1-bit image • An image whose pixels are either black or white. See also Grayscale image; Image file; Monochrome image; paint-type image; TIFF.
8-bit palette TIFF • See Palette TIFF file.
Additive colors • See RGB; Subtractive colors.
Adobe PostScript Color Separation Conventions • A set of PostScript file format conventions developed by Adobe Systems, Inc.
ASCII • Acronym for American Standard Code for Information Interchange. A standard file format that most computer applications can read. See also Binary.
Angle • The direction of lines or rows of dots in a halftone screen.
APD files • Aldus Printer Description files. Description files, developed by Aldus Corporation, that contain detailed information about specific printers. Aldus PageMaker and early versions of Aldus FreeHand use APD files to print publications to an output device or to disk. See also PDX files; PPD files.
Auto enhance • An Image menu command that analyzes the gray values in the image, then redistributes the values to adjust shadows, midtones, and highlights simultaneously. These adjustments improve the image’s overall print quality by redistributing the densities of the tones.
Auto balance • A Color menu command used to eliminate an undesirable color cast. Aldus PrePrint automatically evaluates all the color values in the image to determine if there is an overall cast. If a cast exists, Aldus PrePrint balances the colors in the image to remove it.
Balance to sample • A Color menu command used to eliminate an undesirable color cast. Unlike “Auto balance,” this command lets you choose the color that Aldus PrePrint uses to balance the image.
Binary • The file format Aldus PrePrint uses to store image data within a separation file. Also, a format option for saving image data in a DCS file. See also ASCII.
Black & white image • See 1-bit image.
Bleed • Part of a printed image that extends beyond the page boundary. When the page is trimmed to size, the “bleed” extends to the edge of the paper with no margin.
Brightness • The lightness of an image. Brightness is represented by a value between 0 (dimmest) and 255 (brightest). See Intensity.
Color conversion table • The table of values Aldus PrePrint uses to convert RGB image data to its CMYK equivalent for printing process color separations. You can adjust the values in the Color conversion table by using the “Separation corrections” dialog box.
Color sample box • The box at the left end of the information bar that displays the currently selected color. Also, the box in the top center of the “Separation corrections” dialog box that displays the active color.
Color separation • The process of preparing color artwork or publications for commercial printing by separating the image or publication into individual pages that contain components of each color. Process colors, created on a printing press by printing combinations of the four process inks, are represented on four pages (films). Spot colors, created by printing a single ink of a particular color, are represented on one page (film) for every spot color used.
Composite image • An image produced by printing actual or simulated colors directly on a page.
Contrast • The difference between the dark and light values in an image. High-contrast images contain mostly very dark and very light values, with few intermediate shades. Low-contrast images contain mostly medium gray values.
CMYK • The process color model that combines specified percentages of cyan, magenta, yellow, and black to simulate any color in the spectrum. “K” represents black to eliminate confusion with the color blue. See also Subtractive colors; RGB.
CMYK TIFF file • A TIFF image file preseparated into cyan, magenta, yellow, and black components.
Crop marks • Short, fine lines that mark where a printed page should be trimmed when it is printed on paper that is larger than the image area. You can print crop marks by clicking the “Printer marks” option in the “Print options” dialog box.
Darken • An Image menu command that decreases the brightness of all the pixels in the image.
DCS (Desktop Color Separation) file • A preseparated image consisting of five files: four process color separation files (containing the cyan, magenta, yellow, and black components of the image) and a composite EPS placeholder file. PrePrint allows you to save image files in DCS format. When you open a DCS file, Aldus PrePrint displays the Links window (not the image itself).
Decrease contrast • An Image menu command that decreases the difference between light and dark pixels within the image’s dynamic range. The “Decrease contrast” command is typically used to flatten the tones in an image.
Decrease saturation • A Color menu command that decreases the strength of the colors in your image.
Densitometer • Also known as a transmission or reflective densitometer. An instrument that measures the density (opacity) of a printed area. In Aldus PrePrint, the cursor in the image window simulates a densitometer’s photoelectric eye.
Density • The measure of the opacity of a transparent or translucent object. On a film negative, the greater the density, the darker the area is.
Dither display • A Windows menu command that redefines the colors of the pixels on the screen to simulate more colors than the display can show.
Dynamic range • The range of dark and light values in an image. See also Contrast.
DPI (Dots per inch) • The number of dots printed per linear inch on a separation, displayed on a monitor, or scanned on a scanning device. DPI is dependent upon the resolution of the output device. See also LPI (Lines per inch); Resolution; Frequency.
