Real-Time Object Detection Using YOLOv8: Step-by-Step Walkthrough

This article discusses the advancements in the field of object detection by explaining the latest breakthroughs that happened with the evolution of YOLO. The article covers YOLO architecture and the latest models such as YOLOv8 and YOLONAS, comparing and contrasting the advantages and improvements these techniques have over other approaches.

As AI takes over the software industry and many of its domains, one of the biggest advancements in the field of computer vision has been the advent of YOLO. It has made it possible for every image or video that ever existed to be processed by machines – by the power of machine learning – and offer valuable insights into what the content of the image is. Many softwares and organisations now use YOLO in their AI products.

In this article, we provide a step-by-step guide to understand the technology behind YOLO.

Object Detection in Computer Vision

In the field of computer vision where you can process any image, video – in the form of a live video or recordings, using AI to extract insights from this data – has become very crucial for a lot of applications. One such task defined to extract objects from a given image is called Object Detection. Given an input image, an object detection task will detect the area where an object lies in the image and classify it into a known label.

Traditional approaches used image segmentation and other techniques that often used the understanding of the pixel characteristics of an image. Modern techniques use the power of neural networks to understand the image and the subjects in it. CNNs (Convolutional Neural Networks) are a common neural network technique used in modern-day object detection systems.

Since a video can also be analysed with multiple frames that are images, Object Detection has  widespread application in image and video analysis for self-driving cars, traffic monitoring, surveillance, augmented reality, and much more. 

What Is YOLO? How Does It work?

YOLO is an algorithm and is an acronym for You Only Look Once. With one look into an image or a video, it can figure out the objects in the input. The foundational principles of YOLO rely on CNNs – by using an FCNN (Fully Convolutional Neural Network) and passing the image through it to perform the predictions.

YOLO outperformed many other algorithms for the object detection task. While other algorithms require multiple scanning procedures, the single scan by YOLO proves to be faster, which makes it highly efficient for real-time image processing. Hence it is popular among products that aim to have state-of-the-art image processing capabilities under their hood. 

The working of YOLO can be described with the following steps:

• A neural network model divides the image into regions.
• The model looks at each region and assigns scores (i.e., probabilities) and predict bounding boxes.
• The regions with higher scores are considered to have a detection, and the rest are discarded.
• The score and bounding box belongs to a class, which we now have as the detected object.

How to Use YOLOv8 on E2E Networks

In this section, we can test out how YOLO performs by using some pre-trained weights from the neural network. The cloud platform of our choice will be E2E Networks. The pre-trained weights capture the knowledge gained by the neural network during training and this can be reused in carrying out our detection tasks.

For implementing YOLO, we have to install Ultralytics. Ultralytics has an open-source framework which will help our object detection tasks with YOLO smoother. The Ultralytics project is continuously maintained, and includes releases that contain the latest versions of YOLO. 
Excited to test YOLO out? Here are the steps.

Step 1 - Launching E2E Node

1. Create an Ubuntu 22.04 GPU node on E2E

2. Select a 40GB Machine and hit Create.

3. Check on Enable Backup and hit Create. 

4. The node will now be created with the following specifications:

1. Login to the E2E server using ssh via terminal:

ssh username@IP_address

Step 2 - Installing Ultralytics

Make sure your system has Python and Pip installed.

We can install Ultralytics via Pip.

pip install ultralytics

In case you want the most bleeding edge updates to Ultralytics, you can clone the repo using Git and install from source like this:

git clone https://github.com/ultralytics/ultralytics
cd ultralytics
python setup.py install

Step 3 - Choosing the Pre-trained Models

You could explore any of the pre-trained models by exploring the models page and choosing the model you need for carrying out the experiments. For our experiments, we will be using one of the latest models, the YOLOv8x.

Here is a sample image I used. 

Source: Wikipedia

Step 4 - Testing the YOLO Algorithm with Custom Input

Now run the command like this:

yolo predict model=yolov8x.pt source='/path_to_image/image.jpg

Replace the /path_to_image/ directory path with your custom directory path. Note that you can mention the name pre-trained models – and the command will take care of downloading the models for you. In case you have a custom model that you would like to use for inference, mention the model path instead.

You will see an output like this:

Downloading https://github.com/ultralytics/assets/releases/download/v0.0.0/yolov8x.pt to 'yolov8x.pt'...
100% 131M/131M [00:02 00:00, 56.2MB/s]
Ultralytics YOLOv8.0.145 🚀 Python-3.10.6 torch-2.0.1+cu118 CPU (Intel Xeon 2.20GHz)
YOLOv8x summary (fused): 268 layers, 68200608 parameters, 0 gradients

image 1/1 /content/bear.jpg: 448x640 1 bear, 3318.5ms
Speed: 5.3ms preprocess, 3318.5ms inference, 2.1ms postprocess per image at shape (1, 3, 448, 640)
Results saved to runs/detect/predict4

The above inference has correctly detected the one bear in the image.

YOLO can predict multiple objects in an image. Let’s try another image like this:

‍

Source: Author

Now we can see the output like this:

Ultralytics YOLOv8.0.145 🚀 Python-3.10.6 torch-2.0.1+cu118 CPU (Intel Xeon 2.20GHz)
YOLOv8x summary (fused): 268 layers, 68200608 parameters, 0 gradients

image 1/1 /content/image.jpg: 640x480 1 bench, 1 cat, 4 handbags, 3570.2ms
Speed: 5.9ms preprocess, 3570.2ms inference, 6.3ms postprocess per image at shape (1, 3, 640, 480)
Results saved to runs/detect/predict5

Training a YOLO Model with Your Custom Data

An Object Detection task can be done for any label that you want if you have the right kind of data. Once the images are collected, the data needs to be annotated with the bounding boxes and the preferred labels before training.

