SINGLE-PIXEL IMAGING

NEW Sept 2019: Postdoctoral fellowship offer

We are looking for a motivated Postdoc Fellow who will develop the compressive imaging instrumentation for deep learning reconstruction. The position is funded by the French National Research Agency. Download offer details.

Overview

Single-pixel imaging is an emerging paradigm that allows high-quality images to be provided by a device that is only equipped with a single point detector. Such a device is referred to as a single-pixel camera. A common implementation of the single-pixel camera relies on the use of a digital micromirror device, which is a spatial light modulator (see Figure below).

Optical setup of the SPC

A single-pixel camera is an experimental set-up that can be used to measure the inner product of a scene under view - the image - with any user-defined pattern. Let $\mathbf{f} \in \mathbb{R}^{N^2 \times 1}$ be the $N \times N$ image of the object and $m_i$ be the measurement obtained loading the pattern $\mathbf{p}_i \in \mathbb{R}^{N^2\times 1}$ on the digital micromirror device. We have:

$m_i= \mathbf{f}^\top \mathbf{p}_i \quad$

Post-processing a sequence of measurements $\{m_i\}_{1 \le i \le I}$ obtained with different patterns $\{\mathbf{p}_i\}_{1 \le i \le I}$ allows the image $\mathbf{f}$ to be recovered. For an overview of all pattern choices and approaches to reconstruct $\mathbf{f}$, check the PhD dissertation of F. Rousset.

Adaptive time-resolved multispectral single-pixel camera

F. Rousset et al., 'Time-resolved multispectral imaging based on an adaptive single-pixel camera', Opt. Express, 26(8), 10550-10558, 2018.

We have demonstrated experimentally a time-resolved multispectral acquisition scheme based on single-pixel imaging. Here, we used an adaptive strategy that allows acquisition and image reconstruction times to be reduced drastically with respect to conventional single-pixel approaches that are based on compressed sensing or full basis scans.

Optical setup of the SPC

FIG: Fluorescence lifetimes recovered from time stack acquired in a phantom containing three fluorophores

Pattern generalization in single-pixel imaging

F. Rousset et al., 'A semi nonnegative matrix factorization technique for pattern generalization in single-pixel imaging', IEEE Trans. Comput. Imaging, 4(2), 284-294, 2018.

Real acquisitions require the spatial light modulator patterns to be positive while desired patterns typically have negative values. We have proposed to seek positive patterns that are linear combinations of the desired patterns with negative values. We refer to the problem of finding the positive patterns and the linear combinations as pattern generalization.

Optical setup of the SPC

FIG: Overview of the pattern generalization approach

Adaptive basis scan by wavelet prediction

F. Rousset et al., 'Adaptive basis scan by wavelet prediction for single-pixel imaging', IEEE Trans. Comput. Imaging, 3(1), 36-46, 2017.

We have proposed to choose patterns among a wavelet basis in an adaptive fashion and adopt a multiresolution strategy that exploits the set of measurements acquired at coarse scales to predict the set of measurements to be performed at a finer scales.

Optical setup of the SPC

FIG: Adaptive acquisition in a Daubechies wavelet basis at increasing resolutions (compression ratios: 256:1, 68:1, 18:1, 5:1, 2:1)