Abstract In recent years, one of the most popular techniques in the computer vision community has been the deep learning technique. As a data-driven technique, deep model requires enormous amounts of accurately labelled training data, which is often inaccessible in many real-world applications. A data-space solution is Data Augmentation (DA), that can artificially generate new images out of original samples. Image augmentation strategies can vary by dataset, as different data types might require different augmentations to facilitate model training. However, the design of DA policies has been largely decided by the human experts with domain knowledge, which is considered to be highly subjective and error-prone. To mitigate such problem, a novel direction is to automatically learn the image augmentation policies from the given dataset using Automated Data Augmentation (AutoDA) techniques. The goal of AutoDA models is to find the optimal DA policies that can maximize the model performance gains. This survey discusses the underlying reasons of the emergence of AutoDA technology from the perspective of image classification. We identify three key components of a standard AutoDA model: a search space, a search algorithm and an evaluation function. Based on their architecture, we provide a systematic taxonomy of existing image AutoDA approaches. This paper presents the major works in AutoDA field, discussing their pros and cons, and proposing several potential directions for future improvements.

Crowd counting is required for many situations and has historically been undertaken using approximate (manual) estimations and measures. Deep learning allows to improve this situation. Modern crowd counting models are commonly based on pixel-wise density maps using deep convolutional neural networks (CNNs) comprising tens of millions of parameters. These models require high-performance GPUs for training and subsequent usage and inference. As such, these models are difficult to deliver to edge devices that have limited computing resources such as surveillance cameras, mobile phones and Internet of Things (IoT)-type devices. This paper proposes a new method to tackle this issue based on three key components: feature fusion, Bayesian Loss [19] and datasets utilising bounding-box annotations to increase the efficiency of the crowd counting task. Experiments show that the proposed method can not only provide accuracy close to the latest state-of-the-art deep learning models, but support real-time inference in edge devices offering limited computational capacity.

Computer vision opportunities based on deep learning have seen an increasing trend in recent years through the proliferation of convolutional neural networks (CNN) and related deep learning models. However, limited training data often constrains the performance and accuracy of such models - this is a common situation for many detection and classification tasks especially in the ecological field. In this paper, we present a case study of how one such model: You Only Look Once (YOLO) version 5 can be applied to individual feral cat identification using a small unbalanced data set. We describe the procedures for preparing the training and validation data set, training the model using data augmentation and transfer learning techniques, and testing the model on both in-distribution and out-of-distribution samples. We explore the effectiveness of data augmentation methods including basic image manipulations and more advanced augmentation techniques that are now available.

Hexagonal CNN models have shown superior performance in applications such as IACT data analysis and aerial scene classification due to their better rotation symmetry and reduced anisotropy. In order to realize hexagonal processing, existing studies mainly use the ZeroOut method to imitate hexagonal processing, which causes substantial memory and computation overheads. We address this deficiency with a novel native hexagonal CNN framework named HexCNN. HexCNN takes hexagon-shaped input and performs forward and backward propagation on the original form of the input based on hexagon-shaped filters, hence avoiding computation and memory overheads caused by imitation. For applications with rectangle-shaped input but require hexagonal processing, HexCNN can be applied by padding the input into hexagon-shape as preprocessing. In this case, we show that the time and space efficiency of HexCNN still outperforms existing hexagonal CNN methods substantially. Experimental results show that compared with the state-of-the-art models, which imitate hexagonal processing but using rectangle-shaped filters, HexCNN reduces the training time by up to 42.2%. Meanwhile, HexCNN saves the memory space cost by up to 25% and 41.7% for loading the input and performing convolution, respectively.