Update BE2_GAN_and_cGAN.ipynb

ac92d2d1 · Dellandrea Emmanuel · 51f214fb · ac92d2d1
Commit ac92d2d1 authored 1 year ago by Dellandrea Emmanuel
--- a/BE2_GAN_and_cGAN.ipynb
+++ b/BE2_GAN_and_cGAN.ipynb
@@ -1201,7 +1201,7 @@
   "source": [
    "# How to submit your Work ?\n",
    "\n",
-    "This work must be done individually. The expected output is a repository named gan-cgan on https://gitlab.ec-lyon.fr. It must contain your notebook (or python files) and a README.md file that explains briefly the successive steps of the project. The last commit is due before 11:59 pm on Wednesday, March 29, 2023. Subsequent commits will not be considered."
+    "This work must be done individually. The expected output is a private repository named gan-cgan on https://gitlab.ec-lyon.fr. It must contain your notebook (or python files) and a README.md file that explains briefly the successive steps of the project. Don't forget to add your teacher as developer member of the project. The last commit is due before 11:59 pm on Monday, April 1st, 2024. Subsequent commits will not be considered."
   ]
  }
 ],

 %% Cell type:markdown id: tags:
 <h1 ><big><center>MSO 3.4 - Deep Structured Learning</center></big></h1>
 <h2><big><center> BE 2 - GANs and cGAN </center></big></h2>
 <h5><big><center>Adapted from <i>Projet d'Option</i> of : Mhamed Jabri, Martin Chauvin, Ahmed Sahraoui, Zakariae Moustaïne and Taoufik Bouchikhi
 <p align="center">
 <img height=300px src="https://cdn-images-1.medium.com/max/1080/0*tJRy5Chmk4XymxwN.png"/></p>
 <p align="center"></p>
 %% Cell type:markdown id: tags:
 The aim of this assignment is to discover GANs, understand how they are implemented and then explore one specific architecture of GANs that allows us to perform image to image translation (which corresponds to the picture that you can see above this text ! )
 Before starting the exploration of the world of GANs, here's  what students should do and send back for this assignement :
 * In the "tutorial" parts of this assignement that focus on explaining new concepts, you'll find <font color='red'>**questions**</font>  that aim to test your understanding of those concepts.
 * In some of the code cells, you'll have to complete the code and you'll find a "TO DO" explaining what you should implement.
 %% Cell type:markdown id: tags:
 # Part1: DC-GAN
 %% Cell type:markdown id: tags:
 In this part, we aim to learn and understand the basic concepts of **Generative Adversarial Networks** through a DCGAN and generate new celebrities from the learned network after showing it real celebrities. For this purpose, please study the tutorial here: https://pytorch.org/tutorials/beginner/dcgan_faces_tutorial.html
 %% Cell type:markdown id: tags:
 ##Work to do
 Now we want to generate handwritten digits using the MNIST dataset. It is available within torvision package (https://pytorch.org/vision/stable/generated/torchvision.datasets.MNIST.html#torchvision.datasets.MNIST)
 Please re-train the DCGAN and display some automatically generated handwritten digits.
 %% Cell type:code id: tags:
 ``` python
 #TO DO: your code here to adapt the code from the tutorial to experiment on MNIST dataset
 ```
 %% Cell type:markdown id: tags:
 # Part2: Conditional GAN (cGAN)
 %% Cell type:markdown id: tags:
 Let's take the example of the set described in the next picture.
 ![Map to satellite picture](https://raw.githubusercontent.com/Neyri/Projet-cGAN/master/BE/img/map_streetview.png)
 We have a picture of a map (from Google Maps) and we want to create an image of what the satellite view may look like.
 As we are not only trying to generate a random picture but a mapping between a picture to another one, we can't use the standard GAN architecture. We will then use a cGAN introduced in this [paper](https://arxiv.org/pdf/1611.07004.pdf).
 A cGAN is a supervised GAN aiming at mapping a label picture to a real one or a real picture to a label one. As you can see in the diagram below, the discriminator will take as input a pair of images and try to predict if the pair was generated or not. The generator will not only generate an image from noise but will also use an image (label or real) to generate another one (real or label).
 ![Diagram of how a cGan works](https://raw.githubusercontent.com/Neyri/Projet-cGAN/master/BE/img/cgan_map.png)
 %% Cell type:markdown id: tags:
 ### Generator
 In the cGAN architecture, the generator chosen is a U-Net.
