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This is a Core AI conversion of FLUX.3 [klein] by Black Forest Labs, under the FLUX Kommunity License (LICENSE.md): it may be used and distributed for non-commercial purposes; only a Qualifying User may use its output commercially. You must use content filters or review output before distributing it, and disclose AI generation where the law requires. By agreeing you accept that licence.
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FLUX.3 [klein] β Core AI
Black Forest Labs' FLUX.3 [klein] converted to Core AI diffusion bundles for Apple silicon,
4 steps β used by the imagine tool. Any shape and size up to native 4K, and editing with up to ten pictures.
Two bundles, the same model:
| weights | download | use it for | |
|---|---|---|---|
full/ (imagine --flux3) |
bfloat16 | 17 GB | text β signs and handwriting spelled right |
top level (imagine --flux3-small) |
4-bit | 5.4 GB | drafts β prints signs, garbles handwriting |
Files
Each size β full/ (bfloat16, imagine --flux3) and the top level (4-bit, imagine --flux3-small) β
is one set of files that draws and edits every shape:
| file | what | bfloat16 | 4-bit |
|---|---|---|---|
Transformer_4k.aimodel |
text to image; image and text lengths variable | 9.1 GB | 2.9 GB |
Transformer_img2img_full.aimodel |
editing; image, text and reference lengths variable | 10 GB | 3.2 GB |
VAEDecoder_4k.aimodel, VAEEncoder_4k.aimodel |
any height and width up to 4096 | 0.16 GB | 0.16 GB |
TextEncoder.aimodel, tokenizer, vae_bn_*.npy |
Qwen3-VL text encoder and sidecars | 8.3 GB | 2.5 GB |
Any width and height in multiples of 16, sides up to 4096; imagine allows up to 3840 Γ 2160 (2880 Γ 2880 square), the largest measured β about 18 minutes at bfloat16 and 16 at 4 bits on a 36 GB Mac, the picture decoded in overlapping 1024-pixel tiles (a whole 4K decode alone ran the Mac out of memory). An edit takes up to ten
pictures, each read whole as diffusers' FLUX.3 pipeline reads it β the edited picture at the output's
size, every other one fitted under 1 megapixel at its own shape β each at its own position ids. Core AI
compiles each variable function once, for every size.
Measured on an M3 Max (36 GB) through imagine: the variable transformer agrees with diffusers' own
forward to cosine 0.999912 on saved reference inputs, exactly as the fixed 1:1 export did; a 2048 Γ 2048
poster with its title spelled right in 420 s; a 16:9 picture with its sign right in 116 s; a person
dressed from a cardigan's and a beret's pictures (three in all) kept her face, 242 s; at 4 bits a 3:4
picture in 43 s.
The older files β 0.20's *_any.aimodel (up to 2048) and 0.17β0.19's Transformer.aimodel, VAEDecoder.aimodel
and shapes/ β are kept for the imagine versions that pin earlier revisions; nothing current reads them.
Editing
Instructions are passed as written β the bundles do not include BFL's prompt upsampler β and
imagine guide edit shows the formats (a full instruction, or a paragraph with a JSON table of boxes
on a 0β1000 grid). Measured against diffusers' own pipeline on the same pictures: a mug recoloured, a
notebook removed with a written instruction (a short "remove the notebook" left it, in diffusers too),
a mug moved by a box record, a person dressed from garments' pictures.
Licence β read this first
- FLUX Kommunity License v1.0 (
LICENSE.md). The model and this conversion may be used and distributed for non-commercial purposes; a Qualifying User (under US$5M gross annual revenue, with affiliates) may also use the pictures commercially. Rights come directly from Black Forest Labs to you, not from us. - Β§2(e): you must either use content filters to prevent unlawful, unsafe or infringing
output, or review output before distributing it β and disclose AI generation where the law
requires.
imaginewrites the IPTC digital-source-type field (trainedAlgorithmicMedia) into every file. - BFL's Attribution Notice and our modification statement are in
NOTICE. This is not an official Black Forest Labs product. - The text encoder is the language model of Qwen3-VL as shipped in BFL's release (Apache-2.0,
LICENSE-QWEN3-VL).
Conversion
Apple's recipe, apple/coreai-models (BSD-3), extended for
FLUX.3 in arraypress/coreai-models at tag
1.0.0-nonsquare.8; source revision 3373376.
- bfloat16. float16 overflows (NaN, in diffusers too). Against diffusers in PyTorch the bfloat16 bundle's output agrees to cosine 0.99992.
- 4-bit: weights quantized per block of 32, symmetric, scales stored as float32 (Core AI's 4-bit GPU kernel rejects bfloat16 scales); norms excluded. The VAE is never quantized.
- Recipe, as in diffusers' FLUX.3 pipeline: the text window is the prompt rounded up to a multiple
of 80 tokens (up to 1040); padding sits at position 1 inside Qwen3-VL; image positions are scaled
by 0.5; sigmas
linspace(1, 1/n, n)shifted by 6.93, each step aimed at the next sigma. - 4 steps where diffusers runs 16: on text, faces, hands and crowds, 4 steps matched 8 and 16.
Measured (macOS 27, M3 Max, 36 GB, GPU, 1024 Γ 1024, 4 steps, through imagine)
| Measure | full/ |
4-bit |
|---|---|---|
| chalk menu "Today: tomato soup", seeds 21β24, spelled right | 4 / 4 | 0 / 4 |
| printed signs, labels, covers: six prompts, one seed | 6 / 6 | 5 / 6 |
| one picture, whole command | 77β98 s | 33β38 s |
| each further picture in the same run | 25β32 s | β |
| peak memory footprint / most resident | 6.1β7.7 GB / 23β26 GB | 13.3 GB / 6.3β8.6 GB |
| first run (compiles for this Mac's GPU, cached per program) | β16 min | β30 s |
At 4 bits the model still prints a sign but writes handwriting as near-letters ("yerunaoo soup"), so the bfloat16 bundle is the one to use for text. Faces, hands and crowds look the same at both.
An 8-bit bundle was measured and dropped: 8 GB, but β190 s a picture (Core AI re-attempts a Neural
Engine compile on every load). Core AI also prints six compiler warnings to standard output on each
load of the 4-bit bundle; imagine silences them.
Use
imagine model accept flux3 # once: shows these terms, records acceptance
imagine --flux3 "a chalkboard menu that reads 'Today: tomato soup'" -o menu.png
imagine --flux3-small "a lighthouse on a cliff, poster art" -o draft.png
imagine --flux3 "a wide street sign that reads 'Harbour Road'" --aspect 16:9
imagine --flux3 "a Lisbon travel poster with the word 'LISBOA'" --size 2048x2048
imagine --flux3 --edit person.jpg --ref cardigan.jpg --ref beret.jpg "Create a photograph of the woman from the first image wearing the cardigan from the second image and the beret from the third β¦"
Downloading needs a Hugging Face account that has accepted this repository's terms and a token
(hf auth login); imagine says so with exit 3 when either is missing.
Model tree for arraypress/imagine-flux3-klein
Base model
black-forest-labs/flux-3-image-klein