FLUX.2 klein 4B: Core AI model card

README.md

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+---
+license: apache-2.0
+base_model: black-forest-labs/FLUX.2-klein-4B
+tags:
+  - core-ai
+  - coreai
+  - text-to-image
+  - flux
+  - flux2
+  - on-device
+  - apple-silicon
+pipeline_tag: text-to-image
+library_name: coreai
+---
+
+# FLUX.2 klein 4B — Core AI
+
+[Black Forest Labs' **FLUX.2 [klein] 4B**](https://huggingface.co/black-forest-labs/FLUX.2-klein-4B)
+converted to **Core AI** for on-device image generation on Apple Silicon (macOS 27+),
+running on Apple's official diffusion runtime in
+[apple/coreai-models](https://github.com/apple/coreai-models).
+
+FLUX.2 [klein] is step-distilled: **4 denoising steps at guidance 1.0** produce a full
+1024×1024 image. It pairs a 4B flow-matching diffusion transformer (DiT) with an 8B
+Qwen3 text encoder.
+
+## Components
+
+| Component | Description |
+| --- | --- |
+| `Transformer.aimodel` | Flow-matching DiT (25 blocks), 1024×1024 |
+| `TextEncoder.aimodel` | Qwen3 text encoder (hidden states 9 / 18 / 27) |
+| `VAEDecoder.aimodel` | Latent → 1024×1024 RGB image |
+| `VAEEncoder.aimodel` | 1024×1024 RGB image → latent (image-to-image) |
+| `tokenizer/`, `pipeline.json`, `vae_bn_*.npy` | Sidecar assets (auto-loaded) |
+
+Weights are 4-bit quantized (int4, per-block, block size 32); compute precision
+float16. The full bundle is **4.0 GB** — Transformer 2.0 GB · TextEncoder 1.8 GB ·
+VAE 0.16 GB.
+
+## Usage
+
+### Sample app (easiest)
+
+[**CoreAIImageGenMac**](https://github.com/mlboydaisuke/coreai-samples) — pick
+"FLUX.2 klein 4B", tap **Download & Load**, type a prompt, **Generate**.
+
+### Swift
+
+```swift
+import CoreAIDiffusionPipeline
+
+let pipeline = try await Flux2Pipeline(from: modelURL)
+let config = PipelineConfiguration(
+    prompt: "a photo of a cat",
+    stepCount: 4,
+    guidanceScale: 1.0,
+    schedulerType: .discreteFlow
+)
+let result = try await pipeline.generateImages(configuration: config) { _ in true }
+let image = result.images.first!
+```
+
+### Command line (zoo reference tool)
+
+```bash
+swift run -c release diffusion-runner \
+  --model path/to/FLUX.2-klein-4B \
+  --prompt "a photo of a cat" --steps 4 --guidance-scale 1.0
+```
+
+## How it was converted
+
+```bash
+uv run coreai.diffusion.export flux2-klein-4b --platform macOS
+```
+
+## Performance
+
+M4 Max (128 GB): **~17 s** for a 4-step 1024×1024 image (cold model load + 4 denoising
+steps + VAE decode). The distilled 4-step schedule means no negative prompt / CFG is
+needed (guidance 1.0).
+
+## License
+
+Apache 2.0, inherited from the base model
+[black-forest-labs/FLUX.2-klein-4B](https://huggingface.co/black-forest-labs/FLUX.2-klein-4B).
+The converted weights are redistributed under the same terms, with attribution to
+Black Forest Labs.