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Color Seamlessness in Multi-Projector Displays Using Constrained Gamut Morphing. IEEE Visualization, 2009 Behzad Sajadi Maxim Lazarov Aditi Majumder M. Gopi. Registration Problem. Color: Brightness & Chrominance. Brightness: 1D Chrominance (x, y): 2D 3D color gamut.
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Color Seamlessness in Multi-Projector Displays Using Constrained Gamut Morphing IEEE Visualization, 2009 Behzad Sajadi Maxim Lazarov Aditi Majumder M. Gopi
Color: Brightness & Chrominance • Brightness: 1D • Chrominance (x, y): 2D • 3D color gamut
Overview • Prior Art • Motivation • Algorithm • Results
Prior Art: Overlap Blending 6 Raskar et al SIGGRAPH 1998; Li et al IEEE Computer Graphics and Applications, 2000; Chen et al SPIE Projection Displays, 2001 Proj1 Proj1 Proj2 Proj2 Overlap Region Overlap Region
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 7
8 Prior Art: Overlap Blending Overlap Blending Before Correction
Prior Art: Measurement with High Resolution Camera 9 Multi Projector Brightness Profile Single Projector Brightness Profile
Prior Art: Strict Brightness Uniformity 10 L u IEEE TVCG 2003, PROCAMS 2003 Majumder and Stevens
Prior Art: Strict Brightness Uniformity 11 L L Significant Contrast/ Dynamic Range Compression u
12 Prior Art: Strict Brightness Uniformity After Strict Brightness Uniformity Before
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
Prior Art: Constrained Brightness Smoothing 14 After Strict Brightness Uniformity Before IEEE TVCG 2003, PROCAMS 2003 Majumder and Stevens
15 Prior Art: Constrained Brightness Smoothing After Constrained Brightness Smoothing Before ACM Transactions on Graphics 2005 Majumder and Stevens
Overview • Prior Art • Motivation • Algorithm • Results
Motivation: Our Contribution 18 3D Gamut Morphing 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
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 19
Overview • Prior Art • Motivation • Algorithm • Results
Algorithm: Chrominance Gamut Morphing Horizontal Blending Chrominance Gamut Morphing New Brightness Profiles Vertical Blending Horizontal Blending Attenuation Map Vertical Blending Attenuation Map
Algorithm: Horizontal Blending Before Chrominance Blending After Horizontal Blending
Algorithm: Vertical Blending After Horizontal Blending After Vertical Blending
Algorithm: Pipeline Projector Brightness Profiles Projector Chrominance Gamut Chrominance Gamut Morphing Chrominance Morphing Attenuation Map
Algorithm: Chrominance gamut morphing • Modifies brightness profiles • Removes C0 brightness discontinuity After Horizontal Blending Before Correction After Vertical Blending
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 Brightness Constraining After Vertical Blending
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 Bezier-based Smoothing After Brightness Constraining After Vertical Blending
Algorithm: Brightness Smoothing 29 Perceptual Brightness Constraining Brightness Smoothing New Brightness Profiles Vertical Bezier-based Brightness Smoothing Brightness Smoothing Attenuation Map
Algorithm: Offline Correction Pipeline Projector Brightness Profiles Reconstruct Chrominance Gamut Chrominance Gamut Morphing New Brightness Profiles Final Alpha Mask (A) Brightness Smoothing White Balancing Prior to Correction
Algorithm: Online Image Correction Custom Linearization Function Linearize Input Image Input Image Apply Alpha Mask Final Alpha Mask (A) Apply Projector Transfer Function
Overview • Prior Art • Motivation • Algorithm • Results
36 Results: Comparison Before Correction Overlap Blending Majumder and Stevens 2005 Final Result
Conclusion • First method that • Complete 3D color registration • Addresses spatial variations in both chrominance and brightness • High quality display with commodity projectors
Future Work • Extend to non-developable surfaces • Address intra-projector color variations
Prior Art: Color Seamlessness 40 Brightness Chrominance