Master Negative Prompts in FLUX: A Comprehensive Guide

How to Use Negative Prompts in FLUX Effectively

FLUX is an advanced AI-powered image generation tool that has transformed the digital art landscape. Known for its exceptional ability to create stunning visuals from simple text prompts, FLUX now supports negative prompts, empowering creators with even greater control over their outputs. This guide dives into how to implement negative prompts in FLUX, leveraging dynamic thresholding techniques to optimize your creations.

What Are Negative Prompts?

Negative prompts are instructions that guide the AI to exclude specific elements from an image. By using negative prompts, creators can refine their outputs and eliminate undesired details, ensuring the final image aligns perfectly with their vision.

Originally, FLUX did not support negative prompts or allow adjustments to Classifier-Free Guidance (CFG) values beyond the default setting. However, with the introduction of dynamic thresholding, users can now customize their experience with precision.

Dynamic Thresholding: A Breakthrough for FLUX

Dynamic thresholding is a community-driven innovation that enables the use of negative prompts and CFG adjustments in FLUX. This technique ensures balanced image quality while allowing for detailed customization.

How Dynamic Thresholding Works

Dynamic thresholding operates by:

• Rescaling latent values.
• Clamping extreme values to prevent oversaturation.

This process ensures that the generated image maintains visual balance, even with detailed and complex prompts.

Benefits of Dynamic Thresholding

• Improved Prompt Adherence: Fine-tune images with higher CFG values.
• Enhanced Image Quality: Prevent oversaturation and visual inconsistencies.
• Creative Control: Exclude unwanted elements effectively.

Setting Up Negative Prompts in FLUX

To get started with negative prompts in FLUX, you’ll need:

• The FLUX model.
• ComfyUI or a similar interface.
• The sd-dynamic-thresholding extension.

Step-by-Step Guide:

Install the sd-dynamic-thresholding extension via your chosen interface.

Add the DynamicThresholdingFull node in ComfyUI.

Connect your FLUX model to the input of the DynamicThresholdingFull node.

Link the output to your KSampler’s input.

Optimizing Parameters

Key parameters for dynamic thresholding include:

• CFG Scale: 3–7 (higher values improve prompt adherence).
• Interpolate Phi: 0.7–0.9 (controls saturation levels).
• Mimic Scale and CFG Mode: “Half Cosine Up” for optimal results.

Parameter Tips:

• Realistic Images: CFG 2–3, Interpolate Phi 0.6–0.7.
• Artistic Renderings: CFG 4–6, Interpolate Phi 0.8–0.9.
• Abstract Concepts: CFG 7+ for experimental outputs.

Crafting Effective Negative Prompts

Writing effective negative prompts requires understanding the type of image you want to create. Here are examples for specific styles:

Example: Portrait Photography

• Positive Prompt: Professional portrait of a middle-aged woman with short gray hair, warm smile, and kind eyes. Natural outdoor lighting, shallow depth of field, park bokeh background. High-quality DSLR photo.
• Negative Prompt: Young appearance, long hair, indoor setting, harsh lighting, blurry focus, multiple people, accessories, hats, glasses.

General Negative Prompt Examples

• Blurry, oversaturated colors, modern buildings, people, animals other than koi fish, text, logos, watermarks, distorted proportions, unrealistic lighting.

Troubleshooting and Tips for FLUX Prompts

• Oversaturation: Lower the Interpolate Phi value.
• Prompt Adherence Issues: Gradually increase CFG scale.
• Slow Generation: Start with lower resolutions, then scale up.
• Inconsistent Results: Experiment with different seed values.

Advanced Techniques

• LoRA Integration: Combine dynamic thresholding with LoRA models for finer control.
• Batch Processing: Test multiple prompt variations for the best outcomes.

Conclusion

Negative prompts in FLUX open new creative possibilities by allowing precise control over image generation. Leveraging dynamic thresholding and optimized parameters ensures your outputs align with your artistic vision.