Seedream 4.5 vs Gemini 2.5 Flash Image: Which One, and When
One of these models exposes 4K output, 17 aspect ratios, and up to 14 reference images. The other exposes none of that and is still the right default for most work. Here is the parameter-level difference between Seedream 4.5 and Gemini 2.5 Flash Image, and how to use both without picking a side.
Gemini 2.5 Flash Image, the model most people still call Nano Banana, is the default image model on Treza. Seedream 4.5 is ByteDance's flagship, and it is what you switch to when the default stops being enough. They come up together constantly, usually framed as a fight, and that framing is wrong. Look at what each one actually accepts as input and the two models are barely competing for the same job.
This is a comparison of parameter surfaces, not of vibes. Every number below is what the model advertises through Treza's image catalog, checked in August 2026, and claims about how the image generation pipeline behaves rather than the model say so.
The short version
- Gemini 2.5 Flash Image is the iteration model. It is fast, cheap, takes image input, and edits conversationally: change the background, keep the character, fix the label. It exposes no resolution control and accepts at most three reference images. That is fine, because you are going to run it twenty times.
- Seedream 4.5 is the finals model. It exposes 1K, 2K, and 4K output, seventeen aspect ratios plus auto, and up to fourteen reference images in one composition. Reach for it when the generation leaves the screen or has to satisfy several references at once.
Parameter comparison
| Seedream 4.5 | Gemini 2.5 Flash Image | |
|---|---|---|
| Provider | ByteDance | |
| Also known as | Seedream 4.5 | Nano Banana |
| Input | Text and image | Text and image |
| Output | Image | Image and text |
| Resolution control | 1K, 2K, 4K | Not exposed |
| Aspect ratios | 17 fixed, plus auto | 10 fixed |
| Tallest and widest | 9:21 to 21:9 | 9:16 to 21:9 |
| Reference images accepted | Up to 14 | Up to 3 |
| Images per provider call | Up to 10 | 1 |
Specs as offered through Treza's image model catalog in August 2026. Provider catalogs move, so treat the shape of the difference as the durable part, not the exact integers.
Resolution is the dividing line
This is the whole decision for a lot of people, and it takes one row of the table. Seedream 4.5 takes a resolution parameter with three values. Gemini 2.5 Flash Image takes no resolution parameter at all, so you get what the model gives you and your options afterward are an upscaler or a reshoot.
If the asset stays on a screen at social sizes, that difference never bills you. If the asset is a poster, a banner, a print placement, or a wide crop pulled out of a larger frame, it is the only difference that matters. The Seedream 4.5 model page frames this as removing the upscaling stage from the end of the job, which is the practical version of the same point.
On the canvas this is not something you have to remember. The image node reads the selected model's advertised parameters and only sends a resolution when the model has one, so the control appears when you pick Seedream and disappears when you pick Gemini.
Aspect ratios: seventeen against ten
Seedream's aspect ratio list is a strict superset of Gemini's. Everything Gemini offers, 1:1, 2:3, 3:2, 3:4, 4:3, 4:5, 5:4, 9:16, 16:9, and 21:9, Seedream also offers. Seedream then adds 1:2, 2:1, 9:19.5, 19.5:9, 9:20, 20:9, and 9:21, plus an auto option that lets the model choose.
For the standard social set this is a non-difference. Both cover square, 4:5, vertical, and wide, which is most of what anyone generates. The extra ratios earn their keep in two narrow places: very tall formats past 9:16, where full-bleed mobile and digital signage live, and true 2:1 or 1:2 letterbox, a common web header shape that 16:9 approximates badly. If you have ever generated at 16:9 and cropped a header out of it, Seedream can generate the header.
References: fourteen against three
A reference image is how you stop describing and start showing: this product, that lighting, this style, one frame that respects all of them. Both models take image input, so both can do it. The ceiling is where they part.
Gemini 2.5 Flash Image advertises up to three reference inputs. Three is enough for the common cases, and they are good cases: a product plus a scene, a character sheet plus a pose, a photo plus a style. Its model page is built around exactly that shape of work, and subject consistency across edits is the thing it is genuinely good at.
Seedream 4.5 advertises up to fourteen, which is a different kind of instruction. Fourteen references is a look bible: the product from four angles, three approved shots for palette, a typographic reference, a scene plate, and a couple of previous outputs to keep the series consistent. Whether the model honors all fourteen equally is a judgment call you have to make on your own material, and we are not going to publish a benchmark we did not run. What is certain is that one model accepts the instruction and the other refuses it at four.
