Overview

10 The Flux Workflow

This chapter introduces the Flux image generation workflow in ComfyUI and explains how it differs from the Stable Diffusion setups used earlier. It begins with the practical steps needed to get Flux running locally, including loading the workflow, downloading the required encoder, VAE, and model files, and understanding how Flux’s components are split apart rather than bundled into a single checkpoint.

The chapter then focuses on ways to make Flux usable on limited hardware and on how to control its behavior. It describes quantization as a memory-saving approach that lets Flux run with less VRAM by using lower-precision weights, and it shows that switching to an fp8 model can preserve much of the output quality. It also explains Flux’s dual text-encoder setup and the special guidance system, which differs from traditional CFG and can be adjusted to improve style adherence or reduce the overly synthetic look in photorealistic images.

Finally, the chapter breaks down Flux’s more complex sampling process, including seed control, the effects of different sampler choices, and the meaning of base shift, max shift, and denoise settings. These parameters can noticeably change the denoising schedule and the final image, especially for different aspect ratios and composition goals. The chapter concludes by noting that while Flux already offers strong generation quality, its workflow requires more careful tuning than SD1.5 or SDXL, and later techniques such as LoRAs will further improve style control and realism.

Drag this image to ComfyUI to get the Flux workflow.
The Flux workflow is notably different than SD1.5 and SDXL
Our adorable first image from Flux
The Load Diffusion Model node allows you to select the U-NET.
Using the fp8 model only minorly impacts the quality of our output.
The DualCLIPLoader allows us to use two CLIP encoders.
FluxGuidance and BasicGuider nodes.
The Guidance parameter in Flux can help the model adhere to style better.
Lower Guidance also helps to make images look less “plasticy”.
Sampling is notably more complex when working with Flux.
RandomNoize adds a control_after_generation option.
Noise Schedule when max_shift and base_shift both are 0.0.
With max_shift of 1.5, the noise removal is no longer uniform.
Max shift can have a notable impact on the resulting image generated.
Base shift slightly modifies the denoising curve.
While there is a difference in images, it is more subtle.
Under some aspect ratios, base_shift has no impact at all!
Denoise should be changed in very small increments

Summary

  • The Flux workflow has quite a few differences from the standard Stable Diffusion workflow.
  • When working with models requiring high memory, it is helpful to look for quantized versions of these models.
  • Part of the reason Flux is so good at prompt adherence is because it uses two CLIP encoders.
  • Guidance in Flux is similar to CFG in SD1.5 and SDXL, but doesn’t allow for a negative prompt.
  • Reducing Guidance can help the model pay more attention to the style recommended in the prompt.
  • Flux allows for much more nuanced control over scheduling.
  • Max shift can have a pretty major impact on your final result, but base shift is less impactful and in many cases will have no impact at all.
  • Reducing the Denoise value can make the image look nicer, but should only be done in very small steps as it can quickly degrade the image.

FAQ

What is Flux.1-dev, and why is it used in this chapter?Flux.1-dev is the open Flux image generation model used throughout the chapter. It is described as the most powerful open version of Flux, and the chapter uses it to explore how Flux works in ComfyUI and how its workflow differs from Stable Diffusion.
How do you load the Flux workflow into ComfyUI?You can load the Flux workflow by downloading the example image from the ComfyUI Flux examples page and dragging that image into ComfyUI. The workflow is embedded in the image itself, so importing the image loads the full node setup.
What files do you need to run Flux locally in ComfyUI?You need four main files: two CLIP encoder files, the Flux VAE file, and the Flux model file. The CLIP files are placed in ComfyUI/models/clip, the VAE goes in ComfyUI/models/vae, and the model file goes in ComfyUI/models/unet.
Which CLIP encoder files does Flux require?Flux requires two CLIP encoder files: clip_l.safetensors and t5xxl_fp16.safetensors. They are loaded together with the DualCLIPLoader node.
How does Flux differ from Stable Diffusion in model loading?Unlike SD1.5 or SDXL, which often use a single checkpoint containing everything, Flux loads the UNET, VAE, and text encoders separately. This makes the workflow more modular but also a bit more complex to set up.
What is model quantization in the Flux workflow?Quantization is a way to store model numbers using fewer bits, which reduces memory usage. In the chapter, an fp8 version of the Flux model is used to cut VRAM requirements roughly in half while keeping image quality reasonably close to the full model.
Why does Flux use two CLIP encoders?Flux uses two CLIP encoders to improve prompt understanding and prompt adherence. The chapter explains that having two encoders helps Flux combine strengths from both models when interpreting the prompt.
What is Flux Guidance, and how is it different from CFG?Flux Guidance is a Flux-specific control that is not the same as CFG scale in Stable Diffusion. It is used to balance how strongly the model follows the prompt, and lower guidance can sometimes improve style and realism.
Which sampler-related nodes are important in the Flux workflow?The key sampling-related nodes are RandomNoise, SamplerCustomAdvanced, KSamplerSelect, BasicScheduler, and ModelSamplingFlux. Together they control the seed, sampler choice, denoising schedule, and other generation settings.
What is the best way to adjust Flux to improve realism or style?The chapter suggests lowering Guidance to help with style and realism, and adjusting max_shift in ModelSamplingFlux to change the denoising schedule. It also notes that base_shift often has little or no effect in many common resolutions, so max_shift is usually the more useful setting to tweak.

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