AI blog hero image generator: 16:9 images by API, one style

To generate blog hero images by API, request 16:9, keep the style block identical across posts, and leave text out of the image so the headline lives in your page. On Sume that is one POST /v1/images per post. Most catalog models list 16:9, including GPT Image 2.5, Nano Banana 2 and Pro, FLUX.2 and Seedream (Image API).

One style block

Write a style block of two or three lines and paste it into every prompt: medium, palette, light, composition rule such as "subject on the right, calm space on the left". Then each post adds only a subject line. Without the block, a blog's heroes drift into different styles.

• Keep text out: "no text, no logos".
• Reserve space where your template overlays the title.
• Same model id across the blog, so the look is stable.
• Store the final images on your own storage, not only the returned URL.

Request

Ask for webp or jpeg for page weight. A hero is a first-paint image, so file size matters more than for an inline picture.

curl -X POST https://api.sume.com/v1/images \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "black-forest-labs/flux.2-pro",
  "prompt": "Flat paper-cut illustration, teal and cream palette, soft light. Subject: a server rack growing a plant. Subject on the right, calm space on the left. No text, no logos.",
  "aspect_ratio": "16:9",
  "output_format": "webp"
}''

Cost for a calendar

At the catalog rates after the 1.25 factor, a hero costs $0.04 on FLUX.2 pro, $0.05 on Seedream 5.0 Lite and $0.10 on Nano Banana 2 at 1K. Thirty posts a month on FLUX.2 pro is about $1.20 before retries. The live rate is under pricing in the endpoints call.