{ "cells": [ { "cell_type": "code", "execution_count": null, "metadata": { "id": "_jQ1tEQCxwRx" }, "outputs": [], "source": [ "##### Copyright 2019 The TensorFlow Authors." ] }, { "cell_type": "code", "execution_count": null, "metadata": { "cellView": "form", "id": "V_sgB_5dx1f1", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "#@title Licensed under the Apache License, Version 2.0 (the \"License\");\n", "# you may not use this file except in compliance with the License.\n", "# You may obtain a copy of the License at\n", "#\n", "# https://www.apache.org/licenses/LICENSE-2.0\n", "#\n", "# Unless required by applicable law or agreed to in writing, software\n", "# distributed under the License is distributed on an \"AS IS\" BASIS,\n", "# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n", "# See the License for the specific language governing permissions and\n", "# limitations under the License." ] }, { "cell_type": "markdown", "metadata": { "id": "rF2x3qooyBTI" }, "source": [ "# 深度卷积生成对抗网络" ] }, { "cell_type": "markdown", "metadata": { "id": "0TD5ZrvEMbhZ" }, "source": [ "\n", " \n", " \n", " \n", " \n", "
在 TensorFlow.org上查看 在 Google Colab 中运行 在 GitHub 上查看源代码 下载笔记本
" ] }, { "cell_type": "markdown", "metadata": { "id": "ITZuApL56Mny" }, "source": [ "本教程演示了如何使用[深度卷积生成对抗网络](https://arxiv.org/pdf/1511.06434.pdf) (DCGAN) 生成手写数字的图像。该代码是使用 [Keras 序列式 API](https://tensorflow.google.cn/guide/keras) 与 `tf.GradientTape` 训练循环编写的。" ] }, { "cell_type": "markdown", "metadata": { "id": "2MbKJY38Puy9" }, "source": [ "## 什么是生成对抗网络?\n", "\n", "[生成对抗网络](https://arxiv.org/abs/1406.2661) (GAN) 是当今计算机科学领域最有趣的想法之一。两个模型通过对抗过程同时训练。*生成器*(“艺术家”)学习创建看起来真实的图像,而*判别器*(“艺术评论家”)学习区分真假图像。\n", "\n", "![生成器和判别器图示](https://github.com/tensorflow/docs/blob/master/site/en/tutorials/generative/images/gan1.png?raw=1)\n", "\n", "训练过程中,*生成器*在生成逼真图像方面逐渐变强,而*判别器*在辨别这些图像的能力上逐渐变强。当*判别器*不再能够区分真实图片和伪造图片时,训练过程达到平衡。\n", "\n", "![生成器和判别器图示二](https://github.com/tensorflow/docs/blob/master/site/en/tutorials/generative/images/gan2.png?raw=1)\n", "\n", "本笔记在 MNIST 数据集上演示了该过程。下方动画展示了当训练了 50 个epoch (全部数据集迭代50次) 时*生成器*所生成的一系列图片。图片从随机噪声开始,随着时间的推移越来越像手写数字。\n", "\n", "![输出样本](https://tensorflow.google.cn/images/gan/dcgan.gif)\n", "\n", "要详细了解 GAN,请参阅 MIT 的[深度学习介绍](http://introtodeeplearning.com/)课程。" ] }, { "cell_type": "markdown", "metadata": { "id": "e1_Y75QXJS6h" }, "source": [ "### Import TensorFlow and other libraries" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "WZKbyU2-AiY-", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "import tensorflow as tf" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "wx-zNbLqB4K8", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "tf.__version__" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "YzTlj4YdCip_", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "# To generate GIFs\n", "!pip install imageio\n", "!pip install git+https://github.com/tensorflow/docs" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "YfIk2es3hJEd", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "import glob\n", "import imageio\n", "import matplotlib.pyplot as plt\n", "import numpy as np\n", "import os\n", "import PIL\n", "from tensorflow.keras import layers\n", "import time\n", "\n", "from IPython import display" ] }, { "cell_type": "markdown", "metadata": { "id": "iYn4MdZnKCey" }, "source": [ "### 加载和准备数据集\n", "\n", "您将使用 MNIST 数据集来训练生成器和判别器。生成器将生成类似于 MNIST 数据集的手写数字。" