Faces, clothing, backgrounds, reflections, store names, station names, school names, belongings, notifications, date and time taken, location information. Things other than what the poster wants to show are also captured.
If you want to protect anonymity and privacy, always check photos before publishing them.
"I hid the face, so it is fine" is not enough. With photos, look at the whole frame and surrounding information.
Clues contained in photos
Photo clues are divided into things that are visible and things contained in the file.
Visible things include backgrounds, people, text, and reflections. Things contained in the file include metadata such as capture date and time, device model, and location information.
Type
Example
People
Faces, clothing, uniforms, name tags, companions
Places
Store names, station names, buildings, signs, outside the window
Reflections in mirrors, windows, metal, smartphone screens
Metadata
Capture date and time, device model, GPS information
When looking at a photo, look not at "the subject you want to show" but at "the information another person can read from it."
Faces and people
Faces are the strongest clues.
Check whether not only you, but also family, friends, passersby, store staff, or children appear. In group photos, the information of everyone shown is exposed, not only your own anonymity.
Check item
Reason
Your own face
Can be compared with real-name accounts or past photos
Family and children
Involves people around you
Friends and colleagues
Relationships and workplace become visible
Passersby
Becomes publication without the person's consent
Uniforms and name tags
School, workplace, and names become known
Even when hiding faces, rough paint-over or small stickers may be insufficient.
Pay attention to pre-edit image data, the same photo in other posts, and background information too.
When hiding faces, apply the same standard to people other than yourself.
Even if you hide only your own face, if the faces of friends, children, or colleagues remain, those people may be identified first. From there, your relationships and the places where you live or spend time may become visible again.
In group photos and event photos, you need to check each person one by one. The more people appear, the greater the risks of consent, identification, and reposting.
Backgrounds and reflections
The background of a photo shows the place.
Store names, signs, station names, apartment building names, school notices, scenery outside the window, license plates, shipping labels, and similar items become clues to everyday locations.
Reflections are also easy to miss.
Place
What is visible
Mirror
Photographer's face, room, clothing
Window
Outside buildings, roads, stations, weather
Smartphone screen
Notifications, account name, time
Metal or glass
Photographer or people nearby
Desk
Documents, mail, company name, school name
Before publishing, enlarge the photo and check it.
Small text or reflections may become readable if enlarged after posting.
Metadata
Photo files may contain metadata such as capture date and time, camera model, and location information.
Some social media services remove metadata at posting time, but this is not the same for every service or sharing method. With cloud sharing or file transfer, the original file's metadata may be handed over as-is.
Metadata
Risk
GPS information
Reveals the capture location
Capture date and time
Reveals activity time and daily rhythm
Device information
Becomes a clue to the device or capture environment
Editing software
Work environment or names may remain
Filename
Real name, date, or place may be included
Detailed checking and removal of metadata is covered in the image metadata article.
Here, remember that "photos handed over as files" tend to become more dangerous than social media posts.
Also, even if metadata is removed, the photo content remains.
Even if GPS information is removed, the place is known if a store name appears in the background. Even if capture date and time are removed, the period is known if the post text says "today's school sports day." Even if device information is removed, the filename or owner name in cloud sharing may remain.
Removed information
Remaining clue
GPS
Background signs, station names, store names
Capture date and time
Post text, events, weather
Device information
Filename, sharing account
Face
Clothing, companions, everyday locations
When checking photos, look at both metadata and appearance.
Raise the standard for photos of children and family
For photos that show children or family, it is important not to publish based only on your own judgment.
Children cannot judge future publication risks. Family and friends may not imagine how far the photo will spread.
Check item
Reason
Child's face
Becomes identifying information that remains into the future
Uniforms and school events
School and everyday locations become known
Inside the home
Address, living standard, and family structure become visible
Companions
Involves friends and relatives
Real-time posting
Reveals current location and absence from home
Family photos are memories, and at the same time they are information about the entire family. If you are thinking about anonymity and privacy, do not only narrow the publication scope; also keep the option of not publishing at all.
Combination with post text
Check not only the photo but also the post text together.
The store name is not visible in the photo, but the post text says "the shop in front of the station." The school name is hidden in the photo, but the body text mentions the grade and event name. These combinations reveal places and people.
Photo
Post text
What becomes known
Uniform
Story about an entrance ceremony
School or grade
Food photo
Talk about a store name or region
Activity range
Room photo
Talk about just after moving
Living environment
Event photo
Event date or participant names
Affiliation and relationships
Child photo
Age or lessons
Family structure and everyday locations
Do not look at the photo and text separately. Look at them as one public item.
Pre-publication check
Before publishing a photo, check in the following order.
Order
What to check
1
Whether faces, name tags, uniforms, or companions appear
2
Whether store names, station names, schools, workplaces, or addresses appear in the background
3
Whether information appears in reflections or screen notifications
4
Whether metadata or the filename contains a location or real name
5
Whether everyday locations can be inferred when combined with the post text
For photos you are unsure about, options include not publishing, cropping, blurring, waiting before posting, or using a different photo.
For photos that do not need to be published urgently, waiting is also effective. Photos during travel, events, school events on the day, or work show location and activity at that moment. Even posting later with less place and date information weakens the connection to your current location.
Summary
Check photos not only for faces, but also backgrounds, reflections, text, location information, and post text.
Look for whether faces or names of yourself, family, friends, or passersby appear; whether information close to a school, workplace, store, station, or address is visible; and whether metadata or filenames include a location or real name.
For photo checks that protect anonymity, it is important to look not at "what you want to show" but at "what will be read from it."
Photos that spread after publication cannot be fully taken back.
The few minutes before posting a photo are the most important.
Related tools
Reverse image search
Google Lens
An external resource related to this article. Open it only when it fits your situation and threat model.
Why it is listed: It can help with the article topic, but it is outside Anonymity Sense and should be checked before use.