GPT Image 1.5 API Reference | Nano Banana Pro API

GPT Image

GPT Image 1.5 for high-quality image generation and editing

Endpoint: POST /api/v1/images/generate
model: gpt-image-1.5
Output: Image
Credits: from 2

Submit a task

POST/api/v1/images/generate

Parameters

modelstringRequired
Must be "gpt-image-1.5"
typestringOptionalDefault text-to-image
"text-to-image" or "image-to-image" (default: text-to-image)
text-to-imageimage-to-image
promptstringRequired
Text description of the image
qualitystringOptionalDefault medium
"low", "medium", or "high" (default: medium)
lowmediumhigh
image_sizestringOptional
"1024x1024", "1536x1024", or "1024x1536"
1024x10241536x10241024x1536
num_imagesnumberOptional
Number of images (1-4)
image_urlsstring[]Optional
Input image URLs or base64 for image editing
input_imagestringOptional
Deprecated. Alias for image_urls[0]

Request

curl -X POST https://www.bananapro.site/api/v1/images/generate \
  -H "Authorization: Bearer sk-your-api-key" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-image-1.5",
    "prompt": "A serene Japanese garden with cherry blossoms",
    "quality": "high",
    "image_size": "1024x1024"
  }'

Response200

JSON

{
  "success": true,
  "data": {
    "task_id": "task_gpt123",
    "credits_used": 30,
    "remaining_credits": 470,
    "model": "gpt-image-1.5"
  }
}

The credits_used values shown in these examples are illustrative. Actual usage is calculated when you submit and returned by the API.

Query the task

GET/api/v1/images/{task_id}

status

pending: Accepted and waiting to start. Keep polling.
processing: Running. Keep polling.
completed: Finished. Read image_url; output holds the full result.
failed: Ended without a result. error_message says why and credits_refunded shows what was returned.

Poll every 5 to 10 seconds and stop at completed or failed, or register a webhook to be notified instead. Failed tasks are refunded automatically.

Request

curl https://www.bananapro.site/api/v1/images/task_abc123 \
  -H "Authorization: Bearer sk-your-api-key"

Response200

JSON

{
  "success": true,
  "data": {
    "task_id": "task_abc123",
    "model": "gpt-image-1.5",
    "status": "completed",
    "output": { "images": [{ "url": "https://..." }] },
    "primary_url": "https://...",
    "image_url": "https://...",
    "error_message": null,
    "credits_used": 30,
    "credits_refunded": 0,
    "created_at": "2026-10-04T10:00:00.000Z",
    "updated_at": "2026-10-04T10:01:12.000Z",
    "completed_at": "2026-10-04T10:01:12.000Z"
  },
  "request_id": "req_abc123"
}

Wait for the result

TASK_ID=task_abc123
while true; do
  TASK=$(curl -s https://www.bananapro.site/api/v1/images/$TASK_ID \
    -H "Authorization: Bearer sk-your-api-key")
  STATUS=$(echo "$TASK" | jq -r '.data.status')
  if [ "$STATUS" = "completed" ] || [ "$STATUS" = "failed" ]; then
    echo "$TASK" | jq
    break
  fi
  sleep 10
done

Pricing

Quality	1024×1024	1536×1024
low	2	3
medium	8	10
high	30	40

Total credits = base_credits × num_images

Features

Text-to-image generation
Image editing with prompts
Multiple quality levels
Flexible image sizes

curl -X POST https://www.bananapro.site/api/v1/images/generate \ -H "Authorization: Bearer sk-your-api-key" \ -H "Content-Type: application/json" \ -d '{ "model": "gpt-image-1.5", "prompt": "A serene Japanese garden with cherry blossoms", "quality": "high", "image_size": "1024x1024" }'

{ "success": true, "data": { "task_id": "task_abc123", "model": "gpt-image-1.5", "status": "completed", "output": { "images": [{ "url": "https://..." }] }, "primary_url": "https://...", "image_url": "https://...", "error_message": null, "credits_used": 30, "credits_refunded": 0, "created_at": "2026-10-04T10:00:00.000Z", "updated_at": "2026-10-04T10:01:12.000Z", "completed_at": "2026-10-04T10:01:12.000Z" }, "request_id": "req_abc123" }

TASK_ID=task_abc123 while true; do TASK=$(curl -s https://www.bananapro.site/api/v1/images/$TASK_ID \ -H "Authorization: Bearer sk-your-api-key") STATUS=$(echo "$TASK" | jq -r '.data.status') if [ "$STATUS" = "completed" ] || [ "$STATUS" = "failed" ]; then echo "$TASK" | jq break fi sleep 10 done

Quality

1024×1024

1536×1024

low

medium

high