Understanding colour reproduction in multispectral imaging: measuring camera sensor response in the ultraviolet, visible and infrared

ABSTRACT

The representation of colour in digital images is based on the response of camera used to capture the image, and how light interacts with the sensor in the respective red, green and blue channels. In Ultraviolet and Infrared, we have no reference for how they should look as we cannot directly observe them. A novel approach for the analysis of how a commercial SLR camera captures colour as a function of wavelength in the UV, visible and IR regions is presented here, along with a discussion on how the optical properties of filtration and sensor construction, impact the images produced.

KEYWORDS:

• UV
• calibration
• photography
• validation
• forensics
• dermatology
• skin
• IR
• spectral response

Disclosure statement

No potential conflict of interest was reported by the author.

Notes on contributor

J.M. Crowther have worked for over 15 years in the cosmetics industry (including 2003-2012 for Procter and Gamble and more recently with GSK, and since 2012 as a consultant), in fields ranging from new product research with novel materials through to developing and running clinical studies to provide claims support data for product launches. Even in a corporate environment the author worked across multiple project areas at any one time to translate the needs of the individual teams into executable study designs and plans. Research areas worked on include moisturisers, cleansers, and hair removal methods (shaving, waxing, epilation, depilatory creams, light-based hair removal).

Photography has always been a passion of the author, and a focus area for his research is UV imaging, and how it can be used to visualize skin and sunscreens. UV imaging is extremely challenging, with a unique set of complexities, and my research often requires him to build equipment to help with his work where nothing suitable is commercially available.

The author have a very hands on approach to science and am experienced with the operation and use of a wide range of skin testing equipment including Corneometer, Sebumeter, TEWL, Colourimetry, Confocal In vivo Raman Spectroscopy (for hydration profiles and ingredient penetration), Photographic Imaging techniques, skin grading, tape stripping and SEM, and clinical test design.

After building his expertise in the skin methods field he also became more involved with teaching the science of skin measurement, to audiences from Dermatologists to Journalists and Marketing groups. The author also strongly linked with Academic research, having overseen a number of projects with different universities. The author have authored over 30 papers and book chapters, with an emphasis on skin measurement.

J. M. Crowther graduated from Durham University with a B.Sc. in Chemistry in 1994, and went on to do a Ph.D. in Surface Modification and Analysis which I completed in 1997, and loved the research so much that I stayed on for an extra 3 years as a Post Doctoral research assistant. During this time he developed a strong Analytical chemistry background with a wide variety of surface analytical techniques (XPS, Auger, ToF SIMS, Raman, ATR-IR, SEM and TEM, AFM) for materials analysis, along with cold plasma treatment of materials for the manufacture of metal surfaces and ultra low energy materials.

It is the cross discipline background he have from working at the boundaries between chemistry, physics and engineering, which he have now applied to my assessment of skin. The author apply a strongly analytical approach to his work, and known for being open and impartial and working with the highest integrity. The author is also a scientist through and through, and he is driven to question and understand how the world works.

ORCID

J.M. Crowther http://orcid.org/0000-0002-2549-396X