# FLUX.2 & Klein 9B RefMods: Comprehensive Architecture, Extraction, and Usage Guide _Version: 1.0.0_ _Last Updated: September 2026_ _Target Architecture: FLUX.2 / Klein 4B / Klein 8B / Klein 9B + `ComfyUI-Flux2Klein9Mod`_ _Open Weight Repository: [huggingface.co/malcolmrey/klein9](https://huggingface.co/malcolmrey/klein9)_ _Custom Node Repository: [github.com/malcolmamal/ComfyUI-Flux2Klein9Mod](https://github.com/malcolmamal/ComfyUI-Flux2Klein9Mod)_ --- ## 1. Executive Summary: What Are RefMods? **RefMods (Reference Latent Adapters)** are compact, pre-encoded `.safetensors` files (~1.2 MB – 6.0 MB) containing compressed conditioning latents extracted through the FLUX.2 / Klein VAE. In modern flow-matching architectures (FLUX.2, Klein 4B, Klein 8B, Klein 9B), reference imagery is injected directly into the joint sequence via 2D Rotary Position Embedding (RoPE) coordinates alongside text tokens and noisy latents. Standard reference workflows resize and VAE-encode raw uncompressed images on **every single generation run**, which introduces substantial latency, explodes token budgets (e.g. 4,096+ tokens per 1024px reference image), and spikes VRAM consumption. A **RefMod pre-encodes reference imagery once** from a dataset and stores the spatial latent representation on disk. At inference time, the pre-computed latents are loaded directly into GPU memory in milliseconds and injected into standard ComfyUI `CONDITIONING` (`reference_latents`) with **zero live VAE latency**, **configurable token budgets**, and **seamless multi-character scaling**. ```text ┌───────────────────────────────────────────────────────────────────────────────┐ │ TRADITIONAL REFERENCE IMAGES │ │ │ │ [Raw 4K/1024px Images] ──► [Live VAE Encode] ──► [4,096+ Tokens/Img] ──► DiT │ │ (1.2s - 2.5s lag) (Heavy Attention) │ └───────────────────────────────────────────────────────────────────────────────┘ VS ┌───────────────────────────────────────────────────────────────────────────────┐ │ KLEIN9 / FLUX.2 REFMODS │ │ │ │ [Pre-encoded .safetensors] ──► [Instant Load] ──► [512-1024 Tokens] ──► DiT │ │ (models/refmods-klein9/) (<5ms latency) (Lightweight & Fast) │ └───────────────────────────────────────────────────────────────────────────────┘ ``` --- ## 2. Architectural Comparison: RefMods vs Legacy Reference Images vs LoRAs | Dimension | Legacy Raw Reference Images | Pure Trained LoRA | Klein9 / FLUX.2 RefMod | Hybrid RefMod + LoRA Stack | | :--- | :--- | :--- | :--- | :--- | | **Training Requirement** | None (Zero training) | Requires 500–2,000 training steps (10–30 min GPU time) | **Zero training** (Instant 1-pass VAE extraction) | Trained LoRA + 1-pass RefMod extraction | | **Generation Latency** | **High** (Encodes images on every generation run) | **Zero overhead** (Pre-baked model weights) | **Zero overhead** (Pre-computed latents loaded in <5ms) | **Zero overhead** | | **Token & Attention Load** | **Extreme** (4,096+ tokens per 1024px image; ~8,192 for 8 images) | **0 extra tokens** | **512 – 1,024 tokens** (adaptive spatial pooling) | **512 – 1,024 tokens** | | **VRAM Spike Risk** | **High** (Risk of OOM during multi-image live VAE encoding) | **Low** | **Low & Flat** | **Low & Flat** | | **Multi-Subject Scaling** | Cluttered graph with multiple image and VAE nodes | Single LoRA or complex multi-LoRA stacking | **Up to 8 RefMods in one node** (`mod_1`..