Technical Specifications of mj-fast-inpaint
| Specification | Details |
|---|---|
| Model ID | mj-fast-inpaint |
| Model family | Midjourney inpainting / regional image editing workflow. |
| Primary function | Edit selected regions of an existing image while preserving the rest of the composition. |
| Input type | Typically an existing generated image or prior task reference, plus region-selection data and updated prompt instructions. |
| Output type | A revised image with only the masked or selected area regenerated. |
| Workflow type | Secondary editing step rather than first-pass generation. It is generally used after an image has already been created or upscaled. |
| Speed tier | Fast inpaint variant intended for quicker turnaround than standard editing flows, as indicated by the fast model designation. This is an inference from the model name and platform labeling. (cometapi.com) |
| Commercial use | Listed as supporting commercial use on CometAPI’s model page. (cometapi.com) |
| Pricing on CometAPI | CometAPI lists mj-fast-inpaint at $0.056 per request. (cometapi.com) |
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
fastdesignation 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.