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name: image-generation description: "Guides Janus and Janus-Pro text-to-image generation, classifier-free guidance, and image decoding workflows." disable-model-invocation: true metadata: disco-role: operating license: NOASSERTION

Image Generation

Use this sub-skill when the task is about Janus or Janus-Pro text-to-image generation, classifier-free guidance, output image saving, or adapting the repo's generation scripts.

Read first

• references/workflows.md for end-to-end generation recipes.
• references/api-reference.md for verified generation-loop parameters and helper calls.
• references/troubleshooting.md for CUDA, template, padding, and decode failures.
• scripts/janus_text_to_image.py for a safe dry-run helper and an optional real model run.

For installation and model-family selection, use the root ../../references/installation-and-models.md.

When to use this route

Choose this route when the user asks to:

• Generate images from text with Janus or Janus-Pro.
• Adapt the classifier-free guidance loop or image decode logic.
• Change seeds, batch size, output directory, image size, or patch size.
• Debug pad_id, past_key_values, or token/image shapes in generation.
• Save one or more generated samples from a prompt.

Core workflow

1. Choose Janus or Janus-Pro and the matching model id.
2. Apply the SFT template to a user/assistant conversation.
3. Append vl_chat_processor.image_start_tag to the prompt.
4. Encode the prompt to token ids.
5. Duplicate the batch for CFG and mask the unconditional branch.
6. Run the token loop, alternating language-model forward passes and prepare_gen_img_embeds.
7. Decode tokens with gen_vision_model.decode_code.
8. Convert the decoded tensor into image files.

Dry-run before model execution

Validate the prompt and generation parameters without downloading weights:

python sub-skills/image-generation/scripts/janus_text_to_image.py \
  --family janus-pro \
  --model-id deepseek-ai/Janus-Pro-1B \
  --prompt "A glass of red wine on a reflective surface." \
  --output-dir ./generated_samples

The default mode prints a plan and does not download model weights. Add --run-model only when you are ready for the real generation run.

Route elsewhere

• Use ../multimodal-understanding/SKILL.md for image+question tasks.
• Use ../janusflow-workflows/SKILL.md for JanusFlow rectified-flow image generation.
• Use ../demos-and-serving/SKILL.md for Gradio/FastAPI serving.