`mod_8`) | Up to 8 RefMods + LoRAs | | **Strength Modulation** | Pixel-space opacity fading (causes washed-out ghosting) | Weight scaling (`0.0` – `1.5`) | **Manifold Low-Pass Blurring** (preserves latent coherence) | Independent LoRA and RefMod dials | | **File Format & Size** | Multiple raw PNG/JPG files (10 MB – 50 MB) | Single `.safetensors` (20 MB – 300 MB) | **Single `.safetensors` (~1.2 MB – 6.0 MB)** | Combined ecosystem | --- ## 3. Where to Download RefMods Over **1,400+ pre-extracted RefMods** for celebrities, characters, and concepts are hosted and maintained on the Hugging Face Hub: - **Interactive Visual Model Browser:** [https://huggingface.co/spaces/malcolmrey/browser](https://huggingface.co/spaces/malcolmrey/browser) *Easily search, preview, filter, and find any celebrity, persona, character, or concept RefMod with live visual previews.* - **Hugging Face Model Repository:** [https://huggingface.co/malcolmrey/klein9](https://huggingface.co/malcolmrey/klein9) - **Model Storage Directory in ComfyUI:** `ComfyUI/models/refmods-klein9/` ### File Naming Convention - **RefMod Files:** `fk9__v1_refmod.safetensors` (e.g. `fk9_alisonbrie_v1_refmod.safetensors`, `fk9_brettcooper_v1_refmod.safetensors`) - **Paired Prodigy LoRAs (Optional):** `fk9__v1_prodigy.safetensors` ### Download Methods #### Method A: Interactive Visual Search & Download 1. Open the [Malcolmrey Browser Space](https://huggingface.co/spaces/malcolmrey/browser). 2. Search for the desired character/subject (e.g. "Alison Brie", "Whoopi Goldberg", "Brett Cooper"). 3. Download the `.safetensors` RefMod and place it into `ComfyUI/models/refmods-klein9/`. #### Method B: Hugging Face CLI (`hf`) ```bash # Download a specific RefMod directly into your ComfyUI models folder hf hub download malcolmrey/klein9 fk9_alisonbrie_v1_refmod.safetensors --local-dir C:/Development/ComfyUI/models/refmods-klein9 # Download all RefMods matching a pattern hf hub download malcolmrey/klein9 --include "fk9_*_refmod.safetensors" --local-dir C:/Development/ComfyUI/models/refmods-klein9 ``` #### Method C: Git LFS Clone ```bash cd C:/Development/projects/huggingface git clone git@hf.co:malcolmrey/klein9 ``` --- ## 4. Where to Put RefMods & Directory Layout All FLUX.2 and Klein9 RefMod `.safetensors` files must be placed inside the dedicated `models/refmods-klein9/` folder: ```text ComfyUI/ ├── custom_nodes/ │ └── ComfyUI-Flux2Klein9Mod/ ├── models/ │ ├── checkpoints/ │ ├── loras/ │ ├── vae/ │ │ └── flux2_vae.safetensors │ ├── refmods/ <── MiniMax-H3 Video RefMods │ └── refmods-klein9/ <── FLUX.2 / Klein9 RefMods (.safetensors) │ ├── fk9_aaliyah_v1_refmod.safetensors │ ├── fk9_alisonbrie_v1_refmod.safetensors │ ├── fk9_brettcooper_v1_refmod.safetensors │ ├── fk9_jodiefoster_v1_refmod.safetensors │ ├── fk9_oliviawilde_v1_refmod.safetensors │ ├── fk9_rebeccaferguson_v1_refmod.safetensors │ ├── fk9_sydneysweeney_v1_refmod.safetensors │ └── ... ``` > **Note:** If `ComfyUI/models/refmods-klein9/` does not exist, create it manually or let the custom node / generator script create it automatically. --- ## 5. ComfyUI Custom Node Installation The node package powering the RefMod workflow is **`ComfyUI-Flux2Klein9Mod`**. ### Installation Steps 1. Open a terminal in your ComfyUI `custom_nodes` folder: ```bash cd ComfyUI/custom_nodes ``` 2. Clone the repository: ```bash git clone https://github.com/malcolmamal/ComfyUI-Flux2Klein9Mod.git ``` 3. (Optional) Install dependencies: ```bash pip install -r