Upscale - APIMart

curl --request POST \
  --url https://api.apimart.ai/v1/midjourney/generations/upscale \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
    "task_id": "task_01KQVZAPBW13W63DQNQZT7FCQK",
    "index": 1,
    "speed": "fast"
  }'

{
  "code": 200,
  "data": [
    {
      "status": "submitted",
      "task_id": "task_01KV52C0TEJSYZMCG0NCS4YWKK"
    }
  ]
}

Picks one of U1–U4 from the parent grid (grid_image_url) to produce a single image. This is implemented by cropping from the existing 4 images, composed locally and usually returns instantly.

Item	Value
action	`UPSCALE`
Billing	`midjourney@upscale[-version][-speed]`
Required	`task_id` + `index`, or `task_id` + `custom_id`
Optional	`speed`, `metadata`

Parameters

Field	Type	Notes
`task_id`	string	Parent task ID (must be a SUCCESS imagine / variation / reroll, etc.)
`index`	int	Which tile (U1–U4), range `1`–`4`; one of `index` / `custom_id`
`custom_id`	string	Directly pass the button ID for the corresponding action; one of `index` / `custom_id`; when set, `index` matching is skipped
`speed`	string	`relax` / `fast` / `turbo` (no effect, since it is composed locally)
`metadata`	object	Custom metadata

Request examples

By index:

{
  "task_id": "task_01KQVZAPBW13W63DQNQZT7FCQK",
  "index": 1,
  "speed": "fast"
}

Pass a button directly:

{
  "task_id": "task_01KQVZAPBW13W63DQNQZT7FCQK",
  "custom_id": "MJ::JOB::upsample::1::xxxx"
}

Response

Submission returns a new task_id, usually SUCCESS within milliseconds. On SUCCESS, image_urls has a single element (one image), and buttons contains follow-up actions (zoom / inpaint / pan / variation, etc.).

Notes

The parent task must be in SUCCESS state, otherwise it returns 400 (task is not in SUCCESS state).
index must be 1–4; out of range returns 400. custom_id and index are mutually exclusive; if both are passed, custom_id wins.
The resource-consuming step is imagine; upscale only picks from existing images and rarely fails.
The single image after upscale can continue with Zoom / Inpaint / Variation.

HD upscale (HD enlargement, outputs a single 2x image)

A regular upscale is composed locally—it crops one of the 4 images already in the parent task and returns instantly. If you later want to perform fine-grained operations such as zoom / inpaint on a single image, we recommend using HD upscale instead: it performs a real enlargement, outputs a single 2x HD image, takes about 60–120s to complete, and the resulting single image more reliably supports subsequent zoom / inpaint. HD upscale specifies the enlargement command via custom_id; different imagine versions correspond to different commands:

customId command	Applicable version
`upsample_v5_2x`	v5 imagine
`upsample_v5_4x`	v5 imagine
`upsample_v6_2x_subtle`	v6 / v6.1 imagine
`upsample_v6_2x_creative`	v6 / v6.1 imagine
`upsample_v7_2x_subtle`	v7 / v8.1 imagine
`upsample_v7_2x_creative`	v7 / v8.1 imagine

HD upscale example

{
  "task_id": "task_01KQVZAPBW13W63DQNQZT7FCQK",
  "custom_id": "MJ::JOB::upsample_v7_2x_subtle::1::xxxx"
}

Once complete, you get a true single 2x HD image task, which you can continue to zoom / inpaint.

Comparison with regular upscale

Dimension	Regular upscale	HD upscale
Implementation	Composed locally (cropping)	Real enlargement processing
Time	Millisecond-level	About 60–120s
Output	Picks the Nth of 4 images	Single 2x HD image
Follow-up	zoom / inpaint / variation	zoom / inpaint more reliable

⚠️ pan is still unavailable

Even for the HD single image produced by HD upscale, pan operations are still rejected (returns “invalid image generation request”)—this is a Midjourney limitation on the pan operation itself, unrelated to the enlargement method. See Pan for details.

​Parameters

​Request examples

​Response

​Notes

​HD upscale (HD enlargement, outputs a single 2x image)

​HD upscale example

​Comparison with regular upscale

​⚠️ pan is still unavailable