If you want to train your own model from scratch, there are popular datasets available for a wide variety of image datasets for object detection. One of the most used datasets for the task is the COCO (Common Objects in Context) dataset. Let’s take a look at how to train a COCO dataset with the YOLO architecture.

Coco Dataset

The coco dataset comprises hundreds of thousands of images containing information that could be helpful in training and validating many image recognition tasks like object detection, segmentation and captioning. There are around 80 categories and subcategories to perform object classification. This dataset is also used in evaluating YOLO algorithms and their accuracy.

Dataset Configuration

We will use a YAML (Yet Another Markup Language) file to configure details about the dataset. In the Coco.yaml file, we can configure details such as:

1. Text files for training and validation and test files that contain information about the respective image paths.
2. Image classes and their labels.
3. Optional download script to fetch the dataset from the source.

# Ultralytics YOLO 🚀, AGPL-3.0 license
# COCO 2017 dataset http://cocodataset.org by Microsoft
# Example usage: yolo train data=coco.yaml
# parent
# ├── ultralytics
# └── datasets
#     └── coco  ← downloads here (20.1 GB)


# Train/val/test sets as 1) dir: path/to/imgs, 2) file: path/to/imgs.txt, or 3) list: [path/to/imgs1, path/to/imgs2, ..]
path: ../datasets/coco  # dataset root dir
train: train2017.txt  # train images (relative to 'path') 118287 images
val: val2017.txt  # val images (relative to 'path') 5000 images
test: test-dev2017.txt  # 20288 of 40670 images, submit to https://competitions.codalab.org/competitions/20794

# Classes
names:
  0: person
  1: bicycle
  2: car
  3: motorcycle
  4: airplane
  5: bus
  6: train
  7: truck
  8: boat
  9: traffic light
  10: fire hydrant
  11: stop sign
  12: parking meter
  13: bench
  14: bird
  15: cat
  16: dog
  17: horse
  18: sheep
  19: cow
  20: elephant
  21: bear
  22: zebra
  23: giraffe
  24: backpack
  25: umbrella
  26: handbag
  27: tie
  28: suitcase
  29: frisbee
  30: skis
  31: snowboard
  32: sports ball
  33: kite
  34: baseball bat
  35: baseball glove
  36: skateboard
  37: surfboard
  38: tennis racket
  39: bottle
  40: wine glass
  41: cup
  42: fork
  43: knife
  44: spoon
  45: bowl
  46: banana
  47: apple
  48: sandwich
  49: orange
  50: broccoli
  51: carrot
  52: hot dog
  53: pizza
  54: donut
  55: cake
  56: chair
  57: couch
  58: potted plant
  59: bed
  60: dining table
  61: toilet
  62: tv
  63: laptop
  64: mouse
  65: remote
  66: keyboard
  67: cell phone
  68: microwave
  69: oven
  70: toaster
  71: sink
  72: refrigerator
  73: book
  74: clock
  75: vase
  76: scissors
  77: teddy bear
  78: hair drier
  79: toothbrush

# Download script/URL (optional)
download: |
  from ultralytics.utils.downloads import download
  from pathlib import Path

  # Download labels
  segments = True  # segment or box labels
  dir = Path(yaml['path'])  # dataset root dir
  url = 'https://github.com/ultralytics/yolov5/releases/download/v1.0/'
  urls = [url + ('coco2017labels-segments.zip' if segments else 'coco2017labels.zip')]  # labels
  download(urls, dir=dir.parent)
  # Download data
  urls = ['http://images.cocodataset.org/zips/train2017.zip',  # 19G, 118k images
          'http://images.cocodataset.org/zips/val2017.zip',  # 1G, 5k images
          'http://images.cocodataset.org/zips/test2017.zip']  # 7G, 41k images (optional)
  download(urls, dir=dir / 'images', threads=3)

Training the Model

After setting up the configuration files, you can train the model with the help of the command given below:

yolo train model=yolov8n.pt data=coco8.yaml epochs=3 imgsz=640

You can also specify the hyperparameters such as learning rate, epochs, image size, etc. from the Ultralytics CLI for YOLO. For more information, refer to the CLI docs. 

YOLO Nas: Latest Breakthrough in the Object Detection Industry

So far we have had several releases of YOLO, where each release has been outperforming the previous ones in the evaluation metrics. However, with YOLO Nas, there has been a leap in the speed and memory efficiency as well. This model is built from a neural architecture search engine called AutoNac. 

The major advantage that comes from using YOLO Nas is the ability to perform quantization with maximum precision, which was a challenge for much of the previous YOLO releases. Quantization is the process to reduce the precision of the weights and biases. This will make the model smaller in size, but also makes it faster and more power-efficient.

The Ultralytics framework introduced YOLO Nas in their releases. Here is an example of how to use YOLO Nas. Keep in mind that this model is still new and under lots of development and testing, so it might not be ideal to use it in production right away. 

First, download the pre-trained weights.

And run the below code.

from ultralytics import NAS

model = NAS('yolo_nas_s')
results = model.predict('path/to/image.jpg'')
print(results)

Conclusion

YOLO achieves impressive accuracy and speed with its ability to scan an image just once and leveraging top deep learning methodologies. Using state-of-the-art frameworks like Ultralytics and Darknet that helps train YOLO using neural networks, the task of object detection is made easier. Numerous applications such as autonomous driving, surveillance, and so on have used YOLO for its popularity and ease of creating solutions based on it.