seedream series

Seedream Series Unified Endpoint Guide

1. This page explains how POST /v1/images/generations behaves for the seedream series.
2. Focus is on unified-endpoint parameter behavior, not only surface field names.

Basic Information

Item	Description
Unified endpoint	POST /v1/images/generations
Auth	Authorization: Bearer YOUR_API_KEY
Models	doubao-seedream-4.0, doubao-seedream-4.5, bytedance-seedream-5.0

Prepare these variables:

BASE_URL="https://api-platform.ope.ai"
API_KEY="YOUR_API_KEY"

For pricing, see Model Pricing.

1. Unified Field Behavior

Unified field	Platform handling	Notes
model	Normalization	Seedream aliases are normalized (see table below)
prompt	Direct handling	Used as the generation prompt
size	Direct handling	Default is applied when omitted
response_format	Validation	Only b64_json and url are accepted
image	Direct handling	Supports image-to-image / multi-image blend
stream	Default	Default false
watermark	Default	Default false
sequential_image_generation	Conditional	Seedream-only, allowed: disabled, auto
n	Conditional rewrite	When seedream + n > 1 + sequential_image_generation omitted, auto rewritten to auto + max_images=n

Fields currently ignored on this unified path: quality, style, user, output_format, output_compression, background, moderation.

2. Model ID Normalization (Platform Internal)

Request model	Normalized model
doubao-seedream-4.5 / doubao-seedream-4-5-251128	seedream-4-5-251128
doubao-seedream-4.0 / doubao-seedream-4-0-250828	seedream-4-0-250828
bytedance-seedream-5.0	bytedance-seedream-5.0

size defaults:

• doubao-seedream-3-0-t2i-250415 / seedream-3-0-t2i-250415: 1024x1024
• Other seedream models: 2K

3. Supported size Values (Seedream Native Specs)

size is passed through. You can send 2K / 3K / 4K, or send explicit resolutions (recommended).
Reference: Volcengine official docs Image Generation

Tier	Ratio	Resolution (size)
2K	1:1	2048x2048
2K	4:3	2304x1728
2K	3:4	1728x2304
2K	16:9	2848x1600
2K	9:16	1600x2848
2K	3:2	2496x1664
2K	2:3	1664x2496
2K	21:9	3136x1344
3K	1:1	3072x3072
3K	4:3	3456x2592
3K	3:4	2592x3456
3K	16:9	4096x2304
3K	9:16	2304x4096
3K	2:3	2496x3744
3K	3:2	3744x2496
3K	21:9	4704x2016
4K	1:1	4096x4096
4K	3:4	3520x4704
4K	4:3	4704x3520
4K	16:9	5504x3040
4K	9:16	3040x5504
4K	2:3	3328x4992
4K	3:2	4992x3328
4K	21:9	6240x2656

4. n Semantics (Important)

• n defaults to 1.
• For seedream, n is not a strict "generate exactly n images".
• In sequential mode, n is only used as max_images; actual generated count is decided by the model based on the prompt.
• Recommended official limit is [1, 15]; keep requests within this range.

Gateway auto-rewrite example (when n > 1 and sequential_image_generation is omitted):

{
  "sequential_image_generation": "auto",
  "sequential_image_generation_options": {
    "max_images": 8
  }
}

5. Create Request Example

curl --request POST "$BASE_URL/v1/images/generations" \
  --header "Authorization: Bearer $API_KEY" \
  --header "Content-Type: application/json" \
  --data '{
    "model": "bytedance-seedream-5.0",
    "prompt": "Generate a cohesive set of cinematic posters of the same character from different camera angles.",
    "size": "4096x2304",
    "n": 8,
    "response_format": "url"
  }'