how to use zimage and flux2 with negative prompt?

[chaowenguo]

Describe the bug

from pipeline_flux_with_cfg import FluxCFGPipeline

it allows to use negative prompt with flux, is there any similar stuff with zimage and flux2?

I means diffusers.ZImagePipeline with Tongyi-MAI/Z-Image-Turbo and diffusers.flux2kleinpipeline with black-forest-labs/FLUX.2-klein-9B I see there is negative_prompt_embeds: str | list[str] | None = None, in the call() function but how to convert negative_prompt to negative_prompt_embeds?

Reproduction

N/A

Logs

System Info

ubuntu22.04-cuda12.4.0-py311-torch2.8.0

Who can help?

@yiyixuxu @DN6

[akshan-main]

For Z-Image, negative_prompt is already supported natively:

pipe("photo of apollo 11", negative_prompt="blurry, low quality", guidance_scale=5.0)

For Flux2 Klein, the call doesn't accept a negative_prompt string directly, but you can pass pre-encoded embeddings via negative_prompt_embeds. To encode a negative prompt:

negative_prompt_embeds, _ = pipe.encode_prompt("blurry, low quality")
image = pipe("photo of apollo11", negative_prompt_embeds=negative_prompt_embeds, guidance_scale=5.0).images[0]

[asomoza]

the pipeline_flux_with_cfg is a pipeline that doesn't use real CFG just in case, that's because there was never a Flux.1 base model, this is not the case for Z-Image and Flux.2 Klein.

@akshan-main you're right, we should probably add the negative prompt to that pipeline, but if no one opened an issue about it, probably means that no one uses the base Flux.2 Klein models.

[akshan-main]

great! But if needed, I can add that and open a PR, lmk

[asomoza]

@akshan-main yeah, please open a PR if you want, we should have the negative prompt in the klein pipelines.

[akshan-main]

noticed the same issue in GLM-image

should I add negative prompt to that as well?

[asomoza]

yeah but in a separate PR

[akshan-main]

done