Understanding Fine Tuning in Deep Learning

Unlock the secrets of fine-tuning in deep learning. Explore essential techniques for optimizing pre-trained models for your specific business needs.
September 27, 2023
Understanding Fine Tuning in Deep Learning

In the dynamic landscape of artificial intelligence and deep learning, fine-tuning is a crucial step in leveraging pre-trained models to save time and resources in deep learning projects. It allows businesses to tailor AI models to their specific needs, enhancing their operations and offerings. In this blog, we break down the fine-tuning process and show you how it can be a game-changer for your business.

What Is Fine-Tuning?


Fine-tuning refers to a process where a pre-trained model that was initially developed for a certain task, is adapted for a second related task. It is a subset of transfer learning, a method where a model trained on one task is adapted for a second related task.

Fine-tuning modifies the pre-trained model by changing the final layer or layers of the neural network that were built to create a model tailored to a specific task. During the fine-tuning process, the pre-trained model's weights which had been optimized for the initial task are used as a starting point. They are updated and optimized for the new task at hand during subsequent training on a smaller, task-specific dataset.

Explaining Fine Tuning In The Context Of Deep Learning? 

To understand what fine-tuning is in the deep learning sphere, we first need to have a clear grasp of deep learning itself. 

What Is Deep Learning? 

Deep Learning is a subset of machine learning, which in turn is a subset of artificial intelligence (AI). It is based on neural networks with many layers or "deep"  layers, which allow the model to learn from large datasets hierarchically. 

Typically, a deep learning model is a neural network with three or more layers. These neural networks attempt to simulate the behavior of the human brain—albeit far from matching its ability—allowing it to “learn” from large amounts of data. While a neural network with a single layer can still make approximate predictions, additional hidden layers can help to accurately identify the patterns and features in the input data.

In a neural network, the initial layers generally recognize basic patterns, and as you go deeper into the layers, the complexities of the patterns recognized increase. This hierarchy allows deep learning models to carry out complex tasks and learn intricate patterns in the data, providing the ability to automatically and adaptively learn from data features.

Deep Learning And Fine-Tuning 


In deep learning, pre-trained models are neural networks that have already been trained on a large dataset and have acquired substantial knowledge and understanding of patterns present in the data. Fine-tuning comes into play when we want to transfer the learned patterns and knowledge from the pre-trained model to a new model designed to perform a specific task.

This involves adjusting or ‘fine-tuning’ the parameters in some of the layers (usually the last few layers) of the pre-trained network while keeping others frozen. The fine-tuned layers are then trained on a new, smaller dataset specific to the new task. This approach is beneficial because it allows the new model to learn from the substantial and valuable knowledge accumulated during the initial training process, reducing the amount of new data required and accelerating the training process.

Thus, fine-tuning in deep learning stands as a pivotal practice that presents a pathway to achieving high-performance models with reduced computational resources and time investments.

An Example Of Fine-Tuning

Consider a pre-trained network trained on a large dataset, like the ImageNet dataset, to classify images into a thousand categories. If your new task is to classify images into a new set of categories, you don't have to train the model from scratch. Instead, you take the pre-trained network and fine-tune it with your small dataset to suit your specific task.

Fine-tuning in this scenario involves changing the output layer of the pre-trained model and then training it further with a small dataset for the new task, employing techniques such as data augmentation to enhance the training data available.

What Are The Benefits Of Fine-Tuning A Model?

1. Cost-Effectiveness

Utilizing fine-tuning in the training process allows businesses to cut down significantly on costs. Developing a model from scratch can be a resource-intensive endeavor, demanding both substantial computational power and time. Fine-tuning a pre-trained model reduces the amount of training data needed, thereby not only saving time but also greatly reducing costs associated with data storage and computational resources. This financial efficiency makes fine-tuning a go-to strategy for many enterprises.

2. Leveraging Pre-Existing Knowledge

When fine-tuning a pre-trained model, one can leverage a wealth of knowledge already encoded into the neural network. These pre-trained models have been developed using extensive datasets, which empowers them with a broad understanding of complex patterns and features in various domains. Hence, the fine-tuning process starts with a model that already has a substantial knowledge base, presenting a remarkable advantage.

3. Resource Efficiency

Besides being cost-effective, fine-tuning is resource-efficient in terms of computational demands. You are essentially adapting an existing model to your specific needs, which translates to lesser training time and a reduced requirement for data - a considerable benefit when the dataset for the new task is limited.

4. Improved Performance

Fine-tuned models generally offer improved performance for specific tasks when compared to those trained from scratch, particularly when working with a small dataset. The large dataset used in the pre-trained model serves as a substantial foundation, enhancing the model’s ability to extract nuanced insights from the new data, and thereby increasing its performance metrics.

