Remove EXIF From Your Images

What EXIF actually is

EXIF — Exchangeable Image File Format — is a specification for storing camera data inside an image file. Structurally it is a TIFF header embedded in the file: a byte-order marker, a pointer to a table of entries, and then directories of tags. Each tag has a numeric ID, a type and a value, and the IDs are standardised, which is why a photo from a Canon can be read by software that has never heard of that camera model.

There are several directories. IFD0 holds general image tags. The EXIF sub-IFD holds capture settings. The GPS IFD holds coordinates. IFD1 holds a thumbnail — a small copy of the image which, notoriously, is not always updated when the main image is edited.

The tags most worth removing

Not every EXIF tag is sensitive. Exposure time and aperture say nothing about you. These are the ones that do:

• GPSLatitude and GPSLongitude — the exact spot the photo was taken
• Make, Model and BodySerialNumber — the specific device, sometimes uniquely
• DateTimeOriginal and OffsetTime — when you were there, and in which time zone
• Artist, OwnerName and Copyright — a name, often your real one, set once in the camera and forgotten
• Software — which editor you use and its version
• The embedded thumbnail, which can show a pre-crop version of the image

Removing EXIF from a JPEG, precisely

In a JPEG, EXIF lives in an APP1 marker segment near the start of the file, introduced by the bytes FF E1 and identified by the ASCII string 'Exif'. Removing it means skipping that segment while copying the rest of the file. The scan data — the actual compressed picture — is never touched.

PNG files can also carry EXIF, in an eXIf chunk, and WebP in an EXIF chunk inside its RIFF container. All three are handled the same way: locate the block, omit it, keep everything else byte for byte.