Energy balance in Spectral Filter Array camera design

Pierre-Jean Lapray,Pierre Gouton,Jean-Baptiste Thomas,Yassine Ruichek

doi:10.1186/s41476-016-0031-7

Abstract

BackgroundMultispectral imaging permits to capture more spectral information on object surface properties than color imaging. This is useful for machine vision applications. Transmittance spectral filter arrays combined with a solid state sensor form an emerging technology used for snapshot acquisition. In spectral filter arrays technology, the sensitivities of the camera have critical consequences, not only on applications, but also in the viability of the system. We discuss how to balance the energy of each channel in single exposure multispectral imaging.MethodsWe propose a methodology to design filters that permits to reach an optimal balance of energy. We apply this method on practical illuminations combined with a Gaussian model of transmittance filters.Results and discussionOur results demonstrate that we can optimize energetically the global camera response with few efforts for several cases of illumination environments, for a given sensor and a number of spectral channels. This methodology can be embedded in an application-oriented optimization framework.ConclusionsThis methodology enables achieving a great range of optical design, and it can be embedded in an application-oriented optimization framework.

Highlights

Multispectral imaging permits to capture more spectral information on object surface properties than color imaging
This methodology enables achieving a great range of optical design, and it can be embedded in an application-oriented optimization framework
We propose to base on these previous works and to develop a methodology that provides the best filter bank for a single-shot spectral filter arrays (SFA) camera, while considering energy balance

Summary

Introduction

Multispectral imaging permits to capture more spectral information on object surface properties than color imaging. The generalization of color filter arrays (CFA) into spectral filter arrays (SFA) [3] permits the use of a single sensor and a single exposure to record a multispectral image. This solution can be encapsulated into a compact and affordable MSI solution, easy to handle, which complies with a typical camera pipeline. Each spatial position of the array captures only one spectral channel to the Bayer filters [4], and the filter transmission characteristics determine the sensor spectral properties.

Methods

Results

Discussion

Conclusion