Coursera Learner working on a presentation with Coursera logo and

What is Convolutional Neural Network?

Coursera Learner working on a presentation with Coursera logo and

A neural network is a vast software and/or hardware system resembling the pattern of neurons and their operation in the human brain. Unlike traditional neural networks, convolutional neural networks are more efficient due to their neurons organized like the frontal lobe in human beings and animals. It is the area. For those who don’t know, this area processes visual stimuli.

The neuron layers cover the visual field while ensuring there are no image processing issues like the ones in traditional neural networks. Convolutional neural networks utilize a system similar to a multiplayer perceptron developed for minimizing processing requirements. CNN layers contain an output layer, an input layer, and also a hidden layer including multiple pooling layers, convolutional layers, normalization layers, and fully connected layers.

With improved efficiency and minimal limitations, convolutional neural networks are significantly more effective and easier to train for natural image and language processing.

Training – The Most Important Element of Neural Networks

Training is arguably the most important part of neural networks. Aspiring data scientists often wonder how Conv layers convert into curves and edges and how fully connected layers know which activation map it should be following.

Computers can adjust their weights or filter values through a popular training process known as backpropagation. As discussed earlier, neural networks draw parallels to the human brain, and we must look at how our minds work to understand it.

Our brains are fresh when we are babies, and we don’t know what a bird, dog, or cat is as our minds don’t have enough training. CNN works similarly – its filters filter values, and weights can tell the difference between an object. They don’t know whether they should look for curves, edges, or any other shape. As we become older, our teachers and parents show us various images and videos, providing us with corresponding labels for the things we see in everyday life.

The idea of looking at labels and images is the same training process used for convolutional neural networks. The more you train the filters, the more sophisticated and efficient they become – and judging by the progress in various online platforms, it would be fair to say that there have been monumental advancements in this technology.

It would be fair to say that a CNN is a comprehensive deep learning algorithm capable of taking input images and assigning importance to numerous objects and aspects in the photo to tell the difference between them. You’d be surprised to learn that a convolutional neural network requires significantly lower pre-processing, especially when compared to tons of other algorithms.

Primitive methods used to have hand-engineered filters. However, with adequate training, CNN or ConvNet can learn these characteristics and filters with minimal hassle. The convolutional neural network’s architecture is comparable to the human brain’s neurons and its connectivity pattern. Independent neurons only respond to stimuli in the visual field’s restricted region, which some also like to call “the Receptive Field.” A group of such fields intersect and cover the visual area entirely.

Pooling, Padding, Kernel, and Why they are Important for CNN


The kernel is a filter used in convolutional neural network to extract an image’s features. This matrix moves above the input data and carries out the dot product with its sub region. The Kernel’s movement in the input data is according to the stride value. For example, if there is a stride value of two, the kernel will move by two pixel columns in the matrix. The Kernel is a critical part of CNN as it extracts high detailed features such as edges from various images.


Pooling is primarily the downscaling of an image acquired from previous layers. It is comparable to shrinking a photo for reducing pixel density. Max pooling is a popular pooling type used by many. For example, you plant to pool with a ratio of two. It will cut the width and height of your image into half. Therefore, you mist compress pixels (one in every four) to a 2 by 2 grid, followed by mapping it to a fresh pixel.

You have to take the largest value from the four pixels for max pooling. So, a single new pixel essentially represents four older ones by utilizing the four pixel’s largest value. This process happens for each group containing four pixels all around the image


Padding is vital for convolutional neural networks. Why? Because it adds more pixels at the outer part of the image.If the padding is zero, the value of every pixel you add will also be zero. On the other hand, if zero padding is equals to one, there will be a thick pixel surrounding the original image, and its pixel value will be zero.

Whenever we use the kernel for scanning the image, its size becomes smaller. You can avoid that and preserve the image’s original size by utilizing padding, adding extra pixels to your image’s border.

A Groundbreaking Innovation

At first, hearing the term “convolutional neural networks” will make you think of an odd combination of math, biology, and some CS elements.However, upon taking a closer look, you will realize that it is one of the most groundbreaking innovations in the computer vision field. Neural networks came to prominence in 2012 as machine learning expert Alex Krizhevsky utilized them to get first prize in the ImageNet competition.

Alex dropped the classification error record significantly, bringing it to fifteen percent – a massive improvement over the previous record of twenty-six percent. It is a massive reason why loads of companies have been utilizing deep learning at their service’s core. Here is a list of some high profile online platforms that take advantage of neural networks to provide people with an improved experience:


Have you ever wondered how Facebook’s famous automatic tagging algorithm works? The answer is neural networks.


The product recommendation you get on Amazon and several other similar platforms is because of neural networks.


Neural networks are the reason behind Google’s superb image searching abilities.


Instagram’s solid search infrastructure is possible because the social media network uses neural networks.


The excellent profile personalization you get on Pinterest is possible due to the use of neural networks.

Convolutional Neural Networks Can Capture Temporal and Spatial Dependencies

It would be fair to claim that images are a matrix of various pixel values.Why can’t you flatten the image, feeding it to a high-level perceptron for better classification? Because it is a bit more complicated than that.When it comes to simple binary images, the precision score this method will provide would be average. However, it would not be accurate with complex images, especially those with high pixel dependency.

A ConvNet or CNN can successfully capture an image’s temporal and spatial dependencies by using relevant filters. The architecture’s performance is drastically better and provides a better fit for various image datasets because of the reduction in parameters used, and the reusable nature of weights. With enough time and dedication, you can train the network to understand the image’s sophistication better.

Using Convolutional Neural Networks for Image Processing

The main purpose of CNNs is to process images. Let us look at how experts use convolutional neural networks to classify images.

Image Identification

Image classification or identification is the task of getting an image and providing an output that best describes the objects. Human beings learn this task from the moment they enter this world. It is the first skill they learn, and it comes to them effortlessly and naturally when we become adults. In most cases, we can identify an object, environment, or a person without thinking twice.

How do we adopt these skills? How can we recognize various patterns in milliseconds? The answer is prior knowledge. Machine learning and AI are quite similar to the human brain, and we can train machines to ensure they can recognize images without making a conscious effort.


Weekly newsletter

No spam. Just the latest releases and tips, interesting articles, and exclusive interviews in your inbox every week.