AIREITERA good Klein edit prompt states one change, assigns the reference, and names the identity or composition details that must remain unchanged.
The short answer: use a change-only prompt
FLUX.2 [klein] is the right starting point when you want quick, bounded changes from one or more reference images: swap a jacket, move a subject into a new setting, recolor a product, or adjust light. Black Forest Labs’ official FLUX.2 repository lists text-to-image, single-reference editing, and multi-reference editing for the family.
The practical limitation is consistency. Real ComfyUI users report identity loss and anatomy drift in restoration and iterative workflows. One user described the result plainly:
“The identities are therefore not perfectly preserved.” — u/Hairy-Candy3690, r/comfyui
For that reason, start every edit with two clauses:
- Change: the one visual property you want modified.
- Preserve: the identity, composition, text, or object details that must survive.
The reference-plus-instruction pattern
Name the reference, request one visible transformation, and list the important invariants instead of redrawing the image in prose.
Use this pattern:
Using image 1 as the base, change [one element] to [target state].
Keep [identity, pose, composition, wardrobe, text, and other critical details] unchanged.
Match the existing perspective and lighting unless [specific exception].A reusable edit prompt template
Object swap
Using image 1 as the base, replace the red backpack with a matte black canvas backpack. Keep the same person, face, pose, clothing, framing, and street background unchanged. Match the original perspective and soft overcast light.Relighting
Using image 1 as the base, change the lighting to warm sunset light from camera left. Keep the same person, facial identity, hairstyle, clothing, pose, camera angle, and background composition. Add warm highlights without changing the printed text on the shirt.Recoloring
Using image 1 as the base, change only the jacket to deep cobalt blue, hex #1E3A8A. Keep the person, jacket shape, logo lettering, folds, shadows, and background unchanged. Preserve the existing light direction.Attach a hex code to a named object rather than placing a code on its own. Treat the result as directional color guidance: surface material and lighting can change the perceived hue.
Multi-reference edits: label every image
Assign each reference a job. For example: “use the person from image 1, the room from image 2, and the warm side light from image 3.” Do not rely on “combine these images,” because the model then has to infer which subject, background, and lighting should dominate.
The Black Forest Labs guidance says Klein supports multiple reference images. Reference-count limits vary by endpoint, so check the interface before sending a production request.
Keep the order stable across iterations. If image 1 is the identity reference in pass one, do not silently make image 2 the identity reference in pass two.
Keeping a person stable across edits
Keep the original identity reference available after generating intermediate images. Feeding only the latest output back can let small changes accumulate, so make each pass narrow.
What to preserve explicitly
Write preservation clauses for the things that are expensive to repair:
| Risk | Preservation wording |
|---|---|
| Face drift | “Keep the same facial identity, facial proportions, and hairstyle.” |
| Pose drift | “Keep the same body position, hand placement, and camera angle.” |
| Wardrobe drift | “Keep the same garment, seams, folds, and printed graphics.” |
| Composition drift | “Keep the crop, subject position, lens perspective, and background layout.” |
| Text drift | “Keep the exact lettering ‘NORTHLINE’ in the same position and capitalization.” |
Do not write “preserve everything” and assume that covers these risks. Name the high-value elements individually.
When a correction pass is safer than a longer prompt
Break a complex edit into one-variable passes:
- Change the background while preserving the subject and crop.
- Change the wardrobe color while preserving the face, pose, and logo.
- Adjust lighting while preserving color and text.
- Stop when the required change is correct; do not keep polishing a stable image.
One-variable passes do not guarantee identity preservation, but they make failures diagnosable and reduce the risk of an overloaded recovery prompt. If the face changes after the background pass, you know which instruction caused the problem.
Prompt mechanics that matter in Klein
Put the subject or affected object first, then the requested change, then the constraints that must survive. As a practical starting heuristic, try 30–80 words for a normal edit; add words only when each one names a visible relationship, location, or invariant.
Write connected prose rather than a tag pile. “Replace the mug on the left with a blue ceramic cup, keeping the hand, table, and window reflection unchanged” gives the model relationships that “mug, blue cup, table, hand” does not.
Describe the desired state positively. Instead of “no blur,” write “sharp focus on the face.” Instead of “do not change the background,” write “keep the existing background layout and perspective.” This matters because negative-prompt controls vary by Klein variant and wrapper. Verify the implementation instead of assuming a conventional negative branch.
Avoid conflicting instructions. “Relight the entire product but keep the white label pixel-identical” asks the model to change and preserve the same pixels. Use “add warm light to the scene while keeping the label lettering pure white and readable” when that is the actual goal.
Klein, FLUX 3, or Kontext: choose by failure tolerance
The useful comparison is not a universal quality ranking. It is how much failure your workflow can tolerate.
| Need | Start with | Practical rule |
|---|---|---|
| Fast drafts, bounded edits, or local iteration | FLUX 2 Klein | Choose Klein when you can inspect narrow passes and runtime constraints matter. |
| Complex identity-preserving compositing | A larger FLUX endpoint | Move up when a failed pass costs more than slower iteration; verify the current endpoint’s capabilities first. |
| Conversational, high-level transformations | Kontext | Choose it when a conversational editing interface fits your workflow better than a compact Klein pipeline. |
Use Klein when the edit can be stated as one or two concrete changes and you can inspect each pass. Move to FLUX 3 or Kontext when the request combines identity preservation, complex compositing, typography, and several dependent transformations in one operation.
FAQ
Does FLUX 2 Klein support multi-reference editing?
Yes. Black Forest Labs lists multi-reference editing as a supported capability. The exact reference count depends on the endpoint or interface; verify the current limit for Klein before sending a production request.
Should I use negative prompts?
Do not assume a negative prompt field works in your Klein interface. State the desired visual condition positively, such as “an empty tabletop” or “sharp focus throughout,” and verify the implementation.
How long should a Klein editing prompt be?
Start around 30–80 words. Longer prompts are justified for multiple subjects, precise spatial relationships, or several preservation constraints, but remove any sentence that does not describe a visible result.
How do I stop a face from changing after several edits?
Keep the original identity reference available, make one change per pass, and explicitly preserve facial identity, hairstyle, pose, and crop. Save each intermediate image and stop iterating once the required edit is correct; longer chains increase the chance of identity drift.
Choose FLUX 2 Klein for fast, bounded edits you can inspect pass by pass; choose FLUX 3 or Kontext when identity drift and complex compositing are more costly than slower iteration.