Unfortunately it works only on desktops and I don't want to know why!
Here you can try steganography to encrypt an image in another image.
I recommend not to use unusual aspect ratio.
After you got the image you'll be able to decipher it on this page.
You can encrypt even text. But the last one must be in the image format.
You can any photo or create something on your own or take this one I have created and provide you.
Upload the image that is the medium
Upload the image you want to hide