5. Flexibility

Fine-tuning stands out for its flexibility. It allows the customization of a pre-trained model to suit a variety of tasks. By adjusting different parameters such as learning rate and output layers, you can fine-tune the model to meet the specific demands of your new task, attaining a personalized solution with less hassle.

What Are The Disadvantages Of Fine-Tuning?

1. Risk of Overfitting

While fine-tuning brings numerous benefits, it also harbors the risk of overfitting, notably when the new dataset size is substantially smaller than the one used in the initial training. Overfitting happens when a model learns the noise in the training data, making it perform poorly on unseen data.

Solution: To counter the risk of overfitting during the fine-tuning process, it is advisable to employ techniques like weight regularization where constraints are added to the neural network's optimization process to avoid fitting to the noise in the training data. Another effective strategy is data augmentation, which involves increasing the dataset size by creating new training examples through transformations to in turn help the model to generalize better and avoid overfitting.

2. Complexity in Optimization

The fine-tuning process can become quite complex, involving a careful balance in altering various parameters, including the learning rate, and deciding on the layers to fine-tune. This intricacy requires a deep understanding of neural networks and the specific pre-trained model in use, making the optimization process somewhat challenging.

Solution: Addressing the complexity in optimization necessitates a structured approach towards understanding and experimenting with various parameters meticulously. This involves investing time in learning the intricacies of the pre-trained model, backed with a culture of continuous learning and experimentation can help significantly ease the fine-tuning process. Further, utilizing tools and resources that facilitate hyperparameter tuning can also be a strategic move to streamline the optimization process and make it less daunting for practitioners.

3. Dependency on the Pre-Trained Model

Fine-tuning establishes a dependency on the pre-trained model. If the pre-trained network harbors biases or limitations, those could transfer to your fine-tuned model, potentially diminishing its performance.

Solution: To mitigate the issue of dependency on the pre-trained model, it is imperative to carefully scrutinize and select a pre-trained model that aligns well with the task at hand. Additionally, one should be open to performing iterative fine-tuning and continuously validating the model to identify and correct biases or limitations transferred from the pre-trained model. Encouraging diversity in training data and considering a multi-modal approach can also be pivotal in negating unwanted dependencies.

4. Difficulty in Handling Drastically Different Tasks

Fine-tuning might not always be the best choice for tasks starkly different from the task the pre-trained model was originally trained for. The farther the new task diverges from the original task, the less benefit derived from the pre-trained base model, which might necessitate exploring other strategies for optimum results.

Solution: When fine-tuning for tasks that are vastly different from the original task the pre-trained model was developed for, it may be worthwhile to explore supplementing the fine-tuning process with techniques such as feature extraction to retain the knowledge that is still applicable while building upon it with new layers tailored to the new task. Moreover, one should remain open to the possibility of partial or full retraining from scratch as a viable option in such scenarios, especially when the divergence between the tasks is substantial. Leveraging domain-specific knowledge can further guide the fine-tuning strategy effectively, ensuring that the model performs optimally even in divergent task scenarios.

Examples Of Fine-Tuned Large Language Models

Example 1: Giraffe 


Giraffe optimizes context length and thereby enhances efficiency in various tasks. With variants such as 4k and 16k Giraffe that were fine-tuned from LLaMA and 32k Giraffe that was fine-tuned from LLaMA2, this model family was developed to enhance the contextual understanding capacity of LLMs by enabling them to handle longer contexts without additional training.

These advancements not only facilitate more sophisticated data retrieval and maintain prolonged AI chatbot conversations but also aid in coding on substantial existing codebases. Despite the strides made, the Giraffe model family unveils areas needing further research to prevent performance degradation at unprecedented context lengths. Available on an AI community called HuggingFace, these models epitomize collaborative efforts in deep learning and promise more proficient engagement with substantial data volumes.

Example 2: Baize


Baize is a newly released open-source chat model designed to facilitate intricate multi-turn conversations, effectively simulating human-like interactions where a series of questions and answers unfold organically. The project is the result of a collaboration involving the McAuley lab at UC San Diego, Sun Yat-Sen University, and Microsoft Research, Asia.

To build Baize, the team initially utilized ChatGPT to generate a large volume of chat data through a method called "self-chatting". Here, ChatGPT carried out both sides of a conversation using prompts or "seeds" derived from platforms such as StackOverflow and Quora to initiate the chats.

With a substantial dataset in hand, the LLaMA model was then fine-tuned to enhance its conversational abilities. This fine-tuning process utilized a parameter-efficient technique known as Low-Rank Adaptation (LoRA) to streamline the training, making it feasible even with limited computational resources while maintaining the complexity needed for deep conversations.

Given that Baize has been programmed to avoid engaging in discussions that are deemed sensitive or inappropriate, its added layer of safety and open-source nature can be leveraged to spearhead further innovations and explore new applications in the future.