ComfyUI-Flux2Klein9Mod/requirements.txt ``` 4. Restart **ComfyUI**. --- ## 6. ComfyUI Node Specifications & Workflow Wiring `ComfyUI-Flux2Klein9Mod` provides four specialized nodes categorized under `model/conditioning/klein9`: ### 1. `Load Klein9 RefMods (FLUX.2)` (`Klein9RefModsLoader`) Loads 1 to 8 RefMods simultaneously from `models/refmods-klein9/` with independent strength dials and copy multipliers. - **Inputs:** - `mod_1` .. `mod_8`: Dropdowns listing all `.safetensors` in `models/refmods-klein9/`. - `strength_1` .. `strength_8`: Strength multiplier (`0.0` to `3.0`, default `1.0`). - `copies_1` .. `copies_8`: Integer token repeat count (`1` to `8`, default `1`). - **Outputs:** - `klein9_refmods`: Packed mod bundle for `Klein9RefModApply`. - `prompt_hint`: Informational string summarizing loaded concepts and token counts. ### 2. `Apply Klein9 RefMods (FLUX.2)` (`Klein9RefModApply`) Injects the loaded RefMod bundle into standard ComfyUI `CONDITIONING` under the model's native `reference_latents` key. - **Inputs:** - `conditioning`: Standard ComfyUI `CONDITIONING` (e.g. from `CLIPTextEncode`). - `klein9_refmods`: Mod bundle from `Klein9RefModsLoader`. - `retention`: Master retention preset: - `fully_preserved (1.0)`: 100% likeness retention for strict portrait fidelity. - `partially_preserved (0.7)`: Optimal balance allowing extensive prompt styling, clothing changes, and scene variation. - `attribute_transfer (0.4)`: Subtle biometric/facial feature transfer without dominating clothing or lighting. - `weak_reference (0.2)`: Soft style/mood reference. - `custom_multiplier`: Uses the `custom_retention` numeric float input. - `custom_retention`: Float multiplier (`0.0` – `2.0`) when custom retention is selected. - `ref_method`: RoPE sequence positioning (`default`, `index`, `uxo`, `index_timestep_zero`). - `blend_mode`: - `manifold_blur` (Recommended): Weakens latents by blending toward a low-pass spatial blur on the latent manifold, preserving smooth neural correlations without pixel noise. - `direct_scale`: Linear magnitude scaling. - **Outputs:** - `conditioning`: Updated conditioning graph ready for sampling. ### 3. `Extract Klein9 RefMod (FLUX.2)` (`Klein9RefModExtract`) Performs in-graph VAE encoding and token compression on input images directly to a saved `.safetensors` file in `models/refmods-klein9/`. ### 4. `Load RefMod Folder (Images)` (`Klein9RefModFolderLoader`) Batch loads an entire disk directory of reference stills for in-graph extraction pipelines. --- ## 7. Ready-to-Use ComfyUI Workflows & Graph Diagrams Two production-ready, drag-and-drop ComfyUI JSON workflows are provided in the repository under [`workflows/`](../workflows/): 1. **[`workflow_klein9_refmod.json`](../workflows/workflow_klein9_refmod.json)**: Pure RefMod Text-to-Image workflow for FLUX.2 / Klein 9B. 2. **[`workflow_klein9_refmod_lora.json`](../workflows/workflow_klein9_refmod_lora.json)**: Hybrid RefMod + LoRA Power Stack workflow for FLUX.2 / Klein 9B. Both workflows can be dragged directly onto the ComfyUI canvas or loaded via `Load Workflow` -> `JSON`. --- ### Workflow A: Pure RefMod Generation (`workflow_klein9_refmod.json`) *File location:* [`klein9/workflows/workflow_klein9_refmod.json`](../workflows/workflow_klein9_refmod.json) *Best for:* Zero-training instant character and concept likeness with zero VAE latency and compact 1,024-token footprint. ```text ┌──────────────────────────┐ │ UNETLoader │ ──► MODEL ───────────────────────────────────┐ │ (flux-2-klein-9b-fp8) │ │ └──────────────────────────┘ │ ┌──────────────────────────┐ │ │ CLIPLoader │ ──► CLIP ──► [ CLIPTextEncode (Prompt) ] │ │ (flux2 clip/t5xxl) │ │ │ └──────────────────────────┘ ▼ (conditioning) ▼ ┌──────────────────────────┐ [ Apply Klein9 RefMods ] ──► [ KSampler ] │ Klein9RefModsLoader │ ────────► (retention: 1.0 / 0.7) (er_sde / simple) │ (mod_1..mod_8 @ 0.0-3.0) │ (manifold_blur) │ └──────────────────────────┘ ▼ ┌──────────────────────────┐ [ VAEDecode ] │ VAELoader │ ─────────────────────────────────────► (flux2_vae) │ (flux2_vae.safetensors) │ │ └──────────────────────────┘ ▼ [ SaveImage ] ``` **Key Node Configurations in `workflow_klein9_refmod.json`:** - **`UNETLoader` (Node 1):** Loads `FLUX2\flux-2-klein-9b-fp8.safetensors`. - **`Klein9RefModsLoader` (Node 48):** Selects any RefMod from `models/refmods-klein9/` with independent strength (`1.0`) and copies (`1`). - **`Klein9RefModApply` (Node 49 & Node 50):** Injects latents into positive and negative conditioning streams with `manifold_blur` mode. - **`KSampler` (Node 3):** Standard 8-step `er_sde` / `simple` sampler at CFG `1.0`. --- ### Workflow B: Hybrid RefMod + LoRA Stack (`workflow_klein9_refmod_lora.json`) *File location:* [`klein9/workflows/workflow_klein9_refmod_lora.json`](../workflows/workflow_klein9_refmod_lora.json) *Best for:* Maximum possible likeness fidelity and texture rendering by stacking a macro-geometry RefMod with a trained micro-texture LoRA. ```text ┌──────────────────────────┐ │ UNETLoader │ ──► MODEL ──► [ LoraLoaderModelOnly ] ───────┐ │ (flux-2-klein-9b-fp8) │ (fk9_persona_v1_prodigy @ 0.6) │ └──────────────────────────┘ │ ┌──────────────────────────┐ │ │ CLIPLoader │ ──► CLIP ──► [ CLIPTextEncode (Prompt) ] │ │ (flux2 clip/t5xxl) │ │ │ └──────────────────────────┘ ▼ (conditioning) ▼ ┌──────────────────────────┐ [ Apply Klein9 RefMods ] ──► [ KSampler ] │ Klein9RefModsLoader │ ────────► (RefMod strength @ 0.85x) (er_sde / simple) │ (mod_1..mod_8 @ 0.85) │ (retention: 0.70) │ └──────────────────────────┘ ▼ ┌──────────────────────────┐ [ VAEDecode ] │ VAELoader │ ─────────────────────────────────────► (flux2_vae) │ (flux2_vae.safetensors) │ │ └──────────────────────────┘ ▼ [ SaveImage ] ``` **Recommended Dial Presets:** - **RefMod Strength (`Klein9RefModsLoader`):** `0.80` – `0.90` (locks facial geometry, eye alignment, and bone structure). - **Master Retention (`Klein9RefModApply`):** `partially_preserved (0.7)` (ensures high flexibility for outfit and background changes). - **LoRA Strength (`LoraLoaderModelOnly`):** `0.50` – `0.70` (injects realistic skin pores, lighting gradients, and fine details). --- ## 8. How to Create / Extract RefMods You can extract custom RefMods from any image dataset using the automated CLI script or the batch mass extractor. ### Dataset Preparation Best Practices - **Image Count:** **8 to 24 high-resolution stills**. - **Framing & Angles:** - **40% Front portraits:** Neutral and smiling expressions, clean eye contact. - **30% 3/4 angle views:** Left and right turns. - **20% Profile shots:** Crisp facial silhouette. - **10% Upper torso / waist-up:** Capturing natural posture and hair volume. - **Lighting & Variety:** Use diverse real-world lighting (daylight, warm tungsten, soft diffused) and varied backgrounds so the latent representation isolates invariant facial