Seedream 5.5 API: transparent PNG at $0.035

Seedream 5.5 is the newest Seedream image model from BytePlus ModelArk, released on November 12, 2026. It returns transparent PNGs from a single background parameter and splits a finished image into up to 99 layers, reading the font and color of any text it finds.

Item	Details
Model ID	`seedream-5-5-261028`; the BytePlus name `dola-seedream-5-5-261028` also works, at the same price
Endpoint	`POST https://api.laozhang.ai/v1/images/generations`, JSON body
Operations	Text-to-image, reference-image edits, transparent PNG, and layer decomposition, all on one endpoint
Price	Per output image, the same at every size, plus a fee per reference image; see Billing
Token	`default` group, billing mode Usage first (recommended) or Per-call; no BytePlus account needed
Size	`1K`, `1.5K`, `2K` (default), or exact pixels; no 3K or 4K
Output format	PNG by default, JPEG on request
Typical time	12–20 seconds at 1K, 25–35 seconds at 2K
Launch notes	Seedream 5.5 launch announcement

A bookstore window at night with a cat asleep on a stack of books and a hand-lettered OPEN LATE sign, generated by Seedream 5.5 — Output of the Generate an image example: size 2K, watermark false. Returned at 2496×1664, resized for this page

A white ceramic mug with small blue flowers on a transparent background, generated by Seedream 5.5 — Output of the transparent PNG example: background transparent, output_format png, size 1K. Returned as a 1024×1024 RGBA PNG

Seedream 5.5 vs 5.0

	Seedream 5.5	Seedream 5.0 Flash / 5.0 Pro
Transparent output	`background` on generate and edit requests	Only through layer decomposition
Layer decomposition	Background + up to 99 layers, a cap on the count, text style recognition	Background + up to 16 layers
Price per image	$0.035	Flash $0.018, Pro $0.12
Reference images	$0.008 each	Flash free; Pro $0.003 each after the first
Default output format	PNG	JPEG

Choose 5.5 for transparent product assets, fine-grained layers, and posters whose text you want to edit later.
Choose 5.0 Flash for low-cost bulk generation.
Choose 5.0, 4.5, or 4.0 for 3K or 4K output, or for sequential generation (several related images per request). The Seedream API guide covers all of them.

Before you start

Create a token

Register, then open Token management and create a token in the default group. Set Billing mode to Usage first (recommended) or Per-call.The sk- key you get calls Seedream 5.5 directly. You don’t need a BytePlus or Volcengine account.

Set up your environment

Export the key and install requests for the API calls and Pillow for checking transparency:

export LAOZHANG_API_KEY="YOUR_LAOZHANG_API_KEY"
python3 -m pip install requests pillow

Add a save script

Image URLs in the response are temporary (BytePlus says they last 24 hours), so save each image as soon as it arrives. Save this script as save_images.py. It handles both url and b64_json responses and names each file after the returned output_format:

save_images.py

import base64
import json
import sys
from pathlib import Path

import requests

response_file, stem = sys.argv[1], sys.argv[2]
response = json.loads(Path(response_file).read_text())
if not response.get("data"):
    sys.exit(f"No image in {response_file}: {response}")

for number, item in enumerate(response["data"], start=1):
    if item.get("b64_json"):
        image = base64.b64decode(item["b64_json"].split(",", 1)[-1])
    else:
        download = requests.get(item["url"], timeout=120)
        download.raise_for_status()
        image = download.content
    # output_format is "png" (the default) or "jpeg".
    extension = "jpg" if item.get("output_format") == "jpeg" else "png"
    path = Path(f"{stem}-{number}.{extension}")
    path.write_bytes(image)
    print(f"Saved {path}")

For a general script shared by all image models, see Save images from a response.

Generate an image

Send only prompt to generate an image. This request produced the bookstore sample above:

curl --fail-with-body "https://api.laozhang.ai/v1/images/generations" \
  -H "Authorization: Bearer $LAOZHANG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "seedream-5-5-261028",
    "prompt": "A cozy bookstore window at night with warm light, a cat sleeping on a stack of books, and a hand-lettered sign that reads \"OPEN LATE\"",
    "size": "2K",
    "response_format": "url",
    "watermark": false
  }' \
  -o seedream-5-5-generate.json

python3 save_images.py seedream-5-5-generate.json bookstore

The script prints Saved bookstore-1.png. A successful response looks like this:

{
  "model": "dola-seedream-5-5-261028",
  "created": 1794532892,
  "data": [
    {
      "url": "https://example.com/seedream-5-5.png",
      "size": "2496x1664",
      "output_format": "png",
      "background": "opaque"
    }
  ],
  "usage": {
    "input_images": 0,
    "generated_images": 1
  }
}

With a preset such as 2K, the model picks the aspect ratio from the prompt. To fix the ratio, pass exact pixels instead, such as 2048x2048 or 2848x1600, with the letter x between width and height.

