GANs and Stable Diffusion models are widely used for image generation tasks, with many different goals that can be pursued depending on the specific application. Here are some common goals for image generation using GANs and Stable Diffusion:
- To new images that are similar to the existing training data
- To synthesize new images that do not exist in the original dataset.
- To apply the style of one image to another
- To upscale low-resolution images into high-resolution counterparts.
- To fill in missing or damaged parts of an image.
- To generate images of a certain object category or images with specific attributes.
4.1 System Architecture
Figure 1 demonstrates the proposed approach, comprising the dataset, data-preprocessing, the generator, the discriminator, the adversarial training and information feedback for optimization.
Generative Adversarial Networks (GANs) represent a powerful paradigm in the field of deep learning, enabling the generation of high-quality synthetic data samples across diverse domains. At the core of GANs lies a competitive training framework involving two neural networks: a generator and a discriminator. Through an iterative process, the generator learns to produce data samples that closely resemble those from a target distribution, while the discriminator learns to distinguish between real and fake samples. This adversarial relationship drives the continual improvement of both networks, leading to the generation of increasingly realistic data. GANs have demonstrated remarkable success in various applications, including image generation, text-to-image synthesis, and style transfer. However, training GANs can be challenging due to issues such as mode collapse and instability. Nonetheless, ongoing research efforts continue to advance GAN architectures and training techniques, paving the way for their widespread deployment in real-world scenarios. Here is the respective algorithm.
The algorithm outlines the training function for a Stable Diffusion Model, incorporating com- ponents such as a Text Encoder, Variational Autoencoder (VAE), and UNet architecture. The goal is to train a model capable of generating stable and high-quality samples. Key steps in the training function include setting hyperparameters such as training batch size, gradient steps accumulation, learning rate (lr), maximum training steps, output directory, and gradient checkpointing. If gradi- ent checkpointing is enabled, specific components like the text encoder and UNet are configured accordingly. A dataloader is created for the training dataset, and if scale learning rate is enabled, the learning rate is adjusted accordingly. The optimizer, typically AdamW, is initialized, and the model components are prepared for training using the accelerator. Training progresses through epochs and batches, with the model updated based on accumulated gradients. Input data under- goes encoding through the VAE, with noise injected using a noise scheduler. The UNet processes the latent representations along with additional information from the text encoder to predict noise for diffusion. Overall, this procedure lays the groundwork for training a Stable Diffusion Model us- ing the provided components and hyperparameters, aimed at achieving stable and effective sample generation.
This algorithm pertains to the calculation of loss and gradient updates based on the prediction type specified in the noise scheduler configuration. If the prediction type is ”epsilon,” the target value for the loss calculation is set to the noise itself. If the prediction type is ”vprediction,” the target value is obtained from the noise scheduler’s velocity prediction function. If neither condition is met, a ValueError is raised indicating an unknown prediction type.
The loss is calculated using mean squared error (MSE) loss between the predicted noise and the target value. The resulting loss is then propagated back through the model using the accelerator’s backward function. If multiple processes are utilized, gradients are obtained from the module or model’s parameters accordingly. Additionally, gradient values corresponding to the placeholder token ID are zeroed out to prevent updates to those tokens.
After updating the optimizer’s parameters, gradients are reset, and if gradient synchronization is enabled, progress is updated accordingly. The global steps counter is incremented, and if the specified number of steps for saving progress is reached, the model’s current state is saved. The procedure continues until the maximum training steps are reached, at which point the training loop terminates, and model training is completed. Finally, the trained model is saved to the specified output directory.
4.2 Experimental setup
This section provides detailed information about the hardware and software prerequisites, the datasets utilized, and the evaluation metrics employed.
1. Hardware and Software Table 3 summarizes the essential requirements for implementing image generation using Generative Adversarial Networks (GANs) and the Stable Diffusion model. It specifies an Intel i5 11th generation processor for computational power, a 1TB hard disk drive (HDD) for storage, and 8GB of RAM for efficient data processing. The operating system needed is Windows 11, with Python chosen as the programming language for its versa- tility and extensive machine learning libraries. These specifications ensure a capable setup for successful image generation tasks with GANs and Stable Diffusion.
Table 3: Hardware and Software Specifications for the implementation image generation using GANs and Stable Diffusion
Processor
|
Intel i5 11th generation
|
HDD
|
1TB
|
RAM
|
8GB
|
Operating System
|
Windows 11
|
Programming Language
|
Python
|
2. Dataset Table 4 summarizes the datasets employed in the implementation of image generation using GANs and Stable Diffusion. It includes FFHQ with 3000 images, Flicker with 6000 images, and Celeb with 100 images. These diverse datasets offer a rich variety of images crucial for training and evaluating the effectiveness of the GANs and Stable Diffusion model.
Table 4: Datasets Used for the implentation of Image Generation using GANs and Stable Diffusion
Dataset
|
Count
|
Type
|
FFHQ
|
3000
|
Images
|
Flicker
|
6000
|
Images
|
Celeb
|
100
|
Images
|
3. Evaluation Metrics The Inception score and FID scores are the appropriate evaluation met- rics GANS according to [4].
Inception Score (IS):
This metric assesses the quality and diversity of generated images by comparing their class distribution with that of a pre-trained classifier network. The IS is defined as:
In this equation, p(y|x) denote the class distribution of the generated images predicted by the classifier network, p(y) is the dataset’s marginal class distribution, and KL is the Kullback- Leibler divergence.
Fr´echet Inception Distance (FID):
This metric evaluates the disparity between the feature representations of the generated images and those of the real images, calculated by a classifier network that has been pre-trained. The FID is defined as:
In this equation, mureal and muf ake denote the mean feature representations of the real and fake images, while Sreal and Sf ake denote the covariance matrices of the real and fake feature representations, respectively.