Accurate Color in AutoCAD 2004

Transcription

1 Course VI33-2 Accurate Color in AutoCAD 2004 Peter Sheerin Dec 4, :00 PM 04:30 PM 1

2 2 Color Models RGB Primary model for computer graphics and lightemitting displays (CRT, LCD, LED, etc.) CMYK Primary model for print graphics and light-reflecting media (pencil, chalk, ink, and paint on paper, building materials, and road signs). RGB Additive color model, where the primary colors (Red, Green, Blue) are combined to create all other colors. Equal amounts of red and green create yellow. (Three 8-bit channels=24-bit color) + =

3 3 RGBA RGB + Alpha. A fourth color channel is used to indicate the amount of transparency applied to the RGB color (four 8-bit channels=32-bit color). + = CMYK Subtractive color model, where addition of the primary colors (Cyan, Magenta, Yellow, and black) absorbs light of a particular wavelength, changing the colors of light reflected back to your eyes. Photo printers use more colors of ink to achieve finer Yellow control over the wavelengths that are reflected back. Cyan Magenta = =

4 4 srgb Color Space A precise definition for RGB that allows srgb images to be reproduced accurately on different platforms and media under varying ambient lighting conditions. HTML 3.2 specification, 1997 The standard color space for: The Web, since the HTML 3.2 specification Windows 98 and higher PNG, SVG, and the Digital camera JPEG format (EXIF) Most color printers, especially HP DeskJets and DesignJets Why srgb is Needed

5 5 Configuring Monitors for srgb Poor man's srgb calibration: html (see srgb configuration sidebar at bottom) Configuring Printers for srgb (HP s driver doesn t have an srgb setting)

6 6 Color Spaces RGB srgb linear RGB Adobe RGB Apple RGB ColorMatch RGB ProPhoto RGB Wide Gamut RGB ROMM-RGB RIMM-RGB CIE RGB CMYK U.S. Web (SWOP; web-offset negative) U.S. Sheetfed Euroscale Japan Color Monitor Color Accuracy DisplayMate can be used for: Judging the quality of a monitor Adjusting any monitor to get the best image quality sp

7 7 New Color Features in AutoCAD 2004 First time color accuracy has been available in AutoCAD 24-bit RGB color Pantone colors Gradient Fills srgb, Color accuracy True-Color 8-bit color: palette-based images, 256 colors 24-bit color: 8-bits/channel (red, green, blue) generally recognized as the minimum for accurate display of color 32-bit color: 8-bits/channel (red, green, blue, alpha) Same as 24-bit color, but with variable transparency for each pixel Supported by TIFF and PNG, but not JPEG, for example HDRI (special-purpose) 16-bits/channel (64-bit) or floating-point TIFF

8 8 Cool Things you can do With Alpha-Level Transparency This 6Kb, 4-color PNG has a black background that is 100% transparent, and a sea-green fill that is about 60% transparent. 24-bit color in AutoCAD Standard AutoCAD color dialog has two new tabs, and shows RGB values for each color HSL lets you change the hue, saturation, and luminance RGB lets you change the red, blue, and green separately AutoCAD s dialog is the only one I ve seen with sliders that show the resulting range

9 9 AutoCAD 2004 s Color Dialogs Little-Known Tips Key concept: All PANTONE colors map directly to srgb colors, and will always make a round trip without loss of the color accuracy You can download the Autodesk Color Book Editor to make your own color books: iteid=123112&id= &linkid= Converting ACI colors to RGB (kind of) ID=123112&id= &linkID=

10 10 Industry Colors in AutoCAD Pantone is the leader in color palettes in the US, while RAL is common in Germany AutoCAD 2004 includes the following color books: Pantone a & i-cotton (a.k.a. Textile Color System) Pantone a & i-paper (a.k.a. Textile Color System) Pantone metallic coated Pantone pastel coated Pantone process coated Pantone solid coated (a.k.a. PANTONE MATCHING SYSTEM) Pantone solid uncoated (a.k.a. PANTONE MATCHING SYSTEM) RAL Classic RAL Design Pantone Colors Systems PANTONE MATCHING SYSTEM 1,114 colors for printing on paper E.g. PANTONE 186 C PANTONE TEXTILE Color System 1,757 colors for printing on paper & fabric (a.k.a. PANTONE for Architecture and Interiors) E.g. PANTONE TC PLASTICS Color System 1,005 opaque and 735 transparent colors Not available in AutoCAD 2004

11 11 Matching Real-World Colors Use a color matching chart, such as PANTONE s color guides PANTONE sells a spot scanner to aid you in finding the closest match the PANTONE Color Cue and Color Cue TX PANTONE Color Cue Color Cue PANTONE Color ink formulas, CMYK, Adobe RGB 255, srgb, HTML, L*a*b*, Hexachrome, and XYZ values Color Cue TX PANTONE TEXTILE Color System Paper and Cotton (a.k.a. PANTONE for Architecture and), srgb, HTML, L*a*b* and XYZ values

12 12 Color Standards Resources A Standard Default Color Space for the Internet--sRGB: and scrgb e-srgb spec PRINT Image Matching The International Color Consortium (ICC) Pantone Color Cue &idarea=1&idproduct=373&idarticletype_products=0 The Sheerin Report #16 & #18: Color Accuracy Contacting Me

13 Day Job Peter K. Sheerin Product Review Editor, Game Developer magazine Editor, Gamasutra.com This address accepts only S/MIME messages those using x.509 certificates for encryption and/or signing. Published by CMP Media, former owner of a certain CAD magazine Personal Web Site Peter K. Sheerin PetesGuide.com A blog and reference site about technology mostly Web standards, but other stuff, too. pete@petesguide.com This address accepts only S/MIME messages those using x.509 certificates for encryption and/or signing. peter@petesguide.com if you don t know what this means. 13

14 14 The CAD Society Joe Greco President Peter K. Sheerin Secretary/Webmaster