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Intro to Color Management Part 1

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Intro to Color Management Part 1 Terry Hewitt ([email protected]) • Colour is an enormous subject rich in • Mathematics Make you aware of • Physics Chemistry Issues with colour • • Biology (images, cameras, scanners & printers) • Image Processing • Psychology • ... Key terms and their definitions ICC profiles Colour management tools How to set it all up Colour Management 29 April, 2019 2 Colour Management 29 April, 2019 3 Colour Management 29 April, 2019 4 Colour Management 29 April, 2019 5 Obvious Problem Colours don’t match Which is wrong? Laptop Projector Print Emissive vs Reflective Not So Obvious Each device supports a differing range of colours (gamut) Colour Management 29 April, 2019 6 Colour Management 29 April, 2019 7 165, 5, 6 177, 44, 55 255, 0, 0 127, 0 , 0 194, 84, 97 200, 0, 0 Colour Management 29 April, 2019 8 Colour Event has 3 components: Light Source Object Observer How do we standardise this? Colour Management 29 April, 2019 9 Daylight Fluorescent Flash Gun Colour Management 29 April, 2019 10 CIE 1931 XYZ diagram 3D display of all possible tristimulus values Cone of real (visible) colours Axes outside this cone Expresses colour measurement Basis for all other CIE models Used to convert between models Colour Management 29 April, 2019 11 map points to X+Y+Z=1 plane removes effect of brightness Use xy instead of XYZ Colour Management 29 April, 2019 12 Now we start to see the problem! ProPhotoRGB AdobeRGB sRGB Epson Paper Newsprint Colour Management 29 April, 2019 13 1931 CIE XYZ CIE 1976 UCS uniform chromaticity scale transformation of 1931 diagram CIE 1976 L*u*v* perceptually uniform space distances relate to perceived differences in colour used in film, TV and computer graphics CIE 1976 L*C*Huv CIE 1976 L*a*b* Pantone Munsell sRGB Adobe RGB I lost the will to live at this point ProPhotoRGB Colour Management 29 April, 2019 14 Red=(255,0,0) Green=(0,255,0) Blue=(0,0,255) Green=(0,255,0) Green=(0,255,0) Red=(255,0,0) Red=(255,0,0) Blue=(0,0,255) Blue=(0,0,255) Colour Management 29 April, 2019 15 Take a “line” on the diagram And split into 255 values One line is “sRGB” 0-255 = 0.2 – 0.6 Another line is “AdobeRGB” 0-255 = 0.2 – 0.8 ... And I know how to convert sRGB to CIE XYZ etc Colour Management 29 April, 2019 16 Printers (Cameras, Monitors) Result Devices only convert to/from XYZ (or LAB) Need to convert to/from one or more of these to Software exists on Computer to amount of ink for each do other conversions colour These are called profiles (.ICC files) They also contain the gamut Colour Management 29 April, 2019 17 sRGB Adobe RGB ProPhotoRGB Lowest common Better for RGB data Very large colour space denominator scanning or photography Need to use 16 bit files Consumer equipment Widely used by WWW Photographers Growing in popularity Image libraries Lots of printers Can be a very good choice Default for Lightroom Not too large, but larger Small colour space than most monitors High quality monitors Use carefully now have similar gamuts Built-in to many DLSRs Colour Management 29 April, 2019 18 Colour Management 29 April, 2019 19 Almost all hardware & software you use will use colour management already All of the software is in place The Problem is Device Profiles Wrong ones Inaccurate You must calibrate your devices Colour Management 29 April, 2019 20 Rendering Intent Rendering Intent (HTML) Colour Management 29 April, 2019 21 Colour Management 29 April, 2019 22 Colour Management 29 April, 2019 24 Colour Management 29 April, 2019 25 I.e., let someone else do it E.g., Camera uses sRGB, DS Colour Labs use sRGB Pros Its easy It costs nothing Its quick It allows you to focus on the art of photography Cons Colours vary from device to device Colour Management 29 April, 2019 26 Colour Management 29 April, 2019 27 A calibrated monitor is your stake in the ground Don’t buy a cheap monitor Calibration adjusts the monitor to a specific colour temperature gamma black & white luminance Calibration produces a display profile (.icc) Software + operating system ensure same display profile every time you use your computer Colour Management 29 April, 2019 28 Twiddle knobs with a known image Less effective Calibrize or QuickGamma More With an instrument effective Known image Accurate measurement 29 April, 2019 Colour Management 29 QuickGamma Colour Management 29 April, 2019 30 Calibrize (doesn't work on my laptop!) Colour Management 29 April, 2019 31 Instruments to choose from Spyder5 (express, PRO or Elite) i1Basic Pro, i1Dispaly Pro, i1Photo Pro 2 ColorMunki Photo (I’ve got one of these) Pantone Huey Colour Management 29 April, 2019 32 Keep ambient light low Avoid glare on screen Let monitor warm up for 30 minutes Clean the screen Remove Adobe Gamma if you’ve