FLUX 3 Image 10 reference images vs Sume's 1-10 image_urls

Yes, FLUX 3 Image takes up to ten reference images, and Sume's image edit also takes one to ten. On Sume the field is image_urls, 1 to 10 public HTTPS URLs, on the Image 1.0 compatibility route. Sume's docs list no FLUX 3 model id, so this is a comparison of limits, not a way to call FLUX 3.

Black Forest Labs' side is from its release notes and Sume's from the Image 1.0 and Image generation docs, all read 2026-10-01.

How does FLUX 3 Image use ten references?

The release notes say to name each image by its position in the prompt, to restyle an image or combine references into a new composition. There is one endpoint and no mode field: the prompt decides whether to generate or edit.

How many references does Sume accept?

It depends on the route. Image 1.0 is a compatibility alias for Image Router Auto and is retiring soon; new integrations are told to use POST /v1/images with model: "sume/auto". Per-model reference ceilings on the Image Router are in each catalog record, and a model with {"min": 0, "max": 0} is text-to-image only.

How do I send ten references on Sume?

Put the URLs in image_urls and describe each one in the prompt. Sume's docs do not define a positional naming scheme for the Image 1.0 route, so refer to images in plain words ("the first image") and check the result.

curl -X POST https://api.sume.com/v1/image-1.0/generate \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: image-refs-001" \
  -d '{
    "prompt": "Combine the product from the first image with the room from the second",
    "image_urls": [
      "https://example.com/product.png",
      "https://example.com/room.jpg"
    ],
    "quality": "medium"
  }'

What else can I add to an edit?

A mask_image_url alongside image_urls makes a masked edit; see mask_image_url vs mask_url. For what Sume's catalog does serve from FLUX, read FLUX 3 Image vs FLUX.2.