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Hans HolbeinThe AmbassadorsThe Art and Science of DepictionLimitations of the Medium,compensation or accentuation:Contrast & PaletteFredo DurandMIT- Lab for Computer ScienceLimitations: contrast & paletteMakoto NakamuraLimitations: contrast & paletteMakoto Nakamura3Makoto NakamuraLimitations: contrast & palette2Limitations: contrast & palette4Makoto Nakamura5Limitations: contrast & palette61
Makoto NakamuraLimitations: contrast & paletteMakoto Nakamura7Makoto NakamuraLimitations: contrast & palette8Makoto Nakamura9Makoto NakamuraLimitations: contrast & paletteLimitations: contrast & paletteLimitations: contrast & palette10Makoto Nakamura11Limitations: contrast & palette122
Assignments for Monday 16.Personal Meeting II Solso Cognition and the Visual Arts Class Essay Project– Chapter 5 & 6 Essay– Exploratory or Picture comment– Choose subject– Outline of the issuesLimitations: contrast & palette13Limitations: contrast & palette14PlanContext Real world: 10-6 to 106 cd/m2 PictureThe picture is flatThe viewpoint is uniqueThe image is finite, it has a frameThe picture is staticThe contrast is limited– Max contrast 1:500– Typically 1:50Limitations: contrast & palette15Limitations: contrast & palette16Two problemsTwo problems The image intensity does not match the realconditions The image intensity does not match the realconditions The contrast is not sufficient10-610610-6106Sunny scene10-6High dynamic range10610-6Watched in a dark roomLimitations: contrast & palette106Low contrast17Limitations: contrast & palette183
Three contextsThe limit of illusion Photo Computer Graphics Painting and drawing Pozzo’s ceiling: the Sky is not bright enoughLimitations: contrast & palette19Limitations: contrast & paletteThe limit of illusionEdge detection Bruneleschi’sexperiment Similar to center-surround Measured using micro-electrodes20– Used a mirrorfor the skyLimitations: contrast & palette21Limitations: contrast & paletteLand RetinexPlan Local contrast Problem 1: intensity does not match22– Exposure– Viewing conditions– Night scenes Problem2: insufficient contrast– Tone Reproduction– Lighting– Tone mapping in CG– Flares– PaintingLimitations: contrast & palette23Limitations: contrast & palette244
Photo exposureMetering Centered average Spot Incident– Measure incoming lightLimitations: contrast & palette25Limitations: contrast & paletteNikon 3D Color MatrixPlan Database of 30,000 photos Multiple captors (segments) Exposure depends on Problem 1: intensity does not match– Exposure– Viewing conditions– Night scenes– Brightness from each segments– Color– Contrast– Distance– Focus (where is the subject)Limitations: contrast & palette26 Problem2: insufficient contrast– Tone Reproduction– Lighting– Tone mapping in CG– Flares– Painting27Limitations: contrast & paletteHunt and Stevens effectHunt and Stevens effect Stevens effect Stevens effect– Contrast increases with luminance28– Contrast increases with luminance Bartleson-Breneman effect– Image contrast changes with surround– A dark surround decreases contrast(make the black of the image look less deep) Hunt effect– Colorfulness increases with luminance Hence the need for gamma correctionLimitations: contrast & palette29Limitations: contrast & palette305
SuprathresholdTone mapping Subjective brightness Power law Exponent100 Real scene: large range of luminance– (from 10-6 to 106 cd/m2 ) Limitation of the display– 1-100 cd/m2– 0.33 to 0.5 Gammacorrection Goal:Reproducea faithfulimpression101-3.5 -2.5-1.5 -0.5 0.5 1.50.1Limitations: contrast & palette-6-5-4-3-22.5-13.50Adaptation level(log cd/m2)12Test luminance (log cd/m 2)3431Limitations: contrast & palette32Perceptual tone mappingThreshold [Ferwerda et al. 1996] Match the smallest perceptible intensity in thesimulated scene and in the display condition Rod and cone vision Smallest perceptible stimulus Smallest perceptible stimulus difference543210cone-1-2rod-3-6Limitations: contrast & palette33Limitations: contrast & palette-4-202log Background luminance (cd/m 2)Perceptual tone mappingTime-dependent tone mapping [Ferwerda et al. 1996] Dazzling Slow dark adaptationLimitations: contrast & palette35Limitations: contrast & palette4634366
