关键词: 可逆视觉变换, 图像加密, JPEG 图像, DCT 变换, 隐私保护 

Abstract:  Image reversible visual transformation is an emerging image processing technique that can exactly recover the original image from the visually transformed image． It can be used in the applications of secret image encryption and transmission． A new image reversible visual transformation algorithm is proposed for JPEG images with low complexity． Since JPEG format is one of the most used image types in the daily usages， study of data hiding and reversible visual transformation of JPEG images is important and attracts much attention from the community． The proposed algorithm replaces the last four DCT coefficients to embed the transform information． Consequently， the original image can be restored without any distortion by extracting the hidden data． The experimental results show that the proposed algorithm can change the secret image content while achieving reversible image visual transformation． That means the original JPEG image can be exactly recovered from the corresponding visually transformed one． 

Key words: reversible visual transformation, image encryption, JPEG image, DCT transform, privacy protection