EXIF scrubbing can be enabled via the `ScrubExif` config key. When
enabled, all standard EXIF tags (as defined by the IFD mappings in the
go-exif library) are removed on uploaded JPEG and PNG images.
The `ExifAllowedIds` and `ExifAllowedPaths` config keys can be used to
selectively allow specific tags to survive the scrubbing. This can be
useful if you want to preserve image orientation information for
example. The IDs for standard tags can be found in [1].
The path specification for `ExifAllowedPaths` relies on the format
implemented in go-exif which is "documented" in machine-readable format
in [2]. Multiple paths can be specified, separated by a space. The
path format is as follows:
1. For tags in the main section: `IFD/<GroupName>/<FieldName>`.
Examples: `IFD/Orientation`, `IFD/Exif/Flash`,
`IFD/GPSInfo/GPSTimeStamp`. You will probably want to use both
[1] and [2] in combination if you plan to specify allowed tags by
path.
2. Tags in the thumbnail section follow the same format but paths
start with `IFD1/` instead of `IFD`.
[1]: https://exiv2.org/tags.html
[2]: a6301f85c8/assets/tags.yaml
