How to Write Negative Prompts in FLUX for Precise AI Art Generation

FLUX AI is a cutting-edge tool for generating high-quality images from text prompts, making it a favorite among digital artists and creators. While FLUX offers powerful capabilities, it lacked support for negative prompts—until now. In this guide, we’ll explain how to leverage negative prompts in FLUX to enhance your creative control, offering you the ability to refine and exclude unwanted elements from your generated images.

What Are Negative Prompts?

Negative prompts are instructions that direct the AI to avoid including specific elements in an image. This feature is crucial for creators who wish to fine-tune the output and exclude unwanted details. Before the introduction of this feature, FLUX lacked the flexibility for negative prompts or allowed only basic adjustments to Classifier-Free Guidance (CFG) values. Now, with the use of Dynamic Thresholding, you can gain more control over your creations.

Dynamic Thresholding: A Game-Changer for Negative Prompts in FLUX

Dynamic Thresholding is a user-driven solution that brings the power of negative prompts to FLUX. It allows you to adjust CFG values and rescale latent values, giving you more flexibility when generating images. This breakthrough method significantly improves the quality of images, even when higher CFG values are used, ensuring a balanced result.

How Dynamic Thresholding Works

Dynamic Thresholding works by adjusting the latent values in the model. It prevents oversaturation and ensures that extreme values do not compromise image quality. This results in clearer, more refined images, even when working with complex prompts.

Implementing Dynamic Thresholding in FLUX

To enable Dynamic Thresholding in FLUX, follow these steps:

Install the sd-dynamic-thresholding extension in your FLUX setup.

In ComfyUI or a similar interface, add the DynamicThresholdingFull node.

Connect your FLUX model to the node input.

Link the output to the KSampler input.

Setting Up Negative Prompts for FLUX

To start using negative prompts in FLUX, you will need the following:

• FLUX model

• ComfyUI or a similar interface

• sd-dynamic-thresholding extension

Once you have everything installed, you can start fine-tuning your prompts and generating more specific outputs.

How to Optimize Dynamic Thresholding Parameters

When using Dynamic Thresholding, it’s important to adjust certain parameters for the best results. Here’s a breakdown of the key settings:

• CFG Scale: A value between 3–7 is ideal. Higher values ensure more accurate adherence to prompts but can lead to oversaturation.

• Interpolate Phi: This parameter controls image saturation. Aim for values between 0.7–0.9 for optimal results.

• Mimic Scale and CFG Mode: Set both to "Half Cosine Up" for the best performance.

Tips for Adjusting Parameters

• Realistic Images: Use a lower CFG (around 2–3) and reduce Interpolate Phi to around 0.6–0.7.

• Artistic Renderings: Opt for a higher CFG (4–6) and increase Interpolate Phi (0.8–0.9).

• Abstract Concepts: Experiment with higher CFG values (7+) for more creative results, though they may be less predictable.

Example settings to start with:

• CFG Scale: 3

• Interpolate Phi: 0.7

• Mimic Scale: Half Cosine Up

• CFG Mode: Half Cosine Up

How to Write the Best Prompts for FLUX

When writing negative prompts, it’s essential to be specific about the elements you want to exclude. For example:

Negative Prompts Example:
"Blurry, oversaturated colors, modern buildings, people, animals other than koi fish, text, logos, watermarks, distorted proportions, unrealistic lighting."

When tailoring your negative prompts for specific styles, consider the type of image you're aiming for. For portrait photography:

• Positive Prompt: A professional portrait of a middle-aged woman with short gray hair, a warm smile, and kind eyes. Natural outdoor lighting, shallow depth of field, bokeh background of a park.

• Negative Prompt: Young appearance, long hair, indoor setting, harsh lighting, blurry focus, multiple people, accessories, hats, glasses.

Additional Tips for Writing FLUX Prompts

• Oversaturation: If your images look too saturated, decrease the Interpolate Phi value.

• Lack of Prompt Adherence: Gradually increase the CFG scale, but be mindful of the performance impact.

• Slow Generation: Start with a lower resolution for quick tests, then scale up for final outputs.

• Inconsistent Results: Test with different seed values to find the best starting points.

Frequently Asked Questions (FAQ)

1. What are negative prompts in FLUX?

Negative prompts are instructions that tell FLUX’s AI to exclude specific elements from the generated images. This allows for greater creative control and refined image outputs.

2. How can I use Dynamic Thresholding in FLUX?

You can enable Dynamic Thresholding by installing the sd-dynamic-thresholding extension and setting up the appropriate nodes in ComfyUI or a similar interface.

3. What are the best parameters for generating realistic images in FLUX?

For realistic images, use a lower CFG scale (around 2–3) and reduce the Interpolate Phi value to between 0.6–0.7.

4. Can I write negative prompts for different art styles in FLUX?

Yes, negative prompts can be tailored for specific styles. For example, you can create negative prompts to exclude elements like harsh lighting or unnatural proportions in portrait photography.

By mastering the art of negative prompts in FLUX, you can take your AI-generated artwork to the next level, refining your images to suit your creative vision.