Book Image

Advanced Deep Learning with TensorFlow 2 and Keras - Second Edition

By : Rowel Atienza
Book Image

Advanced Deep Learning with TensorFlow 2 and Keras - Second Edition

By: Rowel Atienza

Overview of this book

Advanced Deep Learning with TensorFlow 2 and Keras, Second Edition is a completely updated edition of the bestselling guide to the advanced deep learning techniques available today. Revised for TensorFlow 2.x, this edition introduces you to the practical side of deep learning with new chapters on unsupervised learning using mutual information, object detection (SSD), and semantic segmentation (FCN and PSPNet), further allowing you to create your own cutting-edge AI projects. Using Keras as an open-source deep learning library, the book features hands-on projects that show you how to create more effective AI with the most up-to-date techniques. Starting with an overview of multi-layer perceptrons (MLPs), convolutional neural networks (CNNs), and recurrent neural networks (RNNs), the book then introduces more cutting-edge techniques as you explore deep neural network architectures, including ResNet and DenseNet, and how to create autoencoders. You will then learn about GANs, and how they can unlock new levels of AI performance. Next, you’ll discover how a variational autoencoder (VAE) is implemented, and how GANs and VAEs have the generative power to synthesize data that can be extremely convincing to humans. You'll also learn to implement DRL such as Deep Q-Learning and Policy Gradient Methods, which are critical to many modern results in AI.
Table of Contents (16 chapters)
14
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15
Index

2. Least-squares GAN (LSGAN)

LSGAN proposes the least squares loss. Figure 5.2.1 demonstrates why the use of a sigmoid cross-entropy loss in GANs results in poorly generated data quality:

Figure 5.2.1: Both real and fake sample distributions divided by their respective decision boundaries: sigmoid and least squares

Ideally, the fake sample distribution should be as close as possible to the true samples' distribution. However, for GANs, once the fake samples are already on the correct side of the decision boundary, the gradients vanish.

This prevents the generator from having enough motivation to improve the quality of the generated fake data. Fake samples far from the decision boundary will no longer attempt to move closer to the true samples' distribution. Using the least squares loss function, the gradients do not vanish as long as the fake sample distribution is far from the real samples' distribution. The generator will strive to improve...