On Treza the canvas accepts up to ten reference images per image node. So with Gemini the model is your ceiling, and with Seedream the canvas is.
Editing: both do it, for different reasons
Conversational editing is Gemini 2.5 Flash Image's entire personality. Feed it an image and a sentence, and it changes what you named and leaves the rest of the frame alone. Characters and products stay recognizable across a run of edits, which is the hard part and the reason it became the default.
Seedream 4.5 also takes image input and also does targeted edits, but the reason to send an edit there is that the edit is the deliverable. Replacing a sky at 4K is a different job from replacing a sky while you are still deciding whether you want a sky.
Using both is not a compromise. Iterate on the cheap model until the composition is settled, then re-render that prompt on the expensive one with the resolution turned up.
Batching and what gets charged
Seedream 4.5 advertises up to ten images per provider call. Gemini returns one.
Treza's image node normalizes this: batch count clamps to four for any model, and the node fans the requests out as parallel calls rather than one multi-image request. The reason is failure behavior. A partial batch returns what succeeded instead of failing the whole node, and empty responses are retried, which matters when a node sits mid-graph. Only successful generations are charged, so a failure costs nothing.
On price, neither model is expensive at this tier. Across billed image generations in a production week ending 2026-07-19, the mean charge was $0.04 and the worst case was $0.23, measured across the whole image catalog rather than any one model. Treza runs on prepaid credits with no subscription, packs start at $5, and credits do not expire.
Where the pipeline changes the answer
Both of these are one dropdown value on the same node, which means the honest recommendation is to stop choosing. Put Gemini on the node while you are working out the prompt, and change the dropdown for the final render. Nothing else in the graph moves, and if the pipeline is published as an endpoint, the API your product calls does not change either.
Two connections are worth knowing about. An image node with a reference image and no prompt acts as a static source: no provider call, no charge, just an asset handed downstream. And a Seedream still drops into a video node as a first frame, which is how you art direct a shot before paying for motion. That is the standard bridge between the AI image generator and the AI video generator, and it is the same bridge whether you are making one clip or running an AI video pipeline on a schedule.
Neither model is the pick for everything. When a final asset needs maximum photorealism or has to render legible typography, FLUX.2 Pro is the better call. And Gemini 2.5 Flash Image is no longer the newest flash tier, so if you are starting fresh, look at Gemini 3.1 Flash Image before you settle.
Bottom line
Seedream 4.5 wins on every parameter that has a number attached: resolution, aspect ratios, reference count, images per call. Gemini 2.5 Flash Image is still the default, because most image work is iteration and iteration wants speed and a low per-image cost more than it wants 4K.
Pick by the destination of the file. Screen and still deciding, use Gemini. Print, large format, or a composition that has to obey more than three references, use Seedream. Build the pipeline so that is a dropdown rather than a rewrite, and the question stops being expensive to get wrong.
Frequently Asked Questions
Is Gemini 2.5 Flash Image the same thing as Nano Banana?
Yes. Nano Banana is the nickname Gemini 2.5 Flash Image picked up at launch and it stuck hard enough that many people never learned the official name. It is one model, and on Treza it appears in the model picker under its official name.
Can Seedream 4.5 generate 4K images?
Yes. Seedream 4.5 exposes a resolution parameter with 1K, 2K, and 4K options, and the value is set on the image node itself. Gemini 2.5 Flash Image exposes no resolution parameter, which is the clearest structural difference between the two models.
How many reference images can each model take?
Gemini 2.5 Flash Image advertises up to three reference inputs. Seedream 4.5 advertises up to fourteen. Treza's image node accepts up to ten reference images on the canvas, so with Gemini you hit the model's limit first and with Seedream you hit the canvas limit first.
Which model is better for product photography?
It depends on where the shot ends up. For iterating a product into different scenes and keeping it recognizable across the set, Gemini 2.5 Flash Image is the faster, cheaper loop. For a final asset at print resolution, or a composition that has to follow a product reference plus a style reference plus a scene plate at once, Seedream 4.5 fits better. For maximum photorealism on a hero shot, compare both against FLUX.2 Pro.
Do I have to rebuild my pipeline to switch between them?
No. The model is a dropdown on the image node. Switching changes which parameters the node offers, since resolution only appears for models that support it, but the graph, the wiring, and the published endpoint stay the same. That is the reason to run image generation through a pipeline rather than a one-off call: the next model release is a dropdown change instead of a migration.
