Share secret informations with someone
You can share secret messages, credentials or any confidential data without generating suspicion about the content, for example you can share your secret message via email or other messaging/social platform hiding it behind your personal photo or your business logo (the important is that the image will not be processed by any editor).
Share secret informations with everyone
You could publicly hide secrets behind your website image gallery, or your business logo or some sharing content platform but only who know this and which is the secret image (and obviously your key) will be able to decrypt your secrets, but technically they will stay there "visible" to everyone.
Store sensible data for your personal use
You could create like "wallets" for to keep personal data secure, for example you could store your sensible informations like bank passwords, credit card pins, sensible website credentials, and keep it behind some photos in your phone gallery or pc folder containing other photos, it will be surely invisible to other eyes.