AES encryption for images Why AES based encryption is not recommended for encrypting images with high redundancy in their content? for example, the encryption of an image which shows a bird in the blue sky. Most of the pixels are blue in that case.
What do you mean "AES is not recommended for highly-redundant images"?

Perhaps you're referring to "ECB mode is not recommended for highly-redundant images" (and yes, AES can be used for ECB mode).

Yes, AES in ECB mode is not recommended for highly-redundant images, because it doesn't disguise when two 128 bit plaintext blocks are exactly the same.  Here is a famous example of a drawing of the Linux penguin encrypted using ECB mode:



As you can see, you can make out significant details of the original image.

AES in other modes (CBC, CFB, Ctr, GCM) doesn't have this weakness, and so are strongly preferred.