This guide shows how to generate images using GPT Image-1.5 model via the Leonardo.AI REST API.

Sample Request

curl --location 'https://cloud.leonardo.ai/api/rest/v2/generations' \
     --header 'authorization: Bearer {api-key}' \
     --header 'Content-Type: application/json' \
     --data '{
       "public": false,
       "model": "gpt-image-1.5",
       "parameters": {
           "mode": "QUALITY",
           "prompt": "Koala with purple hat",
           "quantity": 2,
           "width": 1024,
           "height": 1024,
           "seed": 4294967295,
           "prompt_enhance": "OFF"
           "guidances": {
               "image_reference": [
                   {
                       "image": {
                       "id": "00000000-0000-0000-0000-000000000001",
                       "type": "UPLOADED"
                       },
                       "strength": "MID",
                   }
               ]
           }
        }
     }'

Recipe

API Request Endpoint, Headers, Parameters

Endpoint

https://cloud.leonardo.ai/api/rest/v2/generations

Headers

--header "accept: application/json" \
--header "authorization: Bearer <YOUR_API_KEY>" \
--header "content-type: application/json"

Body Parameters

Parameter	Type	Definition
guidances	`object`	Optional. Object defining image guidance inputs that influence the generated result.
guidances.image_reference	`array`	Optional. Array of up to 6 reference images. Each reference includes image.id, image.type (`GENERATED` or `UPLOADED`), and strength (`LOW`, `MID`, `HIGH`).
height	`integer`	Optional. Height input resolution.
mode	`string`	Optional. Accepts `FAST`, `QUALITY`, or `ULTRA`.
model	`string`	Required. Model identifier. Set to `gpt-image-1.5`
prompt	`string`	Required. Text prompt describing what image you want the model to generate.
prompt_enhance	`string`	Optional. Enables prompt enhancement when set to `"ON"`; disabled when set to `"OFF"`.
public	`boolean`	Optional. Boolean flag that determines whether the generation is public (`true`) or private (`false`).
quantity	`integer`	Optional. Number of images to generate in a single request.
seed	`integer`	Optional. Apply a fixed seed to maintain consistency across generation sets.
width	`integer`	Optional. Width input resolution.

Aspect Ratio Settings

Aspect Ratio	Width	Height
2:3	1024	1536
1:1	1024	1024
3:2	1536	1024