 ![U-Net](https://raw.githubusercontent.com/Neyri/Projet-cGAN/master/BE/img/unet.png)
 A U-Net takes as input an image, and outputs another image.
 It can be divided into 2 subparts : an encoder and a decoder.
 * The encoder takes the input image and reduces its dimension to encode the main features into a vector.
 * The decoder takes this vector and map the features stored into an image.
 A U-Net architecture is different from a classic encoder-decoder in that every layer of the decoder takes as input the previous decoded output as well as the output vector from the encoder layers of the same level. It allows the decoder to map low frequencies information encoded during the descent as well as high frequencies from the original picture.
 ![U-Net](https://www.researchgate.net/profile/Baris_Turkbey/publication/315514772/figure/fig2/AS:485824962797569@1492841105670/U-net-architecture-Each-box-corresponds-to-a-multi-channel-features-maps-The-number-of.png)
 %% Cell type:markdown id: tags:
 The architecture we will implement is the following (the number in the square is the number of filters used).
 ![UNet Architecture](https://raw.githubusercontent.com/Neyri/Projet-cGAN/master/BE/img/unet_architecture.png)
 The encoder will take as input a colored picture (3 channels: RGB), it will pass through a series of convolution layers to encode the features of the picture. It will then be decoded by the decoder using transposed convolutional layers. These layers will take as input the previous decoded vector AND the encoded features of the same level.
 %% Cell type:markdown id: tags:
 Now, let's create or cGAN to generate facades from a template image. For this purpose, we will use the "Facade" dataset available at http://cmp.felk.cvut.cz/~tylecr1/facade/.
 %% Cell type:markdown id: tags:
 Let's first create a few classes describing the layers we will use in the U-Net.
 %% Cell type:code id: tags:
 ``` python
 # Importing all the libraries needed
 import matplotlib.pyplot as plt
 import imageio
 import glob
 import random
 import os
 import numpy as np
 import math
 import itertools
 import time
 import datetime
 import cv2
 from pathlib import Path
 from PIL import Image
 from torch.utils.data import Dataset, DataLoader
 import torchvision.transforms as transforms
 from torchvision.utils import save_image, make_grid
 from torchvision import datasets
 from torch.autograd import Variable
 import torch.nn as nn
 import torch.nn.functional as F
 import torch
 ```
 %% Cell type:code id: tags:
 ``` python
 # code adapted from https://github.com/milesial/Pytorch-UNet/blob/master/unet/unet_parts.py
 # Input layer
 class inconv(nn.Module):
    def __init__(self, in_ch, out_ch):
        super(inconv, self).__init__()
        self.conv = nn.Sequential(
            nn.Conv2d(in_ch, out_ch, kernel_size=4, padding=1, stride=2),
            nn.LeakyReLU(negative_slope=0.2, inplace=True)
        )
    def forward(self, x):
        x = self.conv(x)
        return x
 # Encoder layer
 class down(nn.Module):
    def __init__(self, in_ch, out_ch):
        super(down, self).__init__()
        self.conv = nn.Sequential(
            nn.Conv2d(in_ch, out_ch, kernel_size=4, padding=1, stride=2),
            nn.BatchNorm2d(out_ch),
            nn.LeakyReLU(negative_slope=0.2, inplace=True)
        )
    def forward(self, x):
        x = self.conv(x)
        return x
 # Decoder layer
 class up(nn.Module):
    def __init__(self, in_ch, out_ch, dropout=False):
        super(up, self).__init__()
        if dropout :
            self.conv = nn.Sequential(
                nn.ConvTranspose2d(in_ch, out_ch, kernel_size=4, padding=1, stride=2),
                nn.BatchNorm2d(out_ch),
                nn.Dropout(0.5, inplace=True),
                nn.ReLU(inplace=True)
            )
        else:
            self.conv = nn.Sequential(
                nn.ConvTranspose2d(in_ch, out_ch, kernel_size=4, padding=1, stride=2),
                nn.BatchNorm2d(out_ch),
                nn.ReLU(inplace=True)
            )
    def forward(self, x1, x2):
        x1 = self.conv(x1)
        x = torch.cat([x1, x2], dim=1)
        return x
 # Output layer
 class outconv(nn.Module):
    def __init__(self, in_ch, out_ch):
        super(outconv, self).__init__()
        self.conv = nn.Sequential(
              nn.ConvTranspose2d(in_ch, out_ch, kernel_size=4, padding=1, stride=2),
              nn.Tanh()
        )
    def forward(self, x):
        x = self.conv(x)
        return x
 ```
 %% Cell type:markdown id: tags:
 Now let's create the U-Net using the helper classes defined previously.
