perfecting color reproduction - better light color reproduction.pdfto ensure the most accurate...

PERFECTING COLORPERFECTING COLOR REPRODUCTION

New Method Utilizes Spectral Data

For Improved AccuracyFor Improved Accuracy

Copyright ©2008 Better Light, Inc.

Current State of the ArtCurrent State of the Art

• An ICC camera profile indirectly characterizesAn ICC camera profile indirectly characterizes the camera by analyzing the camera’s response to a specific color chart under controlledto a specific color chart under controlled conditions, and making a correction profile that standardizes the camera’s response (tothat standardizes the camera s response (to the expected values for the color chart)

• The same profile is then used to correct all• The same profile is then used to correct all subsequent images captured by the camera


Indirect Camera Profiling MethodIndirect Camera Profiling MethodRGB data from chartreference chart

ICC profile generator

( l d )

spectral data

camera/lightRGB profile

(spectral data)

artwork

profiled RGB data from artwork


Indirect Camera Profiling MethodIndirect Camera Profiling Method

• Most camera profiling software uses spectralMost camera profiling software uses spectral data for the color reference chart

• Not all profiling software uses spectral data• Not all profiling software uses spectral data for the light source (just color temperature)

P fil i di l h i i h• Profile indirectly characterizes camera without knowing its spectral data

• Characteristics of artwork unknown

• One profile treats all subjects identicallyp j y


A Camera Profile Doesn’t Know Anything b h kabout the Artwork

RGB data from chartreference chart

ICC profile generator

spectral data

camera/lightRGB profile

(spectral data)

artwork

Unless something above changes, this profile won’t change

profiled RGB data f t k? from artwork?


A Camera Profile Doesn’t Know Anything b h kabout the Artwork

• Profile only knows camera’s RGB response to specific reference chart spectra (for a specific or generic light source)

• Spectral characteristics of artwork might be significantly different than reference chart

• Potential color response errors between partwork and camera not known

• Exposure errors can introduce color errorsExposure errors can introduce color errors


Perfecting Color ReproductionPerfecting Color Reproduction

• Ideally the spectral characteristics of theIdeally, the spectral characteristics of the artwork itself would be used to determine the colors in the printed reproductioncolors in the printed reproduction

• Ideally, the spectral characteristics of the rest of the imaging chain would also be consideredof the imaging chain would also be considered to ensure the most accurate reproduction

Id ll ld b l i i l i• Ideally, exposure would be less critical in determining the final result


Direct Spectral™ MethodDirect Spectral Methodartwork raw RGB data

from artwork

Better Light ColorSage™ColorSage powered by HP Artist software

spectral data

spectral data

camera/light/art

spectral data

spectral data

camera/light/artRGB profile



Direct Spectral™ MethodDirect Spectral Method

• Eliminates the color reference chartEliminates the color reference chart

• Uses spectral characteristics of a specific camera and a specific light sourcecamera and a specific light source

• Uses spectral measurements from the artwork

• Generates a specific profile for each artwork

• Can compensate for color response errors p pbetween camera and artwork


Spectral Measurements?Spectral Measurements?

• Most applications can use the relativelyMost applications can use the relatively inexpensive X‐Rite i1 Pro spectrophotometer

• Relatively small probe must gently touch the• Relatively small probe must gently touch the artwork surface for each measurement

M k l 50 di f i l• Make at least 50 readings of important colors in the artwork to help define its color gamut

• At 3 seconds per reading, takes 2.5 minutes– saves much more correction time later!


Overall Workflow ComparisonOverall Workflow Comparison

• In addition to scanning the artwork, scanning a white card in the same lighting can be used to correct illumination non‐uniformity

• Corrected and profiled artwork file is opened p pin a color‐managed image editing application for color correction, finishing, and printing, g, p g


Camera Profile WorkflowCamera Profile Workflowcamera/lightRGB profile

artworkartworkprofiled RGB data from artwork

brightness if it

camera/lightRGB profilecorrected and

white card

light uniformity

uniformity correction software

corrected and profiled RGB data from artwork

correction file

color managed image editing

tedious manual l ti

final print

?? image editing software

color correction ??

printer profile


Direct Spectral™ WorkflowDirect Spectral Workflow

camera

light sourcespectral datacamera spectral dataartwork

raw RGB data from artwork

camera/light/artRGB profilecorrected and

Better Light ColorSage™ powered by corrected and


powered by HP Artist software

artwork spectral datawhite cardspectral data

white card

raw RGB datafrom white card color managed

image editing

final print

white card image editing software

!!significantly less color correction

printer profile


Direct Spectral™ WorkflowDirect Spectral Workflow

• Camera and Light spectral data are constantCamera and Light spectral data are constant

• White card spectral data can be constant

C k i fil d• Capture artwork image file as raw data

• Capture white card image file as raw data

• Take at least 50 spectrophotometer readings of important colors in the artworkp

• ColorSage™ does the rest


But Wait – There’s More…But Wait There s More…

• One of the biggest challenges in reproducingOne of the biggest challenges in reproducing fine art is getting the PRINT copy to match the original’s characteristicsoriginal s characteristics

• HP Artist software was developed for use with the new HP Z3200 wide format printersthe new HP Z3200 wide‐format printers (connected printer required for operation)

HP Z3200 i f b il i l• HP Z3200 printers feature built‐in spectral analysis of ink/media characteristics


HP Z3200 Wide‐Format PrintersHP Z3200 Wide Format Printers

• Next generation 12 ink HP color technologyNext generation 12 ink HP color technology– LC, M, LM, Y, R, Gn, B, PK, MK, Gy, LGy, Enhancer

• Built in i1 spectrophotometer• Built‐in i1 spectrophotometer

• Fully automatic paper calibration and profiling– Calibration adjusts for environmental changes

– Profiling adjusts for media/ink characteristics

• Automatic print head alignment/maintenance

• User replaceable print headsUser replaceable print heads


Complete Direct Spectral™ WorkflowComplete Direct Spectral Workflow

RGB profile

output filecamera spectral data

artwork

RGB profile optimizes color for each artwork

RGB artwork data

artwork spectral data

lights spectral data

white card spectral dataBetter Light ColorSage™ powered by HP A ti tartwork

raw RGB data

white card raw RGB data

corrected for uniformity and color balance

paper calibration

HP Artist software

color managed image editing

HP Z3200

!!Let the computer do more of the thinking, so you

adjusts for environment

software

printer profile

thinking, so you don’t have to


p padjusts for ink & media

Improve your fine artImprove your fine art reproduction by using more colors in your workflow!

BETTER LIGHT ColorSage™d b HP A ti t ft


powered by HP Artist software

perfecting color reproduction - better light color reproduction.pdfto ensure the most accurate...

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