Apple ColorSync 2 offers a programming interface to a fast computing engine which uses ICC profiles as parameters to perform color transformations between different devices. The Apple ColorSync 2.5 color matching module (CMM) has been co-developed by Apple Computer and Linotype-Hell. PDF Handshake's built-in color management is based on the Apple ColorSync 2.5 CMM.
Bilevel images contain only two colors: black and white. "Lineart" is one example of bilevel images.
The different CCITT specifications describe communication protocols for a particular class of devices (e.g. facsimile devices) and represent specific modes of compression. The specifications have been developed by the International Telegraph and Telephone Consultative Committee (CCITT).
The "Commission Internationale de l'Eclairage" (CIE) is responsible for the definition of color models and the standardization of color descriptions. The Lab color space has been defined by the CIE.
Lab colors are defined by the L-value for lightness and the co-ordinates a and b defining the quantitative distance of a color from a reference white point. The Lab color space includes all visible colors and is device independent.
Color printing is based on the CMYK color space. Cyan, magenta, yellow, and black inks are mixed on paper to produce a given color. The definitions of the basic colors cyan, magenta, yellow, and black are slightly different in Europe (Euroscale), the US (SWOP), and Japan.
The process of adjusting colors to achieve maximum similarity from the gamut of one color space to the other. In practice, the color data delivered by a given device - e.g. a scanner - have to be transformed so that the colors can exactly be reproduced by a second device - e.g. a printer.
See:
Bilevel, Grayscale, Indexed, RGB, CMYK, CIE Lab, Spot, Multichannel, Multitones.
See:
LZW, CCITT, JPEG, PackBits RLE.
The process of transforming a high-resolution image into a low-resolution image.
The Encapsulated PostScript File (EPSF) format is meant for pictures that are to be used in different applications or on different platforms. EPSF files contain a text file that lists the PostScript instructions necessary to create the picture and, in addition to that, may contain a PICT preview of the image. If an EPSF file is created by - or exported from - an illustration or DTP application (e.g. FreeHand, PageMaker, QuarkXPress) this file contains object-based PostScript instructions and can only be placed in other documents; it cannot be reloaded or edited again. Editing is only possible, if you are using an image processing application like Photoshop which is able to create raster-based EPSF files. Please note that EPSF files and PC-EPSF files (for DOS/Windows computers) are not identical. PC-EPSF files contain LZW- compressed TIFF previews (instead of PICT previews) and, therefore, behave different in specific situations.
Euroscale defines the European ink set for the process colors cyan, magenta, yellow, and black.
See:
EPSF, JPEG, PICT, TIFF.
The gamut is the range of color that a given device can produce. Gamut mapping means re-defining the colors of a given device so that its gamut becomes (approximately) identical to that of a second device.
Grayscale images are a generalization of Bilevel images. They contain black and white and different shades of gray.
Private directory provided for each UNIX user. The home directory is the current directory when you login to a server.
The "International Color Consortium" (ICC) is a group of vendors who defined the ICC profile format. This format is a cross-platform specification which allows third party vendors to develop profile tools and applications supporting the ICC profile standard. The founding members of this consortium include: Adobe Systems Inc., Agfa-Gevaert N.V., Apple Computer Inc., Eastman Kodak Company, FOGRA (Honorary), Microsoft Corporation, Silicon Graphics Inc., Sun Microsystems Inc., and Taligent Inc. These companies have committed themselves to fully support this specification in their operating systems, platforms and applications. (See also
Profiles.)
Images with indexed colors use colors from a given RGB color map. Every pixel of such an image contains a reference to a specific color in the map.
JPEG is a file format and - at the same time - a mode of compression. Images are compressed by replacing several similar colors by one color only. Thus, a number of color data are lost and cannot be recreated when the files are opened again. JPEG has been developed by the Joint Photographic Experts Group (JPEG).
Our OPI Server generates low-resolution representations of high-resolution image files or PDF files. These representations are called "layout".
LZW (Lempel, Ziv, Welch - names of developers) is a lossless compression that can be used for different color modes and file formats. It collects repetitive patterns in a table and saves references to this table whenever possible.
A Multichannel image contains different color modes - e.g. CMYK colors and several spot colors - at the same time.
Colorized Grayscale (mathematical)
Apple Macintosh OS compression, mainly used for PICT files. See also:
RLE
Portable Document Format (PDF), is a file format developed by Adobe Systems, Inc. PDF files were originally designed for online reading on all platforms.
The PICT file format is the native Macintosh image format.
PostScript is an industry-standard page-description language invented by Adobe and introduced in 1985 for printing documents that integrate text, graphics, images, and color. Built into printers from over 55 major manufacturers worldwide.
In PostScript font files, the character information are given in PostScript code. PostScript printers require PostScript fonts, or some sort of software that is able to transform non-PostScript fonts. For detailed information about the "font business", please read appendix
A 4: "About fonts".
PostScript printer description (PPD), is a file format developed by Adobe Systems, Inc. PPD files contain information enabling software to produce the best results possible for each type of designated printer.
A profile is a device description. It contains information about how a given device (scanner, monitor, or printer) mixes and reproduces colors.
The approach taken when a color management module (CMM) maps or translates the colors of an image to the color gamut of a destination device. Each profile supports different rendering intents. Changing the rendering intent may lead to a different output result, even though you did not change the profile.
The dots per inch (dpi) value of an image indicates its resolution. The dpi value of a given device (e.g. scanner, printer) defines its resolution capacity. Very clear and sharp images require input/output devices with a high resolution (about 300 dpi or more). Monitor resolutions usually range from 72 to 100 dpi.
Screens and monitors produce colors by means of red, green and blue light (RGB). The light intensities make up a given color. Scanners also work with RGB colors. They read the amounts of red, green, and blue light that are reflected from an image (or transmitted if you scan transparent images). RGB images contain three components per pixel, namely a specific amount of red, green, and blue.
A "Raster Image Processor" (RIP) performs the final calculation of the data which are sent to the output device. The RIP may be either an external unit or part of the output device itself. A PostScript laser printer for example contains its RIP.
Run-Length Encoding (RLE) is a mode of compression that saves repetitive patterns only once and adds the number of repetitions. RLE is a lossless compression.
The top-most directory on a UNIX computer is called "root" directory. If you are logged in as "root", you can access all other directories and subdirectories on the system.
A spooler is a set of programs which manage print jobs. A spooler acts as a buffer for the files that have been sent to an output device. In this documentation, "printer queue" may be used as a synonym for "spooler".
A spot color is an exactly defined full tone color. Spot colors are printed on their own separation plates when separations are specified.
The "Specifications for Web Offset Publications" (SWOP) define US standards for color separation and color printing.
This expression is used to specify that an image file or PDF document contains ICC profile information (either embedded or by reference).
The Tagged Image File Format (TIFF) is a standard graphics file format for files that are to be exchanged among several applications and environments, including Macintosh, MS-DOS, and UNIX.
TrueType font files have their own character descriptions; they do not contain PostScript compatible code. TrueType fonts are very popular - especially in Windows PC environments - but require special treatment when printing to a PostScript printer. For detailed information about the "font business", please read appendix
A 4: "About fonts".
Symbol for the CMYK color space.
Symbol for the Lab color space.
Symbol for the RGB color space.
