Hy Image 3.5 Preview: 2K or 4K? Tencent and OpenRouter differ

Two pages read on 2026-10-08 give two output ceilings for Hy Image 3.5 Preview. Tencent Hy's launch post on X says "Up to 2K". The OpenRouter model page lists a resolution parameter with choices from 1K to 4K. Both can be true if a preview endpoint and a router differ, but nothing on either page says so, so treat 4K as unproven until a call returns it.

If your plan needs 4K files, the safer check is on the Sume side: which rows list a 4K tier or a pixel size that reaches it, and what each costs.

Test the ceiling before you plan around it

Send one request at the top tier and read the pixel size of the file you get back, not the label you asked for. For Hy Image that means a call through the route you actually plan to use. A 2K label on the file is a 2K answer, whatever the model page lists.

• Ask for the top tier and read the width and height of the returned file.
• Repeat at one wide and one tall aspect ratio, because a ceiling can be a pixel total, not an edge.
• Log the charge for that call, since the top tier is often the dearest.

Where Sume lists 4K today

Sume reads the tier list from its catalog, so the answer is per row. The Image API docs name resolution as 512, 1K, 2K or 4K, and each model accepts only what its descriptor lists.

Reading the table

ChatGPT Image 2.5 reaches 3840 by 2160 only because 8,294,400 pixels is the stated cap, so a 4K UHD frame fits and a taller square does not. The Nano Banana rows are the ones with a named 4K tier. For a 4K file from a row without one, an upscale step is a separate, separately priced call.

Prices here are the Sume list-times-1.25 figures from the repo's price book. The live pricing line on GET /v1/images/models/{id}/endpoints is the figure you are billed.

When two pages disagree on a ceiling, test the ceiling you intend to use before you build a pipeline around it. Request the size once, check the pixel dimensions of what comes back, and record which page you trusted. A preview model can change its limits between releases, so the note should carry a date.

On the Sume side the check is simpler, because the row you call lists its tiers. Read the resolution descriptor from the endpoints route and request one of those values; a tier the row does not list is refused instead of being rounded to something close.