Tutorial

How to Create Transparent PNGs with Seedream 5.5

Q: Is writing “transparent background” in the prompt enough?

Use the explicit background setting as well. auto leaves the background decision to the model, and the prompt alone does not verify what the file contains.

Q: Can I request JPEG for a transparent asset?

Not on this route. Pair background: transparent with output_format: png; the transparent/JPEG combination is rejected.

Generate transparent PNGs with Seedream 5.5, check real alpha and edges, and preserve cutouts through export. EvoLink settings and a local file check.

Jacey

November 13, 20269 min read

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To create a transparent PNG with Seedream 5.5 on EvoLink, select the generation/editing model, set background to transparent, and keep output_format as png. Then download the original result and inspect its alpha channel and edges. A white preview, a .png extension, or the word “transparent” in a prompt does not establish that the delivered asset is usable.

This workflow is for product cutouts, stickers, icons and other assets you want to place in a new composition. It covers documented settings and file checks, rather than a model-quality benchmark. ByteDance describes native RGBA generation from text or reference images in its official capability guide; the request fields below follow EvoLink’s own route.

Choose the deliverable before generating

An alpha channel controls how each pixel blends with the background behind it. It is separate from the RGB color: a white object can be opaque, while the empty area around it is transparent. Partial alpha can preserve a soft edge or shadow, but still needs visual inspection.

What you need	Choose	What you receive
A complete image with a solid background	Ordinary generation or reference editing	One flat image
One cutout or transparent composition	The same model with transparent PNG output	One flat image with alpha
Several elements to move independently	The separate Layerize model	A base image, PNG layers and layout metadata
Native editable text or a PSD document	An editing application after generation or decomposition	Application-built text objects or a design document

Several stickers in one transparent PNG remain one image. Asking for transparent output does not split them into layers. Use the model selection section when the distinction changes your task.

Generate from text or a reference image

Start with one clearly described asset

In Playground, choose Seedream 5.5, set Background → transparent, and use PNG. Pick a supported quality tier and aspect ratio for the destination layout.

For example: “A single cobalt-blue ceramic ribbon sculpture, centered, the complete silhouette visible, isolated on a transparent background, no text and no surrounding scene.” This is an example instruction, not a claim about a generated result. Name the object and the boundaries you need; avoid asking for a studio wall or a tabletop if those would become unwanted background content.

For an existing product or character, add reference images and describe what to preserve. EvoLink’s ordinary generation/editing model accepts up to 10 references; they do not need to contain alpha already. References are charged as inputs, so start with the materials the task actually needs. Current rates and estimates remain in the existing pricing section.

Make the output explicit in your API request

Use doubao-seedream-5.5 for both text-to-image generation and reference-guided editing. Keep the API key on your server. This text-only example omits references:

curl -X POST https://api.evolink.ai/v1/images/generations \
  -H "Authorization: Bearer $EVOLINK_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "doubao-seedream-5.5",
    "prompt": "A single cobalt-blue ceramic ribbon sculpture, centered, complete silhouette visible, isolated on a transparent background, no text or surrounding scene.",
    "size": "1:1",
    "quality": "1.5K",
    "background": "transparent",
    "output_format": "png"
  }'

For reference editing, add the image_urls array using accessible URLs for your input images. Do not copy another provider’s model ID or field named image into this request.

auto lets the model decide the background; it is not a transparency guarantee. On this EvoLink route, requesting transparent with jpeg is rejected. Use the generation and editing API documentation for the complete limits and request contract.

Wait for completion and save the original file

The create response returns a task record, not the finished image. Save its id and query the task, replacing YOUR_TASK_ID with that value:

curl https://api.evolink.ai/v1/tasks/YOUR_TASK_ID \
  -H "Authorization: Bearer $EVOLINK_API_KEY"

Check the status. After completed, download the result from the returned image URL; handle failed as a failure rather than trying to interpret a missing image. An HTTPS callback is another documented completion path. The result’s background metadata is useful context, but inspect the downloaded file itself before delivery. Store your copy promptly rather than depending on a temporary result link.

The task documentation lists downloadable image URLs in results; result_data holds model-specific metadata such as the reported background. Keep the full task record with the downloaded file. A metadata label does not replace checking the file itself. No EvoLink model API request was executed for this guide; the request example was checked against documentation and the file script was run locally.

Verify the downloaded PNG

Open the original file in an editor that displays transparency. A checkerboard is only a display convention: a model or export can also bake a checkerboard into ordinary image pixels. Renaming a JPEG to .png does not create alpha.

Official BytePlus Seedream 5.5 transparent acrylic artwork example

Official example from BytePlus’s Seedream 5.5 guide, resized for display; not an EvoLink test output. Download the original PNG to inspect the file rather than the web preview.

