Seedream 4.0 image API on Sume: price, ratios, 10 references

Seedream 4.0 is in the Sume image catalog as bytedance-seed/seedream-4 at a list price of $0.0325 per image, read 2026-10-03. That makes it the cheapest of the three Seedream rows Sume lists (4.0, 4.5 and 5.0 Lite) and one of the few that accepts aspect_ratio: "auto". It takes text prompts, up to 10 reference images, n from 1 to 4, and png, jpeg or webp output.

Everything here comes from the catalog descriptors in GET /v1/images/models and the Image API page. Sume serves each model through one sume endpoint, so the model-level and endpoint-level parameters are identical.

What the catalog says Seedream 4.0 accepts

A request that sets a parameter the model does not list is rejected with 400 unsupported_parameter, so the table below is the whole surface.

A text-to-image request

The call is the same shape as every other catalog model. The response holds Sume-hosted URLs in data[].url. A call that is still running after the 30-second wait returns 202 with a job envelope instead of 200, so check the status code before reading data; see Jobs and results.

import os
import requests

resp = requests.post(
    "https://api.sume.com/v1/images",
    headers={"Authorization": f"Bearer {os.environ['SUME_API_KEY']}"},
    json={
        "model": "bytedance-seed/seedream-4",
        "prompt": "a ceramic teapot on a linen cloth, soft window light",
        "aspect_ratio": "4:3",
    },
    timeout=60,
)
resp.raise_for_status()
if resp.status_code == 202:
    print("still running:", resp.json()["data"]["status_url"])
else:
    for image in resp.json()["data"]:
        print(image["url"])

Editing with reference images

Add input_references with public HTTPS URLs (localhost, private-network and non-HTTPS URLs are rejected before submission). Seedream 4.0 is one of the models where aspect_ratio: "auto" is listed, and the docs recommend auto on edit calls to match the reference; omitting the field is not the same as auto.

Seedream 4.5 and 5.0 Lite do not list auto, so on those two you pick an explicit ratio when you edit.

When to pick it

Pick 4.0 when price per image dominates and you want auto aspect ratio on edits. Pick 4.5 or 5.0 Lite when you are comparing newer Seedream versions on your own prompts; Sume does not publish a quality ranking, so run the same prompt on each and compare. At $32.50 per 1,000 images, a 200-image comparison costs $6.50 on this row.