Generate with Python

This version saves the file with the extension that matches the returned output_format:

import base64
import os
from pathlib import Path

import requests

response = requests.post(
    "https://api.laozhang.ai/v1/images/generations",
    headers={"Authorization": f"Bearer {os.environ['LAOZHANG_API_KEY']}"},
    json={
        "model": "seedream-5-5-261028",
        "prompt": (
            "A cozy bookstore window at night with warm light, a cat sleeping "
            'on a stack of books, and a hand-lettered sign that reads "OPEN LATE"'
        ),
        "size": "2K",
        "response_format": "url",
        "watermark": False,
    },
    timeout=180,
)
response.raise_for_status()
item = response.json()["data"][0]

if item.get("b64_json"):
    image = base64.b64decode(item["b64_json"].split(",", 1)[-1])
else:
    download = requests.get(item["url"], timeout=120)
    download.raise_for_status()
    image = download.content

extension = "jpg" if item.get("output_format") == "jpeg" else "png"
output = Path(f"bookstore.{extension}")
output.write_bytes(image)
print(f"Saved {output} ({item['size']})")

Create a transparent PNG

Set background to transparent and output_format to png. This request produced the mug sample above:

curl --fail-with-body "https://api.laozhang.ai/v1/images/generations" \
  -H "Authorization: Bearer $LAOZHANG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "seedream-5-5-261028",
    "prompt": "A ceramic coffee mug with small blue flowers, product shot",
    "background": "transparent",
    "output_format": "png",
    "size": "1K",
    "response_format": "url",
    "watermark": false
  }' \
  -o seedream-5-5-transparent.json

python3 save_images.py seedream-5-5-transparent.json mug
python3 -c "from PIL import Image; print(Image.open('mug-1.png').mode)"

The last command prints RGBA, and the response item reports "background": "transparent". background takes three values:

auto (default): the model decides from the prompt and output_format. JPEG output never has an alpha channel.
transparent: returns an RGBA image with a transparent background.
opaque: returns an RGB image with a solid background.

background also works on edit requests that include image. Don’t combine it with layer_decomposition: that request returns an error.

Edit with reference images

Add image to edit an image or combine several. Pass one reference as a string, or up to 10 as an array.

Each item is a public URL or a data URL such as data:image/png;base64,..., with the format name in lowercase.
References are numbered in array order, so the prompt can say image 1, image 2, and so on.
Each reference image costs $0.008, so this two-image edit costs $0.051 in total.
Size and format limits per image are the same as for other Seedream versions: see local images and their limits.

This example sends two local files as data URLs. Replace mug.png and table.jpg with your own files:

IMG1=$(base64 < mug.png | tr -d '\n')
IMG2=$(base64 < table.jpg | tr -d '\n')

curl --fail-with-body "https://api.laozhang.ai/v1/images/generations" \
  -H "Authorization: Bearer $LAOZHANG_API_KEY" \
  -H "Content-Type: application/json" \
  --data-binary @- \
  -o seedream-5-5-edit.json <<EOF
{
  "model": "seedream-5-5-261028",
  "prompt": "Place the mug from image 1 on the wooden table in image 2, in soft morning light. Keep the mug's shape, pattern, and colors.",
  "image": [
    "data:image/png;base64,$IMG1",
    "data:image/jpeg;base64,$IMG2"
  ],
  "size": "2K",
  "response_format": "url",
  "watermark": false
}
EOF

python3 save_images.py seedream-5-5-edit.json mug-on-table

Edit with Python

import base64
import mimetypes
import os
from pathlib import Path

import requests


def to_data_url(path):
    """Convert a local image file to a data URL."""
    mime_type = mimetypes.guess_type(path)[0] or "image/png"
    encoded = base64.b64encode(Path(path).read_bytes()).decode("ascii")
    return f"data:{mime_type};base64,{encoded}"


response = requests.post(
    "https://api.laozhang.ai/v1/images/generations",
    headers={"Authorization": f"Bearer {os.environ['LAOZHANG_API_KEY']}"},
    json={
        "model": "seedream-5-5-261028",
        "prompt": (
            "Place the mug from image 1 on the wooden table in image 2, in soft "
            "morning light. Keep the mug's shape, pattern, and colors."
        ),
        "image": [to_data_url("mug.png"), to_data_url("table.jpg")],
        "size": "2K",
        "response_format": "url",
        "watermark": False,
    },
    timeout=180,
)
response.raise_for_status()
item = response.json()["data"][0]

download = requests.get(item["url"], timeout=120)
download.raise_for_status()
extension = "jpg" if item.get("output_format") == "jpeg" else "png"
Path(f"mug-on-table.{extension}").write_bytes(download.content)
print(f"Saved mug-on-table.{extension}")

