Digital gift card art via API: generate the art, print the code

For a digital gift card, generate the artwork with an image model on Sume, ask for a clear empty band where the details go, and draw the amount and the code on top in Pillow. A gift code must be exact and unique, so it never belongs in a generated image; the API makes the art and your own code makes the card.

A good choice for the art is openai/gpt-image-2.5. fal lists GPT Image 2.5 as OpenAI's default image model, with natural lighting, rich textures and support for complex layouts (read 2026-10-06, fal). On Sume it takes quality from low to max, defaults to high, and accepts a custom image_size as described in the Image API docs. A landscape card at 3:2 or 16:9 fits most email and wallet layouts.

Split the work between model and code

The split is simple. The model supplies the mood: a seasonal pattern, a border, a texture, a small decorative motif. Your code supplies everything a customer or a clerk will rely on: the amount, the code, the expiry line and the store name if it must be exact. This also makes one art file reusable across many cards, which keeps the cost close to a single generation.

Generate once, stamp many

The script generates one card background, downloads it, and stamps a code on a copy. Replace the text and the position with your layout; the default Pillow font is small, so load a real font file for production.

import io
import os
import requests
from PIL import Image, ImageDraw

r = requests.post(
    "https://api.sume.com/v1/images",
    headers={"Authorization": f"Bearer {os.environ['SUME_API_KEY']}"},
    json={
        "model": "openai/gpt-image-2.5",
        "prompt": "Autumn leaf pattern gift card background, soft gold and "
        "cream, empty clear band across the lower third, no text at all",
        "aspect_ratio": "3:2",
        "quality": "medium",
    },
    timeout=60,
)
r.raise_for_status()
art = requests.get(r.json()["data"][0]["url"], timeout=60).content
card = Image.open(io.BytesIO(art)).convert("RGB")
draw = ImageDraw.Draw(card)
w, h = card.size
draw.text((w // 10, int(h * 0.75)), "$50  CODE: ABCD-1234", fill="black")
card.save("gift-card.png")
print("saved", card.size)

Handling a slow response

A request blocks for up to 30 seconds and returns 200 with the image. High quality or a large size can run past that, and Sume then returns 202 with a job envelope; the call above uses raise_for_status, which accepts a 202, so in production check the status code and fetch GET /v1/jobs/{id}/result as the jobs and results page describes.

Medium quality is plenty for a flat pattern with no text. Spend on high only if you can see a difference in the file.

Checklist before the card goes live

A gift card is money, so treat the image as a document and check it like one.

• The gift code on the image comes from your system of record, not from any model.
• Nothing in the art implies a value, expiry or brand claim that your terms do not support.
• The text area is empty in the art, so the code is easy to read at phone size.
• The final file is a PNG or JPEG you generated, stored under your own control.
• Each card has its own file, because every code is different.

Cost of a card run

Because the art is reused, the cost does not grow with the number of cards. If you want five seasonal designs for a shop, that is five generations at the quality you choose, plus the cost of any rejected drafts. Read the endpoint pricing for GPT Image 2.5 before you start, since the docs say output cost depends on size and quality, and the billed line includes Sume's margin. Keep the best art file and a copy of the prompt so a new season can start from a known look. If a single design should differ per customer, such as a name, draw it in code rather than generating a new image for each person.

What a customer sees

Check the finished card on a phone screen at the size it is displayed, in dark mode if your wallet or email client has one. A pale band that works on a white page can vanish on a dark background. Keep the band a mid-tone or add a solid panel behind the text in Pillow so the code stays readable either way.