 %% Cell type:code id: tags:
 ``` python
 class U_Net(nn.Module):
    '''
    Ck denotes a Convolution-BatchNorm-ReLU layer with k filters.
    CDk denotes a Convolution-BatchNorm-Dropout-ReLU layer with a dropout rate of 50%
    Encoder:
      C64   - C128   - C256   - C512  - C512  - C512 - C512 - C512
    Decoder:
      CD512 - CD1024 - CD1024 - C1024 - C1024 - C512 - C256 - C128
    '''
    def __init__(self, n_channels, n_classes):
        super(U_Net, self).__init__()
        # Encoder
        self.inc = inconv(n_channels, 64) # 64 filters
        # TO DO :
        # Create the 7 encoder layers called "down1" to "down7" following this sequence
        # C64   - C128   - C256   - C512  - C512  - C512 - C512 - C512
        # The first one has already been implemented
        # Decoder
        # TO DO :
        # Create the 7 decoder layers called up1 to up7 following this sequence :
        # CD512 - CD1024 - CD1024 - C1024 - C1024 - C512 - C256 - C128
        # The last layer has already been defined
        self.outc = outconv(128, n_classes) # 128 filters
    def forward(self, x):
        x1 = self.inc(x)
        x2 = self.down1(x1)
        x3 = self.down2(x2)
        x4 = self.down3(x3)
        x5 = self.down4(x4)
        x6 = self.down5(x5)
        x7 = self.down6(x6)
        x8 = self.down7(x7)
        # At this stage x8 is our encoded vector, we will now decode it
        x = self.up7(x8, x7)
        x = self.up6(x, x6)
        x = self.up5(x, x5)
        x = self.up4(x, x4)
        x = self.up3(x, x3)
        x = self.up2(x, x2)
        x = self.up1(x, x1)
        x = self.outc(x)
        return x
 ```
 %% Cell type:code id: tags:
 ``` python
 # We take images that have 3 channels (RGB) as input and output an image that also have 3 channels (RGB)
 generator=U_Net(3,3)
 # Check that the architecture is as expected
 generator
 ```
 %% Cell type:markdown id: tags:
 You should now have a working U-Net.
 %% Cell type:markdown id: tags:
 <font color='red'>**Question 1**</font>
 Knowing the input and output images will be 256x256, what will be the dimension of the encoded vector x8  ?
 <font color='red'>**Question 2**</font>
 As you can see, U-net has an encoder-decoder architecture with skip connections. Explain why it works better than a traditional encoder-decoder.
 %% Cell type:markdown id: tags:
 ### Discriminator
 In the cGAN architecture, the chosen discriminator is a Patch GAN. It is a convolutional discriminator which enables to produce a map of the input pictures where each pixel represents a patch of size NxN of the input.
 ![patch GAN](https://raw.githubusercontent.com/Neyri/Projet-cGAN/master/BE/img/patchGAN.png)
 The size N is given by the depth of the net. According to this table :
 | Number of layers | N |
 | ---- | ---- |
 | 1 | 16 |
 | 2 | 34 |
 | 3 | 70 |
 | 4 | 142 |
 | 5 | 286 |
 | 6 | 574 |
 The number of layers actually means the number of layers with `kernel=(4,4)`, `padding=(1,1)` and `stride=(2,2)`. These layers are followed by 2 layers with `kernel=(4,4)`, `padding=(1,1)` and `stride=(1,1)`.
 In our case we are going to create a 70x70 PatchGAN.
 %% Cell type:markdown id: tags:
 Let's first create a few helping classes.