used it Adjust monitor with OSD Test when completed Colour Management 29 April, 2019 33 Profile saved into correct location. Profile set as default for that monitor. Calibrate Monitor with ColorMunki Colour Management 29 April, 2019 34 After 1st monitor calibration all previous images may look different Hopefully you did non-destructive editing! Suppose your monitor had a Green colour cast You reduced green in images to look OK on screen You calibrate your monitor (remove green colour cast) Those images now lack green! Colour Management 29 April, 2019 35 Colour Management 29 April, 2019 36 X-Rite ColorPassport (I’ve got one of these too!) Plus software Software aimed at Lightroom And Adobe RAW Colour Management 29 April, 2019 37 Show Lightroom Colour Management 29 April, 2019 38 Colour Management 29 April, 2019 39 Good Inkjet prints need Good pigment inks Quality media Correct resolution images Sharpened images Accurate profiles Colour Management 29 April, 2019 40 Ambient lighting should be low and consistent If viewing prints use colour accurate lighting Adjust monitor calibration targets if needed Colour Management 29 April, 2019 41 Accurate paper/ink/printer profiles = richer prints that closely match what you see on your monitor Ink will lay on paper as intended with artful grain patterns Without profiles you need to rely on trial and error, guessing, and luck Paper profiles are easy to obtain and use Some may be swapped for others, but it requires trial & error Colour Management 29 April, 2019 42 Calibration Set printer to known settings Colour management OFF Print a known image Measure it Calculate & Create ICC profile Use Caveat Set printer to known settings For Lightroom & Photoshop Colour management ON Set printer to known settings Select new profile ( Colour management OFF) In LR/PS select new profile Colour Management 29 April, 2019 43 Installed with drivers Download from paper and/or device manufacturers Newer printers may not yet have paper profiles Some OEM profiles can be successfully substituted for branded ones Ilford for Costco or Staples Profiling Services Create your own Colour Management 29 April, 2019 44 X-rite i1Photo Pro 2 Very accurate Expensive X-rite ColorMunki Photo (I’ve got one of these!) Cheaper Not as accurate Show this one! Colour Management 29 April, 2019 45 Scanner (Lprof/ArgyllCMS, Monaco EZColor) May have different gamut Don’t forget to calibrate scanner first! Profiling Service E.g., Can be very accurate. Check what support given. Cheapest option if not many papers. Colour Management 29 April, 2019 46 Select closest media type Turn off application & driver colour management Save settings Check settings Colour Management 29 April, 2019 47 Printing Preferences Colour Management 29 April, 2019 48 Colour Management 29 April, 2019 49 Colour Management 29 April, 2019 50 Colour Management 29 April, 2019 51 . Colour Management 29 April, 2019 52 Colour Management 29 April, 2019 54 Choice of charts - number of patches More not always better Some services/software offer more colour patches Leave chart to dry a minimum of 30 minutes Profile needed for each media Valid only for driver settings that test chart was printed with . Colour Management 29 April, 2019 56 Gamut of Ink/Media Brightness relative to screen Lighting used Blocked nozzles Suitability & correct side of media Colour Management 29 April, 2019 57 Use good special test image not your own work Check for banding & casts - under daylight! Check flesh tones & neutrals Colour Management 29 April, 2019 58 Get them to output test images They will usually send you a test image for free Ask for their colour management preferences Don’t accept poor prints Supply flattened sharpened images at output size Colour Management 29 April, 2019 59 Colour Management 29 April, 2019 60 Colour Management 29 April, 2019 61 Photoshop can be completely colour managed You MUST choose which colour space to work in Starts when image is imported Be consistent Know the delivery targets for your images Paper Website Magazine Poster Colour Management 29 April, 2019 62 Edit Colour Settings Open X—101-Cropped.jpg Open X—101-Full Size.jpg Open No Profile.jpg Show Printing Colour Management 29 April, 2019 63 Colour Management 29 April, 2019 64 Colour Management 29 April, 2019 65 default colour space is ProPhoto RGB the largest one available. You can configure Lightroom to export images to sRGB or Adobe RGB colour spaces. Images going from Lightroom to Photoshop for more editing can be exported in any of the three colour spaces. 29 April, 2019 Colour Management 66 Printing Let Lightroom do it all Don’t forget to disable colour management in printer! 29 April, 2019 Colour Management 67 Colour Management 29 April, 2019 68 Use quality materials Camera, Monitor, printer, paper, inks, Lighting ..
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