Files
remove-ai-watermarks/docs/photo-classify.md
T
Victor Kuznetsov 5b52782f01 Move the receipt gate to the model side
The gate head is fitted on the freeze CLIP-L-ft embedding space, so it
belongs with the model: _load_receipt_gate now prefers
receipt-gate-2026-09-02.npz from the Hub snapshot or the
RAIW_CLASSIFY_WEIGHTS directory, with the package asset kept as the
fallback for weights frozen before the gate existed. Card mode of the
publish workflow now uploads the gate alongside the README and the
operating point, and the snapshot allow-pattern includes it.
2026-09-05 11:51:02 -07:00

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6.8 KiB
Markdown

# Photo pixel classification
`classify` gives a pixel opinion on a **photograph**: camera-like, generated,
or unknown, and optionally which renderer it resembles. It is a separate
command from `identify`. Metadata inspection never starts it.
This page is the library guide. The Hugging Face model card is the same freeze
written for Hub publication: [photo-classify-hf/README.md](photo-classify-hf/README.md).
Campaign notes and rejected variants live in
[AI-generated image classifiers](ai-generated-image-classifiers.md).
## When to use it
Use `identify` for C2PA, IPTC, visible marks, and other provenance. Use
`classify` when those signals are gone and the file is still a photograph.
Do not use `classify` to prove a file is clean. Do not use it on UI or
digital art. Receipt photographs are detected by the receipt-document gate
and abstain to `unknown` instead of a false `ai`; they are still not a
supported verdict. Do not treat `provider=openai` as a decoded SynthID
payload.
## Install and run
```bash
uv tool install --force "remove-ai-watermarks[classify]"
remove-ai-watermarks classify image.png
remove-ai-watermarks classify image.png --json
```
```python
from pathlib import Path
from remove_ai_watermarks.classify import classify_pixels
result = classify_pixels(Path("image.png"))
print(result.label, result.detector, result.provider)
```
Missing extra raises `RuntimeError` with
`pip install 'remove-ai-watermarks[classify]'`. `device` is a library
parameter (`None` / `"auto"` / `"cpu"` / `"cuda"`), not a CLI option.
Weights are not in git. First call downloads
[`wiltodelta/raiw-photo-classify`](https://huggingface.co/wiltodelta/raiw-photo-classify)
at the freeze revision pinned in `classify.py`, or reads
`RAIW_CLASSIFY_WEIGHTS` if that directory already has `clip-l-ft.pt`,
`probe-weights-clip-l-ft.npz`, `detector.pt`, and `provider.pt`. The training
catalog is not published with the package.
## What one call returns
One request runs both heads. The receipt gate and Model 2 run only after
Model 1 is DEFINITELY.
```mermaid
flowchart TD
image[Photograph] --> m1[Model 1 CLIP-L-ft ridge AND MLP]
m1 -->|likely_human| human["label human, provider none"]
m1 -->|possibly| unk["label unknown, provider none"]
m1 -->|definitely| rg[Receipt gate on the same CLIP vector]
rg -->|receipt document| rgu["label unknown, detector definitely, provider none"]
rg -->|not a receipt| m2[Model 2 124-d focal heads]
m2 -->|openai google muse-image tc260| named["label ai plus provider"]
m2 -->|no_ai or extract fail| aiOnly["label ai, provider none"]
```
| Field | Values | Meaning |
| --- | --- | --- |
| `label` | `ai`, `human`, `unknown` | Public verdict. `ai` only on DEFINITELY |
| `domain` | `photo` | This freeze is photographic only |
| `detector` | `definitely`, `possibly`, `likely_human` | Raw Model 1 gate |
| `provider` | `openai`, `google`, `muse-image`, `tc260`, or `None` | Model 2, only if `label` is `ai` |
`unknown` with `detector=definitely` is the receipt-document gate abstaining:
the file looked AI-generated to Model 1 and like a receipt photograph to the
gate, so no verdict is published and no provider is read.
`human` is camera-like under this contract, not a proof of authorship.
