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Color Evaluation/Correction
Color Image Evaluation, Correction and Adjustment by Taz Tally Ph.D. A presentation of Taz Tally Seminars 2007© Color Image Evaluation, Correction and Adjustment Quality Printing Presents Color Image Evaluation, Correction and Adjustment Taz Tally Taz Tally Seminars E-mail: [email protected] Web: www.taztallyhpotography.com www.tazseminars.com Topics for Today ϖ Color Image Correction vs Adjustments ϖ Color Image Fundamentals ϖ Image Evaluation and Correction Tools ϖ Evaluating images ϖ Finding and Correcting Neutrals and Potential Neutrals ϖ Working with Isolations ϖ Evaluating and Correcting Skin Tones ϖ Complex Multipoint Color Corrections ϖ Creative Adjustments ϖ Target Based Adjustments Image Correction vs Adjustment ϖ Color Image Correction ♣ Correcting color that is wrong ϖ Color Image Adjustment ♣ Adjusting color to suit your creative desires ♣ Its not necessarily wrong … It’s just not what you want 1 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Color Image Fundamentals Color Image Fundamentals ϖ Its ALL about Grayscale ♣ ♣ ♣ Digital images don’t have color … only grayscale You capture, measure, adjust and output grayscale All color is created at output devices - RGB for Monitors CMYK (+) for printers RGB Image Red Channel Green Channel Blue Channel Color Image Fundamentals ϖ Its ALL about Grayscale ♣ ♣ ♣ ♣ Digital images don’t have color … only grayscale You capture, measure, adjust and output grayscale Grayscale measured 0-255 GS values for RGB Grayscale measured 0-100% for CMYK RGB Image Red Channel Green Channel Blue Channel 2 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Evaluation Tools Image Evaluation ϖ Histograms ♣ ♣ Shows distribution and quantity of image data Where data is and isn’t! Image Evaluation ϖ Histograms ♣ ♣ Shows distribution and quantity of image data Where data is and isn’t! 3 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Evaluation ϖ Histograms ♣ ♣ Shows distribution and quantity of image data Where data is and isn’t! Image Evaluation ϖ Histograms ♣ ♣ Shows distribution and quantity of image data Where data is and isn’t! Image Evaluation ϖ Histograms ♣ ♣ Shows distribution and quantity of image data Where data is and isn’t! 4 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Evaluation ϖ Histograms ♣ ♣ Shows distribution and quantity of image data Where data is and isn’t! Image Evaluation ϖ Eye Droppers and Info Tool ♣ ♣ Measure rather than view:Info tool will always tell the truth Eye Droppers - Default Eye Dropper - Measure 1 Point Color Sampler - Measure and monitor up to 4 points Image Evaluation ϖ Finding Highlights and Shadows ♣ Histogram Trick ♣ Hold Option/Alt key as you slide HL and SH sliders to ID pixels 5 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Evaluation and Correction: Highlights Image Evaluation ϖ Histogram, Eye Droppers and Info Tool ♣ Use Together ♣ Note: Low HL values and Blue cast Image Correction ϖ Histogram, Eye Droppers and Info Tool ♣ Master Histogram Adjustment ♣ All values rise but are not equal … B&G blow out here ♣ An improvement! 6 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Correction ϖ Histogram, Eye Droppers and Info Tool ♣ Individual Channel Histogram Adjustment ♣ All values rise, are equal (245) … and NO blown out values ♣ Even Better! Image Correction ϖ Histogram, Eye Droppers and Info Tool ♣ Individual Channel Histogram Adjustment ♣ All values rise, are equal (245) … and NO blown out values ♣ Even Better! Image Comparison ϖ Histogram, Eye Droppers and Info Tool ♣ Individual Channel Histogram Adjustment ♣ All values rise, are equal (245) … and NO blown out values ♣ Even Better! ♣ Note how highlights pop and overall brightness and contrast. As well as color saturation improves. 