Generate at 4K or upscale a 1K: $0.20 vs $0.30 on Sume

On Sume, generating a 4K image directly is cheaper than generating small and upscaling. Nano Banana 2.1 at 4K is $0.20; Nano Banana 2.1 at 1K plus Image Upscale is $0.10 + $0.20 = $0.30. For GPT Image 2.5, low quality at 1K plus an upscale is $0.02475 + $0.20 = $0.22475, which is $0.00225 more than the $0.2225 high-quality 4K image.

Four routes to a large image

Image Upscale 1.0 is a flat $0.20 per image in the catalog, reserved against about 16 megapixels of generative output, and takes an upscale_factor between 1 and 4. The generation prices are from the Sume price list.

When upscale still wins

Upscale is the only route when the image already exists: a customer photo, a scan or an older render. It also fits a workflow where you draft many images at low quality and enlarge only the winners. Ten drafts at GPT Image 2.5 low are $0.2475, and upscaling the two you keep adds $0.40, so the set costs $0.6475 instead of ten high-quality 4K images at $2.225.

• Generating at the final size avoids a second job and a second wait.
• A direct 4K generation and an upscaled 1K image are different outputs, and this post makes no claim about which looks better.
• The reserve for an upscale is 20 cents, so a batch of 50 holds $10.00.

The upscale request

Send a public HTTPS image_url and, optionally, upscale_factor and output_format (png, jpg or webp).

curl -X POST https://api.sume.com/v1/image-upscale-1.0/upscale \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: upscale-winner-07" \
  -d '{
    "image_url": "https://example.com/draft-07.png",
    "upscale_factor": 4,
    "output_format": "png"
  }'

A 100-image catalog

For 100 final images the totals are $20.00 for Nano Banana 2.1 at 4K, $30.00 for 1K plus upscale, $22.25 for GPT Image 2.5 high at 4K and $22.475 for GPT Image 2.5 low plus upscale. The spread between the cheapest and dearest of the four is $10.00, so the decision is small unless you generate thousands of images.