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "a4fYMGxGhrna", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "(train_images, train_labels), (_, _) = tf.keras.datasets.mnist.load_data()" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "NFC2ghIdiZYE", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "train_images = train_images.reshape(train_images.shape[0], 28, 28, 1).astype('float32')\n", "train_images = (train_images - 127.5) / 127.5 # Normalize the images to [-1, 1]" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "S4PIDhoDLbsZ", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "BUFFER_SIZE = 60000\n", "BATCH_SIZE = 256" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "-yKCCQOoJ7cn", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "# Batch and shuffle the data\n", "train_dataset = tf.data.Dataset.from_tensor_slices(train_images).shuffle(BUFFER_SIZE).batch(BATCH_SIZE)" ] }, { "cell_type": "markdown", "metadata": { "id": "THY-sZMiQ4UV" }, "source": [ "## 创建模型\n", "\n", "生成器和判别器均使用 [Keras Sequential API](https://tensorflow.google.cn/guide/keras#sequential_model) 定义。" ] }, { "cell_type": "markdown", "metadata": { "id": "-tEyxE-GMC48" }, "source": [ "### 生成器\n", "\n", "生成器使用 `tf.keras.layers.Conv2DTranspose`(上采样)层来从种子(随机噪声)中生成图像。以一个使用该种子作为输入的 `Dense` 层开始,然后多次上采样,直至达到所需的 28x28x1 的图像大小。请注意,除了输出层使用双曲正切之外,其他每层均使用 `tf.keras.layers.LeakyReLU` 激活。" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "6bpTcDqoLWjY", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "def make_generator_model():\n", " model = tf.keras.Sequential()\n", " model.add(layers.Dense(7*7*256, use_bias=False, input_shape=(100,)))\n", " model.add(layers.BatchNormalization())\n", " model.add(layers.LeakyReLU())\n", "\n", " model.add(layers.Reshape((7, 7, 256)))\n", " assert model.output_shape == (None, 7, 7, 256) # Note: None is the batch size\n", "\n", " model.add(layers.Conv2DTranspose(128, (5, 5), strides=(1, 1), padding='same', use_bias=False))\n", " assert model.output_shape == (None, 7, 7, 128)\n", " model.add(layers.BatchNormalization())\n", " model.add(layers.LeakyReLU())\n", "\n", " model.add(layers.Conv2DTranspose(64, (5, 5), strides=(2, 2), padding='same', use_bias=False))\n", " assert model.output_shape == (None, 14, 14, 64)\n", " model.add(layers.BatchNormalization())\n", " model.add(layers.LeakyReLU())\n", "\n", " model.add(layers.Conv2DTranspose(1, (5, 5), strides=(2, 2), padding='same', use_bias=False, activation='tanh'))\n", " assert model.output_shape == (None, 28, 28, 1)\n", "\n", " return model" ] }, { "cell_type": "markdown", "metadata": { "id": "GyWgG09LCSJl" }, "source": [ "使用(尚未训练的)生成器创建一张图片。" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "gl7jcC7TdPTG", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "generator = make_generator_model()\n", "\n", "noise = tf.random.normal([1, 100])\n", "generated_image = generator(noise, training=False)\n", "\n", "plt.imshow(generated_image[0, :, :, 0], cmap='gray')" ] }, { "cell_type": "markdown", "metadata": { "id": "D0IKnaCtg6WE" }, "source": [ "### 判别器\n", "\n", "判别器是一个基于 CNN 的图片分类器。" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "dw2tPLmk2pEP", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "def make_discriminator_model():\n", " model = tf.keras.Sequential()\n", " model.add(layers.Conv2D(64, (5, 5), strides=(2, 2), padding='same',\n", " input_shape=[28, 28, 1]))\n", " model.add(layers.LeakyReLU())\n", " model.add(layers.Dropout(0.3))\n", "\n", " model.add(layers.Conv2D(128, (5, 5), strides=(2, 2), padding='same'))\n", " model.add(layers.LeakyReLU())\n", " model.add(layers.Dropout(0.3))\n", "\n", " model.add(layers.Flatten())\n", " model.add(layers.Dense(1))\n", "\n", " return model" ] }, { "cell_type": "markdown", "metadata": { "id": "QhPneagzCaQv" }, "source": [ "使用(尚未训练的)判别器对所生成的图像进行真伪分类。模型将被训练为对真实图像输出正值,对伪造图像输出负值。" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "gDkA05NE6QMs", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "discriminator = make_discriminator_model()\n", "decision = discriminator(generated_image)\n", "print (decision)" ] }, { "cell_type": "markdown", "metadata": { "id": "0FMYgY_mPfTi" }, "source": [ "## 定义损失函数和优化器\n", "\n", "为两个模型定义损失函数和优化器。\n" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "psQfmXxYKU3X", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "# This method returns a helper function to compute cross entropy loss\n", "cross_entropy = tf.keras.losses.BinaryCrossentropy(from_logits=True)" ] }, { "cell_type": "markdown", "metadata": { "id": "PKY_iPSPNWoj" }, "source": [ "### 判别器损失\n", "\n", "该方法量化判别器从判断真伪图片的能力。