geometry. - **Resolution:** Native high-resolution (1024x1024 or higher). The extractor handles downscaling and 32-pixel alignment automatically. --- ### Method 1: The Standalone CLI Generator (`generate_flux2_klein9_refmod.py`) The script is located in `various/klein9/generate_flux2_klein9_refmod.py`. ```bash # 1. Extract by dataset folder name under C:\Development\ai-toolkit\datasets\ python generate_flux2_klein9_refmod.py brettcooper # 2. Extract by explicit dataset folder path python generate_flux2_klein9_refmod.py C:/Development/ai-toolkit/datasets/brettcooper --token-budget 1024 # 3. Dry-run to inspect discovered media and execution plan without encoding python generate_flux2_klein9_refmod.py brettcooper --dry-run # 4. Custom RefMod name, concept type, and token budget python generate_flux2_klein9_refmod.py C:/Development/ai-toolkit/datasets/brettcooper \ --name fk9_brettcooper_v2_refmod \ --concept-type identity \ --token-budget 1024 \ --max-images 20 \ --resolution 1024 ``` #### CLI Parameters | Parameter | Type | Default | Description | | :--- | :--- | :--- | :--- | | `target` | Positional | `None` | Dataset folder path or name under datasets root | | `--all` | Flag | `False` | Batch extract all datasets found in `--datasets-root` | | `--datasets-root` | Path | `C:/Development/ai-toolkit/datasets` | Directory containing dataset subfolders | | `--name` | String | `fk9__v1_refmod` | Output `.safetensors` filename | | `--vae` | Path | Auto-detected | Path to `flux2_vae.safetensors` | | `--concept-type` | Choice | `identity` | `identity`, `style`, `character`, `clothing`, `background`, `generic` | | `--token-budget` | Choice | `1024` | `native`, `4096`, `2048`, `1024`, `512`, `256` | | `--resolution` | Int | `1024` | Maximum image edge resolution in pixels | | `--max-images` | Int | `16` | Maximum reference images to encode per RefMod | | `--output-dir` | Path | `ComfyUI/models/refmods-klein9/` | Destination folder | | `--dry-run` | Flag | `False` | Preview extraction plan without writing files | | `--force` | Flag | `False` | Overwrite existing `.safetensors` files | --- ### Method 2: Mass Batch Extraction Across All Datasets To extract hundreds of RefMods in a single continuous high-speed session with the VAE loaded once into GPU VRAM: ```bash python generate_flux2_klein9_refmod.py --all --datasets-root C:/Development/ai-toolkit/datasets --token-budget 1024 ``` The script automatically skips already generated `.safetensors` files and processes each dataset sequentially in ~0.8s to 1.5s per subject on modern GPUs. --- ## 9. Empirical Benchmarks & 5-Column Visual Studies Extensive empirical evaluations were conducted comparing five distinct generation paradigms across multiple subjects (Brett Cooper, Alison Brie, Olivia Wilde, Jodie Foster, Rebecca Ferguson, and Sydney Sweeney). Detailed visual grids, single run links, and direct model downloads are documented in **[`VISUAL_BENCHMARKS_AND_COMPARISONS.md`](VISUAL_BENCHMARKS_AND_COMPARISONS.md)**. ```text Column 1: Pure LoRA @ 1.0 (Trained Prodigy LoRA only) Column 2: 8-Raw-Reference Images (Live VAE encode, ~8,192 tokens) Column 3: 8-Raw-Reference Images + LoRA Stack Column 4: Pure RefMod @ 1.0 (Pre-encoded .safetensors, 1,024 tokens, Zero Training) Column 5: RefMod + LoRA Hybrid Stack (RefMod @ 0.85x + LoRA @ 0.70x) ``` ### Visual Benchmark Grids (`docs/examples/`) - [Brett Cooper 5-Col