Seedream 5.0 vs Nano Banana Pro vs GPT Image 1.5: 2026 Image API Routing Guide

This guide reflects public model information and EvoLink routing behavior as of July 8, 2026. The goal is not to declare a universal winner. It is to help API builders route each image request to the model that best matches the job, cost shape, and production risk.

Quick Answer

What Changed For 2026 Image API Selection

By July 8, 2026, image API selection was no longer just a three-way comparison between Seedream 5.0 Lite, Nano Banana Pro, and GPT Image 1.5. Three changes now affect production choices:

1. Seedream 5.0 Pro is now its own decision path. It is not just "Lite but stronger"; it is the route for exact output size, subject preservation, and final delivery.
2. Nano Banana Pro should not be described with a flat low per-image price. The current EvoLink page uses multi-SKU billing: output tier, reference images, web search, text, and thinking tokens can all affect the final cost.
3. GPT Image 1.5 is no longer OpenAI's current image model. OpenAI's model list marks GPT Image 1.5 as deprecated, so new projects should also evaluate GPT Image 2.

That shifts the useful question from "who wins?" to "which image API should own which production workflow?"

The Four Routes

Seedream 5.0 Lite: Complex Generation And Grounded Visuals

Seedream 5.0 Lite is strongest when the prompt is structurally complex. It fits scientific illustrations, data visuals, knowledge-heavy marketing images, and visuals that need real-world context.

For EvoLink users, the key points are:

• Deep Thinking for stronger instruction planning before generation
• Optional web search for current facts and product details
• Up to 14 reference images
• 2K/3K output and custom pixel dimensions
• Multiple images per request, useful for drafts and variants

Start with Lite when your prompt includes data relationships, factual constraints, technical diagrams, or reference-heavy consistency.

Seedream 5.0 Pro: Exact Dimensions And Final Delivery

Current EvoLink route boundaries:

• 1K/2K output tiers
• Exact widthxheight custom dimensions
• Up to 10 reference images
• Each input image billed separately
• One generated image per request
• No web search

Use Pro for campaign finals, ecommerce main images, fixed placement sizes, product edits, and assets where the same subject must survive the edit.

Nano Banana Pro: Text, Realism, And Advanced Editing

Nano Banana Pro is Google's Gemini 3 Pro Image route. Google's November 20, 2025 announcement emphasized improved text rendering, world knowledge, up to 14 inputs, multilingual text, localized editing control, and 2K/4K outputs.

It is a strong fit for:

• Multilingual posters, menus, price cards, and UI mockups
• Product photography and lifestyle images
• Localized edits to lighting, focus, viewpoint, or scene areas
• Multi-input fusion into a coherent image

GPT Image 1.5: Legacy Baseline And Cost-Sensitive Automation

GPT Image 1.5 still deserves a place in this article because many legacy comparisons and automated pipelines were built around it. It remains useful for instruction-following comparisons and low-quality draft economics.

But it should not be presented as OpenAI's current image model in 2026:

• OpenAI's current model list marks GPT Image 1.5 as deprecated
• New projects should test GPT Image 2 alongside any GPT Image 1.5 baseline
• If you keep GPT Image 1.5 in a comparison, label it as a historical or legacy benchmark

Pricing: Compare Cost Shape, Not One Flat Number

Pricing is part of the buying decision, but it changes quickly. The safer structure is to compare pricing shape and send users to live model pages for procurement-level numbers.

Avoid one-size-fits-all conclusions like "cheapest image API" unless the article is a pure pricing page. The more durable decision path is workflow fit plus pricing shape.

Workflow Routing Recommendations

Batch Drafts And Social Variants

Start with Seedream 5.0 Lite or a GPT Image route. Lite is better for complex prompts and reference-driven generation. GPT Image 1.5 can still serve as a legacy low-quality cost baseline, but new builds should test GPT Image 2.

Scientific Diagrams And Knowledge Visuals

Start with Seedream 5.0 Lite. Its Deep Thinking and web search capabilities make it a better first test for fact-heavy visuals. Nano Banana Pro also has world-knowledge and search-grounding strengths, but you should model its multi-SKU cost before bulk use.

Ecommerce Product Images And Final Ads

If the priority is photorealism, text, and localized editing, test Nano Banana Pro. If the priority is keeping a product or character stable at a fixed output size, test Seedream 5.0 Pro.