它将判别器对真实图片的预测值与值全为 1 的数组进行对比,将判别器对伪造(生成的)图片的预测值与值全为 0 的数组进行对比。" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "wkMNfBWlT-PV", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "def discriminator_loss(real_output, fake_output):\n", " real_loss = cross_entropy(tf.ones_like(real_output), real_output)\n", " fake_loss = cross_entropy(tf.zeros_like(fake_output), fake_output)\n", " total_loss = real_loss + fake_loss\n", " return total_loss" ] }, { "cell_type": "markdown", "metadata": { "id": "Jd-3GCUEiKtv" }, "source": [ "### 生成器损失\n", "\n", "生成器的损失可量化其欺骗判别器的能力。直观地说,如果生成器表现良好,判别器会将伪造图像分类为真实图像(或 1)。在此,需要将判别器对生成图像的决策与值全为 1 的数组进行对比。" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "90BIcCKcDMxz", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "def generator_loss(fake_output):\n", " return cross_entropy(tf.ones_like(fake_output), fake_output)" ] }, { "cell_type": "markdown", "metadata": { "id": "MgIc7i0th_Iu" }, "source": [ "判别器和生成器优化器不同,因为您将分别训练两个网络。" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "iWCn_PVdEJZ7", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "generator_optimizer = tf.keras.optimizers.Adam(1e-4)\n", "discriminator_optimizer = tf.keras.optimizers.Adam(1e-4)" ] }, { "cell_type": "markdown", "metadata": { "id": "mWtinsGDPJlV" }, "source": [ "### 保存检查点\n", "\n", "本笔记还演示了如何保存和恢复模型,这在长时间训练任务被中断的情况下比较有帮助。" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "CA1w-7s2POEy", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "checkpoint_dir = './training_checkpoints'\n", "checkpoint_prefix = os.path.join(checkpoint_dir, \"ckpt\")\n", "checkpoint = tf.train.Checkpoint(generator_optimizer=generator_optimizer,\n", " discriminator_optimizer=discriminator_optimizer,\n", " generator=generator,\n", " discriminator=discriminator)" ] }, { "cell_type": "markdown", "metadata": { "id": "Rw1fkAczTQYh" }, "source": [ "## 定义训练循环\n" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "NS2GWywBbAWo", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "EPOCHS = 50\n", "noise_dim = 100\n", "num_examples_to_generate = 16\n", "\n", "# You will reuse this seed overtime (so it's easier)\n", "# to visualize progress in the animated GIF)\n", "seed = tf.random.normal([num_examples_to_generate, noise_dim])" ] }, { "cell_type": "markdown", "metadata": { "id": "jylSonrqSWfi" }, "source": [ "训练循环在生成器接收到一个随机种子作为输入时开始。该种子用于生成一个图像。判别器随后被用于对真实图像(选自训练集)和伪造图像(由生成器生成)进行分类。为每一个模型计算损失,并使用梯度更新生成器和判别器。" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "3t5ibNo05jCB", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "# Notice the use of `tf.function`\n", "# This annotation causes the function to be \"compiled\".\n", "@tf.function\n", "def train_step(images):\n", " noise = tf.random.normal([BATCH_SIZE, noise_dim])\n", "\n", " with tf.GradientTape() as gen_tape, tf.GradientTape() as disc_tape:\n", " generated_images = generator(noise, training=True)\n", "\n", " real_output = discriminator(images, training=True)\n", " fake_output = discriminator(generated_images, training=True)\n", "\n", " gen_loss = generator_loss(fake_output)\n", " disc_loss = discriminator_loss(real_output, fake_output)\n", "\n", " gradients_of_generator = gen_tape.gradient(gen_loss, generator.trainable_variables)\n", " gradients_of_discriminator = disc_tape.gradient(disc_loss, discriminator.trainable_variables)\n", "\n", " generator_optimizer.apply_gradients(zip(gradients_of_generator, generator.trainable_variables))\n", " discriminator_optimizer.apply_gradients(zip(gradients_of_discriminator, discriminator.trainable_variables))" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "2M7LmLtGEMQJ", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "def train(dataset, epochs):\n", " for epoch in range(epochs):\n", " start = time.time()\n", "\n", " for image_batch in dataset:\n", " train_step(image_batch)\n", "\n", " # Produce images