**Cost**: 13 credits per successful call.

Image Replace Background supports two input modes:

1. **JSON URL mode**: send `application/json` with the existing URL field.
2. **Direct upload mode**: send `multipart/form-data` with a local image file in the `image` field. The compatible field name `file` is also accepted for the primary image. Codia checks credits before reading and uploading the file, so insufficient-credit requests return `402` without uploading anything.

Direct upload example:

```bash
curl 'https://openapi.codia.ai/v2/open/image/replace_background' \
  -H 'Authorization: Bearer {codia_api_key}' \
  -F 'image=@./product.png' \
  -F 'prompt=clean white studio background'
```

Keep the foreground subject of an image and synthesize a new background described by a text prompt. Synchronous, single-call. Combines background removal + inpainting + generative rendering in one step.

## What this API is for

Reshooting product photography against new scenes ("on a marble counter", "in front of a sunset window"), reusing portraits across campaigns, or any time you want to keep the subject and change its environment. The subject is preserved; the prompt only steers the new background.

## Request

| Field | Required | Notes |
|---|---|---|
| `image_url` | yes | Public URL of the source image. |
| `prompt` | yes | Natural-language description of the desired new background. Be specific about lighting, surface, and context for best results. |
| `model` | no | Model ID. Defaults to `nano_banana_2`. Also: `nano_banana_pro` (higher fidelity), `ideogram_v3` (alternative aesthetic). |

**Prompt tips**: describe the surface or scene ("clean white marble table"), the lighting ("soft studio lighting from the left"), and the mood. Avoid contradicting the subject's lighting unless you want the subject re-lit (the model may match it).

## Response

Shared `ImageUrlListSuccess` shape — `data.image_urls` is an array of CDN URLs (length 1).

## Billing & limits

- 13 credits per request from the unified Codia Open API balance.
- Synchronous, single-digit-second latency for typical inputs.

## Errors

Standard set — `400` bad input (missing `image_url` or `prompt`), `401`/`403` auth, `402` credits, `429` rate limit, `500` internal.

> **Sync vs. async**
> This synchronous endpoint returns the result inline — the simplest path. For production pipelines that need webhook delivery, automatic retry with idempotency, or explicit task cancellation, call `POST /v2/open/tasks` with `operation=image_replace_background` instead. Inputs and credit cost are identical.

選填，由使用者自訂的冪等鍵（最多 255 個字元）。設定後，成功（2xx）的回應會快取 7 天。以相同的鍵 + 相同的請求主體重試時，會回傳快取的回應（不另外扣除點數）；以相同的鍵但不同的請求主體重試，則回傳 409。可讓 POST 請求在網路故障時安全重試。對於 multipart/form-data 上傳，請求會依表單欄位與檔案內容比對，因此即使用戶端產生新的 multipart boundary，重試的上傳仍會重播先前的結果。

Idempotency-Key

image_url

prompt

產生新背景的模型。預設為 `nano_banana_2`。目前所有支援的模型每次請求皆扣除 13 點。

| 模型 | 適用情境 | 點數 |
| --- | --- | ---: |
| `nano_banana_2` | 快速替換背景（Gemini 3.1 Flash），適合作為大多數圖片的預設選擇。 | 13 |
| `nano_banana_pro` | 攝影棚等級的 4K 背景，光線與反射逼真。 | 13 |
| `ideogram_v3` | 風格化、插畫風或文字較多的背景。 | 13 |

model

image

相容用的來源圖片檔案欄位（已棄用：請改用 `image`）。

file

未上傳圖片時使用的來源圖片 URL

code

message

image_urls

data

請求主體格式錯誤或缺少必要參數

Idempotency-Key 已被用於不同的請求主體。

已達速率限制。請等待 `Retry-After` 標頭中指定的秒數後再重試。

保留主體，並依文字提示詞產生新背景。

替換背景

輸入

輸出

相關 API