# Historical matting export inspection — September 7, 2026

This is a file-format and transparency inspection of existing site artifacts.
It did not run a matting model, alter any image, reconstruct a mask, or verify
the deferred interactive tool. The original generation date and settings are
not known from these retained files. September 7 is the inspection date.

## Repeat

Download these exact public files into one directory, retaining their names:

- [matting-before.png](https://ai-creator.top/home/matting-before.png)
- [matting-after.png](https://ai-creator.top/home/matting-after.png)
- [bg-after.png](https://ai-creator.top/home/bg-after.png)
- [inspect-image-export.py](https://ai-creator.top/resources/evidence/2026-09-07/matting-export-review/inspect-image-export.py)

Run with Python 3; no third-party package is required:

```sh
python3 inspect-image-export.py matting-before.png matting-after.png bg-after.png
```

Compare the resulting object with `inspection.json`, including the full file
SHA-256 values. The order of the three arguments controls the result order.
The script writes JSON to stdout and never changes the images.

On macOS, this independent check was also run against each original file:

```sh
sips -g format -g pixelWidth -g pixelHeight -g hasAlpha matting-before.png matting-after.png bg-after.png
```

`sips-cross-check.txt` retains that command's output with the local directory
replaced by the public `/home/` path. No pixel data or property values were
changed in that transcript. `manifest.json` identifies all evidence files and
original image bytes by SHA-256.

## Observed result

The two names ending in `.png` are baseline JPEG/JFIF files, identified by the
signature, JFIF APP0 segment and SOF0 frame header. They have three components,
8-bit precision and no alpha channel. Dimensions are 512 × 768 for the source
and 681 × 1010 for the result. The result's blue field is already flattened
into the image. The misleading filenames are retained so existing links and
the historical bytes remain inspectable; renaming is not a transparency fix.

The background-removal reference is a separate portrait and a real PNG. It is
indexed color type 3 with a tRNS table. All chunk CRCs passed. Decoding palette
indices through that table yields 212,250 fully transparent, 108,442 partially
transparent and 331,596 opaque pixels, totaling 652,288 = 637 × 1024.
It checks the inspector against an existing transparent asset; it is not a
controlled two-model comparison or a new run of the matting portrait.

## Method limits

The inspector supports only the formats relevant to this record: baseline
three-component 8-bit JFIF headers, and non-interlaced 8-bit PNG color types
2, 3 and 6. Unsupported inputs fail explicitly. A failure on another valid
format must not be interpreted as proof that the image lacks transparency.

JPEG pixels are not decoded; the absence of alpha follows from the inspected
baseline JFIF representation. For PNG, the script validates chunk CRCs,
decompresses scanlines, reverses row filters, applies palette transparency and
counts decoded alpha values. It is a bounded evidence utility, not a full
conformance, security, color-management or perceptual-quality validator.

The alpha values say nothing about whether the desired subject was selected
correctly. No ground-truth mask, exact generation settings or original model
run is available here. The two matting dimensions also differ, preventing a
pixel-aligned quality score. The retained historical output remains a preview
with visible boundary defects, not a reusable transparent master.

The official PNG reference used for interpreting indexed transparency is
[PNG Third Edition, tRNS](https://www.w3.org/TR/png-3/#11tRNS).