Steganographic Method for Colour Image Using Expandable Progressive Exponential Clustering

In this work, we propose a steganographic scheme based on an expandable progressive exponential clustering (EPEC) algorithm for embedding secret message in colour images, which aims to achieve high embedding capacity while keeping distortion low. The EPEC algorithm partitions the colour table into clusters of size equal to a power of 2 so that embeddable pixels can be used efficiently. Our experiments also prove that by adding ´virtual´ colours in an informed manner to the colour table of images with significant low-frequency components can significantly increase the embedding capacity without inflicting distortion on the stego-images.