7 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment – Image Evaluation and Correction – No Highlights - Histogram Only Image Evaluation ϖ Histogram Only Adjustment ♣ ♣ No critical Highlight Master Histogram shows flat areas in HL and SH Image Evaluation ϖ Histogram Only Adjustment ♣ ♣ Individual histograms are centered Master Histogram adjustment OK 8 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Correction ϖ Histogram Only Adjustment ♣ ♣ ♣ Individual histograms are centered Master Histogram adjustment OK Improved brightness, contrast + color saturation Image Evaluation ϖ Histogram Only Adjustment ♣ ♣ No critical Highlight Master Histogram shows flat areas in HL and SH Image Evaluation ϖ Histogram Only Adjustment ♣ ♣ Individual histograms are centered Master Histogram adjustment OK 9 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Correction ϖ Histogram Only Adjustment ♣ ♣ ♣ Individual histograms are centered Master Histogram adjustment OK Improved brightness, contrast + shadow detail – Image Evaluation and Correction – Locating Multiple Neutrals Image Evaluation ϖ Multiple Neutrals ♣ Locate neutrals - Flower petals (HL) Boot fabric (M) Black sole (S) ♣ Avoid ♣ Key image char. - Cast Shadows Color absorbed White highlight Saturated colors Shadow details 10 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Evaluation ϖ Multiple Neutrals ♣ ID Specular and diffuse Highlights Image Evaluation ϖ Multiple Neutrals ♣ Sampler points and values ♣ Note the blue cast in neutrals ♣ Note lack of blue cast in cast shadow ϖ HL 239,239 255 ϖ Midtone 105, 106, 118 ϖ Shadow 40, 39, 53 ϖ Cast shadow 13,13,13 Image Correction ϖ Multiple Neutrals ♣ Curve corrected values - Cmd/Cnt + click on neutral Establish Curve control points ♣ ♣ ϖ ϖ ϖ ϖ Loss of blue cast in neutrals Cast shadow, color cast HL 239,239 239 Midtone 105, 106, 105 Shadow 40, 39, 40 Cast shadow 13,13,9 11 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Comparison ϖ Multiple Neutrals ♣ Before and after ♣ Colors are more saturated - Yellow boots - Pinks - Stripes in boots - Set off neutral gray boot fabric – Image Evaluation and Correction – Skin Tones Image Evaluation ϖ Key Image Areas ♣ Skin tone ♣ Diffuse white highlights ♣ Bright green colors 12 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Evaluation ϖ Skin Tones ♣ R>G>B - R, G and B more separated in lighter areas ♣ Here G and B ~ = Image Evaluation ϖ Skin Tones ♣ Master Histogram shows blown out HL Image Eval ϖ Skin Tones ♣ Master Histogram shows blown out HL - Especially on R and B channels ♣ Also note blue midtone hump 13 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Correct ϖ Skin Tones ♣ Curves correction - Focus on Blue Curve - Tweak Red and Green especially in HL Image Correction ϖ Skin Tones ϖ R > G > B = Warmer skin tones ϖ Note greens are more saturated ϖ White Highlight NOT blown-out – Image Evaluation and Correction – Skin Tones and Neutrals 14 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Evaluation ϖ Key Image Components ♣ Skin tones ♣ Red hair ♣ Orange Colored jacket ♣ Neutral gray fleece Image Evaluation ϖ Skin Tones ♣ Master Histogram shows good overall exposure/data distribution - Full histogram ϖ High Blue values in skin and neutral ♣ G~B Image Evaluation ϖ Skin Tones ♣ Individual histograms show an excess of Blue and Green in image with so much red 15 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Correction ϖ Skin Tones ♣ Lower Blue for R > G > B ♣ But also lower Green - Use the neutral fleece as your guide Use Red (~98) value as the target neutral value Image Correction ϖ Skin Tones ♣ Lower Blue for R > G > B ♣ But also lower Green - Use the neutral fleece as your guide Use Red (~98) value as the target neutral value Image Correction ϖ Start ϖ Blue Correct ϖ Blue + Green Correct ♣ Note: Skin tone, Red hair, neutral fleece - nice set off to > popping orange 16 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment – Image Evaluation and Correction – Using Potential Neutrals Image Evaluation ϖ Image Characteristics ♣ Low contrast ♣ Poor brightness ♣ Low color saturation ♣ Too dark overall ♣ Overall blah ϖ Key Image Components ♣ White diffuse highlight (Hankie) ♣ Skin tones ♣ Colors: Red shirt and green grass ♣ Logs (potential neutral) Image Eval ϖ Set Sampler Points ♣ ♣ ♣ ♣ 1. Hankie White HL: too dark + red cast 2. Skin tone: G ~ B, G should be > B 3. Gray Beard (neutral): Confirms red cast 4. Wood (Potential neutral): Green Low? - Correct others first then re-evaluate RGB values 17 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Eval ϖ Histogram analysis ♣ ♣ ♣ Master shows poor HL and SH values Red data shifted to right Green and Blue ~ ♣ Extra Red Peak (shirt) - Green should have more of a bump Image Correction ϖ Individual histogram channel adjust ♣ Neutralize white highlight ♣ Use Levels Adjustment layer Image Correction ϖ Individual histogram