For this purpose Koya University approve only a passport type professional picture only. This to allow all colleagues to recognise your when they email you. This policy support our standard professional communication with outside the university as well. This needed to show up whenever another user rolls over your name in their inbox, Contacts, Chat list, or when someone looks at your public Google Profile.
Once you apply your picture, you'll be able to view and change it from your Gmail settings page, and other users will see your selection when they roll over your name in conversations or in their contact lists. It will also show up as your picture in chat (Google Chat or Hangouts). Likewise, picture selections made in chat will be reflected in your Gmail interface, though there might be a slight delay for the change to take effect.The image of you
Your photos must show a close-up of your full head and shoulders. It must be only of you with no other objects or people.
The image of you - from the crown of your head to your chin - must be between 29mm and 34mm high (see example below).
Your photos may be rejected unless they show you
See more at: https://support.google.com/mail/answer/35529?hl=en