GET

/v1/schemas/fal/image/fal-ai%2Ffast-lightning-sdxl%2Fimage-to-image

kind inputactivity imagehash 705483edextracted Jul 6, 2026version currentsource upstream spec ↗

Request body

16 properties · 2 required · 2 $defs
propertytypedescriptionconstraints
prompt*stringThe prompt to use for generating the image. Be as descriptive as possible for best results.
image_url*stringThe URL of the image to use as a starting point for the generation.
seedinteger The same seed and the same prompt given to the same version of Stable Diffusion will output the same image every time. nullable
num_inference_stepsenumThe number of inference steps to perform.1 | 2 | 4 | 8 · default: 4
num_imagesintegerThe number of images to generate.1 ≤ n ≤ 8 · default: 1
crop_outputbooleanIf set to true, the output cropped to the proper aspect ratio after generating.default: false
request_idstringAn id bound to a request, can be used with response to identify the request itself.default: ""
image_sizeImageSize | enumThe size of the generated image.default: "square_hd"
safety_checker_versionenumThe version of the safety checker to use. v1 is the default CompVis safety checker. v2 uses a custom ViT model.v1 | v2 · default: "v1"
expand_promptbooleanIf set to true, the prompt will be expanded with additional prompts.default: false
formatenumThe format of the generated image.jpeg | png · default: "jpeg"
strengthnumberdetermines how much the generated image resembles the initial image0.05 ≤ n ≤ 1 · default: 0.95
preserve_aspect_ratiobooleanIf set to true, the aspect ratio of the generated image will be preserved even if the image size is too large. However, if the image is not a multiple of 32 in width or height, it will be resized to the nearest multiple of 32. By default, this snapping to the …default: false
enable_safety_checkerbooleanIf set to true, the safety checker will be enabled.default: true
embeddingsEmbedding[]The list of embeddings to use.default: []
sync_modebooleanIf `True`, the media will be returned as a data URI and the output data won't be available in the request history.default: false

Validate a payload

before you spend tokens
shell
$ curl -X POST https://modelschemas.com/v1/validate \
    -d '{"provider":"fal","endpointId":"fal-ai/fast-lightning-sdxl/image-to-image","payload":{…}}'
→ {"valid": false, "errors": [{"path": "#", "keyword": "required", …}]}