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Advancing Image Generation Through Token Modification

A new method improves image quality from vague text prompts.

― 6 min read


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Recent progress in creating images from text using diffusion models has led to many impressive results. However, there are still some challenges that need to be addressed, especially when the input text is vague or lacks clarity. This can lead to images that do not clearly represent what was intended, especially when trying to capture fine details.

Current Challenges

One major problem with these Image Generation models is that they often lack Accuracy in showing subtle details. For instance, if someone wants an image of an "iron," it might generate a picture of the element iron instead of the household appliance. This confusion happens because words can have multiple meanings, which creates uncertainty in how the model interprets what is being asked.

To tackle these issues, some methods have been proposed using labeled datasets. However, relying on supervised datasets has its downsides. These datasets are usually smaller than the vast amounts of data used to train models. Furthermore, using fixed labels instead of allowing for more natural input limits the flexibility in generating images.

Our Approach

We suggest a method that combines the strengths of existing techniques while avoiding their weaknesses. Our approach allows for modifications to the image generation process without requiring a massive retraining of the entire model. Instead, we fine-tune the model by adjusting a specific input Token that corresponds to a class label, helping the model focus on generating images more accurately based on that token.

This is achieved by making small iterative changes to how this token is represented, guiding the model to create images that are closer to the desired output. Our method is quicker and doesn’t demand a collection of images from the specific class being generated.

How It Works

The main idea is to enhance the information provided to the model by introducing a new token that represents a class. This token is added to the input prompt along with the description. By steering the generated images in line with the feedback from a classifier that recognizes classes, we can improve the Quality of the generated images significantly.

Each time a new image is produced, we check its accuracy against a classifier. If the generated image does not meet expectations, adjustments are made, and this process continues until satisfactory results are achieved.

Rather than adjusting the entire model, we focus on just the new token. This way, the model maintains its original structure while benefiting from the added class-specific features.

Advantages of Our Method

Our method presents several advantages over traditional techniques:

  1. Speed: The process of fine-tuning is faster compared to other methods, which often take a long time to train.

  2. Flexibility: The introduced token can work with various prompts, making it a versatile addition to any image generation.

  3. Quality: The images generated through this method show higher accuracy and detail than those created using standard approaches.

  4. Resource Efficiency: The memory required for our method is low, allowing it to be run on regular GPUs without extensive resources.

  5. No Need for Additional Data: Unlike some methods that require a set of labeled images, our approach uses an existing classifier without needing direct access to its training data.

Evaluation of Our Method

Fine and Coarse-Grained Testing

To highlight the effectiveness of our technique, we tested it under two conditions: fine-grained and coarse-grained settings.

In fine-grained settings, we looked at the model's ability to generate accurate images of specific bird species. The results showed a notable improvement in accuracy when using our method compared to standard methods.

In coarse-grained environments, we assessed the model's performance on a general dataset. Again, our method demonstrated better results, proving its ability to enhance the quality of generated images across different levels of detail.

Metrics of Success

We utilized specific metrics to measure image quality and classification accuracy. By assessing how often generated images were correctly classified by a pre-trained classifier, we were able to evaluate our method's success.

Additionally, we looked at how Classifiers trained on our generated images fared compared to those trained on real images alone, finding that our images significantly improved classification accuracy.

Comparison with Existing Methods

Our approach is distinct from previous methods that focused on specific images for training. Previous techniques either required lengthy training with a small set of images or resulted in generated images that lacked diversity and context.

By introducing a flexible token that can adapt to various contexts, our method allows for the generation of images that not only meet class specifications but also possess the creativity and richness present in larger datasets.

Qualitative Results

In our tests, we generated images for different classes using both standard methods and our own. The results were clear: images generated using our method showcased a richness in detail and clarity that standard methods struggled to achieve. For example, images of specific animal species were significantly more lifelike and accurate when using our technique.

We also examined ambiguous class names, where the model was tasked with generating images based on vague descriptions. Our method proved capable of clarifying these ambiguities and producing images that accurately reflected the intended class.

Limitations and Areas for Improvement

While our method shows promise, some challenges remain. Instances of ambiguity can still persist in certain contexts, and there is room for improving the training process to further enhance image quality.

Additionally, exploring how this method can be applied across other model types beyond image classification will be an important next step.

Future Directions

Looking ahead, we aim to refine our technique and expand its application. By testing our approach on various types of models and datasets, we can unlock new possibilities for generating high-quality images from text.

This might involve working with different categories of images, such as more complex scenes involving multiple objects or styles, as well as exploring ways to adapt our method for real-time applications.

Overall, we believe our approach represents a significant step forward in bridging the gap between textual input and visual output, paving the way for richer and more accurate image generation in the future.

Original Source

Title: Discriminative Class Tokens for Text-to-Image Diffusion Models

Abstract: Recent advances in text-to-image diffusion models have enabled the generation of diverse and high-quality images. While impressive, the images often fall short of depicting subtle details and are susceptible to errors due to ambiguity in the input text. One way of alleviating these issues is to train diffusion models on class-labeled datasets. This approach has two disadvantages: (i) supervised datasets are generally small compared to large-scale scraped text-image datasets on which text-to-image models are trained, affecting the quality and diversity of the generated images, or (ii) the input is a hard-coded label, as opposed to free-form text, limiting the control over the generated images. In this work, we propose a non-invasive fine-tuning technique that capitalizes on the expressive potential of free-form text while achieving high accuracy through discriminative signals from a pretrained classifier. This is done by iteratively modifying the embedding of an added input token of a text-to-image diffusion model, by steering generated images toward a given target class according to a classifier. Our method is fast compared to prior fine-tuning methods and does not require a collection of in-class images or retraining of a noise-tolerant classifier. We evaluate our method extensively, showing that the generated images are: (i) more accurate and of higher quality than standard diffusion models, (ii) can be used to augment training data in a low-resource setting, and (iii) reveal information about the data used to train the guiding classifier. The code is available at \url{https://github.com/idansc/discriminative_class_tokens}.

Authors: Idan Schwartz, Vésteinn Snæbjarnarson, Hila Chefer, Ryan Cotterell, Serge Belongie, Lior Wolf, Sagie Benaim

Last Update: 2023-09-10 00:00:00

Language: English

Source URL: https://arxiv.org/abs/2303.17155

Source PDF: https://arxiv.org/pdf/2303.17155

Licence: https://creativecommons.org/licenses/by/4.0/

Changes: This summary was created with assistance from AI and may have inaccuracies. For accurate information, please refer to the original source documents linked here.

Thank you to arxiv for use of its open access interoperability.

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