sammcj/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