GPT Image 1.5 vs 2: Which One to Use

OpenAI ships GPT Image updates quickly, and on Apiframe you can currently call two active model IDs: gpt-image-1.5 and gpt-image-2. Worth noting upfront: OpenAI's original GPT Image 1, released in April 2025, isn't available on Apiframe at all. Only the two current versions are. Here's what actually changed between them, and which one to use.

The lineup at a glance

The real differences, straight from Apiframe's own docs

Our GPT Image 2 API guide has a section comparing it directly against gpt-image-1.5, a genuinely useful reference if you want the full parameter list. Four things actually changed:

No transparent backgrounds on GPT Image 2. gpt-image-1.5 accepts background: "transparent". gpt-image-2 only accepts auto or opaque. If you need transparent PNGs, product cutouts, logos, or UI assets meant to sit on top of other content, stay on 1.5.

No input_fidelity setting on GPT Image 2. GPT Image 1.5 lets you choose between low and high fidelity when editing with a reference image. GPT Image 2 always processes input images at high fidelity, so there's no lower-cost, lower-fidelity option to fall back on.

New moderation field on GPT Image 2. Not present on 1.5. Set it to low for less restrictive content filtering. auto is the default on both models, but only version 2 lets you loosen it.

Default output format changed. GPT Image 1.5 defaults to png. GPT Image 2 defaults to webp. Set output_format explicitly if your pipeline expects one or the other.

Pricing: nearly identical, not a premium upgrade

GPT Image 2 is slightly cheaper at high and auto quality, 19 credits versus 20, despite adding a reasoning step that no earlier version had. That's not a rounding artifact either: OpenAI's own token pricing puts GPT Image 2's output-token cost at $30 per million tokens, versus $32 per million for GPT Image 1.5, a real, if modest, reduction that carries through to Apiframe's credit costs too. Worth stating plainly: this is a meaningfully better model at the same or slightly lower cost, not a premium tier you pay more to access.

Which one should you actually use?

If your workflow depends on transparent backgrounds, product cutouts, sticker-style assets, or UI icons, GPT Image 1.5 is the only one of the two that supports it. Upgrading to 2 means losing that capability entirely. For everything else, reasoning-driven layout, multi-image consistency, stronger multilingual text, and better instruction following, GPT Image 2 is the better default for new projects, and it costs the same or slightly less to run. For more on what the reasoning step and multi-image consistency actually look like in practice, see the full GPT Image 2 API guide.

Both run through the same API key and billing, so switching is a one-line change:

import requests

def generate(model, prompt, params):
    return requests.post(
        "https://api.apiframe.ai/v2/images/generate",
        headers={"X-API-Key": "afk_your_api_key_here"},
        json={
            "model": model,
            "prompt": prompt,
            ("gptImageParams" if model == "gpt-image-1.5" else "gptImage2Params"): params,
        },
    )

# Need a transparent PNG for a UI asset
icon = generate("gpt-image-1.5", "a minimalist app icon of a mountain, flat design",
                 {"background": "transparent", "quality": "high"})

# Everything else, default to the newer model
poster = generate("gpt-image-2", "a bilingual event poster in English and Japanese, clean layout",
                   {"quality": "high", "aspect_ratio": "3:2"})

No separate OpenAI account, no re-integration, just a different model string and the matching params key.

Get an API key and start with free credits, or try either model directly in Apiframe Studio without writing code. Full parameter references live in the docs, and current plan limits are on the pricing page. If you're weighing Apiframe against other ways to call GPT Image 2, see 4 Best GPT Image 2 API Providers Compared.

If you're building an editing-heavy workflow with either model, our AI Image Editing API guide covers the broader landscape, and if keeping the same character consistent across a set of images matters to your project, see how to keep AI-generated characters consistent. For a wider view of the image API market before you commit to either version, check out 8 Best AI Image Generator APIs in 2026 or Best AI Image APIs in 2026: Midjourney, Flux, Stable Diffusion & More Compared.