Image Classification is one of the most fundamental tasks that a computer can perform, and it is the core of what makes Computer Vision so valuable. It aims to digitally explain the features in an image to the machine so that it can interpret them and determine what the picture is about. It is often combined with image localization to enable the system to find the objects present in the image and then make a decision on which object category the picture belongs to. There are two main types of image classification: supervised and unsupervised. The former requires that the model be fed a set of reference images and their associated labels (the name of each distinct object). Once trained, it will be able to identify the classes in new images by analyzing pixel patterns and determining whether they match those of the labeled training images.
Unsupervised classification is a more complex process that relies on a statistical difference between the pixel patterns of different classes. This process is used for more generalized objects such as plants or animals. To get the best results, it is important to carefully pre-process the image to remove any unwanted pixel features. This includes reading the image, resizing it, and performing some data augmentation such as removing noise, reversing color channels, smoothing, equalization, and Gaussian blurring. It is also necessary to define an appropriate classification schema for the target image.
The primary tools used for image classification are Deep Learning algorithms. This advanced field of Machine Learning enables computers to understand and interpret patterns in a way that can surpass even the most experienced human analysts. It uses neural networks with a high number of layers which are modeled after the human brain and eyes to achieve astounding levels of recognition and classification.
For example, a deep CNN model might take a set of region proposals as input and pass them through a custom layer called a region of interest pooling layer that extracts the regions of interest in the image. Then, the output from this layer is analyzed by a fully connected neural network to produce a prediction. This is done in a fashion that aims to mimic the human brain to avoid overfitting and ensure accuracy. With these powerful tools, Machine Learning is enabling us to detect, recognize and categorize more items in a single image than ever before. The applications of this technology are vast and include environmental and agricultural monitoring, remote sensing, disaster control, geographic mapping, surveillance, item identification and more. In a world where visuals are more prevalent than ever, the power of this technology is only growing.