Spectral Colorimetry using LabPQR: An Interim Connection Space

Derhak, Maxim W.; Rosen, Mitchell R.

doi:10.2352/j.imagingsci.technol.(2006)50:1(53)

Cited by 31 publications

(17 citation statements)

References 6 publications

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“…There are several methods identified in the literature for generating metameric blacks . However, the set of metameric black basis vectors determined for the purposes of this research used a method similar to that previously proposed by Derhak and Rosen for the purposes of spectral gamut mapping …”

Section: Object‐based Materials Color Shiftsmentioning

confidence: 99%

“…5,13 However, the set of metameric black basis vectors determined for the purposes of this research used a method similar to that previously proposed by Derhak and Rosen for the purposes of spectral gamut mapping. 14 The following equation uses a matrix E to estimate a set of spectral reflectance vectors (represented as a matrix S est ) from a set of corresponding Wpt vectors (represented as a matrix W actual ):…”

Section: Decomposing Metameric Blacksmentioning

confidence: 99%

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Waypoint shift manifolds for object color evaluation and comparison

Derhak

Luo

Berns

2020

Color Research & Application

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Variability in object appearance is common in everyday experience and this variability can generally be attributed to the relationships between viewing conditions and the composition of an object's spectral reflectances. This paper proposes that objects, illuminants, and observers can be evaluated using a Wpt (Waypoint) shift manifold (WSM), which is defined as a set of Wpt points associated with one or more objects, observers, and/or illuminants. Since spectral reflectances of an object can be decomposed to three components (a wavelength invariant nonselective component, a characteristic reflectance, and a metameric black reflectance), WSMs of any object for an observing condition is composed of three Wpt vectors associated with a perfect reflecting diffuser, the characteristic reflectance, and the metameric black reflectance of the object. Material shift potential (MSP) can be defined as shapes and orientations of object WSMs for evaluation and comparison of object colors. Experimental results show that MSP are dramatically influenced by Wpt vectors associated with the characteristic reflectance and the metameric black reflectance for an object rather than the Wpt vectors associated with nonselective reflectance. Thus, MSP can be preserved for objects having similar characteristic reflectances and metameric black reflectances. In other words, spectral reflectances that have been manipulated to have similar overall shapes exhibit similar color inconstancy.

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Section: Object‐based Materials Color Shiftsmentioning

confidence: 99%

Section: Decomposing Metameric Blacksmentioning

confidence: 99%

Waypoint shift manifolds for object color evaluation and comparison

Derhak

Luo

Berns

2020

Color Research & Application

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“…Recently, Derhak and Rosen described a low dimensional transform of spectral space for use in spectral color management 8 . This space is called LabPQR and is in a class of spaces that fall under the category Spectral Colorimetry due to the fact that it has explicit colorimetric portions and explicit spectral reconstruction portions.…”

Section: Labpqr For Spectral Gamutsmentioning

confidence: 99%

Spectral gamuts and spectral gamut mapping

Rosen

Derhak

2006

SPIE Proceedings

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All imaging devices have two gamuts: the stimulus gamut and the response gamut. The response gamut of a print engine is typically described in CIE colorimetry units, a system derived to quantify human color response. More fundamental than colorimetric gamuts are spectral gamuts, based on radiance, reflectance or transmittance units. Spectral gamuts depend on the physics of light or on how materials interact with light and do not involve the human's photoreceptor integration or brain processing. Methods for visualizing a spectral gamut raise challenges as do considerations of how to utilize such a data-set for producing superior color reproductions. Recent work has described a transformation of spectra reduced to 6-dimensions called LabPQR. LabPQR was designed as a hybrid space with three explicit colorimetric axes and three additional spectral reconstruction axes. In this paper spectral gamuts are discussed making use of LabPQR. Also, spectral gamut mapping is considered in light of the colorimetric-spectral duality of the LabPQR space.

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“…31 Traditional color management uses the human visual system as its profile connection space (PCS), while spectral color management uses the six-dimensional LabPQR as its interim connection space (ICS). The LabPQR includes three colorimetric dimensions (CIELAB) and three approximate metameric black dimensions (PQR).…”

Section: Matrix R Theorymentioning

confidence: 99%

Image‐based spectral reflectance reconstruction using the matrix R method

Zhao

Berns

2007

Color Research & Application

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The ultimate goal of spectral imaging is to achieve high spectral accuracy, so that the spectral information can be used to calculate colorimetrically accurate images for any combination of illuminant and observer. A new spectral reconstruction method, called the matrix R method, was developed to reconstruct spectral reflectance factor accurately while simultaneously achieving high colorimetric performance for a defined illuminant and observer. The method combines the benefits of both colorimetric and spectral transformations. Tristimulus values were predicted by a colorimetric transformation from multi-channel camera signals, while spectral reflectance factor was estimated by a spectral transformation from the same signals. The method reconstructed reflectance factor by combining the fundamental stimulus from the predicted tristimulus values with the metameric black from the estimated spectral reflectance, based on the Wyszecki hypothesis. The experimental results verified the new method as a promising technique for building a spectral image database.

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Spectral Colorimetry using LabPQR: An Interim Connection Space

Cited by 31 publications

References 6 publications

Waypoint shift manifolds for object color evaluation and comparison

Waypoint shift manifolds for object color evaluation and comparison

Spectral gamuts and spectral gamut mapping

Image‐based spectral reflectance reconstruction using the matrix R method

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