Separate user accounts in OS X allow the system to sequester data, settings, and other details for individual users. To identify user account, there are of course the long and short usernames for it, but in addition OS X includes an account picture that while not functional is aesthetically useful at the login window, in Mail and chat messages, among other aspects of the system.
The generic account picture in OS X is a gray silhouette on a darker gray background, that can be seen by enabling the Guest user account in the system, but other accounts are randomly assigned one of the provided account icons. The account picture can be changed to a different built-in one, or even to a separate image altogether (including one taken by your iSight webcam) but if needed then you can also remove the picture entirely and force the account to use the generic icon, though this is not a default option in the system.
Recently MacFixIt reader Paul wrote in asking about the options for removing account pictures entirely to make all accounts on the system appear more standardized at the log-in window:
How would I modify the picture to nothing? For example, I'm using OS X 10.6.8 and have modified the pic to something other than default. I would lid to modify it to nothing. I don't see a "delete" or minus option.
When the account picture is set for a user, it is stored as a setting within the system's directory services. Changing the account picture will only update this setting, but you can manually remove the setting and thereby force the system to resort to the generic user account icon. To do this, open the Terminal and run the following command, substituting the text "USERNAME" with the short name of the user for which you would like to remove the picture:
sudo dscl . delete /Users/USERNAME jpegphoto
When you run this command, you will be required to supply your password; after that, the picture should be removed.
This approach does modify the directory services, which will not harm the account or the system at all if used as mentioned above, but some people might prefer to avoid such modification unless it is absolutely necessary. In these cases, an alternative to removing the picture is to assign a separate generic picture to the account. You can find numerous such pictures online, but there are also several in the system that you can use as well, which are available in the following directories:
- System > Library > PrivateFrameworks > LoginUIKit.framework > Versions > A > Frameworks > LoginUICore.framework > Versions > A > Resources > GuestUser.png
- System > Library > CoreServices > CoreTypes.bundle > Contents > Resources > GuestUserIcon.icns
Note that in the second path above, the "CoreTypes.bundle" is a bundled folder, which you can open by right-clicking and choosing "Show Package Contents."
With these images at hand, simply drag them to the account picture field in the Users & Groups system preferences, and you should be good to go.