Overview

9 Better Image Generation with Flux

This chapter introduces Flux as a major new diffusion model in the Stable Diffusion ecosystem and uses it to show how much image generation has advanced. The author frames Flux as both a continuation of earlier models and something meaningfully new, then revisits familiar prompts to compare results across generations of models. The goal is not just to praise Flux, but to use it as a concrete example for thinking about what makes a model genuinely better.

Across several tests, Flux stands out for producing higher-quality images with striking reliability. It generates more realistic coffee photos, handles human anatomy far better than SD 1.5 and SDXL, renders text on objects much more accurately, and follows complex prompts with much stronger adherence. A key point is that these results often appear on the first generation, which matters when evaluating models because impressive outputs can be misleading if they require many attempts. The chapter argues that model quality should be judged by both output quality and how easily that quality is achieved.

At the same time, the chapter explains why older Stable Diffusion models still matter. Flux is demanding to run and even harder to fine-tune, while SD 1.5 and SDXL remain more accessible on consumer hardware and have large ecosystems of checkpoints and stylistic tools. The biggest weakness of Flux highlighted here is style control: older models can better capture specific artistic looks, such as medieval illumination, even when Flux wins on realism and prompt accuracy. The broader lesson is that choosing a model depends on the task, hardware, and desired aesthetic, so evaluating new models means balancing capability, cost, and community adoption rather than chasing the newest release blindly.

Image (1028x1028 resolution) generated on a first try with the prompt.
Characteristic example of the oddities that appear when generating human images with SD1.5
Using a high quality checkpoint like Deliberate, can improve the results over base SD 1.5.
SDXL has a strong preference for creating images that look like illustrations.
Flux does a fantastic job creating a fairly realistic image on its first attempt.
SD 1.5 struggles to generate text, a word is missing and none are spelled correctly.
SDXL does create a better looking image, but still fails to correctly render text.
Flux again correctly renders the text on the first pass.
SD1.5 can only render some of the items described and struggles with the arrangement of them.
SDXL creates an arguably better looking image but is worse at following the prompt.
Once again Flux takes the cake (...er pie?) and get the best result.
The image in SD1.5 looks a little “melted” but the style is spot on.
SDXL is capable of creating a higher quality image that also captures the style well.
Flux creates a great looking image, but fumbles on getting the style correct.

Summary

  • Flux is a very powerful open diffusion model developed by the original creators of Stable Diffusion.
  • The first thing to check when evaluating a new model is how well it generates an image in a few tries.
  • Traditionally diffusion models have struggled to generate realistic humans, Flux does quite well for this.
  • “Prompt adherence” describes how well the model listens to details of our prompts, especially related to the composition of objects in the scene.
  • Flux can be used to reliably create legible text in images.
  • For all its power, Flux struggles to create interesting styles.
  • There is typically never a “best” model, but rather the “best” model for certain tasks.
  • Stable Diffusion 1.5 and Stable Diffusion XL will likely remain important models even as Flux increases in popularity.

FAQ

What is Flux, and why is it important in this chapter?Flux is a powerful diffusion model developed by Black Forest Labs. It is important because it represents a major step forward in image generation, producing higher-quality results, better prompt following, and stronger text rendering than earlier Stable Diffusion versions in many cases.
How does Flux compare to Stable Diffusion 1.5 and SDXL?Flux generally outperforms SD 1.5 and SDXL in overall image quality, realism, and prompt adherence. However, SD 1.5 and SDXL can still be better for certain tasks, especially style reproduction and custom checkpoint workflows.
What makes Flux’s image quality stand out?Flux can generate very high-resolution, highly detailed images right away, often on the first try. The chapter emphasizes that its output looks impressively realistic without needing many sample generations or special tuning.
Why is Flux better at generating human faces and hands?Compared with SD 1.5 and SDXL, Flux produces more believable human anatomy. In the examples from the chapter, Flux handles eyes and hands more naturally, avoiding many of the uncanny distortions common in older models.
How well does Flux render text in images?Flux is much better than SD 1.5 and SDXL at rendering readable, accurate text. The chapter shows that Flux can correctly produce text on a coffee mug, while the older models often miss words or misspell them.
What is prompt adherence, and why does it matter?Prompt adherence is the model’s ability to follow complex instructions about multiple objects and their arrangement in a scene. It matters because a model can create a beautiful image while still failing to match the prompt accurately.
Does Flux support negative prompts or prompt emphasis?According to the chapter, Flux does not support negative prompts or prompt emphasis. The reason given is that Flux is strong enough at following prompts that it does not need those extra techniques in the same way older Stable Diffusion models do.
Why are older models like SD 1.5 and SDXL still useful?Older models remain useful because they require fewer system resources, are easier to run on more devices, and are much easier to fine-tune. They also still have strengths in certain style-focused tasks where Flux may perform worse.
In what cases do SD 1.5 or SDXL outperform Flux?The chapter highlights style as a key area where older models can be better. For example, SD 1.5 and SDXL do a better job than Flux at generating images in a medieval illuminated manuscript style.
How should you evaluate a new image generation model?You should test whether strong examples are representative or cherry-picked, check how well the model follows prompts, compare quality across different tasks, consider resource requirements, and pay attention to community reaction over time.

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