for the GIF as you go\n", " display.clear_output(wait=True)\n", " generate_and_save_images(generator,\n", " epoch + 1,\n", " seed)\n", "\n", " # Save the model every 15 epochs\n", " if (epoch + 1) % 15 == 0:\n", " checkpoint.save(file_prefix = checkpoint_prefix)\n", "\n", " print ('Time for epoch {} is {} sec'.format(epoch + 1, time.time()-start))\n", "\n", " # Generate after the final epoch\n", " display.clear_output(wait=True)\n", " generate_and_save_images(generator,\n", " epochs,\n", " seed)" ] }, { "cell_type": "markdown", "metadata": { "id": "2aFF7Hk3XdeW" }, "source": [ "**生成与保存图片**\n" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "RmdVsmvhPxyy", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "def generate_and_save_images(model, epoch, test_input):\n", " # Notice `training` is set to False.\n", " # This is so all layers run in inference mode (batchnorm).\n", " predictions = model(test_input, training=False)\n", "\n", " fig = plt.figure(figsize=(4, 4))\n", "\n", " for i in range(predictions.shape[0]):\n", " plt.subplot(4, 4, i+1)\n", " plt.imshow(predictions[i, :, :, 0] * 127.5 + 127.5, cmap='gray')\n", " plt.axis('off')\n", "\n", " plt.savefig('image_at_epoch_{:04d}.png'.format(epoch))\n", " plt.show()" ] }, { "cell_type": "markdown", "metadata": { "id": "dZrd4CdjR-Fp" }, "source": [ "## 训练模型\n", "\n", "调用上面定义的 `train()` 方法来同时训练生成器和判别器。注意,训练 GANs 可能是棘手的。重要的是,生成器和判别器不能够互相压制对方(例如,他们以相似的学习率训练)。\n", "\n", "在训练之初,生成的图片看起来像是随机噪声。随着训练过程的进行,生成的数字将越来越真实。在大概 50 个 epoch 之后,这些图片看起来像是 MNIST 数字。使用 Colab 中的默认设置可能需要大约 1 分钟每 epoch。" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "Ly3UN0SLLY2l", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "train(train_dataset, EPOCHS)" ] }, { "cell_type": "markdown", "metadata": { "id": "rfM4YcPVPkNO" }, "source": [ "恢复最新的检查点。" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "XhXsd0srPo8c", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "checkpoint.restore(tf.train.latest_checkpoint(checkpoint_dir))" ] }, { "cell_type": "markdown", "metadata": { "id": "P4M_vIbUi7c0" }, "source": [ "## 创建 GIF\n" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "WfO5wCdclHGL", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "# Display a single image using the epoch number\n", "def display_image(epoch_no):\n", " return PIL.Image.open('image_at_epoch_{:04d}.png'.format(epoch_no))" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "5x3q9_Oe5q0A", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "display_image(EPOCHS)" ] }, { "cell_type": "markdown", "metadata": { "id": "NywiH3nL8guF" }, "source": [ "使用训练过程中生成的图片通过 `imageio` 生成动态 gif" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "IGKQgENQ8lEI", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "anim_file = 'dcgan.gif'\n", "\n", "with imageio.get_writer(anim_file, mode='I') as writer:\n", " filenames = glob.glob('image*.png')\n", " filenames = sorted(filenames)\n", " for filename in filenames:\n", " image = imageio.imread(filename)\n", " writer.append_data(image)\n", " image = imageio.imread(filename)\n", " writer.append_data(image)" ] }, { "cell_type": "code", "execution_count": null, "metadata": { "id": "ZBwyU6t2Wf3g", "vscode": { "languageId": "python" } }, "outputs": [], "source": [ "import tensorflow_docs.vis.embed as embed\n", "embed.embed_file(anim_file)" ] }, { "cell_type": "markdown", "metadata": { "id": "k6qC-SbjK0yW" }, "source": [ "## 下一步\n" ] }, { "cell_type": "markdown", "metadata": { "id": "xjjkT9KAK6H7" }, "source": [ "本教程展示了编写和训练 GAN 所需的完整代码。下一步,您可能想尝试不同的数据集,例如 [Kaggle 上提供的](https://www.kaggle.com/jessicali9530/celeba-dataset) Large-scale Celeb Faces Attributes (CelebA) 人脸识别数据集。要详细了解 GAN,请参阅 [NIPS 2016 教程:生成对抗网络](https://arxiv.org/abs/1701.00160)。\n" ] } ], "metadata": { "accelerator": "GPU", "colab": { "collapsed_sections": [], "name": "dcgan.ipynb", "toc_visible": true }, "kernelspec": { "display_name": "Python 3", "name": "python3" } }, "nbformat": 4, "nbformat_minor": 0 }