# Benefiting from Duplicates of Compressed Data: Shift-Based Holographic Compression of Images

## TL;DR

This paper introduces a shift-based holographic compression method for images that creates multiple compressed representations, allowing high-quality reconstruction from any subset, thus improving storage efficiency and robustness.

## Contribution

It proposes a novel holographic compression technique exploiting shift sensitivity, with two implementations, enhancing image reconstruction quality over traditional duplication methods.

## Key findings

- Achieves several dBs PSNR improvement over exact data duplication.
- Demonstrates effectiveness of shift-based holographic representations with JPEG2000.
- Provides an optimization-free and a rate-distortion optimized implementation.

## Abstract

Storage systems often rely on multiple copies of the same compressed data, enabling recovery in case of binary data errors, of course, at the expense of a higher storage cost. In this paper we show that a wiser method of duplication entails great potential benefits for data types tolerating approximate representations, like images and videos. We propose a method to produce a set of distinct compressed representations for a given signal, such that any subset of them allows reconstruction of the signal at a quality depending only on the number of compressed representations utilized. Essentially, we implement the holographic representation idea, where all the representations are equally important in refining the reconstruction. Here we propose to exploit the shift sensitivity of common compression processes and generate holographic representations via compression of various shifts of the signal. Two implementations for the idea, based on standard compression methods, are presented: the first is a simple, optimization-free design. The second approach originates in a challenging rate-distortion optimization, mitigated by the alternating direction method of multipliers (ADMM), leading to a process of repeatedly applying standard compression techniques. Evaluation of the approach, in conjunction with the JPEG2000 image compression standard, shows the effectiveness of the optimization in providing compressed holographic representations that, by means of an elementary reconstruction process, enable impressive gains of several dBs in PSNR over exact duplications.