invokeai-image-gen

InvokeAI Image Generation

Generate images via InvokeAI's REST API. Supports FLUX.2 Klein (default), Z-Image Turbo, FLUX.1, and SDXL.

Quick Start

Simply call the script with your prompt and the output file name:

python scripts/generate.py -p "A dramatic sunset over snow-capped mountains, warm orange light reflecting off a still alpine lake in the foreground. Soft clouds catch the fading light." -o sunset.png

Overriding The Default Model

If the user asks you to use a specific model, first find the model key, then use it in the command:

python scripts/generate.py --list-models | grep -i 'flux'

python scripts/generate.py -p "A tabby cat with bright green eyes sits on a weathered wooden windowsill, soft afternoon light streaming through lace curtains. Cosy, intimate mood." --model MODEL_KEY -o cat.png

Options

Option	Description
--prompt, -p	Generation prompt (required)
--negative, -n	Negative prompt (SDXL only)
--model, -m	Model key (UUID) or partial name match
--width, -W / --height, -H	Dimensions
--steps, -s	Denoising steps
--cfg, -c	CFG scale
--guidance, -g	Guidance strength (FLUX.1 only)
--scheduler	Sampling scheduler
--seed	Random seed
--output, -o	Output path (default: invokeai-{seed}.png)
--list-models	List installed models
--json	JSON output

Model Defaults

Note: FLUX.2 Klein is the latest model which is used by default.

Model	Steps	Guidance	CFG	Scheduler
FLUX.2 Klein	4	3.5	1.0	euler
Z-Image Turbo	9	-	1.0	euler
FLUX.1 dev	28	3.5	1.0	euler
FLUX.1 Krea dev	28	4.5	1.0	euler
FLUX.1 Kontext dev	28	2.5	1.0	euler
FLUX.1 schnell	4	0.0	1.0	euler
SDXL	25	-	6.0	dpmpp_2m_k
SDXL Turbo	8	-	1.0	dpmpp_sde

All models default to 1024x1024. FLUX requires dimensions divisible by 16, SDXL by 8.

FLUX.1 Variant Notes

• FLUX.1 dev: Standard text-to-image model, balanced quality/speed
• FLUX.1 Krea dev: Fine-tuned for aesthetic photography, use higher guidance (4.5)
• FLUX.1 Kontext dev: Image editing model, use lower guidance (2.5)
• FLUX.1 schnell: Distilled fast model, 4 steps, no guidance needed

Model Selection

Auto-priority: Klein > Z-Image > FLUX > SDXL

Detection by name/base:

• flux2_klein: "klein" in name or "flux2" in base
• flux_krea: "krea" in name (FLUX.1 base)
• flux_kontext: "kontext" in name (FLUX.1 base)
• flux_schnell: "schnell" in name (FLUX.1 base)
• flux: "flux" in base (standard dev)
• zimage: "z-image" in base or "z-image/zimage" in name
• sdxl: "sdxl" in base (turbo/lightning variants auto-detect)

Prompting (general information, but especially useful for FLUX.2 Klein)

Write prose, not keywords. Structure: Subject -> Setting -> Details -> Lighting -> Atmosphere

A weathered fisherman in his late sixties stands at the bow of a wooden boat,
wearing a salt-stained wool sweater. Golden hour sunlight filters through
morning mist, creating quiet determination and solitude.

Key techniques:

1. Front-load critical elements (word order matters)
2. Specify lighting: source, quality, direction, temperature
3. Include sensory texture: materials, reflections, atmosphere

Good: "A woman with short blonde hair poses against a light neutral background wearing colourful earrings, resting her chin on her hand."

Bad: "woman, blonde, short hair, neutral background, earrings"

Append style tags: Style: Country chic. Mood: Serene, romantic.

Troubleshooting

Issue	Solution
Connection refused	Check InvokeAI is running
Model not found	Use --list-models for valid keys
Dimensions error	FLUX: multiples of 16, SDXL: 8
Black images (macOS)	Set precision: bfloat16 in invokeai.yaml

If the script fails to find the URL or authentication token, you can set or ask the user to set environment variables:

export INVOKEAI_API_URL='http://localhost:9090'
export INVOKEAI_AUTH_TOKEN='your-token'  # Optional

Resources

• scripts/generate.py - Main generation script