Multi-Reference Generation

Seedream 5.0 Lite supports up to 14 reference images and is better for broad planning or batch exploration. Seedream 5.0 Pro supports up to 10 references and is better for final edits. Nano Banana Pro also supports up to 14 inputs and is strong when multiple elements must merge into one polished scene.

Text Inside Images

Nano Banana Pro is the first route to test for multilingual posters, product labels, UI mockups, and text-led creatives. GPT Image 1.5 can remain a historical comparison point, but OpenAI's own image docs still warn that GPT Image models can struggle with precise text placement and clarity.

API Integration Pattern

All four routes are easier to operate when the model name is a product decision rather than a code rewrite:

import requests

EVOLINK_API_KEY = "your-api-key"
BASE_URL = "https://api.evolink.ai/v1/images/generations"

headers = {
    "Authorization": f"Bearer {EVOLINK_API_KEY}",
    "Content-Type": "application/json"
}

payload = {
    "model": "doubao-seedream-5.0-pro",
    "prompt": "Generate a product hero image at exact campaign dimensions.",
    "size": "2048x1152"
}

response = requests.post(BASE_URL, headers=headers, json=payload)
print(response.status_code, response.text)

Recommended routing table:

Why Still Compare GPT Image 1.5?

From a product lifecycle view, GPT Image 1.5 is no longer OpenAI's current image model. From a search view, however, users still search for "Seedream 5 vs Nano Banana Pro vs GPT Image" because older comparisons and workflows used GPT Image 1.5.

Keeping GPT Image 1.5 in the title preserves the original search intent, while the body clarifies its lifecycle and points new builders toward GPT Image 2.

Bottom Line

• Use Seedream 5.0 Lite when the image needs reasoning, web search, multi-reference planning, or batch drafts.
• Use Seedream 5.0 Pro when the image needs exact dimensions, subject preservation, and final delivery.
• Use Nano Banana Pro when text rendering, photorealism, multilingual visuals, or localized editing are central.
• Use GPT Image 1.5 for legacy comparisons or existing low-cost automation baselines, while testing GPT Image 2 for new products.

The production answer is not one winner. It is one EvoLink API key with request-level model routing.

FAQ

What is the difference between Seedream 5.0 Lite and Seedream 5.0 Pro?

Lite is the reasoning and exploration route: Deep Thinking, web search, up to 14 references, and batch-style generation. Pro is the final-delivery route: exact dimensions, subject-preserving edits, up to 10 references, and one generated image per request.

Is Seedream 5.0 Pro always better than Seedream 5.0 Lite?

No. Pro is better for final assets and exact-size delivery. Lite is better for web-grounded visuals, complex prompts, grouped images, and lower-cost batch exploration.

Is Nano Banana Pro still worth comparing with Seedream 5.0?

Yes, but compare workflow fit instead of a flat price. Nano Banana Pro is strong for text rendering, photorealism, multi-input fusion, and localized editing. Its current billing shape is more complex than the old flat-price comparison implied.

Should GPT Image 1.5 still appear in a 2026 comparison?

Yes, if the article serves historical search intent or legacy workflows. But label it correctly: OpenAI's current model list marks GPT Image 1.5 as deprecated, so new projects should also evaluate GPT Image 2.

Which model is cheapest?

There is no single answer without specifying quality, size, input images, and lifecycle requirements. GPT Image 1.5 low-quality output can still be a low-cost historical baseline, Seedream 5.0 Lite fits cost-aware complex generation, and Nano Banana Pro or Seedream 5.0 Pro fit higher-value final assets.

Which model is best for ecommerce product images?

Test Nano Banana Pro first for photorealistic product photography and text-heavy creative. Test Seedream 5.0 Pro when you already have product references and need fixed campaign dimensions. Use Seedream 5.0 Lite for draft exploration.

Which model is best for text inside images?

Nano Banana Pro is the first route to test for multilingual posters, menus, price cards, and UI mockups. GPT Image 1.5 can remain a baseline, while Seedream 5.0 Pro is better positioned as a final-edit route.

Can I use all of these models with one API key?

Can I use this article's prices for procurement?

No. Treat this as a July 8, 2026 editorial snapshot. Use the live EvoLink model pages and billing rules before making procurement or customer-facing pricing commitments.

Sources

• EvoLink Seedream 5.0 Lite
• EvoLink Seedream 5.0 Pro
• EvoLink Nano Banana Pro
• EvoLink GPT Image 1.5
• Google: Introducing Nano Banana Pro
• OpenAI: Image generation guide
• OpenAI: All image models