x): 0.1683 D(G(z)): 0.3333: : 33it [00:31, 1.06it/s]
0it [00:00, ?it/s]
[INFO] Image saved successfully!
[8/100] Loss_D: 1.0000 Loss_G: 0.0262 D(x): 0.1667 D(G(z)): 0.1667: : 33it [00:31, 1.05it/s]
0it [00:00, ?it/s]
[INFO] Image saved successfully!
···
[56/100] Loss_D: 1.0000 Loss_G: 0.0119 D(x): 1.0000 D(G(z)): 1.0000: : 33it [00:32, 1.01it/s]
0it [00:00, ?it/s]
[INFO] Image saved successfully!
[57/100] Loss_D: 1.0000 Loss_G: 0.0084 D(x): 1.0000 D(G(z)): 1.0000: : 33it [00:32, 1.03it/s]
0it [00:00, ?it/s]
[INFO] Image saved successfully!
[58/100] Loss_D: 1.0000 Loss_G: 0.0065 D(x): 1.0000 D(G(z)): 1.0000: : 33it [00:32, 1.03it/s]
0it [00:00, ?it/s]
[INFO] Image saved successfully!
在Img文件夾中保存了每次訓練的可視化結果,在訓練中,第一輪的結果如下所示:
而在第58輪中的結果爲:
3 結果可視化
接下來將構造結果可視化的代碼。
該代碼的頭文件爲
import torch.nn as nn
import torch.nn.functional as F
import torch
from PIL import Image
import torchvision.transforms as transforms
import torch.nn as nn
import torch.nn.functional as F
import numpy as np
import matplotlib.pyplot as plt
首先我們需要引入生成模型
class ResBlock(nn.Module):
"""殘差模塊"""
def __init__(self,inChannals,outChannals):
"""初始化殘差模塊"""
super(ResBlock,self).__init__()
self.conv1 = nn.Conv2d(inChannals,outChannals,kernel_size=1,bias=False)
self.bn1 = nn.BatchNorm2d(outChannals)
self.conv2 = nn.Conv2d(outChannals,outChannals,kernel_size=3,stride=1,padding=1,bias=False)
self.bn2 = nn.BatchNorm2d(outChannals)
self.conv3 = nn.Conv2d(outChannals,outChannals,kernel_size=1,bias=False)
self.relu = nn.PReLU()
def forward(self,x):
"""前向傳播過程"""
resudial = x
out = self.conv1(x)
out = self.bn1(out)
out = self.relu(out)
out = self.conv2(x)
out = self.bn2(out)
out = self.relu(out)
out = self.conv3(x)
out += resudial
out = self.relu(out)
return out
class Generator(nn.Module):
"""生成模型(4x)"""
def __init__(self):
"""初始化模型配置"""
super(Generator,self).__init__()
#卷積模塊1
self.conv1 = nn.Conv2d(3,64,kernel_size=9,padding=4,padding_mode='reflect',stride=1)
self.relu = nn.PReLU()
#殘差模塊
self.resBlock = self._makeLayer_(ResBlock,64,64,5)
#卷積模塊2
self.conv2 = nn.Conv2d(64,64,kernel_size=1,stride=1)
self.bn2 = nn.BatchNorm2d(64)
self.relu2 = nn.PReLU()
#子像素卷積
self.convPos1 = nn.Conv2d(64,256,kernel_size=3,stride=1,padding=2,padding_mode='reflect')
self.pixelShuffler1 = nn.PixelShuffle(2)
self.reluPos1 = nn.PReLU()
self.convPos2 = nn.Conv2d(64,256,kernel_size=3,stride=1,padding=1,padding_mode='reflect')
self.pixelShuffler2 = nn.PixelShuffle(2)
self.reluPos2 = nn.PReLU()
self.finConv = nn.Conv2d(64,3,kernel_size=9,stride=1)
def _makeLayer_(self,block,inChannals,outChannals,blocks):
"""構建殘差層"""
layers = []
layers.append(block(inChannals,outChannals))
for i in range(1,blocks):
layers.append(block(outChannals,outChannals))
return nn.Sequential(*layers)
def forward(self,x):
"""前向傳播過程"""
x = self.conv1(x)
x = self.relu(x)
residual = x
out = self.resBlock(x)
out = self.conv2(out)
out = self.bn2(out)
out += residual
out = self.convPos1(out)
out = self.pixelShuffler1(out)
out = self.reluPos1(out)
out = self.convPos2(out)
out = self.pixelShuffler2(out)
out = self.reluPos2(out)
out = self.finConv(out)
return out
隨後,我們初始化並構建可視化函數
device = torch.device("cpu")
net = Generator()
net.load_state_dict(torch.load("你的模型pth文件路徑"))
def imshow(path,sourceImg = True):
"""展示結果"""
preTransform = transforms.Compose([transforms.ToTensor()])
pilImg = Image.open(path)
img = preTransform(pilImg).unsqueeze(0).to(device)
source = net(img)[0,:,:,:]
source = source.cpu().detach().numpy() #轉爲numpy
source = source.transpose((1,2,0)) #切換形狀
source = np.clip(source,0,1) #修正圖片
if sourceImg:
temp = np.clip(img[0,:,:,:].cpu().detach().numpy().transpose((1,2,0)),0,1)
shape = temp.shape
source[-shape[0]:,:shape[1],:] = temp
plt.imshow(source)
img = Image.fromarray(np.uint8(source*255))
img.save('./result/' + path.split('/')[-1][:-4] + '_result_with_source.jpg') # 將數組保存爲圖片
return
plt.imshow(source)
img = Image.fromarray(np.uint8(source*255))
img.save(path[:-4] + '_result.jpg') # 將數組保存爲圖片
最後,只需要簡單調用就好
imshow("你的圖片路徑",sourceImg = True)
以本次訓練模型爲例,拿一張從未見過的圖片作爲測試
能夠看出細節問題還是很多的,因此可以考慮一下增加模型的訓練時間,或者是修改一下模型的結構。