EXIF Internals
Also known as: exif structure, exif tags layout, how exif is stored, exif internals
EXIF is metadata embedded inside JPEG and HEIF photos using a TIFF-style structure of IFDs and tags. It records camera settings, timestamps, and often GPS coordinates, adding bloat and personally identifying information to every shot.
- EXIF uses a TIFF-style layout of IFDs and tags, stored in the JPEG APP1 segment or a HEIF metadata box.
- A separate GPS IFD can record exact capture coordinates, making photos personally identifying.
- iOS can strip location via the share sheet's Options > Location toggle before sharing.
How EXIF is structured
EXIF (Exchangeable Image File Format) data lives inside the image file itself. In a JPEG it sits in the APP1 marker segment near the start; in HEIF/HEIC it is carried in a metadata item box. The payload uses a TIFF-based layout of IFDs (Image File Directories).
Each IFD is a table of tags, where every entry has a tag ID, a data type, a count, and a value or an offset to the value. The 0th IFD holds basic image fields, a dedicated Exif IFD holds camera settings (exposure, ISO, lens, DateTimeOriginal), and a GPS IFD holds latitude, longitude, and altitude when location is enabled. A byte-order marker (II or MM) sets endianness for the whole block.
Why it matters for storage and privacy
EXIF adds overhead to every photo, and embedded camera thumbnails or duplicated maker-note blocks can inflate that further across thousands of images. More importantly, the GPS IFD can pin exactly where a photo was taken, making it PII that travels with the file when you share it.
On iOS, Settings > Privacy & Security > Location Services > Camera controls whether GPS is written, and the share sheet offers Options > Location > Off to strip it on export. On Android, the camera app's location toggle does the same. Stripping or rewriting EXIF reduces file size slightly and removes identifying metadata before sharing.