Dark adaptationTime-dependent tone mapping Slow recovery after dramatic decrementfrom top to bottom,initial adaptation luinance:125,000 cd/m26,000 cd/m21,000 cd/m260 cd/m24cone mediated20rod mediated-20Limitations: contrast & palette102030Times in dark (minutes)4037Limitations: contrast & palettePlanRepresenting night scenes Problem 1: intensity does not match – Exposure– Viewing conditions– Night scenes Problem2: insufficient contrast38Rods, no color visionBlue shiftLower acuityUnable to adapt in shadows– Tone Reproduction– Lighting– Tone mapping in CG– Flares– PaintingLimitations: contrast & palette39Limitations: contrast & paletteRepresenting night scenesRepresenting night scenes Pissaro, Montmartre James Abbott Mc Neil WhistlerNocturne in Blue And Silver The Lagoon Venice1879-1880Limitations: contrast & palette41Limitations: contrast & palette40427
Representing night scenesRepresenting night scenes Whistler,Old Battersea Bridge Archibald J. Motley Jr, Gettin’ Religion 1948Limitations: contrast & palette43Limitations: contrast & palette44Night scenes in the moviesPlan Problem 1: intensity does not matchOften Day for nightFilm during the dayFew fill light (dark shadows)Add blue castAvoid the sky– Exposure– Viewing conditions– Night scenes Problem2: insufficient contrast– Tone Reproduction– Lighting– Tone mapping in CG– Flares– PaintingLimitations: contrast & palette45Limitations: contrast & palette46Tone Reproduction Not linear Not linear GammacorrectionγlinearshoulderxLog print densityLog print densityTone Reproductionlineartoelog luminanceshadowlog luminancehighlightLimitations: contrast & paletteSnapshot-Perspective -Speed, aperture-Filter-Lighting-Processing & Print-Make up-Retouching47shadowhighlightLimitations: contrast & paletteSnapshot-Perspective -Speed, aperture-Filter-Lighting-Processing & Print-Make up-Retouching488
Texture and contrastLimitations: contrast & paletteThe Zone System49Expansion and contractionLimitations: contrast & paletteLimitations: contrast & paletteSnapshot-Perspective -Speed, aperture-Filter-Lighting-Processing & Print-Make up-Retouching50Contraction51Pre- exposureLimitations: contrast & palette52Pre- exposure Expose withuniform whitebefore taking thephoto Raise the dark tonesLimitations: contrast & palette53Limitations: contrast & palette549
Two-solution developmentRed Filter Different development of high and low valueLimitations: contrast & palette55Limitations: contrast & paletteThe PrintDodging and Burning W. Eugene Smith photo of Albert Schweitzer 5 days to print! Locally darken or lighten Use masks to expose some parts less Has to be done for each print!Limitations: contrast & paletteSnapshot-Perspective -Speed, aperture-Filter-Lighting-Processing & Print-Make up-Retouching57Dodging/burningLimitations: contrast & paletteSnapshot-Perspective -Speed, aperture-Filter-Lighting-Processing & Print-Make up-Retouching5658Gradient Filter The sky is too bright– Gradient filter for thetop of the photo The house is too dark– Gradient filter forthe bottom of the photoLimitations: contrast & palette59Limitations: contrast & paletteSnapshot-Perspective -Speed, aperture-Filter-Lighting-Processing & Print-Make up-Retouching6010
