What are Convolutional Neural Networks (CNNs)?
Artificial intelligence has reached a position that would be impossible to imagine a few years back. Machine learning models are capable of producing output that would have required months of work from expert data scientists. Artificial intelligence technology has helped in achieving significant wonders that would be impossible for human beings. You might wonder why you should focus on questions like “What is convolutional neural networks (CNNs)?” in discussions about artificial intelligence and ML.
The most important reason to focus on convolutional neural networks in AI is the limitations of AI in image processing. AI models have not proved as effective as the human brain in recognizing and processing images. The human brain works in mysterious and complex ways. You could not find a definitive way to understand the cognition and rendering mechanisms of the brain. You can find different layers of interconnected neurons in the human brain. Interestingly, AI can replicate the structure of your brain with the help of artificial neurons.
In the mid-20s, artificial neural networks gained momentum as they offered capabilities for learning from data in a theoretical manner. However, artificial neural networks had to evolve into convolutional neural networks. It was a vital necessity to adapt to the use cases of image recognition and processing. Let us learn more about convolutional neural networks and how they work.
What is a Convolutional Neural Network or CNN?
Neural networks are an important subset in the domain of machine learning. You can understand convolutional neural networks (CNNs) as an important component in the world of deep learning algorithms. Neural networks include node layers featuring an input layer alongside one or multiple hidden layers and an output layer. When the output of individual nodes exceeds a specific threshold value, the node starts working and sends data to the next layer in the network. Without such procedures, it is impossible to pass data along to the next layer in the network.
You can come across different types of neural networks that are suitable for different data types and use cases. For example, recurrent neural networks are generally used in speech recognition and natural language processing tasks. On the other hand, a convolutional neural network example would show that CNNs are generally used for computer vision tasks. CNNs can also support image classification tasks. Before the arrival of convolutional neural networks, the identification of objects in images involved time-intensive methods for feature extraction.
Convolutional neural networks offer a scalable approach for object recognition and image classification tasks. CNNs utilize linear algebra principles, such as matrix multiplication, for effective identification of patterns in an image. However, the working of CNNs may demand excessive use of computational resources, such as graphical processing units or GPUs.
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Working Mechanism of Convolutional Neural Networks
Another important highlight in a guide to learn convolutional neural networks (CNNs) is the working mechanism of CNNs. You can learn more about the workings of CNNs by uncovering information about their architecture. Convolutional neural networks are different from other neural networks in that they have superior performance for image, audio, and speech signal inputs. The architecture of convolutional neural networks includes three layers: a convolutional layer, a pooling layer, and a fully-connected layer.
It is important to note that the CNN becomes more complex with every layer and identifies larger portions in the image. The initial layers emphasize simple features, such as edges and colors. When the image data moves through different layers of the CNN, it recognizes the larger elements or shapes of objects until it identifies the desired object. Here is an outline of the different ways in which the different layers in CNNs work.
The most integral component of a convolutional neural network is the convolutional network. The working mechanism of convolutional neural networks explained to beginners, revolves around the convolutional layer, which is the core building block of CNNs. It is the site where most of the computation works in a convolutional neural network.
Some of the notable components in the convolutional layer include input data, feature maps, and filters. For example, the input for the convolutional layer can be a color image that includes a matrix of 3D pixels. Therefore, the input would have three different dimensions, height, depth, and width, which correlate with the RGB in the image.
Convolutional layer also includes a feature detector or a filter. Also known as kernel, the feature detector would traverse through receptive areas of the image to check for a feature. The process that helps in recognition of objects in images is convolution.
The feature detector in the convolutional layer of CNNs is a two-dimensional array of weights that represents different parts of the image. Although the array can vary in size, the filter size is generally a 3×3 matrix, which also determines the size of the receptive field. The filter is implemented on an area of the image, followed by calculation of a dot product between the filter and the input pixels.
You can then feed the dot product into an output array. Subsequently, the filter would shift by a huge margin and repeat the process until the kernel covers the complete image. The final output obtained from the sequence of dot products from the input and filter serves as the feature map or activation map.
The description of convolutional neural network introduction also emphasizes the fact that weights in the feature detector are fixed during movement through the image. Parameter sharing enables consistency in the weights of feature detector. However, some of the parameters, such as weight values, can vary during the course of training through gradient descent and backpropagation.
On the other hand, you can find three hyper-parameters that influence the volume size of the output that you must set prior to the training of neural networks. The three hyper-parameters include a number of filters, stride, and zero-padding.
Additional Convolutional Layer
The architecture of convolutional neural network also includes an additional convolutional layer other than initial convolution layer. It is an important tool in convolutional neural network applications as the additional convolutional layer follows the first convolutional layer.
