論文 / 著書情報
Article / Book Information
題目(和文)
Title(English)

A Practical One-Shot Multispectral Imaging System Using a Single
Image Sensor

著者(和文)

紋野雄介

Author(English)

Yusuke Monno

出典(和文)

学位:博士（工学）,学位授与機関:東京工業大学,
報告番号:甲第9624号,
授与年月日:2014年9月25日,
学位の種別:課程博士,
審査員:田中 正行,奥富 正敏,蜂屋弘之,大山真司,小酒Citation(English)

Degree:,Conferring organization: Tokyo Institute of Technology,
Report number:甲第9624号,
Conferred date:2014/9/25,
Degree Type:Course doctor,
Examiner:,,,,

学位種別(和文)

博士論文

Category(English)

Doctoral Thesis

種別(和文)

要約

Type(English)

OutlinePowered by T2R2 (Science Tokyo Research Repository)英範

A Practical One-Shot Multispectral Imaging System
Using a Single Image Sensor
byYusuke Monno

Dissertation

Submitted in Partial Fulfillment of the Requirements
for the Degree of Doctor of Engineeringin the Department of Mechanical and Control Engineering
Graduate School of Science and Engineering
Tokyo Institute of Technology
August 2014

Copyright © 2014 by Yusuke Monno. All Right Reserved.

Dissertation Outline

The energy of light emitted from a light source and reflected by an object continuously spansa wide range of wavelengths. A conventional color imaging system observes only three spectral bands, typically called RGB bands, among the continuous wavelengths. This is because
the conventional color imaging system imitates the human visual system. However, a considerable amount of potentially available spectral information is lost. In contrast, a multispectral
imaging system with more than three spectral bands can oﬀer reliable spectral informationthat is very useful for many computer vision and image processing applications including
digital archive, high-fidelity color reproduction, relighting, segmentation, and tracking. However, existing multispectral imaging systems still have limitations in terms of size, cost, andreal-time processing.
In contrast to existing multispectral imaging systems, single-sensor imaging with a color filter
array (CFA) and demosaicking is well-established for current compact and low-cost color
digital cameras. The extension from the CFA to a multispectral filter array (MSFA) enables
us to capture a multispectral image in one shot without increase in size and cost. However, theextension from the CFA to the MSFA is not straightforward and there are several challenges todo this including the design of the MSFA, the development of the multispectral demosaicking
algorithm, and the design of spectral sensitivity functions (SSFs) of the sensor.
In this dissertation, we address the above challenges and propose a practical one-shot multispectral imaging system using a single image sensor with a MSFA. The outline of the dissertation is as follows.
Chapter 1 Introduction. In this chapter, we explain motivations of this research with a brief
review of existing multispectral imaging systems and their problems.
Chapter 2, A One-Shot Multispectral Camera Prototype. In this chapter, we develop a pracii

tical one-shot multispectral camera prototype. We first propose a novel high-performance
demosaicking algorithm and a novel five-band MSFA pattern suitable for the proposed demosaicking algorithm at the same time. This joint design of the demosaicking algorithm
and the MSFA pattern significantly improves the quality of acquired multispectral images.
Then, based on the proposed demosaicking algorithm and five-band MSFA pattern, we develop a real one-shot multispectral camera prototype, which can capture a five-band full-HD
multispectral video at 30fps. To the best of our knowledge, it is first attempt to develop ahigh-quality one-shot multispectral camera prototype in a compact digital camera fashion.
Chapter 3, Toward a More Accurate System. In this chapter, we discuss some improvementsof the developed multispectral camera prototype toward a more accurate system. Specifically,
we discuss the following three aspects.
• Further improvements of the demosaicking algorithm. Although our proposed demosaicking algorithm in the chapter 1 can give a reasonably high performance, there is stillroom for improvements. Here, we improve the algorithm by proposing a novel residualinterpolation (RI) and incorporating the RI into the demosaicking algorithm.
• Study on an optimal number of spectral bands. Here, we discuss an optimal number ofspectral bands for our proposed one-shot multispectral imaging system. We first generalize our proposed MSFA and demosaicking algorithm to evaluate a diﬀerent numberof spectral bands. Then, we experimentally investigate the optimal number of spectral
bands in the scope of our proposed MSFA and demosaicking algorithm.
• Optimization of SSFs. Here, we discuss optimize SSFs for the proposed MSFA anddemosaicking algorithm. We first propose a simple optimization framework to findoptimal SSFs considering our proposed MSFA and demosaicking algorithm. Then, wefind the optimal SSFs in terms of the estimation accuracy of the spectral reflectance.

Chapter 4, Direct Spectral Reflectance Estimation. In this chapter, we propose a novel spectralreflectance estimation method. The acquired multispectral image by our proposed systemiii

can be used directly or transformed to some diﬀerent domains, representatively, the spectralreflectance, the sRGB, or the Adobe RGB domain. Although this depends on applications,one of the most important tasks in multispectral imaging is the accurate estimation of thespectral reflectance. In contrast to a typical approach, which estimates the spectral reflectanceafter demosaicking, our proposed method accurately estimates the spectral reflectance directlyfrom raw MSFA data acquired by our proposed one-shot multispectral imaging system.
For each chapter, we conduct experiments to demonstrate the advantages of our proposed system over existing one-shot multispectral imaging systems and a conventional color imagingsystem.
Chapter 5, Conclusion and Future Works. In this chapter, we conclude the dissertation andbriefly discuss future works.

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