You may have noticed that some of the TF2 and CS:GO screenshots uploaded to Steam Community have a link to the profile of the person depicted. When someone publishes such a screenshot with you, you’ll see it in your friend activity feed even if you don’t have the author in your friends list. It’ll say something like ‘such and such uploaded a screenshot of Team Fortress 2 with you in it.’

The game creates a link when you take a picture while looking directly at another player. But sometimes, it doesn’t work quite right. The tag might not get created; the player standing behind the person in the foreground might get tagged instead. You may be taking a wide scenic shot or trying to capture a group of players, but then some random person might get tagged even though the picture isn’t really about them.

Anyway, there is a way to add these tags to screenshots from any game. You can also edit them, tag multiple people in one picture and add links to workshop submissions. Here’s how it’s done:

You’ll have to do all the editing before you upload the screenshot. It is possible to delete an old screenshot and reupload it with new metadata, but you’ll lose all the likes and views.

1. Take a picture.
   
2. Open Screenshot Uploader (View → Screenshots).
   
3. Find a screenshot you want to tag and click ‘Show on Disk’. If you have a ton of screenshots in this folder, it may be faster to double click the screenshot in the uploader and open it in your default image viewer.
   
4. Copy the file name to clipboard. It should be something like ‘2014-12-06_00037’.
   
5. Go to \Steam\userdata\***\760. *** stands for the user folder. If you’re the only person using Steam on this computer, there will be a single folder inside userdata.
   
6. Open screenshots.vdf in a plain text editor (Notepad will do, but it doesn’t display line breaks properly, so I’d get something like Notepad++).
   
7. Press Ctrl+F (Find) and insert the filename you got in step 4.
   
8. You'll find a code block that looks like this:
   
   
   "2" { "filename" "1280/screenshots/2014-12-06_00037.jpg" "thumbnail" "1280/screenshots/thumbnails/2014-12-06_00037.jpg" "imported" "1" "width" "2560" "height" "1440" "gameid" "1280" "creation" "1417816510" "caption" "" "permissions" "8" "hscreenshot" "541886257828364690" }
   
   Add this bit after "imported" "1":
   
   
   "location" "MAP NAME" "taggedusers" { "0" "STEAMID" }
   
   
9. Replace "MAP NAME" with the name of the map. This won't create a link, so you can spell it in any way you want.
   
   
10. Replace "STEAMID" with the steamID64 of the person you want to tag. For example, my steamID is "76561197992892379". Where to get it? Just go to his or her profile. You’ll see it in the address bar as a part of the URL: http://gtm.steamproxy.vip/profiles/76561197992892379. If you’re using the built-in Steam Browser and don’t have the address bar enabled, you can enable it (Steam → Settings → Interface → Display Steam URL address bar when available). Alternatively, you can right click on the page and select ‘Copy page URL’.
    
    Some people like to use custom URLs, so if you actually go to my profile, the URL will look like this: http://gtm.steamproxy.vip/id/savv/ In this case you can go to http://www.steamrep.com and paste the url there to convert it to standard steamID64: http://steamrep.com/search?q=http%3A%2F%2Fgtm.steamproxy.vip%2Fid%2Fsavv%2F If you’re using Chrome or Firefox, try this handy extension: http://www.enhancedsteam.com/ It will add steamID64s to every profile page on Steam.
    
    It is possible to tag multiple people, just duplicate that line and replace "0" with "1", "2", "3" etc for each additional steamID.
    
    The end result should look like this:
    
    "2" { "filename" "1280/screenshots/2014-12-06_00037.jpg" "thumbnail" "1280/screenshots/thumbnails/2014-12-06_00037.jpg" "imported" "1" "location" "Konigsplatz" "taggedusers" { "0" "76561198023672325" "1" "76561198067290797" } "width" "2560" "height" "1440" "gameid" "1280" "creation" "1417816510" "caption" "" "permissions" "8" "hscreenshot" "541886257828364690" }
    
    
11. If you’re using any custom models, skins or maps from Steam Workshop, you can list these by adding this bit before "width":
    
    
    "taggedpublishedfiles" { "0" "000000000" "1" "000000000" "2" "000000000" }
    
    Replace the zeroes with numbers you can get from URLs of workshop submissions. You can probably skip this step for Left 4 Dead 2, as the game does a decent job of creating these links automatically.
    
    
12. Save the file.
    
13. Restart Steam.
    
14. Go to Screenshot Uploader again and upload the screenshot.
    
    That's it, enjoy.

Here’s the screenshot I used as an example:
http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=351751418

And a couple of screenshots from other games, why not:
http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=146902956
http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=198602035