Abstract
This study investigates an essential secret image sharing scheme, which entails encoding a confidential image into two distinct sets of shadows referred to as essential shadows and non-essential shadows. This dual-shadow strategy is designed to fault-tolerantly and differentially preserve the confidentiality of the secret image. However, the inherent limitations of the essential secret image sharing mechanism become apparent when the number of shadows falls below the specified threshold, making the recovery of the secret image based solely on essential shadows unattainable. The reliance on non-essential shadows in such instances presents a dilemma for users. In response to this challenge, the present paper introduces a novel threshold preview-able essential secret image sharing method. In this approach, upon receiving a sufficient number of essential shadows, a preview of the distorted version of the secret image becomes possible. The proposed mechanism extends its applicability to two primary variations of threshold preview-able essential secret image sharing: (t, s, k, n)- and (t, k, n)-threshold preview-able essential secret image sharing. This research contributes to the advancement of secure and fault-tolerant secret image sharing techniques, alleviating the challenges associated with an insufficient number of essential shadows for image recovery.