Complete quality preserving data hiding in animated GIF with reversibility and scalable capacity functionalities

A technique is put forward to hide data into an animated GIF by exploiting the transparent pixels. Specifically, a new frame is crafted based on the data to be embedded. The newly crafted frame is inserted between 2 existing frames, and the delay time of the affected frames are adjusted accordingly to achieve complete imperceptibility. To the best of our knowledge, this is the first attempt to hide data into an animated GIF by exploiting the transparent pixel. Irregardless of the characteristics of the animated GIF image, the proposed method can completely preserve the quality of the image before and after hiding data. The hiding capacity achieved by the proposed method is scalable, where more information can be embedded by introducing more frames into the animated GIF. While file size expansion is inevitable, reverse zero run length is adopted to suppress the expansion. The proposed method is reversible, i.e., the original image can be recovered.