Curve tool in photo editing softwareThe infamous 8 bits Digital photography8 bits means 1 to 255 contrastEnough for displayNot enough for– Editing– Tone reproduction– Dodging & burning– Etc.Limitations: contrast & palette61Limitations: contrast & palettePlanThree Point Lighting Problem 1: intensity does not match Key light– Exposure– Viewing conditions– Night scenes– Main and visible lighting Fill light– Fill-in shadows Problem2: insufficient contrast Back light– Tone Reproduction– Lighting– Tone mapping in CG– Flares– PaintingLimitations: contrast & palette– Emphasize silhouette– Make subject stand out Independent lighting63Limitations: contrast & paletteSnapshot-Perspective -Speed, aperture-Filter-Lighting-Processing & Print-Make up-RetouchingLightingPortrait Lighting Fill light Ansel AdamsLimitations: contrast & palette6265Limitations: contrast & paletteSnapshot-Perspective -Speed, aperture-Filter-Lighting-Processing & Print-Make up-Retouching646611
Fill-inLighting Painting with lightLimitations: contrast & paletteSnapshot-Perspective -Speed, aperture-Filter-Lighting-Processing & Print-Make up-Retouching67PlanLimitations: contrast & palette68Local contrast Problem 1: intensity does not match– Exposure– Viewing conditions– Night scenes Problem2: insufficient contrast– Tone Reproduction– Lighting– Tone mapping in CG– Flares– PaintingLimitations: contrast & palette69Limitations: contrast & paletteLocal compensationLocal contrast Use local average to compensate Haloing effects [Tumblin 1999] Organization into regionsLimitations: contrast & palette71Limitations: contrast & palette707212
Local contrastHistogram adjustment [Tumblin 1999] Organization into regions [Larson et al. 1997] Disregard empty portions of the histogram10610-6High dynamic range10-6106Low contrastLimitations: contrast & palette73Limitations: contrast & paletteHistogram adjustmentPlan [Larson et al. 1997] Disregard empty portionsof the histogram Problem 1: intensity does not match74– Exposure– Viewing conditions– Night scenes Problem2: insufficient contrast– Tone Reproduction– Lighting– Tone mapping in CG– Flares– PaintingLimitations: contrast & palette75Flare, haloLimitations: contrast & palette76Flare, halo Le Corbusier, Notre Dame du Haut, 1950-55Limitations: contrast & palette77Limitations: contrast & palette7813
Flare, haloBlue-yellow Van Gogh, Le Semeur, 1880 Karl Schulpig, 1925Limitations: contrast & palette79Limitations: contrast & paletteFlare in CGFlare in CG [Spencer et al 1995] Flare: scattering in the eye [Spencer et al 1995] Flare: scattering in the eye Size is constantLimitations: contrast & palette81Limitations: contrast & paletteFlare in CGPlan [Spencer et al 1995] Flare: scattering in the eye Size is constant Problem 1: intensity does not match8082– Exposure– Viewing conditions– Night scenes Problem2: insufficient contrast– Tone Reproduction– Lighting– Tone mapping in CG– Flares– PaintingLimitations: contrast & palette83Limitations: contrast & palette8414
Local lightingChinese painting Typically FlorenceRenaissance Mostly to reveal shape RaphaelLimitations: contrast & palette85TenebrismLimitations: contrast & palette86Rembrandt Early 17th CaravaggioLimitations: contrast & palette87Limitations: contrast & paletteRadial balanceWhite Georges de La Tour,Joseph the Carpenter,1645 FilippoLippiLimitations: contrast & palette89Limitations: contrast & palette889015
SilhouetteContrast Wolfrang WeberThe Lash Bird DancerOn MadagascarLate 20s Bert SternLimitations: contrast & palette91Limitations: contrast & palettePure drawingPure color Diego RivieraMother And Child1936 Henri Matisse, Harmony in Red, 1908-1909Limitations: contrast & palette93Limitations: contrast & palette9294Pure colorLimitations: contrast & palette9516
– Night scenes Problem2: insufficient contrast – Tone Reproduction – Lighting – Tone mapping in CG – Flares – Painting Limitations: contrast & palette 40 Representing night scenes Rods, no color vision Blue shift Lower acuity Unable to adapt in shadows Limitations: contrast &a
