OmniGen v2

AI Image Editing Model

Image $$$$ · 8.8¢

Unified multimodal model for text-to-image generation, instruction-guided image editing, personalized generation, and virtual try-on

omnigen2 API OpenAI-compatible

Base URL
https://api.lumenfall.ai/openai/v1
Model
omnigen-v2

Code Examples

Text to Image

/v1/images/generations
curl -X POST \
  https://api.lumenfall.ai/openai/v1/images/generations \
  -H "Authorization: Bearer $LUMENFALL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "omnigen-v2",
    "prompt": "",
    "size": "1024x1024"
  }'
# Response:
# { "created": 1234567890, "data": [{ "url": "https://...", "revised_prompt": "..." }] }

Image Edit

/v1/images/edits

Parameter Reference

Required Supported Not available

Core Parameters

Parameter Type Description Modes
prompt string Required. Text prompt for image generation
T2I Edit
negative_prompt string Negative prompt to guide generation away from undesired content
T2I Edit
seed integer Random seed for reproducibility
T2I Edit

Size & Layout

Parameter Type Description Modes
size string Image dimensions as WxH pixels (e.g. "1024x1024") or aspect ratio (e.g. "16:9")
WxH determines both shape and scale (aspect_ratio and resolution are ignored when size is provided). W:H format is equivalent to aspect_ratio.
T2I Edit
aspect_ratio string Aspect ratio of the output image (e.g. "16:9", "1:1")
Controls shape independently of scale. Use with resolution to control both. If size is also provided, size takes precedence. Any ratio is accepted and mapped to the nearest supported value.
T2I Edit
resolution string Output resolution tier (e.g. "1K", "4K")
Controls scale independently of shape. Higher tiers produce larger images and cost more. If size is also provided, size takes precedence for scale. Any tier is accepted and mapped to the nearest supported value.
T2I Edit
size

Exact pixel dimensions

"1920x1080"
aspect_ratio

Shape only, default scale

"16:9"
resolution

Scale tier, preserves shape

"1K"

Priority when combined

size aspect_ratio + resolution aspect_ratio resolution

size is most specific and always wins. aspect_ratio and resolution control shape and scale independently.

How matching works

Shape matching – we pick the closest supported ratio. Ask for 7:1 on a model with 4:1 and 8:1, you get 8:1.
Scale matching – providers use different tier formats: K tiers (0.5K 1K 2K 4K) or megapixel tiers (0.25 1). If the exact tier isn't available, you get the nearest one.
Dimension clamping – if a model has pixel limits, we clamp dimensions to fit and keep the aspect ratio intact.

Media Inputs

Parameter Type Description Modes
image file Required. Input image(s) to edit
Supports PNG, JPEG, WebP.
Up to 3 images per request.
T2I Edit

Output & Format

Parameter Type Description Modes
response_format string How to return the image
url b64_json
Default: "url"
T2I Edit
output_format string Output image format
png jpeg gif webp avif
Gateway converts to requested format if provider doesn't support it natively.
T2I Edit
output_compression integer Compression level for lossy formats (JPEG, WebP, AVIF)
T2I Edit
n integer Number of images to generate
Default: 1
Gateway generates multiple images in parallel even if provider only supports 1.
T2I Edit

Additional Parameters

Provider-specific passthrough fields, available only when the request is routed to the listed provider.

Parameter Type Description Modes
Universal
cfg_range_end number CFG range end value.
T2I Edit
cfg_range_start number CFG range start value.
T2I Edit
image_guidance_scale number The Image Guidance scale controls how closely the model follows the input images. For image editing: 1.3-2.0, for in-context generation: 2.0-3.0
T2I Edit
num_inference_steps integer The number of inference steps to perform.
T2I Edit
scheduler string The scheduler to use for the diffusion process.
dpmsolver euler
T2I Edit
text_guidance_scale number The Text Guidance scale controls how closely the model follows the text prompt. Higher values make the model stick more closely to the prompt.
T2I Edit
fal
enable_safety_checker boolean If set to true, the safety checker will be enabled.
T2I Edit
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.
T2I Edit
replicate
height integer Height of output image
T2I Edit
image_2 string Optional second input image for multi-image operations
T2I Edit
image_3 string Optional third input image for multi-image operations
T2I Edit
max_input_image_side_length integer Maximum input image side length
T2I Edit
max_pixels integer Maximum number of pixels in output
T2I Edit
width integer Width of output image
T2I Edit

Parameter Normalization

How we handle parameters across different providers

Not every provider speaks the same language. When you send a parameter, we handle it in one of four ways depending on what the model supports:

Behavior What happens Example
passthrough Sent as-is to the provider style, quality
renamed Same value, mapped to the field name the provider expects prompt
converted Transformed to the provider's native format size
emulated Works even if the provider has no concept of it n, response_format

Parameters we don't recognize pass straight through to the upstream API, so provider-specific options still work.