"passphrase" ???s

[BDiana]

I understand that the 'passphrase' doesn't work with .jpg and .png formats.
I understand the idea behind
the feature itself.
My first question:
How is 'passphrase' supposed to execute? I tried it with a .GIF format and it scrambled the image itself and not just the image info (data), therefore rendering the image useless.

My 2nd question:
Is there somewhere a tutorial on 'passphrase' on how extactly to enter info in the given input fields on the INPUT and OUTPUT pages? Examples perhaps?
I couldn't find anything about it on Anthony's great instruction pages.
I am just curious on how this feature works and how we can use it with our original graphics.
Thanks for any help in advance.

[magick]

Scrambling an image works with most non-colormapped image formats-- including PNG and excluding GIF. The passphrase can be any set of characters, however, for reasonable security use 8 characters of more. For testing purposes, create a PNG image with the passphrase 'test' and read it back in on the Input tab with the same passphrase and you should recover the original image. If not, let us know.

[BDiana]

Thanks Magick for the clarifications. I'll test it with a .PNG.
Of course now I wonder why it
would work with a .png and not with a .jpg. Aren't the two formats somewhat related?
Are there any other formats supported with 'passphrase', besides .png?

[magick]

JPEG is a lossy format. Enciphering is supported for any ImageMagick format that is non-lossy. They are image formats that are not colormapped such as GIF and not lossy such as JPEG.