The structure of the convolutional neural network becomes hierarchical, and later layers can witness the pixels in receptive fields of previous layers. Finally, the convolutional layer transforms the image to numerical values, thereby helping the neural network in interpretation and extraction of relevant patterns.
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The next important layer in the architecture of CNNs refers to pooling layers or downsampling. It helps in conducting dimensionality reduction alongside reducing the number of parameters in the input. Just like the convolutional layer, the pooling layer would pass a filter throughout the complete input. However, the filter in the pooling layer does not rely on weights. On the contrary, the kernel utilizes an aggregation function to the values in the receptive field, thereby filling the output array.
The review of pooling layer in the convolutional neural networks (CNNs) shows that you can utilize two variants of pooling. You can find two types of pooling when working with convolutional neural networks: average pooling and max pooling. When the filter moves through the input, it can choose the pixel with the maximum value for transferring to the output array in max pooling.
Interestingly, max pooling is a commonly used approach in the pooling layer. You can understand the mechanisms of average pooling when the filter moves through the input and determines the average value in the receptive field that it should send to the output array. The pooling layer is the site in a CNN where it loses a lot of information. However, it presents multiple advantages, including reduction of complexity, reduced risks of overfitting, and improved efficiency.
The final addition among the components in the architecture of convolutional layer networks is the fully-connected layer. As the name implies, it serves as a comprehensively connected layer in the CNNs. One of the important aspects of a convolutional neural network introduction points to how the pixel values of the input images do not have a direct connection to output layer in the partially connected layers. On the other hand, a fully connected layer has every node in the output layer connecting directly to another node in a previous layer.
The fully connected layer addresses the requirements of tasks, such as classification according to features identified through previous layers and different filters. Convolutional and pooling layers generally use ReLu functions, and fully connected layers rely on a softmax activation function for appropriate classification of inputs.
Differences between CNNs and Traditional Neural Networks
The rise of convolutional neural networks has become a formidable highlight in the domain of AI. However, it is important to review every convolutional neural network example from the perspective of previous traditional neural networks. Traditional neural networks, such as multilayer perceptrons, include different types of fully connected layers. The neural networks can be versatile, albeit without optimization for spatial data such as images. It can create different types of problems when used to manage larger and more complex input data.
In the case of smaller images with limited color channels, traditional neural networks can produce satisfactory results. However, the increasing image size and complexity can lead to the requirement of computational resources. In addition, traditional neural networks experience concerns of overfitting because fully connected architectures do not prioritize the relevant features automatically. Convolutional neural networks are different in many ways.
First of all, the fundamentals of convolutional neural networks explained the ways in which every node is not connected to all nodes in the next layer. Convolutional layers have limited parameters as compared to fully connected layers in traditional neural networks. Therefore, CNNs can perform image processing tasks with better efficiency.
Convolutional neural networks utilize the parameter-sharing technique for efficiency in management of image data. The convolutional layers work with the same filter for scanning the complete image, thereby reducing the number of parameters. Subsequently, the pooling layers also present promising advantages by reducing dimensionality of the data to improve overall generalization and efficiency of a convolutional neural network.
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How Can Convolutional Neural Networks Support Deep Learning?
Deep learning is a prominent subdomain of machine learning and utilizes neural networks with multiple layers to achieve benefits that are impossible to achieve with single-layer networks. Convolutional neural networks are a prominent variant of deep learning algorithms. More people want to learn convolutional neural networks (CNNs) because they are the best tools for computer vision tasks, including image classification and object recognition. CNNs are designed to learn the spatial hierarchies of features in an image by capturing the essential features in early layers alongside complex patterns in the deeper layers.
The most significant benefit of CNN for deep learning is the ability to perform feature learning and automatic feature extraction. It eliminates the necessity of extracting features through manual measures that involve intensive use of labor and complex processes. The review of convolutional neural network applications also shows that they are useful for transfer learning. In this approach, you can fine-tune a pre-trained model for new tasks.
The reusability ensures that CNNs are efficient in dealing with a versatile range of tasks with limitations on training data. ML developers can use CNNs in different real-world scenarios without building up computational costs. Therefore, convolutional neural networks can serve as a valuable resource in different sectors such as retail, healthcare, social media, and automotive industry.
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Final Words
The applications of convolutional neural networks (CNNs) spelled new benchmarks for transformation of conventional perspectives regarding usability of AI models. You can notice how the structure of CNNs helps them address the tasks of image classification and object detection. For example, convolutional neural networks can serve the healthcare sector with enhancements in medical imaging and diagnostics.
The architecture of CNNs is different from traditional neural networks and ensures optimal use of resources. As you unravel the new perspectives on usability of CNNs in different sectors, you can discover more about their potential. Learn more about the different types of convolutional neural networks and how they can transform the usability of artificial intelligence and machine learning models.