 %% Cell type:code id: tags:
 ``` python
 class conv_block(nn.Module):
    def __init__(self, in_ch, out_ch, use_batchnorm=True, stride=2):
        super(conv_block, self).__init__()
        if use_batchnorm:
            self.conv = nn.Sequential(
                nn.Conv2d(in_ch, out_ch, kernel_size=4, padding=1, stride=stride),
                nn.BatchNorm2d(out_ch),
                nn.LeakyReLU(negative_slope=0.2, inplace=True)
            )
        else:
            self.conv = nn.Sequential(
                nn.Conv2d(in_ch, out_ch, kernel_size=4, padding=1, stride=stride),
                nn.LeakyReLU(negative_slope=0.2, inplace=True)
            )
    def forward(self, x):
        x = self.conv(x)
        return x
 class out_block(nn.Module):
    def __init__(self, in_ch, out_ch):
        super(out_block, self).__init__()
        self.conv = nn.Sequential(
            nn.Conv2d(in_ch, 1, kernel_size=4, padding=1, stride=1),
            nn.Sigmoid()
        )
    def forward(self, x):
        x = self.conv(x)
        return x
 ```
 %% Cell type:markdown id: tags:
 Now let's create the Patch GAN discriminator.
 As we want a 70x70 Patch GAN, the architecture will be as follows :
 ```
 1. C64  - K4, P1, S2
 2. C128 - K4, P1, S2
 3. C256 - K4, P1, S2
 4. C512 - K4, P1, S1
 5. C1   - K4, P1, S1 (output)
 ```
 Where Ck denotes a convolution block with k filters, Kk a kernel of size k, Pk is the padding size and Sk the stride applied.
 *Note :* For the first layer, we do not use batchnorm.
 %% Cell type:markdown id: tags:
 <font color='red'>**Question 3**</font>
 Knowing input images will be 256x256 with 3 channels each, how many parameters are there to learn ?
 %% Cell type:code id: tags:
 ``` python
 class PatchGAN(nn.Module):
    def __init__(self, n_channels, n_classes):
        super(PatchGAN, self).__init__()
        # TODO :
        # create the 4 first layers named conv1 to conv4
        self.conv1 =
        self.conv2 =
        self.conv3 =
        self.conv4 =
        # output layer
        self.out = out_block(512, n_classes)
    def forward(self, x1, x2):
        x = torch.cat([x2, x1], dim=1)
        x = self.conv1(x)
        x = self.conv2(x)
        x = self.conv3(x)
        x = self.conv4(x)
        x = self.out(x)
        return x
 ```
 %% Cell type:code id: tags:
 ``` python
 # We have 6 input channels as we concatenate 2 images (with 3 channels each)
 discriminator = PatchGAN(6,1)
 discriminator
 ```
 %% Cell type:markdown id: tags:
 You should now have a working discriminator.
 %% Cell type:markdown id: tags:
 ### Loss functions
 As we have seen in the choice of the various architectures for this GAN, the issue is to map both low and high frequencies.
 To tackle this problem, this GAN rely on the architecture to map the high frequencies (U-Net + PatchGAN) and the loss function to learn low frequencies features. The global loss function will indeed be made of 2 parts :
 * the first part to map hight frequencies, will try to optimize the mean squared error of the GAN.
 * the second part to map low frequencies, will minimize the $\mathcal{L}_1$ norm of the generated picture.
 So the loss can be defined as $$ G^* = arg\ \underset{G}{min}\ \underset{D}{max}\ \mathcal{L}_{cGAN}(G,D) + \lambda \mathcal{L}_1(G)$$
 %% Cell type:code id: tags:
 ``` python
 # Loss functions
 criterion_GAN = torch.nn.MSELoss()
 criterion_pixelwise = torch.nn.L1Loss()
 # Loss weight of L1 pixel-wise loss between translated image and real image
 lambda_pixel = 100
 ```
 %% Cell type:markdown id: tags:
 ### Training and evaluating models
 %% Cell type:code id: tags:
 ``` python
 # parameters
 epoch = 0 #  epoch to start training from
 n_epoch = 200  #  number of epochs of training
 batch_size =10  #  size of the batches
 lr = 0.0002 #  adam: learning rate
 b1 =0.5  #  adam: decay of first order momentum of gradient
 b2 = 0.999  # adam: decay of first order momentum of gradient
 decay_epoch = 100  # epoch from which to start lr decay
 img_height = 256  # size of image height
 img_width = 256  # size of image width
 channels = 3  # number of image channels
 sample_interval = 500 # interval between sampling of images from generators
 checkpoint_interval = -1 # interval between model checkpoints
 cuda = True if torch.cuda.is_available() else False # do you have cuda ?
 ```
 %% Cell type:markdown id: tags:
 Download the dataset.
 %% Cell type:code id: tags:
 ``` python
 import urllib.request
 from tqdm import tqdm
 import os
 import zipfile
 def download_hook(t):
    """Wraps tqdm instance.
