Ideogram 4

Ideogram 4 is a flow-matching text-to-image model that uses a multimodal text encoder and an asymmetric classifier-free guidance scheme: a dedicated unconditional_transformer produces the negative branch with zeroed text features, while the main transformer consumes the full packed text + image sequence.

The pipeline defaults are the recommended settings for best quality, so a plain pipe(prompt) call produces best-quality results out of the box: 48 flow-matching steps on a logit-normal schedule (mu=0.0, std=1.5) with classifier-free guidance held at 7.0 for the main steps and dropped to 3.0 for the final 3 "polish" steps.

Key inference-time knobs are exposed via the pipeline call:

num_inference_steps, mu, and std control the resolution-aware logit-normal flow-matching schedule.
guidance_scale (or a full per-step guidance_schedule) blends the conditional and unconditional velocities.

Text-to-image

python

import torch
from diffusers import Ideogram4Pipeline

pipe = Ideogram4Pipeline.from_pretrained("ideogram-ai/ideogram-v4", torch_dtype=torch.bfloat16)
pipe.to("cuda")

prompt = "A photo of a cat holding a sign that says hello world"
# The defaults are the recommended settings for best quality.
image = pipe(prompt, height=1024, width=1024, generator=torch.Generator("cuda").manual_seed(0)).images[0]
image.save("ideogram4.png")

Prompt upsampling

Ideogram 4 is trained on a structured JSON caption rather than a free-form prompt, so a short prompt is best expanded into that native schema before generation. There are two ways to produce the caption.

Remote (Ideogram API)

For the best results, expand the prompt with Ideogram's hosted magic-prompt API and pass the returned caption straight to the pipeline (get a key at developer.ideogram.ai):

python

import json
import requests
import torch
from diffusers import Ideogram4Pipeline

pipe = Ideogram4Pipeline.from_pretrained("ideogram-ai/ideogram-4-nf4", torch_dtype=torch.bfloat16)
pipe.to("cuda")

# Expand the prompt into a structured JSON caption with Ideogram's hosted magic-prompt API.
response = requests.post(
    "https://api.ideogram.ai/v1/ideogram-v4/magic-prompt",
    headers={"Api-Key": "your_ideogram_api_key"},
    json={"text_prompt": "A photo of a cat holding a sign that says hello world", "aspect_ratio": "1x1"},
).json()
caption = json.dumps(response["json_prompt"])

# The caption is already upsampled, so pass it directly (no prompt_upsampling).
image = pipe(caption, height=1024, width=1024, generator=torch.Generator("cuda").manual_seed(0)).images[0]
image.save("ideogram4_upsampled.png")

Local (on-device)

For a fully local pipeline, load a small [Ideogram4PromptEnhancerHead] (the Qwen3-VL LM head) as the optional prompt_enhancer_head component and pass prompt_upsampling=True. The head is grafted onto the shared text_encoder, so no second text encoder is loaded. Install outlines for schema-constrained captions (the nf4 checkpoint also needs bitsandbytes):

python

import torch
from diffusers import Ideogram4Pipeline, Ideogram4PromptEnhancerHead

prompt_enhancer_head = Ideogram4PromptEnhancerHead.from_pretrained(
    "diffusers/qwen3-vl-8b-instruct-lm-head", torch_dtype=torch.bfloat16
)
pipe = Ideogram4Pipeline.from_pretrained(
    "ideogram-ai/ideogram-4-nf4", prompt_enhancer_head=prompt_enhancer_head, torch_dtype=torch.bfloat16
)
pipe.to("cuda")

prompt = "A photo of a cat holding a sign that says hello world"
image = pipe(
    prompt,
    height=1024,
    width=1024,
    prompt_upsampling=True,
    generator=torch.Generator("cuda").manual_seed(0),
).images[0]
image.save("ideogram4_upsampled.png")

Ideogram4Pipeline

[[autodoc]] Ideogram4Pipeline - all - call

Ideogram4PromptEnhancerHead

[[autodoc]] Ideogram4PromptEnhancerHead

Ideogram4PipelineOutput

[[autodoc]] pipelines.ideogram4.pipeline_output.Ideogram4PipelineOutput