Seedream

Seedream is sync only, returns one image per request, and gives you an image URL valid for 24 hours.

Available models

Choosing a model: only Pro can output 1K, and on Pro 1.5K costs the same as 1K with better quality, so prefer 1.5K; Lite and 4.5 output at least 2K. The Seedance overseas + Seedream group offers only seedream-5-0-pro.

Request parameters

Generate

POST /v1/images/generations with a JSON body. Adding image turns it into a single-image edit, multi-image composition, or local edit.

Per-model limits:

A WIDTHxHEIGHT aspect ratio must be within 1:16–16:1. An invalid size returns 400 before generation and is not billed.

Each image item is an http(s) URL or a base64 Data URL; each Data URL must be ≤ 30 MB. Supported formats: JPEG, PNG, WebP, BMP, TIFF, GIF, HEIC, HEIF. URLs are not downloaded or size-checked at submission and must be public addresses the server can reach.

Local edits do not use a mask: draw the annotation on a reference image and describe its coordinates, bounding box, arrow, or painted region in the prompt.

Edit

POST /v1/images/edits is a compatibility entry for existing OpenAI Images editing code. Prefer multipart/form-data; the same JSON as generations also works. At least one reference image is required.

Any mask field returns 400, even null. Multipart fields not listed above are ignored.

Response

A sync response in the standard OpenAI Images JSON; the image is in data[].url.

{
  "model": "seedream-5-0-pro",
  "created": 1760000000,
  "data": [
    {
      "url": "https://…/result.jpeg?X-Signature=…",
      "size": "2048x2048"
    }
  ],
  "usage": {
    "generated_images": 1,
    "output_tokens": 16384,
    "total_tokens": 16384
  }
}

Examples

Text to image

curl https://api.hop-base.com/v1/images/generations \
  -H "Authorization: Bearer sk-your-key" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "seedream-5-0-pro",
    "prompt": "A futuristic city street at neon night, cinematic framing",
    "size": "2048x2048",
    "response_format": "url"
  }'

Edit with references

curl https://api.hop-base.com/v1/images/generations \
  -H "Authorization: Bearer sk-your-key" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "seedream-5-0-pro",
    "prompt": "Move the cup in the first image to the right; keep the rest",
    "image": ["https://example.com/source.png"],
    "size": "2K",
    "output_format": "png",
    "response_format": "url"
  }'

Notes

• Each request returns one image; send separate requests for more.
• Sync only: Prefer: respond-async is ignored and the request still returns synchronously.
• Results come only as url; b64_json is not supported.
• size does not accept auto, and Lite and 4.5 output at least 2K.
• seedream-4-5 outputs JPEG only.
• Traditional masks are not supported; for local edits, use an annotated reference plus a prompt description.

Common errors

Invalid parameters return 400 before generation and are not billed. Content-safety rejections also return 400 without charge, with the reason in error.message.

model seedream-5-0-pro only supports size 1K, 1.5K, 2K or a valid WIDTHxHEIGHT pixel size   # e.g. "size": "auto"
model seedream-5-0-lite requires the total pixel count of size to be between 3686400 and 16777216
size aspect ratio must be between 1:16 and 16:1
missing prompt
response_format only supports url
only a single output is supported (n=1)
model seedream-4-5 only supports output_format jpeg
model seedream-5-0-lite only supports optimize_prompt_options.mode standard
optimize_prompt_options must be an object
image must be a URL/data URL string or an array of strings
every item in the image array must be a URL or data URL string
image must not be empty
at most 10 reference images are supported
reference image 1 is invalid: data URL must be base64-encoded
reference image 1 is invalid: unsupported image format image/svg+xml
reference image 1 is invalid: a single image must not exceed 30 MB
image edits require at least one image reference            # /v1/images/edits without an image
seedream does not accept a traditional mask; ...            # any "mask" on /v1/images/edits, even null

Billing

Billed per output image, and 5.0 Pro also charges for each reference image; failed generations and safety rejections are not billed. 5.0 Pro is priced by output pixel tier, and 1K and 1.5K cost the same.

See each model card and the signed-in model catalog for unit prices.

Next steps

• Image generation overview
• GPT Image, Gemini images, Grok images, Kling images
• API reference: Create image, Edit image
• When something fails, check Troubleshooting