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Posted on • Originally published at apidog.com

GPT Image 1.5 vs Seedream 4.5: which AI image model wins in 2026?

TL;DR

GPT Image 1.5 (OpenAI) ranks #1 on LM Arena with Elo 1,264 and leads on overall quality, photorealism, and prompt adherence. Seedream 4.5 (ByteDance) ranks #10 (Elo 1,147) but leads on typography accuracy, 4K native resolution, and multi-image generation. GPT Image 1.5 is better for versatile high-quality output; Seedream 4.5 is better for commercial design work with text. Both are available through WaveSpeedAI.

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Introduction

GPT Image 1.5 is the highest-rated AI image model on LM Arena benchmarks. Seedream 4.5 is ByteDance’s commercially-focused model with unique typography capabilities. Neither is universally better — the right choice depends on what you’re generating.

This comparison covers benchmark data, key strengths, and practical use case guidance.

Benchmark comparison

Feature GPT Image 1.5 Seedream 4.5
Developer OpenAI ByteDance
LM Arena Elo 1,264 (#1) 1,147 (#10)
Max resolution 2048x2048 4096x4096 (4K)
Generation time 8-15 seconds 15-25 seconds
Text rendering Good Excellent
API access OpenAI API WaveSpeedAI exclusive

The 117-point Elo gap is significant. In head-to-head blind testing, users preferred GPT Image 1.5 output roughly 60-65% of the time for general use cases.

GPT Image 1.5 strengths

Overall quality and versatility:

GPT Image 1.5 excels at generating complex scenes with multiple subjects, nuanced lighting, and sophisticated composition. The model understands context in prompts and adds realistic details without explicit instructions.

Prompt adherence:

Consistently interprets nuanced prompts. You can describe mood, atmosphere, and abstract concepts and receive output matching your intent.

Generation speed:

At 8-15 seconds per image, GPT Image 1.5 is faster than Seedream 4.5 for most workflows.

API documentation:

OpenAI’s API documentation is comprehensive, with standard integration patterns for developers.

Seedream 4.5 strengths

Typography accuracy:

Seedream 4.5 specializes in accurate text rendering—letter formation, spacing, kerning, and multiple fonts/styles are handled correctly. This is a key differentiator for images containing text.

4K native resolution:

Generates images at 4096x4096 pixels, compared to GPT Image 1.5’s 2048x2048. This is important for print production, large-format displays, or editable source material.

Multi-image generation:

Supports up to 4 variations per prompt in a single request, enabling efficient A/B testing for creative concepts.

Cost:

Generally 20-30% lower cost than GPT Image 1.5 at comparable quality tiers.

The professional recommendation

For most teams, use GPT Image 1.5 for general creative work, concept art, and rapid prototyping. Switch to Seedream 4.5 when your project requires accurate typography or maximum resolution.

Many production teams run both models in parallel and select the best output per image type.

Use case table

Use case Better choice Why
Photorealistic scenes GPT Image 1.5 Higher benchmark quality
Graphic design with text Seedream 4.5 Typography accuracy
Marketing materials (text-heavy) Seedream 4.5 Text rendering
Concept art, illustration GPT Image 1.5 Versatility and quality
Print production Seedream 4.5 4K native resolution
Speed-sensitive workflows GPT Image 1.5 Faster generation
A/B variation testing Seedream 4.5 Multi-image per request
Brand identity work Seedream 4.5 Color consistency

Testing both with Apidog

To compare typography and generation quality, use identical prompts with both APIs in Apidog:

GPT Image 1.5 Example:

POST https://api.openai.com/v1/images/generations
Authorization: Bearer {{OPENAI_API_KEY}}
Content-Type: application/json

{
  "model": "gpt-image-1.5",
  "prompt": "A social media banner reading 'Summer Sale 2026' in bold white text on a sunset beach background",
  "size": "1792x1024"
}
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Seedream 4.5 via WaveSpeedAI Example:

POST https://api.wavespeed.ai/api/v2/bytedance/seedream-4-5
Authorization: Bearer {{WAVESPEED_API_KEY}}
Content-Type: application/json

{
  "prompt": "A social media banner reading 'Summer Sale 2026' in bold white text on a sunset beach background",
  "image_size": "landscape_16_9"
}
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Compare the accuracy of the text “Summer Sale 2026” in both outputs. This is the most direct way to evaluate typography capabilities.

Apidog setup:

  1. Create two environments: “OpenAI” and “WaveSpeed.”
  2. Store OPENAI_API_KEY and WAVESPEED_API_KEY as Secret variables in their respective environments.
  3. Use the same prompt variable across both requests.
  4. Run both requests in parallel and compare outputs using the Apidog response viewer.

FAQ

Does GPT Image 1.5 support 4K resolution?

Maximum is 2048x2048. Use Seedream 4.5 for 4K native output.

Is Seedream 4.5 available through the OpenAI API?

No. Seedream 4.5 is exclusive to WaveSpeedAI. Access requires a WaveSpeedAI account and API key.

Why does GPT Image 1.5 score higher on LM Arena but Seedream 4.5 handles text better?

LM Arena benchmarks overall image quality across varied prompts. Seedream 4.5 was engineered for text rendering, excelling at that specific task even with a lower overall score.

Can I use both models in the same application?

Yes. Route requests by content type: use Seedream 4.5 for assets with text, GPT Image 1.5 for everything else.

What’s the pricing difference?

GPT Image 1.5 costs $0.04-0.08 per image. Seedream 4.5 via WaveSpeedAI is generally 20-30% cheaper. At scale, this difference is significant.

Streamline API testing and image model evaluation with Apidog.

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