Seedream 5.5 vs Nano Banana 2.1 vs GPT Image 2.6: 5 Tests
ImagesArt.ai
11/15/2026
Seedream 5.5 (ByteDance), Nano Banana 2.1 (Google) and GPT Image 2.6 (OpenAI) are the newest image models from the three companies. We gave all three the same five prompts on ImagesArt at the same size and aspect ratio. For GPT Image 2.6 we used Sunburst, the top of its three tiers.
Short answer: GPT Image 2.6 made the best edits: it won both photo-editing rounds and kept every product detail. Nano Banana 2.1 was the cheapest, 34 credits for our seven images, and set the cleanest poster. Seedream 5.5 was the fastest, finishing every image in 15 to 37 seconds, and with GPT Image 2.6 it was one of two that made a real transparent PNG.
Try Seedream 5.5 →Seedream 5.5 vs Nano Banana 2.1 vs GPT Image 2.6 at a glance
| Seedream 5.5 | Nano Banana 2.1 | GPT Image 2.6 Sunburst | |
|---|---|---|---|
| Made by | ByteDance | OpenAI | |
| Our score (5 tests) | 1 draw | 1 win, 1 draw | 2 wins, 2 draws |
| Credits on ImagesArt | 4 at 1K, 7 at 2K, +2 per reference photo | 4 at 1K, 6 at 2K, 9 at 4K | Up to 15 at 1K, 30 at 2K, 60 at 4K, +5 per reference; unused credits are refunded |
| What our 7 images cost | 45 credits | 34 credits | 68 credits |
| Our render times (7 images each) | 15 to 37 seconds | 28 to 57 seconds | 29 to 50 seconds |
| Image size at 2K, 3:4 | 1776 × 2368 | 1792 × 2400 | 1536 × 2048 |
| Top resolution | 2K | 4K | 4K |
| Transparent PNG | Yes, Background setting | No, it painted a checkerboard | Yes, ask for it in the prompt |
All images were made in our generators between November 13 and 15, 2026, with the same prompts and settings. GPT Image 2.6 Sunburst holds the maximum when you press Create and refunds what the image did not use; ours settled at 7 to 13 credits each.
Test 1: realistic portrait with a chalkboard
Text to image, 3:4, 2K:
Cinematic close-up portrait of a 30-year-old woman with freckles and loose auburn hair, sitting by a rain-streaked café window at dusk, warm tungsten light on her face, neon reflections in the glass, natural skin texture with visible pores, 85mm lens, shallow depth of field. A small chalkboard behind her reads "Open Late · Fresh Pastries" in neat handwriting, and that is the only text on it.
All three spelled "Open Late · Fresh Pastries" right. Nano Banana 2.1 and GPT Image 2.6 also followed "that is the only text on it"; Seedream 5.5 added a line of made-up handwriting at the top of the board. Nano Banana 2.1 has the most natural, unposed look and the woman reads closest to 30. GPT Image 2.6 went for a styled café shot with a latte and croissants.
This round: a draw between Nano Banana 2.1 and GPT Image 2.6.
Test 2: event poster with English and Japanese text
Text to image, 16:9, 2K:
A clean modern event poster for a fictional night market called "Lantern Street Market". Warm paper lanterns hang over a street of food stalls at blue hour. Large headline "LANTERN STREET MARKET" at the top, with the Japanese line "ちょうちん横丁ナイトマーケット" beneath it. Small info text at the bottom reads "Fri–Sun · 6 PM – Midnight · 120 Food Stalls · Free Entry". Crisp editorial layout, readable typography, rich warm light.
Every line is spelled right in all three, Japanese included. Nano Banana 2.1 made the cleanest layout: one large headline at the top, the Japanese line under it, the info line at the bottom, and nothing else. GPT Image 2.6 also printed only what we asked for, but broke the headline over two lines and filled the street with signs. Seedream 5.5 added four short taglines we never asked for.
This round: Nano Banana 2.1.
Test 3: sticker on a transparent background
Text to image, 1:1, 1K:
A cute die-cut sticker of a smiling cartoon avocado wearing tiny sunglasses and holding a surfboard, bold clean outlines, vibrant flat colors, with the words "Stay Chill" in rounded bubble letters under it.
On Seedream 5.5 we turned on Background: Transparent. Nano Banana 2.1 and GPT Image 2.6 have no such setting on our site, so we added "On a transparent background." to their prompts.