    Don't forget to close() or __exit__()
    the tqdm instance once you're done with it (easiest using `with` syntax).
    Example
    -------
    >>> with tqdm(...) as t:
    ...     reporthook = my_hook(t)
    ...     urllib.request.urlretrieve(..., reporthook=reporthook)
    """
    last_b = [0]
    def update_to(b=1, bsize=1, tsize=None):
        """
        b  : int, optional
            Number of blocks transferred so far [default: 1].
        bsize  : int, optional
            Size of each block (in tqdm units) [default: 1].
        tsize  : int, optional
            Total size (in tqdm units). If [default: None] remains unchanged.
        """
        if tsize is not None:
            t.total = tsize
        t.update((b - last_b[0]) * bsize)
        last_b[0] = b
    return update_to
 def download(url, save_dir):
    filename = url.split('/')[-1]
    with tqdm(unit = 'B', unit_scale = True, unit_divisor = 1024, miniters = 1, desc = filename) as t:
        urllib.request.urlretrieve(url, filename = os.path.join(save_dir, filename), reporthook = download_hook(t), data = None)
 if __name__ == '__main__':
    # Download ground truth
    if not os.path.exists("CMP_facade_DB_base.zip"):
        download("http://cmp.felk.cvut.cz/~tylecr1/facade/CMP_facade_DB_base.zip", "./")
    # Extract in the correct folder
    with zipfile.ZipFile("CMP_facade_DB_base.zip", 'r') as zip_ref:
        zip_ref.extractall("./facades")
        os.rename("./facades/base", "./facades/train")
    # Download ground truth
    if not os.path.exists("CMP_facade_DB_extended.zip"):
        download("http://cmp.felk.cvut.cz/~tylecr1/facade/CMP_facade_DB_extended.zip", "./")
    # Extract in the correct folder
    with zipfile.ZipFile("CMP_facade_DB_extended.zip", 'r') as zip_ref:
        zip_ref.extractall("./facades")
        os.rename("./facades/extended", "./facades/val")
 ```
 %% Cell type:markdown id: tags:
 Configure the dataloader
 %% Cell type:code id: tags:
 ``` python
 class ImageDataset(Dataset):
    def __init__(self, root, transforms_=None, mode='train'):
        self.transform = transforms.Compose(transforms_)
        self.files_img = sorted(glob.glob(os.path.join(root, mode) + '/*.jpg'))
        if mode == 'val':
            self.files_img.extend(
                sorted(glob.glob(os.path.join(root, 'val') + '/*.jpg')))
        self.files_mask = sorted(glob.glob(os.path.join(root, mode) + '/*.png'))
        if mode == 'val':
            self.files_mask.extend(
                sorted(glob.glob(os.path.join(root, 'val') + '/*.png')))
        assert len(self.files_img) == len(self.files_mask)
    def __getitem__(self, index):
        img = Image.open(self.files_img[index % len(self.files_img)])
        mask = Image.open(self.files_mask[index % len(self.files_img)])
        mask = mask.convert('RGB')
        img = self.transform(img)
        mask = self.transform(mask)
        return img, mask
    def __len__(self):
        return len(self.files_img)
 # Configure dataloaders
 transforms_ = [transforms.Resize((img_height, img_width), Image.BICUBIC),
               transforms.ToTensor()]  # transforms.Normalize((0.5,0.5,0.5), (0.5,0.5,0.5))
 dataloader = DataLoader(ImageDataset("facades", transforms_=transforms_),
                        batch_size=16, shuffle=True)
 val_dataloader = DataLoader(ImageDataset("facades", transforms_=transforms_, mode='val'),
                            batch_size=8, shuffle=False)
 # Tensor type
 Tensor = torch.cuda.FloatTensor if cuda else torch.FloatTensor
 ```
 %% Cell type:markdown id: tags:
 Check the loading works and a few helper functions
 %% Cell type:code id: tags:
 ``` python
 def plot2x2Array(image, mask):
    f, axarr = plt.subplots(1, 2)
    axarr[0].imshow(image)
    axarr[1].imshow(mask)
    axarr[0].set_title('Image')
    axarr[1].set_title('Mask')
 def reverse_transform(image):
    image = image.numpy().transpose((1, 2, 0))
    image = np.clip(image, 0, 1)
    image = (image * 255).astype(np.uint8)
    return image
 def plot2x3Array(image, mask,predict):
    f, axarr = plt.subplots(1,3,figsize=(15,15))
    axarr[0].imshow(image)
    axarr[1].imshow(mask)
    axarr[2].imshow(predict)
    axarr[0].set_title('input')
    axarr[1].set_title('real')
    axarr[2].set_title('fake')
 ```
 %% Cell type:code id: tags:
 ``` python