For a quick local check, install Pillow with python -m pip install pillow, save this as check_alpha.py, and run python check_alpha.py asset.png:

import sys
from PIL import Image

with Image.open(sys.argv[1]) as image:
    if image.format != "PNG":
        raise ValueError("The downloaded file is not PNG")
    alpha = image.convert("RGBA").getchannel("A")
    minimum, maximum = alpha.getextrema()
    print(f"8-bit alpha range: {minimum}..{maximum}")
    if minimum == 255:
        print("No transparent pixels")
    elif maximum == 0:
        print("Fully transparent: no visible subject")
    else:
        print("Transparency exists; inspect edges and subject")

Converting to RGBA makes this check work for palette transparency too. In the inspected 8-bit alpha channel, 0 is transparent and 255 is opaque. A range containing transparent pixels does not establish correct cutout boundaries, convincing glass or preserved product details. It is a file check, not a visual quality score.

Inspect edges against the destination background

Schematic of one asset checked on light, dark and colored backgrounds

Inspection schematic, not model output. Check the same asset against contrasting backgrounds before approving it.

Place the PNG on a light background, a dark background and the actual campaign or interface color. Inspect at the delivery size and zoom in where necessary:

Look for pale or dark halos around the silhouette, especially if the input had a solid background.
Check small gaps, hair, fur and thin structures for missing material or retained background pixels.
Check soft shadows and translucent regions in context; do not force every edge to be fully opaque or fully transparent.
Confirm the subject’s shape, branding and text. A technically transparent image can still depict the wrong product.

A white asset that disappears on white may be correct; check it on another color. If the file is usable but has a local edge defect, an editor may be the appropriate next step. Regenerate when the object or composition is wrong, rather than using repeated requests to fix an export mistake.

Preserve transparency through delivery

Keep the original PNG as the reusable master. Place it in a design editor or application as an image asset; moving it does not make its text independently editable. If you export a final opaque ad, keep a separate transparent master for later variants.

Inspect what your product actually serves after upload, optimization or export. A pipeline can flatten alpha onto white or convert to an incompatible format even when the downloaded source was correct. Compare the source file with the delivered asset before blaming the model or generating another image.

Symptom	Check first	Next action
White background remains	Actual request settings and downloaded alpha	Request transparent PNG explicitly if the source is opaque
Checkerboard appears in the final layout	Whether it is baked into image pixels	Replace the baked background or regenerate; a preview pattern is not alpha
Looks correct locally, opaque after upload	Served file format and processing	Preserve alpha through the delivery pipeline
Elements cannot move separately	Whether you requested one flat PNG	Use Layerize when independent elements are the actual requirement

For repeated generation and editing, EvoLink lets you use the same key, balance and asynchronous task flow while choosing the right model for the job. Try a transparent asset in Playground, or compare the Seedream family if you are deciding between versions.

Frequently asked questions

Can Seedream 5.5 generate transparency from text alone?

Yes. EvoLink’s documented route supports text-to-image transparent output. Select background: transparent and PNG; no reference image is required.

Does my reference image already need an alpha channel?

No. Seedream 5.5 accepts reference editing without pre-existing alpha input. The ordinary route supports up to 10 reference images; inspect the resulting cutout before using it.

Is writing “transparent background” in the prompt enough?

Use the explicit background setting as well. auto leaves the background decision to the model, and the prompt alone does not verify what the file contains.

Can I request JPEG for a transparent asset?

Not on this route. Pair background: transparent with output_format: png; the transparent/JPEG combination is rejected.

Why does a PNG still look white?

It may be displayed over white, or the file may contain an opaque white background. Check the original alpha and place the image on a contrasting background.

Does a valid alpha channel guarantee clean edges?

No. Check halos, fine structures, soft shadows, subject identity and text at the intended display size. The script only checks pixel transparency.

Do I need Layerize for transparent output?

No. Ordinary generation/editing can return one transparent PNG. Choose the separate Layerize route when you need individual image elements and layout metadata; it does not directly deliver a PSD or native text objects.

Where should I check the current cost?

Use the model page’s current pricing and estimates. Ordinary output and any reference images contribute to the request cost; this guide does not maintain a separate rate table.

Sources

BytePlus Seedream 5.5 capability guide: native RGBA capability and the attributed illustration.
EvoLink Seedream 5.5 API documentation: platform model ID, request controls and async handling.
W3C PNG specification: PNG and alpha representation.
Pillow Image reference: local channel conversion and inspection.

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#Seedream 5.5 #Transparent PNG #Image editing #Alpha channel