Fixing constant validation accuracy in CNN model training


The categorization of images and the identification of objects are two computer vision tasks that frequently employ convolutional neural networks (CNNs). Yet, it can be difficult to train a CNN model, particularly if the validation accuracy approaches a plateau and stays that way for a long time. Several factors, including insufficient training data, poor hyperparameter tuning, model complexity, and overfitting, might contribute to this problem. In this post, we'll talk about a few tried-and-true methods for improving constant validation accuracy in CNN training. These methods involve data augmentation, learning rate adjustment, batch size tuning, regularization, optimizer selection, initialization, and hyperparameter tweaking. These methods let the model acquire robust characteristics and generalize to new data more effectively. To identify the optimum answer, experimenting is necessary, and the approach chosen may depend on the particular issue at hand.

Fixing Methods

Convolutional Neural Networks (CNNs) have proven to be remarkably effective in the deep learning space for a variety of computer vision applications, including segmentation, object identification, and picture categorization. Yet, it might be difficult to train CNNs when the validation accuracy reaches a plateau and stays that way for a long time. The performance of the model will be enhanced by addressing some of the typical causes of this in this article.

Data Augmentation

The lack of sufficient training data is one of the most frequent causes of accuracy in constant validation. CNN models need a lot of data to generalize properly since they include millions of parameters. As a result, if the training dataset is short, the model might not be able to pick up enough characteristics to correctly categorize unobserved data. Techniques for enhancing data can be used to fictitiously expand the training dataset. These methods could involve moving, flipping, rotating, and zooming the photos. We may generate extra training examples that are somewhat different from the original photos by using these changes. As a result, the model may acquire stronger features and be better able to generalize to new data.

Learning Rate

The learning rate is another often-cited factor in constant validation accuracy. The gradient descent step size used to update the model's weights is dependent on the learning rate. The model may exceed the ideal weights and fail to converge if the learning rate is too high. On the other side, if the learning rate is too low, the model may converge too slowly and become trapped in an unfavorable solution. As just a consequence, it's indeed needed to adjust the learning rate to an adequate point. One approach to solving this is to use a schedule that gradually slows down learning. This can help the model's delayed convergence and keep it from becoming stuck in unsatisfactory solutions.

Model Complexity

CNNs are capable of learning a wide range of properties from the data because of their tremendous flexibility. This flexibility, though, is sacrificed for a more intricate model. The model could overfit the training set and be unable to generalize to new data if it is very complicated. Reducing the complexity of the model by eliminating pointless layers or lowering the number of filters in each layer is one technique to deal with this problem. This can enhance the model's capacity to categorize unknown input and help it learn more generalizable features.

Batch Size

The amount of samples needed to update the model's weights during each gradient descent iteration depends on the batch size. The model might not learn enough features to correctly identify the data if the batch size is too small. Nevertheless, if the batch size is too big, the model might not be able to adapt to new data. Hence, setting the batch size to the right amount is crucial. Using a batch size that is both large enough to capture data variability and small enough to fit into memory is one technique to do this.


Regularization strategies can be used to prevent the model from overfitting the training data. L1 and L2 regularization, dropout, and early halting are all regularization strategies. A penalty term that is added to the loss function by L1 and L2 regularization pushes the model to learn sparse weights. To prevent the model from overfitting the training set, dropout randomly removes certain neurons during training. When the validation loss stops improving, early halting terminates the training process. By doing so, the model will be less likely to overfit the training set and will be better able to generalize to new sets of data.


Throughout gradient descent, the optimizer is in charge of updating the weights of the model. Stochastic Gradient Descent (SGD), Adam, RMSprop, and Adagrad are a few examples of optimizers. Because each optimizer has advantages and disadvantages of its own, choosing one over another might affect the model's performance. For instance, SGD may be more successful when the data has few dimensions whereas Adam and RMSprop may perform better when the data has numerous dimensions. It is important to test out several optimizers to find the one that is best for a particular problem.


The performance of the model can be impacted by the weights' starting settings. Whenever the starting weights are very large or little, the model may not converge. Thus, it is essential to initialize the weights to the correct value. Xavier initialization is one popular initialization method that establishes the initial weights according to the quantity of input and output neurons in each layer. His initialization is a different method that, while similar to Xavier's initialization, performs better for deeper networks.

Hyperparameter Tuning

Many hyperparameters, including learning rate, batch size, number of filters, and number of layers, can influence how well CNN models perform. To identify the combination that works best for the particular situation, it is crucial to test out several hyperparameter settings. A grid search or random search can be used to sample various hyperparameter values and assess their performance.


The use of data augmentation, adjusting the learning rate, reducing model complexity, adjusting the batch size, utilizing regularization techniques, testing various optimizers, appropriately initializing the weights, and adjusting the hyperparameters can all be used to address constant validation accuracy in the CNN model training. The strategy might need to be modified to address the particular issue because no one answer suits all problems. To identify the optimum answer, it is crucial to experiment with several strategies and gauge their effectiveness.

Updated on: 13-Apr-2023

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