Ever heard of steganography? I hadn't until this morning when I read this (https://vitux.com/how-to-hide-confidential-files-in-images-on-debian-using-steganography/) article, referred to by LXer. Steganography is an alternative to encryption. In it, confidential data is embedded in a camouflage file in a way that only the sender and recipient would know it exists. It involves making a cover file that hides what you want to hide. You can hide text, pictures, audio or video files. There is a GUI app called Stegosuite that makes it easy to set this up.
What I like about this approach is that it doesn't depend on a fancy password that you're likely to forget (I'm likely to forget), which is important with encryption. A steganographic file depends on disguise to hide its contents, not encryption, so you can use a simple password to open it. I'm sure that there are downsides to this, but it looks promising and I plan to try it for confidential files that I have been storing on Google Drive. (I didn't know until recently that Google Drive doesn't encrypt files.
I remember playing with this years ago, putting not entire files but messages in pictures and the like. I'm not sure how safe it is to use since it's depending on security by obscurity, which is not a very good security technique. It's like what people do when they put a spare key to their door under their welcome mat or in the flower pot.
If someone has reason to believe that your picture files have your data in them, then they should be able to find it, too. I also believe that for it to not be noticed you could only put information it that wouldn't make the file size of the image suspect. Although if it's a large image file like 1080 or 4K or a raw image file from a camera of most resolutions, then you could likely fit a fair amount of data inside it assuming it's not graphical itself. Hmm, burying a picture inside a picture, cool. The other way the data could be found is if you're using a particular software program to do this than someone could run a batch series of tests to discover the algorithm it uses, which will make it easier to find the information within the graphic.
I really should read the article before I comment, though. :)