`unknown` is POSSIBLY, or a domain this freeze does not support. `provider=None`
on an `ai` file is often FLUX or another generator that is not one of the four
heads, or a 124-d extract refusal.
## Approach
CLIP-L content embeddings separate generated photographs from camera
photographs. They do not separate generated photographs from receipts or UI.
A ridge on fine-tuned CLIP-L (last two vision blocks, 224 letterbox) is Model
1. A small MLP on the same vectors, ANDed with the ridge, is the freeze
DEFINITELY gate.
Provider attribution uses a different feature: 124-d residual ratios on 256 px
patches. OpenAI versus Gemini is a strong split there. "AI or not" is the
wrong job on that bank, which is why Model 2 is gated.
Provider names the renderer, not the product UI. Bing Image Creator signed
Microsoft, OpenAI scores `openai`. Designer signed Microsoft, Google LLC
scores `google`. There is no Microsoft pixel class. `openai` and `google` are
provider classes. `muse-image` is Muse Image output, not a general Meta
class. `tc260` is the China AIGC label standard, not one producer: Doubao,
Jimeng, Qwen, Kling, and others share that residual class.
## Evaluation
Two CPU retrains were byte-identical. DEFINITELY is the shipped cut.
| Head | Cell | Result |
| --- | --- | ---: |
| Detector DEFINITELY | AI-test | 92.4% (n=1,847) |
| Detector DEFINITELY | Open Images fresh | 1.3% (n=3,000) |
| Detector DEFINITELY | Kodak | 0/24 |
| Detector DEFINITELY | FLUX hold | 83.0% (n=300) |
| Class | OpenAI | 90.8% (345/380 of 381) |
| Class | Google | 90.9% (339/373 of 377) |
| Class | TC260 | 78.6% (298/379 of 384) |
| Class | Muse Image hold-out v3 | 89.4% (177/198) |
| Class | Muse Image hold-out pooled | 88.4% (243/275 listed 277) |
| Class | meme templates, ungated | 29.1% leak |
The ungated meme row is why Model 2 never runs on `human` or `unknown`.
## Receipt-document gate
Added 2026-09-02. A linear head on the CLIP-L-ft vector Model 1 already
computes, trained on CORD-v2 train (800, CC BY 4.0) plus 200 synthetic
capture-style receipts against 2,400 ai_train negatives. The threshold is
certified on CORD validation plus a synthetic holdout; no field-receipt
pixels were used for training or the threshold. On DEFINITELY only: a hit
publishes `unknown` and skips the 124-d provider pass.
| Cell | Result |
| --- | ---: |
| Field phone receipts, false `ai` before | 19/59 -> **2/59** |
| Field phone receipts, gated to `unknown` | 57/59 |
| CORD photographs (99) | **0/99** false `ai` |
| ai_test DEFINITELY cost | 7/1,847 (0.38%) |
Artifacts: `receipt-gate-shipped-2026-09-02/report.json` (private research
tree). The head ships with the model (`receipt-gate-2026-09-02.npz` in the
Hub snapshot, package asset as the fallback for pre-gate freezes); the
operating point records it in
[photo-classify-hf/operating-point.json](photo-classify-hf/operating-point.json).
## Limits
- Receipts abstain through the 2026-09-02 gate (below); a photorealistic AI
receipt can still score as `human`. UI, scans, maps, and community art
remain out of contract.
- Not SynthID, not C2PA, not `is_ai_generated`.
- Images under 256 px cannot yield 124-d features, so provider abstains.
- FLUX is a hold-out at 83% DEF, not a named provider class.
- `tc260` is mixed producers under one label standard. A later retrain
should split it by manufacturer.
`identify`, `has_invisible_target`, `all`, and `invisible` do not import this
module. A no-signal provenance result stays unknown until you call `classify`
yourself.
Training data, the retrain pack (caches only, no images), and
`scripts/retrain_photo_classify.py` are in
[photo-classify-training.md](photo-classify-training.md).