# Bifrequency 3D Ghost Imaging with Haar Wavelet Transform

## TL;DR

This paper introduces a novel ghost imaging method using Haar wavelets and bi-frequency illumination that achieves high contrast, high SNR, and reduced sampling rates, enabling high-resolution 3D imaging with fewer measurements.

## Contribution

It presents a new ghost imaging scheme combining Haar wavelet patterns and bi-frequency projection, significantly improving contrast, SNR, and reducing sampling requirements for high-resolution 3D imaging.

## Key findings

- Achieved 512x512 resolution with less than 5% sampling rate.
- The method provides 100% image contrast and high detection SNR.
- Successfully reconstructed high-resolution 3D images from multi-angle data.

## Abstract

Recently, ghost imaging has been attracting attentions because its mechanism would lead to many applications inaccessible to conventional imaging methods. However, it is challenging for high contrast and high resolution imaging, due to its low signal-to-noise ratio (SNR) and the demand of high sampling rate in detection. To circumvent these challenges, we here propose a ghost imaging scheme that exploits Haar wavelets as illuminating patterns with a bi-frequency light projecting system and frequency-selecting single-pixel detectors. This method provides a theoretically 100% image contrast and high detection SNR, which reduces the requirement of high dynamic range of detectors, enabling high resolution ghost imaging. Moreover, it can highly reduce the sampling rate (far below Nyquist limit) for a sparse object by adaptively abandoning unnecessary patterns during the measurement. These characteristics are experimentally verified with a resolution of 512 times 512 and a sampling rate lower than 5%. A high-resolution (1000 times 1000 times 1000) 3D reconstruction of an object is also achieved from multi-angle images.