Design an AI system that can generate unique and personalized digital portraits based on user input. The AI should be able to analyze facial features, styles, and preferences provided by the user to create one-of-a-kind digital artworks. These artworks should be generated in high-resolution and be suitable for printing and display purposes. The final output should be in the form of NFTs, ensuring each artwork is tokenized and can be traded on blockchain platforms. Additionally, the AI system should have the capability to authenticate and verify the ownership of the NFTs to ensure the integrity