 image, mask = next(iter(dataloader))
 image = reverse_transform(image[0])
 mask = reverse_transform(mask[0])
 plot2x2Array(image, mask)
 ```
 %% Cell type:markdown id: tags:
 Initialize our GAN
 %% Cell type:code id: tags:
 ``` python
 # Calculate output of image discriminator (PatchGAN)
 patch = (1, img_height//2**3-2, img_width//2**3-2)
 if cuda:
    generator = generator.cuda()
    discriminator = discriminator.cuda()
    criterion_GAN.cuda()
    criterion_pixelwise.cuda()
 # Optimizers
 optimizer_G = torch.optim.Adam(generator.parameters(), lr=lr, betas=(b1, b2))
 optimizer_D = torch.optim.Adam(discriminator.parameters(), lr=lr, betas=(b1, b2))
 ```
 %% Cell type:markdown id: tags:
 Start training
 %% Cell type:code id: tags:
 ``` python
 def save_model(epoch):
    # save your work
    torch.save({
                'epoch': epoch,
                'model_state_dict': generator.state_dict(),
                'optimizer_state_dict': optimizer_G.state_dict(),
                'loss': loss_G,
                }, 'generator_'+str(epoch)+'.pth')
    torch.save({
                'epoch': epoch,
                'model_state_dict': discriminator.state_dict(),
                'optimizer_state_dict': optimizer_D.state_dict(),
                'loss': loss_D,
                }, 'discriminator_'+str(epoch)+'.pth')
 def weights_init_normal(m):
  classname = m.__class__.__name__
  if classname.find('Conv') != -1:
      torch.nn.init.normal_(m.weight.data, 0.0, 0.02)
  elif classname.find('BatchNorm2d') != -1:
      torch.nn.init.normal_(m.weight.data, 1.0, 0.02)
      torch.nn.init.constant_(m.bias.data, 0.0)
 ```
 %% Cell type:markdown id: tags:
 <font color='red'>Complete the loss function </font>  in the following training code and train your network:
 %% Cell type:code id: tags:
 ``` python
 # ----------
 #  Training
 # ----------
 losses = []
 num_epochs = 200
 # Initialize weights
 generator.apply(weights_init_normal)
 discriminator.apply(weights_init_normal)
 epoch_D = 0
 epoch_G = 0
 # train the network
 discriminator.train()
 generator.train()
 print_every = 400
 for epoch in range(epoch_G, num_epochs):
    for i, batch in enumerate(dataloader):
        # Model inputs
        real_A = Variable(batch[0].type(Tensor))
        real_B = Variable(batch[1].type(Tensor))
        # Adversarial ground truths
        valid = Variable(Tensor(np.ones((real_B.size(0), *patch))), requires_grad=False)
        fake = Variable(Tensor(np.zeros((real_B.size(0), *patch))), requires_grad=False)
        # ------------------
        #  Train Generators
        # ------------------
        optimizer_G.zero_grad()
        # GAN loss
        # TO DO: Put here your GAN loss
        # Pixel-wise loss
        # TO DO: Put here your pixel loss
        # Total loss
        # TO DO: Put here your total loss
        loss_G.backward()
        optimizer_G.step()
        # ---------------------
        #  Train Discriminator
        # ---------------------
        optimizer_D.zero_grad()
        # Real loss
        pred_real = discriminator(real_A, real_B)
        loss_real = criterion_GAN(pred_real, valid)
        # Fake loss
        pred_fake = discriminator(fake_A.detach(), real_B)
        loss_fake = criterion_GAN(pred_fake, fake)
        # Total loss
        loss_D = 0.5 * (loss_real + loss_fake)
        loss_D.backward()
        optimizer_D.step()
        # Print some loss stats
        if i % print_every == 0:
            # print discriminator and generator loss
            print('Epoch [{:5d}/{:5d}] | d_loss: {:6.4f} | g_loss: {:6.4f}'.format(
                    epoch+1, num_epochs, loss_D.item(), loss_G.item()))
    ## AFTER EACH EPOCH##
    # append discriminator loss and generator loss
    losses.append((loss_D.item(), loss_G.item()))
    if epoch % 100 == 0:
        print('Saving model...')
        save_model(epoch)
 ```
 %% Cell type:markdown id: tags:
 Observation of the loss along the training
 %% Cell type:code id: tags:
 ``` python
 fig, ax = plt.subplots()
 losses = np.array(losses)
 plt.plot(losses.T[0], label='Discriminator')
 plt.plot(losses.T[1], label='Generator')
 plt.title("Training Losses")
 plt.legend()
 ```
 %% Cell type:markdown id: tags:
 If the training takes too much time, you can use a pretrained model in the meantime, to evaluate its performance.
