ROY S. BERNS

Chester F. Carlson Center for Imaging Science

Rochester Institute of Technology54 Lomb Memorial Drive

Rochester, New York 14623-5604rsbpph@rit.edu

Multispectral-Based Color Reproduction Research at the

Munsell Color Science Laboratory

Multispectral-Based Color Reproduction Research at the

Munsell Color Science Laboratory

Overview for PDFOverview for PDF

This talk was presented at the Center for Imaging Science Fall Industrial Associates Meeting on October 20, 1997. It is an overview talk for a session on multispectral imaging. The session included the following speakers: Peter Burns, Geoff Woolfe, Jonathan Arney, and Roger Easton.

All of the artwork images were copied from Microsoft Art Gallery, a collection of the National Gallery, London. No attempt has been made by R. Berns to achieve color accuracy.

The Goal: The "Virtual" World Matches The Real WorldThe Goal: The "Virtual" World Matches The Real World

The Goal: The "Virtual" World Matches The Real WorldThe Goal: The "Virtual" World Matches The Real World

The Goal: The "Virtual" World Matches The Real WorldThe Goal: The "Virtual" World Matches The Real World

The Apparent Solution:Color ManagementThe Apparent Solution:Color Management

Device ProfileDevice Profile

L*

a*

b*

DeviceProfile

X

Y

Z

or

referencedevice

Reference device: Reflection print viewed at 45/0 by the 1931 observer under D

50 without flare

"Profile Connection Space (PCS)"

ImplementationImplementation

drdgdb

CRTColorimetry

XYZ

AppearanceModel

(CRT conditions)

LCH

AppearanceModel

(PCS conditions)

-1L*a*b*0

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100

L*

-100-50050

100 a*

-100 -50 0 50 100b*

0

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00

-100-50050

100 a*

dcdmdydk

LCH

AppearanceModel

(PCS conditions)

AppearanceModel

(Print conditions)

-1

L*a*b*0

20

40

60

80

100

L*

-100-50050

100 a*

-100 -50 0 50 100b*

0

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-100-50050

100 a*

GamutMapping

L*a*b*

PrintColorimetry

-1

CRT Profile

PrinterProflie

PCS

CRT to Print Via Color ManagementCRT to Print Via Color Management

Color Imaging Matches Are, By Definition, MetamericColor Imaging Matches Are, By Definition, Metameric

Real objects are not composed of cyan, magenta, yellow, and black ink

Problems Remain: Controlling LightingProblems Remain: Controlling Lighting

Monet's GardenMonet's Garden

Yes, we expect lighting to affect color, but...

Metameric Matches Are Unstable With Changes in Lighting Metameric Matches Are Unstable With Changes in Lighting

6806205605004403803800.0

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Wavelength (nm)

Ref

lect

ance

F

acto

r

6806205605004403803800.0

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Wavelength (nm)R

efle

ctan

ce

Fac

tor

Two painted surfaces, each colored with different pigments

Daylight IlluminationDaylight Illumination

What the average observer sees:

Note match

Incandescent IlluminationIncandescent Illumination

What the average observer sees:

Note mismatch

Conventional Imaging Input Devices Are Not Linearly Transformable To Humans

Conventional Imaging Input Devices Are Not Linearly Transformable To Humans

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The Camera Is Not A HumanThe Camera Is Not A Human

What the camera really sees under daylight:What the camera really sees under daylight:

Note mismatch

The Camera Is Not A HumanThe Camera Is Not A Human

What the camera really sees under incandescent:

Note mismatch

Note lack of color balance

Problems Remain: Gamut MismatchProblems Remain: Gamut Mismatch

The Original and its Reproduction Do Not MatchThe Original and its Reproduction Do Not Match

Original Reproduction

Copyright © 1993, The National Gallery, LondonCopyright © 1993, The National Gallery, London

The Solution: Multispectral-Based Color Reproduction

The Solution: Multispectral-Based Color Reproduction

Image capture

Multi-channel image storage

Spectral-based printing

separation minimizing

metamerism

Multi-ink direct digital

printing

Copyright © 1993, The National Gallery, LondonCopyright © 1993, The National Gallery, London

Spectral reconstruction

Ink selection

Multispectral-Based SystemMultispectral-Based System

Multispectral digital image capture

Multi-channel image storage

Colorimetric and appearance conversion

Gamut mappingCRT device colorimetric

characterization (inverse)

Desktop printer device colorimetric

characterization (inverse)

Spectral-based printing separation

minimizing metamerism

Multi-ink direct digital printing

Copyright © 1993, The National Gallery, LondonCopyright © 1993, The National Gallery, London

Spectral reconstruction

Research AccomplishmentsResearch Accomplishments

Debra Vent, M.S. Imaging Science, 1994Multichannel Analysis of Object-Color Spectra

James Shyu, M.S. Color Science, 1994Colorimetric Characterization of a Desktop Drum Scanner Using a Spectral Model

Rick Alfvin, M.S. Color Science, 1995Computational Analysis of Observer Metamerism in Cross-Media Color Matching

Research AccomplishmentsResearch Accomplishments

Brian Hawkins, M.S. Color Science, 1996Defining a Gamut Space Given a Set of Colorants

Peter Burns, Ph.D. Imaging Science, 1997Analysis of Image Noise in Multispectral Color Acquisition

Koichi Iino, Visiting Scientist, 1995-1997Spectral Modeling of Ink on Paper

Research ProposalResearch Proposal

Current Research EffortsCurrent Research Efforts

Di-Yuan Tzeng, Ph.D. CandidateSpectral-Based Color Separation Algorithm Development for Multiple-Ink Color

Francisco Imai, Postdoctoral FellowMultispectral Scene Estimation Using Commercial Imaging Devices

Related Research EffortsRelated Research Efforts

Jonathan Arney, Faculty Imaging ScienceLight Scattering and Halftone Modeling

Mark Fairchild, Faculty Imaging ScienceColor Appearance Psychophysics

Ethan Montag, Faculty Imaging ScienceColor Gamut Mapping

Geoff Woolfe, M.S. Imaging Science 1997Spectral Data to Improve Modeling Accuracy

Di-Yuan TzengDi-Yuan Tzeng

Ph.D. Candidate in Imaging Science

Preliminary ComputationsPreliminary Computations

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Wavelength (nm)

K/S

Mean

V1: 86.778%

V2: 06.899%

V3: 03.935%

V4: 01.766%

V5: 00.439%

The Optimal Ink- S

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400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700Wavelength

R fl

Warm red

Purple

Reflex blue

Process blue

process black

process yellow

Ink selection scheme:continuous-tone assumptioncanonical correlation analysis

ConclusionsConclusions

Multispectral-Based Color Reproduction Has Tremendous Possibilities

We Invite Our Industrial Associates To Get Involved