# 2026-08-28 — Pick the output format for generated images (improvement · API · BREAKING)

> Ask for png, jpg, or webp and the result tells you what you got.

`output.format` on `POST /image/generate` now decides the encoding. Pass `png`, `jpg`, or `webp` and Mynth converts the image before delivering it. Leave it out and you get whatever the provider returned.

```json
{
  "model": "black-forest-labs/flux.2-pro",
  "prompt": "A futuristic cityscape at sunset with flying cars",
  "output": { "format": "webp" }
}
```

Every successful image in the result now carries a `format` field, so you can read what was actually delivered instead of inferring it from the URL.

Two fields went away. `output.quality` is gone, and each format encodes at its own default. Per-image `cost` is gone from the result as well, so read the task-level `cost` instead.

Results also report `magic_prompt` again when [magic prompt](/features/magic-prompts) rewrites your prompt. It had been dropped from the payload.

Permalink: https://mynth.io/changelog/2026-08-28-image-output-format · Markdown: https://mynth.io/changelog/2026-08-28-image-output-format.md