Split an image into layers

Layer decomposition turns one finished image into a background plus transparent PNG layers, one element per layer. Use it to move elements, swap the background, or rebuild a poster in a design tool. A layer request needs:

"layer_decomposition": true.
Exactly one image in image: PNG or JPEG, at least 512×512 pixels in total, up to 30 MB.
No background field.

Two options go in layer_decomposition_options:

max_images: the most images to return, counting the background. Accepts 2–100 and defaults to 30. Set it to cap the cost.
text_recognition: set true to get the text, font, and color of ordinary text layers.

curl --fail-with-body --max-time 360 "https://api.laozhang.ai/v1/images/generations" \
  -H "Authorization: Bearer $LAOZHANG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "seedream-5-5-261028",
    "image": "https://example.com/your-poster.jpg",
    "layer_decomposition": true,
    "layer_decomposition_options": {
      "max_images": 6,
      "text_recognition": true
    },
    "size": "1K",
    "response_format": "url",
    "watermark": false
  }' \
  -o seedream-5-5-layers.json

python3 save_images.py seedream-5-5-layers.json poster-layer

Replace the image URL with a publicly downloadable image of your own, or pass a data URL. With max_images set to 6, this request returns at most 6 images and costs at most $0.218. At 1K it usually takes 20–30 seconds; 2K takes longer, so keep the client timeout at 300 seconds or more.

Read the text recognition result

The first item in data[] is the opaque background, with z_index 0. Each later item is one transparent layer. With text_recognition on, a text layer looks like this (trimmed, from a poster):

{
  "size": "1616x649",
  "output_format": "png",
  "z_index": 2,
  "bounding_box": {"absolute": [0, 0, 836, 336], "normalized": [0, 0, 1000, 268]},
  "name": "Bold uppercase text \"SUMMER\"",
  "background": "transparent",
  "text_recognition": {
    "text": "SUMMER",
    "lines": [{"runs": [{"text": "SUMMER", "style": {"similar_font_family": "TikTok Sans", "foreground_color": "#FFFFFF", "bold": true, "italic": false}}]}]
  }
}

text_recognition.text holds the full text. lines splits it into lines, and each line into runs that share one style:

Style field	Meaning
`similar_font_family`	The closest matching font family
`foreground_color`	Text color as a hex value
`bold`, `italic`, `underline`, `strikethrough`	Text decoration, `true` or `false`
`shadow`, `translucent`	Whether the text has a shadow or is semi-transparent

Artistic lettering and handwriting don’t get a text_recognition object.

Recompose the layers

Each layer also carries bounding_box.absolute, its position on the background in pixels, plus an English name and a description. A layer PNG isn’t necessarily the size of its box: the example above is a 1616×649 file that belongs in an 836×336 box. Scale each layer into its absolute box when you put the image back together. Read the layer response on the Seedream page explains every layer field, and Save the layers and recompose the image has a Pillow script that reads the same fields.

Parameters

Parameter	Type	Required	Description
`model`	string	Yes	`seedream-5-5-261028` or `dola-seedream-5-5-261028`
`prompt`	string	For generate and edit	Image description or editing instruction; refer to references as image 1, image 2, and so on
`image`	string or array	For edits and layers	Up to 10 public URLs or data URLs; exactly one for layer decomposition
`size`	string	No	`1K`, `1.5K`, `2K` (default), or `WIDTHxHEIGHT`. Exact pixels must total 921,600 to 4,624,220, with an aspect ratio from 1/16 to 16
`output_format`	string	No	`png` (default) or `jpeg`
`background`	string	No	`auto` (default), `transparent`, or `opaque`; not allowed with layer decomposition
`response_format`	string	No	`url` (default) or `b64_json`
`watermark`	boolean	No	Defaults to `true`, which adds an “AI generated” mark; send `false` to omit it
`layer_decomposition`	boolean	No	`true` splits one image into a background and transparent layers
`layer_decomposition_options`	object	No	`max_images` (2–100, default 30) and `text_recognition` (boolean)
`optimize_prompt_options`	object	No	`mode` accepts only `standard`

Seedream 5.5 doesn’t support sequential generation, streaming, or web search. Leave sequential_image_generation, stream, and web search options out of the request.

