Children's story clip from one illustration: Seedance 2.5 or 2.0

To animate a single storybook illustration, send it as the only reference_image_urls entry on a Seedance request and describe a small motion. For a 15-second page, seedance-2 costs about $5.67 at 720p on Sume and seedance-2.5 about $8.67. Use 2.0 for clips up to 15 seconds and 2.5 only when you need longer than that.

Reference image or first frame

The two shapes behave differently. image_url makes the picture the exact first frame, which keeps the page layout but may leave the artwork static or fade away from it. A reference image uses the picture as visual guidance, so style and characters carry over while the framing can change. One reference image is treated as reference-to-video, not as a first frame, as explained in this post.

Pick based on the page: a locked page layout wants image_url; a style you want continued wants a reference image. On /v1/videos, the Video generation docs say that if frame images and reference images are both sent, the frame images win and the request becomes image-to-video, so send one or the other.

Which model for how long

The Sume catalog row for seedance-2 lists durations from 4 to 15 seconds, and seedance-2.5 from 4 to 30 seconds, per the Video generation docs and Video Router docs read on 2026-10-04. A story page rarely needs more than 15 seconds, so 2.0 is usually enough and cheaper.

Prompt for gentle motion

Ask for motion a picture book would show: leaves moving, a character blinking and turning, a slow zoom. Ask for the same illustration style to continue, and avoid asking for text on the page to change. Keep the camera mostly still so the artwork stays recognizable.

curl -X POST https://api.sume.com/v1/video-router/generate \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: story-page-001" \
  -d '{
    "model": "seedance-2",
    "prompt": "The fox in the illustration looks up as snow falls, the camera slowly pushes in, watercolor style continues.",
    "reference_image_urls": ["https://example.com/page-3.png"],
    "resolution": "720p",
    "duration": 8,
    "aspect_ratio": "16:9",
    "mode": "async"
  }'

Keep it safe for young viewers

Review every clip yourself before publishing to children; generative video can produce unexpected content, and no benchmark on the pages read says otherwise. Keep the original illustration and your prompt on file so you can reproduce the intent.