YOLO

What is YOLO (You Only Look Once)? YOLO Explained

YOLO (You Only Look Once) is a real-time object detection algorithm that can detect and classify multiple objects in an image or video frame. It gained popularity for its speed and accuracy in object detection tasks.

The YOLO algorithm follows a single-pass approach, where it divides the input image into a grid and predicts bounding boxes and class probabilities directly from the grid cells. Here are the key steps involved in YOLO object detection:

Input Image: YOLO takes an input image and divides it into a grid of cells. Each cell is responsible for predicting objects located in that region.

Anchor Boxes: Before training, YOLO defines a set of anchor boxes of different sizes and aspect ratios. These anchor boxes are used to predict bounding boxes around objects.

Convolutional Neural Network (CNN): YOLO uses a CNN architecture to extract features from the input image. The network is typically pre-trained on a large dataset like ImageNet to learn general object representations.

Prediction: For each grid cell, YOLO predicts bounding boxes and class probabilities. Each bounding box consists of four values: the coordinates of the top-left corner, width, and height. The class probabilities represent the likelihood of an object belonging to a particular class.

Non-Maximum Suppression (NMS): Since YOLO can generate multiple overlapping bounding box predictions for the same object, NMS is used to eliminate redundant detections. It selects the most confident bounding box and suppresses others that have a high overlap.

Output: The final output of YOLO is a list of bounding boxes with associated class labels and confidence scores.

One advantage of YOLO is its real-time capability, as it processes images and videos quickly, making it suitable for applications that require fast object detection. YOLO also handles object occlusion and small object detection relatively well. However, it may struggle with accurately localizing small objects compared to other algorithms like Faster R-CNN.

YOLO has seen various iterations, with the latest versions being YOLOv4 and YOLOv5. These newer versions introduce improvements to the architecture and training techniques, resulting in better performance in terms of accuracy and speed.

Overall, YOLO is widely used in various applications such as autonomous driving, surveillance, robotics, and object tracking, where real-time object detection is crucial.