See and remove image metadata

How it works

A photograph from a phone is two things in one file. There is the compressed picture, and in front of it a short stack of labelled blocks that no viewer draws on screen. Those blocks name the camera body and its serial number, the lens, the exposure, the second the shutter opened, very often the place, and sometimes the registered owner. Every program that touches the file afterwards may add to them, so an image that has been through a phone, an editing app and a messaging client can carry three overlapping accounts of where it came from.

Three standards in one file

The blocks are not one system. Exif is a TIFF directory, standardised by CIPA as DC-008 and by JEITA as CP-3451, and it is what cameras write. IPTC's Information Interchange Model came out of newspaper wire services and lives inside a Photoshop resource block in a JPEG's APP13 segment; it carries captions, credit lines and keywords rather than exposure settings. XMP is Adobe's RDF/XML packet, standardised as ISO 16684-1, and it holds anything either of the others holds plus editing history.

All three can be present at once and they are free to disagree. A caption edited in one application is written to XMP and to the legacy IPTC record; an application that reads only the older record shows the older text indefinitely. The consequence for anyone cleaning a file is direct: deleting the Exif block leaves the IPTC credit line and the XMP packet exactly where they were, and a photographer's name survives a removal that looked complete. This tool takes out all three, and reports each one separately so the accounting is visible.

Where the location actually sits

Coordinates live in their own directory, reached from a pointer at tag 0x8825 in the main Exif directory. GPSLatitude is tag 0x0002 and holds three RATIONALs — degrees, minutes and seconds, each stored as a pair of unsigned 32-bit integers. Because the type is unsigned, the value cannot express a hemisphere. That is a separate tag: GPSLatitudeRef at 0x0001, a single ASCII character, N or S. Longitude repeats the arrangement at 0x0004 and 0x0003 with E or W.

A reader that decodes the rationals and ignores the reference letters therefore places every photograph in the northern and eastern hemispheres, which is a class of bug that puts Buenos Aires in China. The conversion here is degrees plus minutes over sixty plus seconds over three thousand six hundred, negated for S and for W. Phones commonly write the seconds component with a large denominator, so the answer is good to a few metres. That resolution identifies a doorway rather than a neighbourhood.

The tag that breaks the picture

Orientation is tag 0x0112, an integer from 1 to 8. A phone's sensor is bolted to the body and cannot turn, so tilting the handset turns the scene relative to the sensor. Rather than rotating several megabytes of pixel data, the camera stores the picture the way the sensor saw it and writes down which way up it should be shown. Value 6, the most common one after upright, means turn it a quarter turn clockwise for display.

Remove that tag and the pixels are untouched and every viewer shows them exactly as stored, which is on their side. Nothing is corrupted and nothing can be recovered from the file, because the only record of the rotation was the tag. This is the origin of the reputation metadata removers have for turning portraits sideways. The default here keeps a 36-byte Exif segment containing that one tag and nothing else, so the picture stays upright while the camera, the timestamp and the coordinates go. Turning that off is offered, with the consequence stated on the control.

Rebuilt rather than re-encoded

Removal is a container edit. In a JPEG the segments before the start-of-scan marker are filtered and everything from that marker to the final byte is copied across unchanged, so the entropy-coded data is identical and the decoded picture is identical. In a PNG the IDAT chunks are copied whole. The usual alternative is to decode the image and encode it again, which strips metadata as a side effect and costs a generation of quality on any lossy format for a job that never needed to look at a pixel.

Three things are kept on purpose because dropping them changes what you see. An ICC profile describes the colour space the numbers are in; delete it from a Display P3 photograph and browsers fall back to sRGB, and saturated colours shift. A JPEG's APP14 Adobe marker declares whether the scan is YCbCr, RGB or YCCK, and a decoder guessing wrong inverts a CMYK image. An APP2 Multi-Picture index addresses a second image appended after the first, as recent iPhones do for gain maps; its offsets are relative, so removals ahead of it are safe and any removal behind it is declined instead.

Who reads it, and who removes it

Handling differs sharply by destination, so the useful question is not whether metadata is dangerous but where a given file is going. X removes it: photographs posted through the site or the official apps are recompressed on upload, and an image downloaded back from a post carries no Exif and no coordinates. Flickr does the opposite by design. It stores the block, shows it under the photo, and offers an account setting that hides the display, which Flickr's own help pages describe as hiding it from other members while the data stays in the file the service holds.

Neither behaviour protects you from the service itself, which received the original. That is the argument for removing the data before the upload rather than relying on the recipient, and it is the argument for a remover that runs in the page rather than on somebody's server. Beyond social platforms, the readers are ordinary: file managers show capture dates, desktop search indexes camera models, and a shared drive at work exposes every one of these fields to anyone who can list the folder.

The order that works is to look first and decide second. A screenshot has nothing in it and needs no treatment; a photograph off a phone usually has a full directory and a coordinate. Both answers are visible before anything is downloaded.