mj_fast_inpaint

Technical Specifications of mj-fast-inpaint

What is mj-fast-inpaint?

mj-fast-inpaint is a Midjourney-oriented image editing model endpoint exposed through CometAPI for inpainting workflows. In practice, it is used when you already have an image and want to change only a specific part of it—such as replacing an object, fixing a face detail, changing clothing, or altering a background element—without regenerating the whole image from scratch. (cometapi.com)

Across Midjourney API documentation from multiple providers, inpainting is described as the API equivalent of editing a selected region of an upscaled image, often corresponding to the “Vary (Region)” style workflow. That means the model keeps the surrounding composition largely intact while re-rendering only the user-selected area according to the new prompt or edit instructions.

For developers, mj-fast-inpaint is useful when building AI design tools, creative editors, asset iteration pipelines, and post-generation correction flows. Instead of asking users to regenerate entire images repeatedly, you can offer targeted edits that are faster, more controllable, and usually more cost-efficient for refinement tasks. This characterization is based on the documented behavior of Midjourney inpainting endpoints and the positioning of mj-fast-inpaint as a dedicated inpaint model on CometAPI. (cometapi.com)

Main features of mj-fast-inpaint

• Region-specific editing: Regenerates only a selected or masked portion of an image, leaving the rest of the composition unchanged as much as possible.
• Prompt-guided modifications: Lets you describe what should appear in the edited area, enabling controlled replacements, additions, or removals.
• Built for refinement workflows: Works as a follow-up editing step after initial image creation or upscaling, making it well suited for iterative creative pipelines.
• Fast-turnaround variant: The fast designation indicates a speed-focused inpainting option for teams that prioritize quick edits and rapid iteration. This is an inference from the model naming and marketplace labeling. (cometapi.com)
• API-friendly automation: Can be integrated into applications that need programmatic image correction, personalization, or asset versioning rather than manual editing only.
• Commercial project support: CometAPI explicitly marks the model as available for commercial use, which is relevant for production deployments. (cometapi.com)

How to access and integrate mj-fast-inpaint

Step 1: Sign Up for API Key

Sign up on CometAPI and generate your API key from the dashboard. CometAPI provides a unified API gateway, so you can access mj-fast-inpaint using the same authentication pattern you use for other models on the platform. Store the API key securely and load it from environment variables in production environments. (cometapi.com)

Step 2: Send Requests to mj-fast-inpaint API

Use CometAPI's Midjourney-compatible endpoint at POST /mj/submit/edits.

curl https://api.cometapi.com/mj/submit/edits \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $COMETAPI_API_KEY" \
  -d '{
    "prompt": "a futuristic cityscape at sunset --v 6.1",
    "botType": "MID_JOURNEY",
    "accountFilter": {
      "modes": ["FAST"]
    }
  }'

Step 3: Retrieve and Verify Results

The API returns a task object with a task ID. Poll GET /mj/task/{task_id}/fetch to check generation status and retrieve the output image URL when the task reaches a terminal state.