Estimation of bispectral Donaldson matrices of fluorescent objects by using two illuminant projections

Tominaga, Shoji; Hirai, Keita; Horiuchi, Takahiko

doi:10.1364/josaa.32.001068

Cited by 10 publications

(15 citation statements)

References 14 publications

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“…In practice, this matrix is not known but the radiance factor can be measured in the actual illuminations and in an illumination without UV to retrieve the luminescent radiance factors. Recent methods to estimate the Donaldson matrix from spectrophotometer measurements [12], [13] could also be used.…”

Section: Resultsmentioning

confidence: 99%

Spectral gamut mapping and ink separation with fluorescing substrates

Coppel¹

2015

2015 Colour and Visual Computing Symposium (CVCS)

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Spectral workflows in printing aim at achieving an illuminant-invariant visual match between an original and its reproduction and require the spectral reflectance of the original as input. When printing on a fluorescing substrate, the reflectance factor of the reproduction is however no longer independent of the illumination. In the present work, we propose an extension of a spectral gamut mapping and separation algorithm accounting for the fluorescence of the substrate. The forward model relies on an extended Neugebauer model accounting for the attenuation by the ink halftones of the incident excitation radiation and emitted light. The algorithm searches for all reproducible paramers of each particular target under one spectral power distribution (SPD) with UV included and minimize the colour difference under subsequent SPDs. We test the framework on a set of 1269 Munsell patches by simulating the output of a CMYKRGB printer on a fluorescing paper and show that the proposed framework leads to significantly lower multi-illuminant colour differences as compared to a framework only taking as input the measured spectral reflectance in one single SPD.2015 Colour and Visual Computing Symposium (CVCS) 978-1-4799-1765-5/15/$31.00 c 2015 IEEE

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Section: Resultsmentioning

confidence: 99%

Spectral gamut mapping and ink separation with fluorescing substrates

Coppel¹

2015

2015 Colour and Visual Computing Symposium (CVCS)

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“…The luminescence efficiency was determined by applying Eq. (13) to direct measurements of ( ) β λ and ( ) S λ for 12 fluorescent samples from different products, such as sheet, paint, cardboard, and plastic [11]. We obtained the Donaldson matrix for each object with the bispectrometer system.…”

Section: Estimation Of Both Reflectance and Emissionmentioning

confidence: 99%

“…12 suggest that the fluorescent material emits more saturated green light than the original green color of the object because the emission range is narrower than the reflectance range. [11], where two light sources (1) and (2) were used to illuminate the same samples.…”

Section: Estimation Accuracymentioning

confidence: 99%

“…Rather, they separate fluorescent emission and reflectance (e.g., see [4][5][6][7]). Some approaches towards Donaldson matrix estimation are found in a limited number of papers [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

“…Tominaga et al [11] presented an approach using a spectral imaging system where only two illuminants with different spectra are projected onto an object without controlling the spectral shapes. The Donaldson matrix was modeled with high spectral resolution.…”

Section: Introductionmentioning

confidence: 99%

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Estimation of fluorescent Donaldson matrices using a spectral imaging system

2018

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The present paper proposes a method to estimate the bispectral Donaldson matrices of fluorescent objects in a scene with a spectral imaging system. Multiple ordinary light sources with continuous spectral-power distributions are projected sequentially onto object surfaces without controlling the spectral shape of the illumination source. The estimation problem of the Donaldson matrices is solved as an optimization problem, where the residual error of observations by the spectral imaging system is minimized. The reflection, emission, and excitation spectral functions are estimated at each wavelength without using a basis function approximation. To improve the estimation efficiency, the output visible range is segmented into two types of wavelength ranges: one for only reflection and another for both reflection and emission. An iterative algorithm is then developed based on the wavelength segmentation and the physical excitation model. The usefulness of the proposed method is examined in experiments using different fluorescent objects and illuminants. We show the estimation accuracy of the Donaldson matrices, discuss the effective selection of illuminants, and demonstrate an application to spectral analysis and reconstruction of a fluorescent image.

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Appearance synthesis of fluorescent objects with mutual illumination effects

Tominaga

Guarnera

2021

Color Research & Application

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We propose an approach for the appearance synthesis of objects with matte surfaces made of arbitrary fluorescent materials, accounting for mutual illumination. We solve the problem of rendering realistic scene appearances of objects placed close to each other under different conditions of uniform illumination, viewing direction, and shape, relying on standard physically based rendering and knowledge of the three‐dimensional shape and bispectral data of scene objects. The appearance synthesis model suggests that the overall appearance is decomposed into five components, each of which is expanded into a multiplication of spectral functions and shading terms. We show that only two shading terms are required, related to (a) diffuse reflection by direct illumination and (b) interreflection between two matte surfaces. The Mitsuba renderer is used to estimate the reflection components based on the underlying Monte Carlo simulation. The spectral computation of the fluorescent component is performed over a broad wavelength range, including ultraviolet and visible wavelengths. We also address a method for compensating for the difference between the simulated and real images. Experiments were performed to demonstrate the effectiveness of the proposed appearance synthesis approach. The accuracy of the proposed approach was experimentally confirmed using objects with different shapes and fluorescence in the presence of complex mutual illumination effects.

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Estimation of bispectral Donaldson matrices of fluorescent objects by using two illuminant projections

Cited by 10 publications

References 14 publications

Spectral gamut mapping and ink separation with fluorescing substrates

Spectral gamut mapping and ink separation with fluorescing substrates

Estimation of fluorescent Donaldson matrices using a spectral imaging system

Appearance synthesis of fluorescent objects with mutual illumination effects

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