I encrypt an image using this code:
ImageEnView1.Proc.Encrypt(Edit1.Text, ieeaTEA2);
The Documentation says: "There is no way to know whether an image is encrypted unless you insert special tags"
UPDATE: Unfortunately, the XMP metadata fields don't seem to be editable in the TIEMetaListView control, although the XMP Specification https://archimedespalimpsest.net/Documents/External/XMP/XMPSpecificationPart3.pdf states about PNG files: "An XMP packet is embedded in a PNG graphic file by adding a chunk of type iTXt."
UPDATE2: Is there a reason why TIEMetaListView does not handle the file-type-specific meta-data? Example:
PNG_TextKeys, PNG_TextValues, etc.
GIF_Comments, etc.
etc.
UPDATE3: I have now started to tag the image when encrypting it with this code:
ImageEnView1.IO.Params.PNG_TextKeys.Add('IEEncryption');
ImageEnView1.IO.Params.PNG_TextValues.Add('True');
In this way, when I reload the encrypted PNG file, I can automatically show the Encryption/Decryption Panel to allow the user to decrypt the image.