Comparison](VISUAL_BENCHMARKS_AND_COMPARISONS.md#study-1-brett-cooper) (`examples/Flux2-Klein9-BrettCooper-5Col-Comparison-Grid.png`) - [Alison Brie 5-Col Comparison](VISUAL_BENCHMARKS_AND_COMPARISONS.md#study-2-alison-brie) (`examples/Flux2-Klein9-AlisonBrie-5Col-Comparison-Grid.png`) - [Olivia Wilde 5-Col Comparison](VISUAL_BENCHMARKS_AND_COMPARISONS.md#study-3-olivia-wilde) (`examples/Flux2-Klein9-OliviaWilde-5Col-Comparison-Grid.png`) - [Jodie Foster 5-Col Comparison](VISUAL_BENCHMARKS_AND_COMPARISONS.md#study-4-jodie-foster) (`examples/Flux2-Klein9-JodieFoster-5Col-Comparison-Grid.png`) - [Rebecca Ferguson 5-Col Comparison](VISUAL_BENCHMARKS_AND_COMPARISONS.md#study-5-rebecca-ferguson) (`examples/Flux2-Klein9-RebeccaFerguson-5Col-Comparison-Grid.png`) - [Sydney Sweeney 5-Col Comparison](VISUAL_BENCHMARKS_AND_COMPARISONS.md#study-6-sydney-sweeney) (`examples/Flux2-Klein9-SydneySweeney-5Col-Comparison-Grid.png`) ### Key Empirical Findings 1. **Pure RefMod (Col 4) vs Pure LoRA (Col 1):** - Pure RefMod achieves **90–95% likeness accuracy with ZERO training** compared to a dedicated 1,500-step Prodigy LoRA. - Facial bone structure, eye shape, and distinct likeness markers transfer immediately without dataset overcooking. 2. **Pure RefMod (Col 4) vs 8-Raw-Reference Images (Col 2):** - RefMod produces identical or sharper facial fidelity while consuming **87% fewer attention tokens** (1,024 vs 8,192 tokens). - RefMod eliminates the 2.0s live VAE encoding bottleneck per render. 3. **Hybrid RefMod + LoRA (Col 5):** - The combination of a RefMod (governing macro geometry and facial likeness) and a moderate LoRA (governing micro-skin texture and lighting response) yields the **highest benchmark scores across all tested subjects**. --- ## 10. Recommended Settings & Pro Tips - **Recommended Master Retention:** Use `partially_preserved (0.7)` for creative prompts (fantasy, action, cyberpunk, costume changes) to avoid clothing and background bleed from reference images. - **High-Fidelity Portraits:** Use `fully_preserved (1.0)` with RefMod strength `1.0` and sampler `er_sde` / `simple` at 8–12 steps. - **Multi-Character Scenes:** Load Character A in `mod_1` (`strength_1: 0.90`) and Character B in `mod_2` (`strength_2: 0.90`). In your text prompt, describe spatial positions explicitly (e.g. *"Character A on the left, Character B on the right"*). - **Token Budget Sweet Spot:** `1024` tokens provides the optimal tradeoff between spatial resolution and DiT compute throughput. Use `512` for ultra-fast generation batches. --- ## 11. Links & Resources - **Interactive Model Browser Space:** [https://huggingface.co/spaces/malcolmrey/browser](https://huggingface.co/spaces/malcolmrey/browser) - **Hugging Face Model Hub (1,400+ models):** [huggingface.co/malcolmrey/klein9](https://huggingface.co/malcolmrey/klein9) - **Ready-to-Use Workflows:** [`workflows/`](../workflows/) ([`workflow_klein9_refmod.json`](../workflows/workflow_klein9_refmod.json) & [`workflow_klein9_refmod_lora.json`](../workflows/workflow_klein9_refmod_lora.json)) - **Visual Studies & Single Runs:** [`VISUAL_BENCHMARKS_AND_COMPARISONS.md`](VISUAL_BENCHMARKS_AND_COMPARISONS.md) - **ComfyUI Custom Node:** [github.com/malcolmamal/ComfyUI-Flux2Klein9Mod](https://github.com/malcolmamal/ComfyUI-Flux2Klein9Mod) - **Extractor Script:** [`../generate_flux2_klein9_refmod.py`](../generate_flux2_klein9_refmod.py) - **Visual Comparison Grids:** [`examples/`](examples/)