Post on 19-Jan-2016
Color Seamlessness in Multi-Projector Displays Using Constrained Gamut
Morphing
IEEE Visualization, 2009
Behzad SajadiMaxim LazarovAditi Majumder
M. Gopi
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Registration Problem
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Color: Brightness & Chrominance
Brightness: 1D Chrominance (x, y): 2D
3D color gamut
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Color Variation Visualization
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Overview
Prior Art Motivation Algorithm Results
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Prior Art: Overlap Blending
Proj1 Proj2 Proj1 Proj2Overlap Region Overlap Region
Raskar et al SIGGRAPH 1998; Li et al IEEE Computer Graphics and Applications, 2000; Chen et al SPIE Projection Displays, 2001
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Prior Art: Overlap blending
Assumes Uniform brightness in each projector All projectors have similar brightness Projectors are linear devices
Addresses the overlaps only No measurement or correction of intra
or inter projector brightness variation
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BeforeCorrection
OverlapBlending
Prior Art: Overlap Blending
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Prior Art: Measurement with High Resolution Camera
Single ProjectorBrightness Profile
Multi ProjectorBrightness Profile
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Prior Art: Strict Brightness Uniformity
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IEEE TVCG 2003, PROCAMS 2003 Majumder and Stevens
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Prior Art: Strict Brightness Uniformity
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Significant Contrast/ Dynamic Range Compression
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Before
After Strict Brightness Uniformity
Prior Art: Strict Brightness Uniformity
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Prior Art: Constrained Brightness Smoothing
Smoothing is sufficient for perceptual seamlessness Non-linear filtering Maximize dynamic range Solved using dynamic programming
ACM Transactions on Graphics 2005 Majumder and Stevens
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Before
After Strict Brightness Uniformity
Prior Art: Constrained Brightness Smoothing
IEEE TVCG 2003, PROCAMS 2003 Majumder and Stevens
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Before
After Constrained Brightness Smoothing
ACM Transactions on Graphics 2005 Majumder and Stevens
Prior Art: Constrained Brightness Smoothing
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Overview
Prior Art Motivation Algorithm Results
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Motivation: Does it solve the problem?
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Motivation: Our Contribution
Chrominance is constant within projector
Chrominance varies across projectors and in overlaps
Brightness smoothing does not guarantee chrominance smoothing
Constrained chrominance smoothing in addition to brightness smoothing
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3D Gamut Morphing
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Motivation: Key Insight
Smooth transition of chrominance across overlap region Blending of the chromaticity coordinates Only need to manipulate the brightness
proportions of overlapping projectors Manipulate brightness to address
chrominance variation
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Overview
Prior Art Motivation Algorithm Results
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Algorithm: Chrominance profile before registration
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Algorithm: Chrominance Gamut Morphing
ChrominanceGamut Morphing
Horizontal Blending
Vertical Blending
New BrightnessProfiles
Horizontal BlendingAttenuation Map
Vertical BlendingAttenuation Map
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Algorithm: Horizontal Blending
Before Chrominance Blending
After Horizontal Blending
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Algorithm: Vertical Blending
After Horizontal Blending
After Vertical Blending
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Algorithm: Pipeline
Projector BrightnessProfiles
ProjectorChrominance Gamut
Chrominance MorphingAttenuation Map
Chrominance Gamut Morphing
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Algorithm: Chrominance gamut morphing
Modifies brightness profiles Removes C0 brightness discontinuity
Before Correction After Horizontal Blending After Vertical Blending
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Algorithm: Perceptual Brightness Constraining
Does not guarantee imperceptible brightness changes
Apply Majumder et. al. 2005 to constrain the brightness variations
Retains chrominance gamut morphing
After Vertical BlendingAfter Brightness Constraining
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Algorithm: Bezier-based Brightness Smoothing
Brightness profile is not derivative continuous after Majumder et. Al. 2005
Assures Cn intensity continuity Retains chrominance gamut morphing
After Vertical BlendingAfter Brightness ConstrainingAfter Bezier-based Smoothing
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Algorithm: Brightness Smoothing
BrightnessSmoothing
PerceptualBrightness Constraining
Vertical Bezier-basedBrightness Smoothing
New BrightnessProfiles
Brightness SmoothingAttenuation Map
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Algorithm: Offline Correction Pipeline
Chrominance Gamut Morphing
Projector BrightnessProfiles
ReconstructChrominance Gamut
New BrightnessProfiles
Brightness Smoothing
Final AlphaMask (A)
White BalancingPrior to Correction
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Color Variation Visualization
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Algorithm: Online Image Correction
Apply Alpha Mask
Apply Projector Transfer Function
InputImage
Custom Linearization Function
Linearize Input Image
Final AlphaMask (A)
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Overview
Prior Art Motivation Algorithm Results
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Results: More General Pictures
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Results: Extends to any Geometry
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BeforeCorrection
OverlapBlending
Final Result
Majumderand Stevens
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Results: Comparison
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Conclusion
First method that Complete 3D color registration
Addresses spatial variations in both chrominance and brightness
High quality display with commodity projectors
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Future Work
Extend to non-developable surfaces Address intra-projector color
variations
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Questions?
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Prior Art: Color Seamlessness
Brightness Chrominance
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