channel adjust ♣ ♣ ♣ ♣ Neutralize white highlight (pt. 1) Improves B & C Better skin tones: R > G > B (pt.2) Enhanced color saturation (reds and greens) 18 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Correction ϖ Individual histogram channel adjust ♣ ♣ ♣ Neutralize white highlight Improves B & C and color saturation Note Strong blue value in Neutral? Wood (pt. 4) Image Correction ϖ Blue Channel Curve Adjust ♣ ♣ ♣ Lower Blue midtone to ~ neutralize wood Wood looks more natural Improves red and green saturation Image Correction ϖ Start, ϖ Intermediate: ♣ HL & SH adjust ϖ Final: ♣ Blue Curve neutralization 19 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment – Image Evaluation and Correction – Highlights, Skin Tones and Isolations Image Evaluation ϖ Key Image Components ♣ White diffuse highlight (T-Shirt) ♣ Skin tones (Mark and Tauna) ♣ Marks gray shirt (potential neutral) ϖ Image Characteristics ♣ Low contrast ♣ Poor brightness ♣ Low color saturation ♣ Too dark overall ♣ Overall blah Image Eval ϖ Neutrals, Skin tones, Isolation ♣ HL too dark ♣ Sky values lighter than critical diffuse Highlight ♣ Isolate Sky to prevent blow out 20 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Correction ϖ Select Sky ♣ Use Blue channel for selection: Best contrast ♣ Select with Magic Wand + Similar ♣ Return to composite RGB image ♣ Select > Feather > 2-3 pixels - Prevents apparent abrupt transitions View selection edges with Quick Mask Image Correction ϖ Save Sky and Foreground Selections ϖ Selections can be loaded at any time ♣ Cmd/Cnt + Opt/Alt + Channel # - Cmd + Opt + 4 = Loads Sky Mask (Mac) Cnt + Alt + 5 = Loads Foreground Mask (Win) Image Evaluation ϖ Eye Droppers and Info Tool ♣ Establish Color Sampler points on key areas - Measure and monitor up to 4 points 21 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Evaluation ϖ Histograms Evaluation: Full Image ♣ Highlight too low/dark ♣ Blue channel offset = Blue cast - Make individual channel corrections Image Evaluation ϖ Histograms Evaluation: Foreground ♣ Data offset to left - too low/dark ♣ Blue channel offset = Blue cast - Could make individual channel corrections in levels - Image Correction ϖ Correct Foreground ♣ Curves correction ♣ Use Curves Adjustment Layer 22 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Correction ϖ Correct Foreground ♣ Curves correction ♣ Use Curves Adjustment Layer Image Correction ϖ Correct Background Sky ♣ Levels correction ♣ Use Levels Adjustment Layer ♣ Master or individual channel adjustment Image Correction ϖ Correct Foreground ♣ Use Levels Adjustment Layer - Background ♣ Use Curves Adjustment Layer - Foreground 23 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment – Image Evaluation and Correction – Complex Multipoint Color Correction Image Evaluation ϖ Key Image Components ♣ White diffuse highlights - direct sun ♣ Cast shadow neutrals ϖ Image Characteristics ♣ Lower Contrast ♣ Lower brightness ♣ Color cast - From low angle sun Yellow (R+G) ♣ Soft focus ϖ Goals ♣ Improve overall B&C ♣ Remove color cast - Neutralize snow ♣ Sharpen focus Image Adjustment ϖ Create Levels Adjustment Layer ♣ Most important in complex image corrections 24 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Locate + Set Initial Highlight and Shadow ϖ Highlight and Shadow locations ♣ Levels trick ♣ Diffuse highlight on ridge ♣ Foreground shadow: Fill in Set Middle Highlight ϖ Highlight and Shadow locations ♣ Set #1 HL Sampler point - Note Yellow (R+G) cast ♣ Slide Master HL till G = 242 ♣ Remainder of adjustments - Curves Image Evaluation ϖ Note improvement in overall B & C ♣ Master levels adjustments ϖ Locate other 3 Sampler Points ♣ 2 White diffuse highlights - direct sun (1 & 2) ♣ 1 Midtone - semi direct sun (3) ♣ 1 Cast shadow neutrals (4) ϖ Note color casts ♣ Inconsistent 25 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Evaluation ϖ Evaluate Sample Points ♣ White diffuse highlights (1 & 2): R > G >>B ♣ Midtone neutrals (3): (R ~ G) > B ♣ Cast shadow (4): B > (R~G) Image Adjustment ϖ Add Curves Adjustment Layer ♣ Most important in complex image corrections Image Adjustment ϖ Set four control points Red curve ♣ Cmd/Cnt + Click on each Sampler point ϖ Adjust 4 Sampler points till R = G 26 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Adjustment ϖ Set four control points Blue curve ♣ Cmd/Cnt + Click on each Sampler point ϖ Adjust 4 Sampler points till B = G Image Adjustment ϖ Neutralized Image ♣ Complex cast removed Image Sharpening ϖ Convert to Lab ♣ Image > Mode > Lab ϖ Select L channel ♣ Sharpen L channel - Prevents creation of edge color casts - Amount = 50-200 Radius = 1 Threshold = 3-4 (prevents texture in snow) ♣ Sharpening values 27 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Image Adjustment ϖ Before and After ♣ B&C improved ♣ Complex cast removed ♣ Sharper ϖ Key points ♣ Image evaluation - Inset HL and SH ID Complex Cast ♣ Proper tools ♣ Adjustment order - Multipoint Sampler Adjustment Levels Adjustment Curves Lab sharpening Initial HL Master Level Red channel Blue channel Mode convert Sharpening – Creative Adjustments – or why NOT to use Auto-Anything Image Evaluation ϖ Key Image Components ♣ No Diffuse white HL ♣ Really no easy neutrals ϖ Image Characteristics ♣ Low contrast ♣ Low brightness ♣ Blue Color cast ϖ Goals ♣ Improve overall B&C ♣ Pop Rainbow ♣ Experiment with color cast 28 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Auto Levels ϖ Minor improvement ♣ Shadow point stays far left Manual Levels ϖ Major improvement ♣ Much better contrast and color saturation Manual Levels ϖ Master vs Individual Channels Adjustments ♣ Change in color cast 29 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment – Target-Based Color Correction – Using Grayscale Swatches Image + Target Capture ϖ Capture multi-step grayscale target with image ϖ Neutralize the grayscale swatches ♣ Swatches have known values ϖ Color is corrected as a result ♣ Concept: All color is controlled by grayscale – Simple 2-Step/2-Swatch – Eye Dropper Correction 30 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Target-Based Correction ϖ Set Levels HL Dropper to HL Swatch = 245 ♣ Double click on the Levels HL dropper to open Color Picker ♣ Set RGB values = 245 ♣ Close Color Picker Target-Based Correction ϖ Click on the target’s 245 highlight swatch ϖ Starting Target HL RGB values = 229, 255, 255 ϖ Corrected target HL RGB values = 245, 245, 245 Target-Based Correction ϖ Click on the target’s 245 highlight swatch ϖ Target HL is neutralized to 245 ϖ Colors in HL range are corrected 31 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Target-Based Correction ϖ Set Levels Midtone Dropper to midtone Swatch = 135 ♣ Double click on the Levels HL dropper to open Color Picker ♣ Set RGB values = 135 ♣ Close Color Picker Target-Based Correction ϖ Click on midtone 135 swatch ϖ Target midtone is neutralized to 135 ϖ Colors near midtone range are corrected Target-Based Correction ϖ Before and After 2 Step Neutralization 32 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment – Multi-Swatch Curves Correction – Image + Target Capture ϖ Capture multi-step grayscale target with image ϖ Neutralize EACH grayscale swatch ♣ Using known Swatches values ϖ Color is corrected very accurately Target-Based Correction ϖ Capture multi-step grayscale target with image ϖ Neutralize EACH grayscale swatch ♣ Using known Swatches values ♣ Cmd/Cnt click on swatch to set Curve point ♣ Set Output value = to swatch value (here 135) ϖ Color is corrected very accurately 33 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Target-Based Correction ϖ Capture multi-step grayscale target with image ϖ Neutralize EACH grayscale swatch ♣ Using known Swatches values ♣ Cmd/Cnt click on swatches to set Curve points ♣ Set Output values for each swatch/point pair ϖ Color is corrected very accurately ϖ Note: Use Curve Adjustment Layer Target-Based Correction ϖ Before and After Multi-Step Curve Neutralization Target-Based Correction ϖ Save Curves ϖ Load Curves ♣ Correct multiple images captured under same lighting 34 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Target-Based Correction ϖ Save Curves ϖ Load Curves ♣ Correct multiple images captured under same lighting The Book! Taz Tally Taz Tally Seminars Homer Alaska Phone: 907-235-3794 E-mail: [email protected] The Color Correction Kit! Send me an Email [email protected] I will send you a secure PayPal invoice and ship you your kit! 35 Copyright 2007 – Taz Tally Seminars Color Image Evaluation, Correction and Adjustment Taz Tally Taz Tally Seminars E-mail: [email protected] Web: www.taztallyhpotography.com www.taztallyphotography.com 36 Copyright 2007 – Taz Tally Seminars