 It is available at : https://partage.liris.cnrs.fr/index.php/s/xwEFmxn9ANeq4zY
 %% Cell type:markdown id: tags:
 ### Evaluate your cGAN
 %% Cell type:code id: tags:
 ``` python
 def load_model(epoch=200):
    if 'generator_'+str(epoch)+'.pth' in os.listdir() and 'discriminator_'+str(epoch)+'.pth' in os.listdir():
        if cuda:
            checkpoint_generator = torch.load('generator_'+str(epoch)+'.pth')
        else:
            checkpoint_generator = torch.load('generator_'+str(epoch)+'.pth', map_location='cpu')
        generator.load_state_dict(checkpoint_generator['model_state_dict'])
        optimizer_G.load_state_dict(checkpoint_generator['optimizer_state_dict'])
        epoch_G = checkpoint_generator['epoch']
        loss_G = checkpoint_generator['loss']
        if cuda:
            checkpoint_discriminator = torch.load('discriminator_'+str(epoch)+'.pth')
        else:
            checkpoint_discriminator = torch.load('discriminator_'+str(epoch)+'.pth', map_location='cpu')
        discriminator.load_state_dict(checkpoint_discriminator['model_state_dict'])
        optimizer_D.load_state_dict(checkpoint_discriminator['optimizer_state_dict'])
        epoch_D = checkpoint_discriminator['epoch']
        loss_D = checkpoint_discriminator['loss']
    else:
        print('There isn\' a training available with this number of epochs')
 ```
 %% Cell type:code id: tags:
 ``` python
 load_model(epoch=200)
 # switching mode
 generator.eval()
 ```
 %% Cell type:code id: tags:
 ``` python
 # show a sample evaluation image on the training base
 image, mask = next(iter(dataloader))
 output = generator(mask.type(Tensor))
 output = output.view(16, 3, 256, 256)
 output = output.cpu().detach()
 for i in range(8):
    image_plot = reverse_transform(image[i])
    output_plot = reverse_transform(output[i])
    mask_plot = reverse_transform(mask[i])
    plot2x3Array(mask_plot,image_plot,output_plot)
 ```
 %% Cell type:code id: tags:
 ``` python
 # show a sample evaluation image on the validation dataset
 image, mask = next(iter(val_dataloader))
 output = generator(mask.type(Tensor))
 output = output.view(8, 3, 256, 256)
 output = output.cpu().detach()
 for i in range(8):
    image_plot = reverse_transform(image[i])
    output_plot = reverse_transform(output[i])
    mask_plot = reverse_transform(mask[i])
    plot2x3Array(mask_plot,image_plot,output_plot)
 ```
 %% Cell type:markdown id: tags:
 <font color='red'>**Question 4**</font>
 Compare results for 100 and 200 epochs
 %% Cell type:code id: tags:
 ``` python
 # TO DO : Your code here to load and evaluate with a few samples
 #         a model after 100 epochs
 ```
 %% Cell type:code id: tags:
 ``` python
 # And finally :
 if cuda:
    torch.cuda.empty_cache()
 ```
 %% Cell type:markdown id: tags:
 # How to submit your Work ?
-This work must be done individually. The expected output is a repository named gan-cgan on https://gitlab.ec-lyon.fr. It must contain your notebook (or python files) and a README.md file that explains briefly the successive steps of the project. The last commit is due before 11:59 pm on Wednesday, March 29, 2023. Subsequent commits will not be considered.
+This work must be done individually. The expected output is a private repository named gan-cgan on https://gitlab.ec-lyon.fr. It must contain your notebook (or python files) and a README.md file that explains briefly the successive steps of the project. Don't forget to add your teacher as developer member of the project. The last commit is due before 11:59 pm on Monday, April 1st, 2024. Subsequent commits will not be considered.