3:2 photo ratio image API: which Sume models list it and which do not

3:2 is the ratio of a full-frame camera sensor and a 4x6 inch print, so it is the ratio people ask for when they want a photo-like image. On Sume you can send aspect_ratio: "3:2" to 13 of the 16 image model families in the catalog. It is not on the list for google/imagen-4-fast, google/imagen-4-ultra, openai/gpt-image-2.5.

The lists come from the per-model native catalogs in Sume's contract package (read 2026-10-07). A model accepts only the values its catalog descriptors list; anything else returns 400 unsupported_parameter rather than being silently snapped.

Models that list 3:2, cheapest first

Prices here are Sume's list-times-1.25 figures. The catalog states the billable formula as "list × 1.25 → ceil usd cents", so treat the dollar amounts as the pre-rounding value and read the exact charge from billable_amount_usd_micros in the submit envelope. Failed or cancelled generations are not billed.

Getting 3:2 from GPT Image 2.5

The GPT Image 2.5 preset list is auto, 1:1, 16:9, 9:16, 4:3, 3:4, 5:4, 9:8 and 4:5. For 3:2, send custom pixels instead: image_size of 1536x1024 (both edges are multiples of 16, well inside the 3840 cap and the 3:1 limit). That prices at $0.0515 at high, $0.01287 at medium and $0.006 at low.

Imagen 4 Fast and Ultra cannot do it: their catalog is fixed at five ratios and takes no custom pixels. Use 4:3 and crop 6.25 percent off the top and bottom, or pick a model from the table.

Request

Use one sizing field per request.

{
  "model": "bytedance-seed/seedream-5-lite",
  "prompt": "street photo, rainy tram stop, 35mm",
  "aspect_ratio": "3:2"
}

Source: Sume Image API docs and GET /v1/images/models/{id}/endpoints for the definitive per-model list (read 2026-10-07).