Investigating the Impact of Hilbert Vibrational Decomposition on Chaos Based Image Encryption Algorithm

Image encryption is a crucial technique used to protect the confidentiality of digital images. Advanced encryption techniques are driven by sophisticated mathematical algorithms. In this work, the role of Hilbert vibrational decomposition (HVD) is highlighted for improving the security of existing chaotic map-based image encryption algorithm. The HVD breaks down the input image into its instantaneous amplitude and frequency components, ordered by descending energy levels. These components are then subjected to successive confusion-diffusion process before being reintegrated to produce the final encrypted image. The effect of HVD on security of encrypted image is evaluated through four key parameters i.e. entropy, correlation coefficient of adjacent pixels, NPCR (net pixel change ratio) and UACI (unified average change in intensity) values. The experiment suggests a significant improvement in security by incorporating HVD.