vllm-omni/docs/user_guide/examples/online_serving/image_to_image.md

Image-To-Image

Source https://github.com/vllm-project/vllm-omni/tree/main/examples/online_serving/image_to_image.

This example demonstrates how to deploy Qwen-Image-Edit model for online image editing service using vLLM-Omni.

For multi-image input editing, use Qwen-Image-Edit-2509 (QwenImageEditPlusPipeline) and send multiple images in the user message content.

Start Server

Basic Start

vllm serve Qwen/Qwen-Image-Edit --omni --port 8092

!!! note If you encounter Out-of-Memory (OOM) issues or have limited GPU memory, you can enable VAE slicing and tiling to reduce memory usage, --vae-use-slicing --vae-use-tiling

Multi-Image Edit (Qwen-Image-Edit-2509)

vllm serve Qwen/Qwen-Image-Edit-2509 --omni --port 8092

Start with Parameters

Or use the startup script:

bash run_server.sh

To serve Qwen-Image-Edit-2509 with the script:

MODEL=Qwen/Qwen-Image-Edit-2509 bash run_server.sh

API Calls

Method 1: Using curl (Image Editing)

# Image editing
bash run_curl_image_edit.sh input.png "Convert this image to watercolor style"

# Or execute directly
IMG_B64=$(base64 -w0 input.png)

cat <<EOF > request.json
{
  "messages": [{
    "role": "user",
    "content": [
      {"type": "text", "text": "Convert this image to watercolor style"},
      {"type": "image_url", "image_url": {"url": "data:image/png;base64,$IMG_B64"}}
    ]
  }],
  "extra_body": {
    "height": 1024,
    "width": 1024,
    "num_inference_steps": 50,
    "guidance_scale": 1,
    "seed": 42
  }
}
EOF

curl -s http://localhost:8092/v1/chat/completions   -H "Content-Type: application/json"   -d @request.json | jq -r '.choices[0].message.content[0].image_url.url' | cut -d',' -f2 | base64 -d > output.png

Method 2: Using Python Client

python openai_chat_client.py --input input.png --prompt "Convert to oil painting style" --output output.png

# Multi-image editing (Qwen-Image-Edit-2509 server required)
python openai_chat_client.py --input input1.png input2.png --prompt "Combine these images into a single scene" --output output.png

Method 3: Using Gradio Demo

python gradio_demo.py
# Visit http://localhost:7861

Request Format

Image Editing (Using image_url Format)

{
  "messages": [
    {
      "role": "user",
      "content": [
        {"type": "text", "text": "Convert this image to watercolor style"},
        {"type": "image_url", "image_url": {"url": "data:image/png;base64,..."}}
      ]
    }
  ]
}

Image Editing (Using Simplified image Format)

{
  "messages": [
    {
      "role": "user",
      "content": [
        {"text": "Convert this image to watercolor style"},
        {"image": "BASE64_IMAGE_DATA"}
      ]
    }
  ]
}

Image Editing with Parameters

Use extra_body to pass generation parameters:

{
  "messages": [
    {
      "role": "user",
      "content": [
        {"type": "text", "text": "Convert to ink wash painting style"},
        {"type": "image_url", "image_url": {"url": "data:image/png;base64,..."}}
      ]
    }
  ],
  "extra_body": {
    "height": 1024,
    "width": 1024,
    "num_inference_steps": 50,
    "guidance_scale": 7.5,
    "seed": 42
  }
}

Multi-Image Editing (Qwen-Image-Edit-2509)

Provide multiple images in content (order matters):

{
  "messages": [
    {
      "role": "user",
      "content": [
        {"type": "text", "text": "Combine these images into a single scene"},
        {"type": "image_url", "image_url": {"url": "data:image/png;base64,..."} },
        {"type": "image_url", "image_url": {"url": "data:image/png;base64,..."} }
      ]
    }
  ]
}

Generation Parameters (extra_body)

Parameter	Type	Default	Description
height	int	None	Output image height in pixels
width	int	None	Output image width in pixels
size	str	None	Output image size (e.g., "1024x1024")
num_inference_steps	int	50	Number of denoising steps
guidance_scale	float	7.5	CFG guidance scale
seed	int	None	Random seed (reproducible)
negative_prompt	str	None	Negative prompt
num_outputs_per_prompt	int	1	Number of images to generate

Response Format

{
  "id": "chatcmpl-xxx",
  "created": 1234567890,
  "model": "Qwen/Qwen-Image-Edit",
  "choices": [{
    "index": 0,
    "message": {
      "role": "assistant",
      "content": [{
        "type": "image_url",
        "image_url": {
          "url": "data:image/png;base64,..."
        }
      }]
    },
    "finish_reason": "stop"
  }],
  "usage": {...}
}

Common Editing Instructions Examples

Instruction	Description
Convert this image to watercolor style	Style transfer
Convert the image to black and white	Desaturation
Enhance the color saturation	Color adjustment
Convert to cartoon style	Cartoonization
Add vintage filter effect	Filter effect
Convert daytime scene to nighttime	Scene conversion

File Description

File	Description
run_server.sh	Server startup script
run_curl_image_edit.sh	curl image editing example
openai_chat_client.py	Python client
gradio_demo.py	Gradio interactive interface

Example materials

??? abstract "gradio_demo.py" py --8<-- "examples/online_serving/image_to_image/gradio_demo.py" ??? abstract "openai_chat_client.py" py --8<-- "examples/online_serving/image_to_image/openai_chat_client.py" ??? abstract "run_curl_image_edit.sh" sh --8<-- "examples/online_serving/image_to_image/run_curl_image_edit.sh" ??? abstract "run_server.sh" sh --8<-- "examples/online_serving/image_to_image/run_server.sh"