Sony, Nikon, and DNG Metadata Parsers

Sony, Nikon, and DNG Metadata Parsers

RawParserKit 1.3.0, revision d2175ed880d39021bdb5f5a2a842b460af0b316c, provides one neutral result shape for Sony ARW, Nikon NEF, and Adobe DNG autofocus metadata. RawCull enters through RawImageLoader.metadata(for:) or RawFormatRegistry; diagnostics and package tests may call a format parser directly.

Current Source Map

RawFormatRegistry.all registers SonyRawFormat for .arw, NikonRawFormat for .nef, and DNGRawFormat for .dng. Each conformer supplies focus-point parsing, thumbnail and embedded-preview extraction, compression labels, and RAW size thresholds.

Shared Focus Contract

All three parser paths return:

imageWidth imageHeight focusX focusY

RawFocusPoint validates four numbers, positive dimensions, and normalized coordinates in 0...1. The RawCull adapter converts that value to CGPoint for FileItem.afFocusNormalized while retaining the four-number compatibility string for the focus overlay.

flowchart LR
    Parser["ARW / NEF / DNG parser"] --> Format["RawFormat.focusLocation"]
    Format --> Meta["RawImageLoader metadata + RawFocusPoint"]
    Meta --> Adapter["RawParserKitImageLoader"]
    Adapter --> Item["FileItem.afFocusNormalized"]
    Adapter --> Overlay["FocusPointsModel and overlay"]
    Item --> Analysis["focus evidence and ranking"]

For example, "6000 4000 3000 2000" normalizes to (0.5, 0.5). A Nikon AFInfo2 value such as "8256 5504 2064 1376" normalizes to (0.25, 0.25). The examples describe the contract; package tests use synthetic TIFF/MakerNote structures rather than camera files.

Fallback Order

RawImageLoader.metadata(for:) asks the registered format for a focus location first. If none is produced, it reads kCGImagePropertyExifSubjectArea, treats the first two numbers as pixel X/Y, and normalizes them against image width and height. Invalid dimensions or out-of-range values produce no point.

RawCull then has a catalog-wide compatibility fallback: ScanFiles reads focuspoints.json only when the entire native-point collection is empty. If even one file has a native MakerNote or EXIF point, JSON is not merged into the partly populated result. JSON supplies overlay compatibility data; it does not retroactively populate every FileItem.afFocusNormalized.

Format-Specific Parsing

• Sony follows TIFF IFD0 to EXIF and the Sony MakerNote IFD, including FocusLocation 0x2027, and reports embedded JPEG candidates.
• Nikon validates the Type-3 MakerNote and reads supported AFInfo2 0x00B7 layouts. Unsupported layouts return nil.
• DNG walks TIFF IFD0 and SubIFDs. Standards-classified files use NewSubFileType plus Compression to distinguish thumbnails/previews from JPEG-compressed raw strips. Files without NewSubFileType retain a positional fallback. DNG compression labels include uncompressed, JPEG, Deflate, PackBits, Lossy DNG, and JPEG XL.

The DNG container is camera-neutral, so its size classes use generic megapixel thresholds with overrides for known high-resolution, full-frame, and smaller sensor camera families.

Tests At The Pinned Revision

Checklist For Another RAW Format

1. Add a stateless RawFormat conformer with extensions, display name, extraction, focus location, compression labels, and size thresholds.
2. Register it in RawFormatRegistry.all; keep app code on the registry and RawImageLoader facade.
3. Normalize autofocus output to "width height x y" and prove bounds, endianness, truncation, missing tags, and unsupported versions are safe.
4. Add synthetic parser, registry, metadata-fallback, preview, orientation, cancellation, and diagnostics tests.
5. Verify the RawCull adapter maps the result into the same visual coordinate system and preserves the catalog-wide JSON fallback rule.