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- You can store a text to be hidden within a normal PNG, JPG or GIF image file. The output image (always PNG) created would work just as normal, but you’d have the secret text within it.
Don't do this, especially if you plan to keep the image online. This could work 10 years ago, but not today. Now you have plenty of auto image scanners with the ability to detect these 'hidden' messages.
Just use a hardware wallet...