Recovery and representation of spectral bidirectional reflectance distribution function from an image‐based measurement system

Kim, Duck Bong; Jang, In Yeop; Choi, Han Kyun; Lee, Kwan H.

doi:10.1002/col.21973

Cited by 5 publications

(5 citation statements)

References 40 publications

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“…The materials' colors must not be defined based on digital color models but based on the bidirectional reflectance distribution function (BRDF). 25 The BRDF can be measured with different methods, 26,27 also considering the spectral component, 28 approximated with analytical models based on the parameters of the material, 29,30 or more simply retrieved from online databases. [31][32][33][34][35][36][37] The calculations of direct and indirect lighting must be physically correct.…”

Section: Discussionmentioning

confidence: 99%

A design‐oriented approach for managing colored light sources in lighting design software

Rossi

2022

Color Research & Application

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In the last decade, the extensive introduction of LED lighting sources has brought elements of innovation to interior lighting design in terms of color. Besides the new tunable white LED source, lighting is no longer exclusively white; indeed, colored lighting has entered the design practice thanks to the positive effects on people's health and mood. Unfortunately, this element of lighting innovation, color, cannot be computed correctly in commercial lighting design software. These computations are based on the assumption that light is only white or defined in terms of RGB triplets in the relative digital color space of computer graphics, which does not have a physically correct relationship with the actual spectral power distribution (SPD) of luminaires. In this paper, attention is focused on a practical design-oriented approach for describing luminaires in lighting design software that also considers the real SPD and the luminous intensity distribution.The focus is on information available to lighting designers who do not have a laboratory to measure light sources and luminaires. This information could be available in online datasheets or as a Cartesian graph from luminaires and light sources manufacturers. Following this approach, a set of functions is proposed that can be easily implemented in lighting design software to improve light sources' color management and allow lighting designers to add SPD data to luminaires.

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Section: Discussionmentioning

confidence: 99%

A design‐oriented approach for managing colored light sources in lighting design software

Rossi

2022

Color Research & Application

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“…Surface spectral reflectance is useful for the color reproduction of industrial products and artwork [1][2][3]. It can be measured directly with an imaging spectrometer [4,5].…”

Section: Introductionmentioning

confidence: 99%

Auxiliary Reference Samples for Extrapolating Spectral Reflectance from Camera RGB Signals

Wen

Hsu

et al. 2022

Sensors

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Surface spectral reflectance is useful for color reproduction. In this study, the reconstruction of spectral reflectance using a conventional camera was investigated. The spectrum reconstruction error could be reduced by interpolating camera RGB signals, in contrast to methods based on basis spectra, such as principal component analysis (PCA). The disadvantage of the interpolation method is that it cannot interpolate samples outside the convex hull of reference samples in the RGB signal space. An interpolation method utilizing auxiliary reference samples (ARSs) to extrapolate the outside samples is proposed in this paper. The ARSs were created using reference samples and color filters. The convex hull of the reference samples and ARSs was expanded to enclose outside samples for extrapolation. A commercially available camera was taken as an example. The results show that with the proposed method, the extrapolation error was smaller than that of the computationally time-consuming weighted PCA method. A low cost and fast detection speed for spectral reflectance recovery can be achieved using a conventional camera.

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“…In recent years, the demand to recover spectral reflectance is increasing due to more precise and accurate color representation. Many related industries will obtain large benefits from several applications, including the color reproduction of traditional printing, color management in publishing, digital archiving of artworks, and digital compositing in the film industry . Although the spectral data provide more useful information on color properties than trichromatic representation, it is difficult to measure in usual cases because of the high cost of instruments, the geometrical limitation in a scene, and the special materials needed .…”

Section: Introductionmentioning

confidence: 99%

“…Many related industries will obtain large benefits from several applications, including the color reproduction of traditional printing, color management in publishing, digital archiving of artworks, and digital compositing in the film industry. 1,2 Although the spectral data provide more useful information on color properties than trichromatic representation, it is difficult to measure in usual cases because of the high cost of instruments, the geometrical limitation in a scene, and the special materials needed. 3,4 The recovery of surface spectra using a conventional trichromatic camera therefore becomes a relatively realistic approach in many application fields.…”

Section: Introductionmentioning

confidence: 99%

Recovering spectral reflectance based on natural neighbor interpolation with model‐based metameric spectra of extreme points

Chou

Hsieh

Chen

2019

Color Research & Application

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In this article, we proposed a new method based on natural neighbor interpolation to recover the spectral reflectance of objects from an image captured by a traditional Red‐Green‐Blue (RGB) digital camera. The concept of model‐based metameric spectra of eight extreme points in the standard RGB (sRGB) color gamut was further introduced to ensure that almost all test samples in the entire gamut can be simply and properly recovered without needing the extrapolation or any other auxiliary techniques. The quasi‐Newton method was used to estimate iteratively the optimal parameters of these metameric spectra, satisfying the constraints of the gamut extreme points. Several experiments were performed. The effectiveness of the method with and without the metameric spectra was evaluated, including some performance comparisons with the principal component analysis (PCA) method of transformational type (classic PCA and weighted PCA) and that of interpolation type. The results showed that the proposed method greatly enlarged the accurately applicable domain of the interpolation strategy and offered spectra with feasibility and naturalness much superior to the PCA‐based methods. The proposed method was obviously better than the conventional interpolation ones, and had a similar performance with the weighted PCA method in terms of color difference.

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Recovery and representation of spectral bidirectional reflectance distribution function from an image‐based measurement system

Cited by 5 publications

References 40 publications

A design‐oriented approach for managing colored light sources in lighting design software

A design‐oriented approach for managing colored light sources in lighting design software

Auxiliary Reference Samples for Extrapolating Spectral Reflectance from Camera RGB Signals

Recovering spectral reflectance based on natural neighbor interpolation with model‐based metameric spectra of extreme points

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