Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 1 Integrated Color Solutions A presentation of an ICC Standard and how it relates to DICOM Jack Ladson Franz Herbert

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 2 What is the ICC? International Color Consortium –1993 by 8 industry Suppliers –GOAL Create, promote, and encourage the evaluation of an open, supplier neutral, cross platform, color management system, architecture, and components.

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 3 Who were the founders? Adobe Agfa Apple Kodak FOGRA Microsoft Silicon Graphics Sun Microcomputers

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 4 What are the problems without Color Management? Color Fidelity Color Predictability Inconsistency - Color looks different –An image viewed on different monitors by same manufacturer –An image viewed on the same monitor type by different manufacturers –An image viewed on different monitor types –An image on a monitor comparing it to a print (negative) –Printing a copy of a negative

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 5 Why are Colors Reproduced Differently? Input devices capture color differently –Scanners –Digital Cameras –Human Eye Output devices are different –Monitors CRT’s, LCD’s, Video, etc. –Printers Laser, Inkjet, Offset, Gravure, etc. Media/Ink combinations OS’s Interpret & reproduce colors differently –MAC, MS, Unix, Linux, Legacy –Device Drivers have different I & O

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 6 What is the solution? A mathematical transform is needed to map the colors from one source (input device color space) to another output (destination color space) device. –Note that this transform must account for the color characteristics of the source and the destination devices and all other functions affecting appearance.

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 7 What does this look like? Source Color Values TRANSFORMTRANSFORM Destination Color Values

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 8 Two Methodologies Device dependent transforms Device independent transforms

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 9 Device Dependent Transforms Disadvantages n devices needs n 2 transforms A new device requires n transforms Recalibration requires n transforms Note that each is a different device to device transform

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 10 Device Independent Transforms PCS Advantages (n=1) n devices requires n transforms A new device needs one transform Recalibration requires one new transform PCS Definition PCS, Profile Connection Space, is the reference color space in which colors are encoded to provide an interface & transform for connecting the source to the destination.

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 11 Gamut Mapping A “gamut”can be defined as; the the total amount of color (space) that the device is able to reproduce. Note that typically CMYK (a printer gamut for example) is less than RGB (a display gamut for example) which means that the printer has less saturated colors and fewer colors.

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 12 Gamut Mapping Illustrated Play Movie Here In this case gamut mapping refers to the mapping from the color space of one device to the color space of another. The colors that cannot be represented in the destination device need to be altered by mapping so that they can be represented.

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 13 Rendering Intents 1.Perceptual Preferred method for pictures. Even colors that match will usually be changed, because the human visual system is more sensitive to relative color difference. 2. Saturated Business graphics and schematic want the most saturated color - color accuracy is not important 3. Relative Colorimetric Colorimetrically accurate but relative to media 4. Absolute Colorimetric Colorimetrically accurate & calibrated to the “perfect diffuser”

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 14 Where to improve? 1.Gamut Mapping We must understand when to gamut map as data are lost. 2.White Point/ Black Point Mapping Black (no signal; although some light including ambient effects four judgment and induces a bias. The tristimulus values is not always 0,0,0. This decision - encoding 0,0,0 or defining the black point effects the white point scaling & corresponding vector lengths. 3. Viewing Environment Illumination intensity, reflections, & color temperature 4. Chromatic Adaptation CIECAM02

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 15 How do we proceed? Characterization Input Display Environment Dynamic Range Resolution True Color False Pseudo Absolute Density Dynamic Range Resolution Real Estate Calibration Profiling Electronics, etc. Illumination Level Ambient Light Illuminant Color Reflections Walls Normal Color Vision Color appearance Models Stimulants Observer

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 16 Display Calibration

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 17 Display Calibration

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 18 A Display Calibration Methodology 1.Set Video LUT’s to identity values (curves) 2.Compute desired XYZ values from standard spectrum of desired illuminant 3.Measure white patch (for standardization) 4.Use white patch values as scalars for XYZ calculations 5.Modify end points of Video LUT’s until desired white point is within 0.1 ∆E units 6.Measure a 33 step grayscale 7.Compute correction function which turns display response into perfect Gamma function of Add correction function into Video LUT’s 9.Measure 25%, 50% and 75% gray patch, iterating to ensure correct white chromaticity values and correct Gamma value 10.Measure RGB grid 11.Compute ICC Profile

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 19 Calibration Results Target Gamma of 2.2, D65

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 20 Video Display Response Display Calibrated to: Illuminant D-65  (gamma) 2.2 Results for Apple Cinema Display - before (blue) - after (magenta)

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 21 Calibration Results D65: x =.3127, y =.3293 White Point Uniformity at D65

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 22 The Environment

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 23 Viewing Environments

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 24 Test Image Full Range

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 25 Test Image SWOP

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 26 Test Image - Newsprint

Click to edit Master title style Click to edit Master text styles Second level Third level Fourth level Fifth level 27 The FINALE A demonstration of Soft Copy Images Reproduced Across Platforms Remote Interactive Collaboration Across Networks