Book Image

Hands-On Convolutional Neural Networks with TensorFlow

By : Iffat Zafar, Giounona Tzanidou, Richard Burton, Nimesh Patel, Leonardo Araujo
Book Image

Hands-On Convolutional Neural Networks with TensorFlow

By: Iffat Zafar, Giounona Tzanidou, Richard Burton, Nimesh Patel, Leonardo Araujo

Overview of this book

Convolutional Neural Networks (CNN) are one of the most popular architectures used in computer vision apps. This book is an introduction to CNNs through solving real-world problems in deep learning while teaching you their implementation in popular Python library - TensorFlow. By the end of the book, you will be training CNNs in no time! We start with an overview of popular machine learning and deep learning models, and then get you set up with a TensorFlow development environment. This environment is the basis for implementing and training deep learning models in later chapters. Then, you will use Convolutional Neural Networks to work on problems such as image classification, object detection, and semantic segmentation. After that, you will use transfer learning to see how these models can solve other deep learning problems. You will also get a taste of implementing generative models such as autoencoders and generative adversarial networks. Later on, you will see useful tips on machine learning best practices and troubleshooting. Finally, you will learn how to apply your models on large datasets of millions of images.
Table of Contents (17 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

Evaluation Metrics


We also need to be careful when selecting the evaluation metrics for our model. Suppose that we have two algorithms with accuracies of 98% and 96% respectively, for a dog/not dog classification problem. At first glance the algorithms look like they both have similar performance. Let us remember that classification accuracy is defined as the number of correct predictions made divided by the total number of predictions made. In other words the number of True Positive (TP) and True Negative (TN) prediction, divided by the total number of predictions. However, it might be the case that along with dog images we are also getting large number of background or similar looking objects falsely classified as dogs, commonly known as false positives (FP). Another undesirable behavior could be that many dog images are misclassified as negatives or False Negative (FN). Clearly, by definition the classification accuracy does not capture the notion of false positives or false negatives...