Seedream 5.0 pro layer decomposition vs a Sume Seedream result

Layer decomposition is a Seedream 5.0 pro feature: with layer_decomposition set to true and exactly one input image, BytePlus returns a base image plus up to 16 independently editable PNG layers, each with a z_index. Sume's catalog lists Seedream 5.0 Lite, not Pro, and returns one Sume-hosted URL per image, so this is not available there.

BytePlus facts are from its Seedream 5.0 overview; Sume facts from the Image API docs and catalog code, read 2026-09-30.

What does layer decomposition return?

The overview says each layer is a PNG with an alpha channel, and the response includes each layer's position, stacking order (z_index) and a content description. The prompt is optional and can name elements to separate. It reserves 17 IPM per request (one base plus up to 16 layers) and returns unused quota afterwards. The overview lists it as not available on 5.0 lite or the 4.x models.

What does a Sume Seedream request return?

The catalog entry is seedream-5-lite (Seedream 5.0 Lite), with Seedream 4.5 alongside it. Images return as Sume-hosted URLs, data[].url and signed, rather than inline base64, with usage data. There is no layers array in the documented payload. If you send a parameter the model does not list, you get 400 unsupported_parameter, so do not send layer_decomposition.

How do I get separate elements on Sume?

Generate elements as separate requests, or edit one region at a time. Sume documents no alpha-channel layer output for Seedream, so any compositing happens in your own tool. Check the catalog before choosing: Seedream 5.0 Pro vs Lite on Sume covers the ids.