Seedream 5.5 and GPT Image 2.6 both returned a PNG with a real alpha channel. Nano Banana 2.1 drew the gray-and-white checkerboard you see in image editors into a normal JPG, so it looks transparent but is not; you would still need a background remover. GPT Image 2.6 drew the most polished sticker. Seedream 5.5 did it for 4 credits instead of 10, with a switch instead of a prompt trick.
This round: a draw between Seedream 5.5 and GPT Image 2.6.
Test 4: edit a product photo
Image to image, one reference photo, 4:3, 2K. This is the photo all three got:
Keep the canister, its label text and the camera angle exactly the same. Change only the setting: place it on a dark walnut table in a cozy morning kitchen with soft steam rising from a cup of coffee beside it.
All three kept the label word for word. GPT Image 2.6 kept the camera angle, the plant on the left and the scattered beans in the same spots, so it reads as the same product shot in a new room. Nano Banana 2.1 was close: it kept the beans and the plant but moved the camera in a little. Seedream 5.5 pulled the camera back and up and dropped the beans and the plant.
This round: GPT Image 2.6.
Test 5: three edits in a row
We started from the same canister photo and fed each result back in as the next input, at 4:3 and 1K:
- "Keep the canister, its label text and the camera angle exactly the same. Change only the setting: place it on a white marble kitchen counter in a bright minimalist kitchen."
- "Keep everything in the scene exactly the same: the canister, its label, the coffee beans and the camera angle. Change only the lighting: warm golden-hour sunlight streaming in from the left window, with long soft shadows across the marble."
- "Keep everything exactly the same: the canister, its label, the coffee beans, the camera angle and the golden-hour light. Add only two props on the counter: a white ceramic cup of latte with heart latte art to the right of the canister, and a small linen napkin under the cup."
Seedream 5.5, rounds 1–3 · 23 s, 21 s, 15 s · 6 credits each
Nano Banana 2.1, rounds 1–3 · 48 s, 46 s, 39 s · 4 credits each
GPT Image 2.6 Sunburst, rounds 1–3 · 41 s, 29 s, 41 s · 7, 9 and 7 credits
All three kept the label and the beans through three rounds. GPT Image 2.6 kept the canister's sage green and put the latte to the right of the jar, exactly as asked. Nano Banana 2.1 also placed the cup correctly, but the canister turned olive in the golden-hour round and stayed that way, and the small label line went soft. Seedream 5.5 kept the color but put the cup in front of the jar, where it covers the end of the small label line.
This round: GPT Image 2.6.
What it costs
- Seedream 5.5: a fixed 4 credits at 1K or 7 at 2K, plus 2 per reference photo. A transparent PNG costs the same.
- Nano Banana 2.1: 4 credits at 1K, 6 at 2K or 9 at 4K. Our edits cost the same as plain images.
- GPT Image 2.6 Sunburst: holds up to 15 credits at 1K, 30 at 2K or 60 at 4K, plus 5 per reference photo, then refunds what the image did not use. Ours settled at 7 to 13. GPT Image 2.6 Economy is a fixed 5 credits at 1K.
Across our seven test images, Nano Banana 2.1 used 34 credits, Seedream 5.5 used 45 and GPT Image 2.6 Sunburst used 68. Credits are only used when an image comes out.
Which one should you use?
- GPT Image 2.6 for product edits that must keep the framing and colors, and for final images you need at 4K.
- Nano Banana 2.1 for the most images per credit and clean poster text. Do not count on it for transparent backgrounds.
- Seedream 5.5 for speed and for transparent PNGs at a low price. Watch for extra text it adds to posters and signs.
A good workflow is to draft on Seedream 5.5 or Nano Banana 2.1 and run the final edit on GPT Image 2.6.
Try all three on ImagesArt
Seedream 5.5 has its own page with the Transparent background setting and a Layers tab. GPT Image 2.6 offers Economy, Flare and Sunburst in one GPT Image 2.6 generator. Nano Banana 2.1, Nano Banana Pro and all three are also in the model list of our AI Image Generator. No Google, OpenAI or ByteDance account is needed.
Open the Seedream 5.5 generator →Related reading
Want a closer look at one pair? Read Seedream 5.5 vs GPT Image 2.6 and Seedream 5.5 vs Nano Banana Pro. Deciding between Seedream versions? Read Seedream 5.5 vs 5.0 Pro vs 4.5.