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POST
/
v1
/
upscale
Upscale Image
curl --request POST \
  --url https://api.legnext.ai/api/v1/upscale \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "jobId": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "imageNo": 0,
  "type": 0,
  "callback": "<string>"
}
'
{
  "code": 400,
  "message": "Invalid request parameters",
  "raw_message": "Invalid request parameters",
  "detail": null
}

​
Headers

HeaderTypeRequiredDescription
x-api-keystringYesYour API key

​
Request Body

ParameterTypeRequiredDescription
jobIdstringYesID of the original image generation task
imageNointegerYesImage number to upscale (0/1/2/3)
typeintegerYesUpscaling type (0 or 1)
callbackstringNoCallback URL for task completion notifications

​
Upscale Types

TypeNameDescriptionSupported Models
0SubtleConservative enhancement preserving original detailsv6, niji6, v6.1, v7
1CreativeMore aggressive enhancement with artistic interpretationv6, niji6, v6.1, v7
22x2x resolution increase (deprecated)v5, niji5
34x4x resolution increase (deprecated)v5, niji5

​
Example Requests

​
Subtle Upscale

curl -X POST "https://api.legnext.ai/api/v1/upscale" \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "jobId": "5dd94ec3-7282-4f04-9445-59e850ef1822",
    "imageNo": 0,
    "type": 0,
    "callback": "https://webhook.site/c98cb890-fb92-439f-8d60-42c8a51eb52d"
  }'

​
Creative Upscale

curl -X POST "https://api.legnext.ai/api/v1/upscale" \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "jobId": "5dd94ec3-7282-4f04-9445-59e850ef1822",
    "imageNo": 0,
    "type": 1,
    "callback": "https://webhook.site/c98cb890-fb92-439f-8d60-42c8a51eb52d"
  }'

​
Response

Returns a task object containing the task information. 
{
    "job_id": "8541c46c-6af7-49a5-a5a2-dd82eae7e6c8",
    "model": "midjourney",
    "task_type": "upscale",
    "status": "pending",
    "config": {
        "service_mode": "public",
        "webhook_config": {
            "endpoint": "https://webhook.site/c98cb890-fb92-439f-8d60-42c8a51eb52d",
            "secret": ""
        }
    },
    "input": null,
    "output": {
        "image_url": "",
        "image_urls": null,
        "seed": ""
    },
    "meta": {
        "created_at": "",
        "started_at": "",
        "ended_at": "",
        "usage": {
            "type": "point",
            "frozen": 120,
            "consume": 0
        }
    },
    "detail": null,
    "logs": [],
    "error": {
        "code": 0,
        "raw_message": "",
        "message": "",
        "detail": null
    }
}
This is the initial success response. Use the job_id to check the task status via the Get Task endpoint to retrieve the completed result with image URLs.

​
Upscale Types Comparison

​
Subtle (Type 0)

  • Best For: Photography, realistic images, preserving original details
  • Characteristics:
    • Minimal artistic interpretation
    • Preserves original composition and style
    • Clean, sharp enhancement
    • Suitable for professional use

​
Creative (Type 1)

  • Best For: Artistic images, illustrations, creative projects
  • Characteristics:
    • Enhanced artistic details
    • More dramatic improvement
    • May add creative interpretation
    • Good for artistic workflows

Authorizations

​
x-api-key
string
header
required

API key for authentication

Body

application/json
​
jobId
string<uuid>
required

ID of the original image generation task

​
imageNo
integer
required

Image number to upscale (0, 1, 2, or 3)

Required range: 0 <= x <= 3
Example:

0

​
type
enum<integer>
required

Upscaling type (0=Subtle, 1=Creative)

Available options:
0,
1
​
callback
string<uri>

Callback URL for task completion notifications

Response

Upscale task created successfully