Common Techniques For Model Fine-Tuning

Fine-tuning a pre-trained model to enhance its performance involves a series of technical steps and techniques. Let’s walk through some commonly adopted techniques. A few others can be found in our detailed guide to fine-tuning

Technique #1: Learning Rate Adjustment

A fundamental technique in the fine-tuning process involves adjusting the learning rate. This refers to the size of the steps that the model takes during the training process. A smaller learning rate means the model learns slowly, refining the pre-trained parameters delicately to better suit the new task. Conversely, a higher learning rate might speed up the training process but at the risk of overshooting the optimal solution. Thus, finding the right balance is essential to ensure that fine-tuning yields a model that is both accurate and efficient.

Source: The graph above shows that if your learning rate is set too low, training will progress very slowly as you are making very tiny updates to the weights in your network. However, if your learning rate is set too high, it can cause undesirable divergent behavior in your loss function. 

Example: a retail company is using a deep learning model to forecast sales. Over time, new data regarding changing consumer behavior becomes available. By fine-tuning the existing model with a carefully chosen learning rate, the company can effectively incorporate this new data and enhance the model’s predictive accuracy without starting the training process anew.

Technique #2: Layer Re-training

Fine-tuning often involves re-training certain layers of a neural network while keeping others frozen or unchanged. In many cases, the lower layers that are responsible for extracting general features from the data are kept unchanged, while the top layers that are closer to the output layer are fine-tuned to tailor the model to the specific task at hand. This method leverages the pre-trained model’s existing knowledge base, fine-tuning only the necessary portions to suit the new data.

Example: a healthcare company is aiming to develop a neural network to identify rare diseases from medical images by using a pre-trained model originally trained to recognize common diseases. By re-training the top layers of the neural network to become attuned to the specific features of rare diseases while retaining the knowledge encapsulated in the lower layers, the firm can cost-effectively develop a robust diagnostic tool.

Technique #3: Data Augmentation


When the training dataset is small, a technique called data augmentation can be employed. It involves creating new training examples by applying various transformations like rotations, flips, and shifts to the existing data. This way, the model learns to recognize different perspectives of the same object, enhancing its ability to generalize from a small dataset and reducing overfitting.

Example: a startup in the agriculture sector wants to create a model that can identify pests in crop images, but has a limited dataset to train the model. By using data augmentation, the startup can significantly expand its training dataset. This allows the model to learn from a more diverse set of training examples, thereby enhancing its ability to identify pests accurately.

Technique #4: Weight Regularization

In this technique, certain constraints are added to the neural network’s optimization process to prevent it from fitting to the noise in the training data. This is often a problem often encountered when the training dataset size is small. Hence, this technique helps ensure that the fine-tuned model maintains a good balance between learning the new data and retaining the knowledge acquired from the pre-trained network.

Example: a financial services company wants to update a fraud detection model, but the only available training data are a few recent cases which presents a risk of overfitting to this small dataset. By altering only the weights of the model, the company can prevent the model from fitting too closely to the noise in the limited data and achieve a fine-tuned model that is generalized enough to detect potential frauds effectively.

Technique #5: Early Stopping


To prevent overfitting during the fine-tuning process, early stopping is utilized. Here, the training is halted as soon as there is no improvement observed in the model’s performance on a validation dataset. This ensures that the model is fine-tuned just the right amount, neither too much nor too little.

Example: an e-commerce platform is enhancing its recommendation system. The system is complex, and training it from scratch is time-consuming and expensive. By utilizing early stopping during the fine-tuning process and ensuring that the system learns the new patterns in user behavior without overfitting, the platform can save on computational resources and time while achieving a high-performance recommendation system.


What is the difference between pre-training and fine-tuning?

Pre-training involves training a neural network from scratch on a large dataset to learn a broad range of features. This pre-trained model then serves as the base model for the fine-tuning process, where it is further trained on a smaller, specific dataset to specialize in a particular task. To understand this in-depth, refer to our previous post.

Is there a difference between transfer learning and fine-tuning?

Yes, while they are related, there is a subtle difference. Transfer learning encompasses a broader spectrum of techniques where knowledge gained while solving one problem is applied to a different but related problem. Fine-tuning is a subset of transfer learning, where a pre-trained model is slightly adjusted to perform the new task efficiently.

Interested In Fine-Tuning Models For Your Business? Let’s Talk.

Navigating the intricate world of fine-tuning, we at Multimodal stand as experienced guides ready to showcase the true potential of this dynamic field. Positioned at the forefront of this rapidly evolving landscape, we utilize the power of fine-tuned large language models to craft solutions tailored to individual consumers, enhancing efficiency and paving the way for innovative possibilities.

Reach out to us to discover how fine-tuning can improve  your business approach, allowing you to unlock the full potential of custom AI agents and steer your business towards transformative success attuned to consumer needs.

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