GET

/v1/schemas/fal/image/fal-ai/fast-sdxl/image-to-image

Accept:

kind inputactivity imagehash 41fd6992…extracted Oct 29, 2026version currentsource upstream spec ↗

field	recorded source
schema	Source linked above. upstream-spec Source trace `85265b56944a6d3b513606b895323cfcdf1efd1726d55170a1197699aad5ebc4` { "fetchedAt": 1793250001, "extractorVersion": "1", "verifiedAt": null }

Request body

19 properties · 2 required · 3 $defs

property	type	description	constraints
image_url*	string	The URL of the image to use as a starting point for the generation.
prompt*	string	The prompt to use for generating the image. Be as descriptive as possible for best results.
seed	integer	The same seed and the same prompt given to the same version of Stable Diffusion will output the same image every time.	nullable
image_size	ImageSize \| enum	The size of the generated image.	default: "square_hd"
safety_checker_version	enum	The version of the safety checker to use. v1 is the default CompVis safety checker. v2 uses a custom ViT model.	v1 \| v2 · default: "v1"
guidance_scale	number	The CFG (Classifier Free Guidance) scale is a measure of how close you want the model to stick to your prompt when looking for a related image to show you.	0 ≤ n ≤ 20 · default: 7.5
request_id	string	An id bound to a request, can be used with response to identify the request itself.	default: ""
strength	number	determines how much the generated image resembles the initial image	0.05 ≤ n ≤ 1 · default: 0.95
crop_output	boolean	If set to true, the output cropped to the proper aspect ratio after generating.	default: false
format	enum	The format of the generated image.	jpeg \| png · default: "jpeg"
num_inference_steps	integer	The number of inference steps to perform.	1 ≤ n ≤ 65 · default: 25
negative_prompt	string	The negative prompt to use.Use it to address details that you don't want in the image. This could be colors, objects, scenery and even the small details (e.g. moustache, blurry, low resolution).	default: ""
enable_prompt_expansion	boolean	If set to true, the prompt will be expanded with additional prompts.	default: false
embeddings	Embedding[]	The list of embeddings to use.	default: []
loras	LoraWeight[]	The list of LoRA weights to use.	default: []
num_images	integer	The number of images to generate.	1 ≤ n ≤ 8 · default: 1
enable_safety_checker	boolean	If set to true, the safety checker will be enabled.	default: true
sync_mode	boolean	If `True`, the media will be returned as a data URI and the output data won't be available in the request history.	default: false
preserve_aspect_ratio	boolean	If 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

Types

3 $defs

Embeddingobject

tokens	string[]	The list of tokens to use for the embedding. When omitted, tokens are generated as <s0>, <s1>, ... to match the number of vectors in the embedding file.	nullable
path*	string	URL or the path to the embedding weights.

ImageSizeobject

height	integer	The height of the generated image.	0 < n ≤ 14142 · default: 512
width	integer	The width of the generated image.	0 < n ≤ 14142 · default: 512

LoraWeightobject

path*	string	URL or path to a LoRA safetensors file. Or HF model name that resolves to safetensors weights.
force	boolean	If set to true, the embedding will be forced to be used.	default: false
scale	number	The scale of the LoRA weight. This is used to scale the LoRA weight before merging it with the base model.	0 ≤ n ≤ 1 · default: 1

Validate a payload

before you spend tokens

shell

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