Seedream 5.5 vs GPT Image 2.6: editing controls before integration

GPT Image 2.6 Sunburst (max) has the stronger published general editing-preference result. GPT is also the first candidate for schema-documented region controls. Consider Seedream 5.5 for successive natural-language revisions, but its vendor demonstration is not comparative proof.

Our engineering problem is narrower: change a red mug to cobalt blue and replace a price label without disturbing the ad. No primary comparative test reviewed settles that task. We ran no generation requests; the AIHubMix comparison page is navigation, not evidence of a task or equal-setting cost winner.

Specify acceptance before requests

Start with an owned 2048×2048 PNG. Require:

• A cobalt-blue mug with unchanged geometry and material appearance.
• Exactly US$19.99, with the label's position and shape preserved.
• Unchanged logo, other text, shadows, props, background, and crop, inspected at full resolution.
• Each accepted intermediate image checked against the original if successive revisions matter.

These are proposed checks, not results.

Separate benchmark variants from workflow evidence

ByteDance's November 9, 2026 launch post demonstrates 100 successive edits and claims better preservation outside edited areas. It is vendor evidence, not an independent reproduction. Its named external comparators are GPT Image 2.5 Sunburst and Nano Banana 2.1—not GPT Image 2.6.

AA-Image-Editing v2.1 measures blind human pairwise preferences for outputs using the same source image and instruction. Overall editing snapshot: 2026-11-12 06:24:03 UTC.

This establishes neither exact-task success nor a 100-revision winner. We infer no statistical significance from these intervals alone. Default settings and the high example below cannot inherit the (max) result.

Inspect the gateway contract

The Seedream schema and GPT schema, inspected November 12, 2026, document POST /ai/v1/images/generations:

GPT lists top-level quality: low, medium, high, xhigh, max, auto. Deprecated extra.quality is overridden by it. Separate complexity lists low, medium, high. Allowed values depend on the model; acceptance of every value was not verified.

markup is a transparent PNG annotation layer matching the first source image's dimensions; it cannot accompany mask. These are documented controls, not tested fidelity guarantees: a mask does not prove unselected pixels remain unchanged.

Seedream also exposes no layer_decomposition here. Missing gateway fields do not prove model-level inability or imply unsupported fields pass through. ByteDance describes native full and partial transparency, but PNG alone proves no alpha output through this route. GPT documents extra.background="transparent" with PNG or WebP; inspect actual alpha when required. Neither output was verified.

Calculate costs without inventing usage

OpenAI's official rates are USD per million tokens: $5 text input, $8 image input, $30 image output, not a fixed image price.

Hypothetically, 1,000 text-input, 1,000 uncached image-input, and 2,000 image-output tokens cost $0.005 + $0.008 + $0.060 = $0.073. This uses uncached official token rates and is not measured usage, an AIHubMix quote, or a resolution/high/max estimate; retries are excluded. No complete official Seedream 5.5 rate table was found in the reviewed material, so no equal-setting cost winner or savings ratio follows. Compare accepted-edit costs, including retries, after requirements and usage are known.

Starting requests, not a benchmark

The unified image API guide documents reference inputs. Use Bash, curl, jq, base64, an environment key, and an owned ./source-ad.png. These unexecuted examples submit billable requests. They share input, prompt, n=1, dimensions, and output format; GPT's additional quality="high" has no Seedream equivalent here. Equal dimensions do not mean equal compute effort or reproduce AA's (max).

set -euo pipefail : "${AIHUBMIX_API_KEY:?Set AIHUBMIX_API_KEY first}" SOURCE_IMAGE="./source-ad.png" test -r "$SOURCE_IMAGE" SOURCE_DATA_URI="data:image/png;base64,$(base64 < "$SOURCE_IMAGE" | tr -d '\r\n')" PROMPT='Change only the red mug to cobalt blue and replace the price label text with exactly "US$19.99". Preserve the label position and shape, logo, shadows, other objects, background, framing, and all other text.' # Seedream 5.5: no quality field on this route. printf '%s' "$SOURCE_DATA_URI" | jq -Rs --arg prompt "$PROMPT" '{ model: "doubao-seedream-5-5", prompt: $prompt, image: ., n: 1, size: "2048x2048", output_format: "png", extra: {watermark: false} }' | curl --fail-with-body --silent --show-error \ https://aihubmix.com/ai/v1/images/generations \ -H "Authorization: Bearer $AIHUBMIX_API_KEY" \ -H "Content-Type: application/json" --data-binary @- # GPT Image 2.6 Sunburst: high is not the leaderboard's max. printf '%s' "$SOURCE_DATA_URI" | jq -Rs --arg prompt "$PROMPT" '{ model: "gpt-image-2.6-sunburst", prompt: $prompt, image: ., n: 1, size: "2048x2048", output_format: "png", quality: "high" }' | curl --fail-with-body --silent --show-error \ https://aihubmix.com/ai/v1/images/generations \ -H "Authorization: Bearer $AIHUBMIX_API_KEY" \ -H "Content-Type: application/json" --data-binary @- 

Watermarks and protected task URLs

Seedream's schema declares a visible-watermark default of true; extra.watermark=false requests omission, but that behavior was not output-tested.

Both schemas permit optional asynchronous execution. Check account-level task-feature activation first; 403 async_not_enabled means activation is required. Download a returned content_url using the same API key/Bearer token that created the task. It is not a public reference-image URL: download the accepted image and build a fresh data URI for another revision.

Choose candidates by requirements, then inspect outputs. If exact label text fails acceptance, retain the label as an editable design element rather than approving a plausible mistake.

Keep reading: the Seedream 5.5 series

• Replacing an existing workflow? Read Seedream 5.5 vs 5.0 Pro: check the output contract before migrating.
• Implementing generation or migration? Read Seedream 5.5 API with Python: generate, save, then edit.

Sources

1. Introducing Seedream 5.5 — ByteDance Seed.
2. AA-Image-Editing v2.1 leaderboard — Artificial Analysis; snapshot 2026-11-12 06:24:03 UTC.
3. GPT Image 2.6 Sunburst model page and official pricing — OpenAI.
4. Seedream 5.5 endpoint schema — AIHubMix.
5. GPT Image 2.6 Sunburst endpoint schema — AIHubMix.