Billing

Each output image costs $0.035 at 1K, 1.5K, or 2K, and each reference image adds $0.008, including the first.

Request	Images returned	Cost
Text-to-image or transparent PNG	1	$0.035
Edit with 1 reference image	1	$0.043
Edit with 2 reference images	1	$0.051
Edit with 10 reference images	1	$0.115
Layer decomposition of 1 image	6 (background + 5 layers)	$0.218

Non-200 responses, such as parameter errors and moderation blocks, aren’t charged.
A client timeout doesn’t cancel the request. If the server finishes, the images are charged, so check call logs before you resend.
Call logs are the record of what each request actually cost.

Layer decomposition charges $0.035 for every returned image, including the background.

Without max_images, a request can return up to 30 images and cost up to $1.058.
Set layer_decomposition_options.max_images to cap the count. A cap of 6 keeps the cost at $0.218 or less.
Set the client timeout to at least 300 seconds. If your client disconnects first, the request still finishes and is charged.

Frequently asked questions

What is the Seedream 5.5 model ID?

seedream-5-5-261028. The BytePlus name dola-seedream-5-5-261028 also works at the same price, and the model field in the response shows dola-seedream-5-5-261028 either way.

How much does the Seedream 5.5 API cost per image?

$0.035 per output image, whether you ask for 1K, 1.5K, or 2K. Each reference image adds $0.008, and layer decomposition is billed for every returned image. The Billing table lists common requests.

Does Seedream 5.5 support fast mode?

No. optimize_prompt_options.mode accepts only standard. Sending fast returns HTTP 400 with a message containing must be standard for Seedream 5.5, and the request isn’t charged. In the Seedream family, only 5.0 Pro and 4.0 accept fast mode.

Can Seedream 5.5 generate 4K images?

No. The largest output is the 2K preset or exact pixels up to 4,624,220 in total, such as 2048x2048 or 2848x1600. There is no 3K or 4K preset. For 3K use Seedream 5.0, and for 4K use 4.5 or 4.0; see which Seedream version to use.

Can one Seedream 5.5 request return several images?

Only through layer decomposition, which returns a background plus layers in one response. Seedream 5.5 doesn’t support sequential generation, so send one request for each image you need. To get several related images from one request, use Seedream 5.0’s sequential generation.

Do I need a BytePlus account to use Seedream 5.5?

No. A LaoZhang API token in the default group with the Usage first or Per-call billing mode is enough. You don’t need a BytePlus or Volcengine account or key.

Seedream 5.5 launch announcement: what’s new and how it compares with 5.0
Seedream API guide: Seedream 5.0 Flash, 5.0 Pro, 5.0, 4.5, and 4.0, plus layer fields and the recompose script
Choose an image generation API: compare Seedream with other image models
Images API reference: shared request and response format
Model and pricing catalog: current prices and groups
Call logs: check the model and charge for each request

Sources

BytePlus ModelArk image generation API (checked November 13, 2026): request parameters, size ranges, background, layer options, and URL lifetime
BytePlus ModelArk model list: Seedream 5.5 model name and release

Get started

Image Generation & Editing APIs

Video Generation APIs

Text APIs

Multimodal & Audio APIs

Seedream 5.5 API: transparent PNG at $0.035

Seedream 5.5 vs 5.0

Before you start

Generate an image

Generate with Python

Create a transparent PNG

Edit with reference images

Edit with Python

Split an image into layers

Read the text recognition result

Recompose the layers

Parameters

Billing

Frequently asked questions

What is the Seedream 5.5 model ID?

How much does the Seedream 5.5 API cost per image?

Does Seedream 5.5 support fast mode?

Can Seedream 5.5 generate 4K images?

Can one Seedream 5.5 request return several images?

Do I need a BytePlus account to use Seedream 5.5?

Sources

Seedream 5.5 vs 5.0

Before you start

Generate an image

Generate with Python

Create a transparent PNG

Edit with reference images

Edit with Python

Split an image into layers

Read the text recognition result

Recompose the layers

Parameters

Billing

Frequently asked questions

What is the Seedream 5.5 model ID?

How much does the Seedream 5.5 API cost per image?

Does Seedream 5.5 support fast mode?

Can Seedream 5.5 generate 4K images?

Can one Seedream 5.5 request return several images?

Do I need a BytePlus account to use Seedream 5.5?

Related documentation

Sources