Enhance • An Image menu command that lets you enhance detail in the shadows, midtones, or highlights of an image.
EPS (Encapsulated PostScript) • A file format consisting of PostScript code and comments that describe a draw-type illustration. If the illustration contains an image, the EPS file also contains link information. See also Link; OPI; PostScript.
Eyedropper • The cursor that appears in the image window when you hold down the mouse button. In Aldus PrePrint, you can use the eyedropper to collect a sample color to use for balancing the image tones or for correcting the color conversion table.
Frequency • The number of lines per inch in a halftone screen. See also LPI (Lines per inch).
Gain compensation • In Aldus PrePrint, a setting used to compensate for the increase in dot size when wet ink spreads. You can apply gain compensation to an entire document or just to the images in the document by choosing the appropriate setting in the “Press controls” dialog box.
GCR (Gray component replacement) • A printing process in which black ink is substituted for equal percentages of cyan, magenta, and yellow inks to adjust the overall ink density in the printed image. A 30% GCR setting indicates that 30% of the three process inks will be replaced with black ink throughout the image. See also UCR (Under Color Removal).
Grayscale • The full range of gray values, ranging from black (0) to white (255). See also Brightness; Intensity.
Gray value • A number from 0 to 255 that specifies a particular shade of gray.
Grayscale image • An image whose pixels have brightness values that range throughout the gray scale. The number of gray values displayed depends on the amount of information (number of bits) saved with the image. In Aldus PrePrint, you can adjust 8-bit grayscale images using commands on the Image menu. See also 1-bit image.
Halftone • Traditionally, a reproduction of a continuous tone image created by photographing the image through a halftone screen, which breaks the gray tones in the image into dots of varying size. When the dots are printed, they create the illusion of the various gray values in the image. In Aldus PrePrint, halftone screens are computed using information from the PPD and PDX files. See also PDX files; PPD files.
High-resolution image • An image file created by a high-resolution scanner. Aldus PrePrint uses the high-resolution images linked to the OPI file when printing separations. See also Link; Low-resolution image.
HLS (Hue, Lightness, Saturation) • A color model, based on transmitted light, that uses hue, lightness, and saturation instead of primary colors (red, green, and blue). To see the HLS values of an image, hold down the Option key and click the mouse button. PrePrint replaces the RGB values in the Image window information bar with the HLS values. Note: The HLS values calculated by PrePrint may vary from the HLS values in other applications. PrePrint’s formula for calculating saturation produces a value that more closely corresponds to the perceptual distance from the gray axis of the color space.
Illustration file • A file created in a graphics application, such as Aldus FreeHand.
Imagesetter • A high-resolution printing device that produces separations or composites on film or paper.
Image file • A file containing scanned image data (as in a TIFF or DCS file) or drawn image data (as in a paint-type file).
Image window • The window that Aldus PrePrint displays when you open a TIFF file.
Increase contrast • An Image menu command that increases differences between light and dark pixels within the image’s dynamic range. You can use the “Increase contrast” command to enhance a flat image whose gray values fall within a narrow range.
Increase saturation • A Color menu command that increases the overall strength of the colors in an image.
Information bar • The area located beneath the menu bar in the image window. The information bar contains the Color sample box, and displays the CMYK and RGB values of the pixel currently under the densitometer cursor. It also displays the amount of available free space on the disk that contains the image.
Information window • The area at the bottom of the “Print” dialog box that displays a summary of the settings in the “Print options” and “Press controls” dialog boxes.
Intensity • The lightness of an image. See also Brightness.
Knockout • A printing technique for printing overlapping elements without mixing the inks used to print them. For example, when one element overlaps another, the ink used to print the bottom element knocks out (does not print) in any area where the two elements overlap. Knockout is the opposite of overprint. See also Overprint.
Lighten • An Image menu command that increases the brightness of all the pixels in the image.
Link • The connection between an image file and an OPI file. The link information code contained in the OPI file describes the image file and its location. When you print, Aldus PrePrint uses this link to locate and separate the high-resolution versions of the image.
Links window • The window Aldus PrePrint displays when you open an OPI, EPS, or DCS file. From this window you can print, create links between OPI files and image files, and open image files.
Low-resolution image • A low-resolution version of a scanned image placed in PageMaker which is used for display purposes. The low-resolution image is contained within the OPI file. (High-resolution images linked to the publication are used for printing separations.) See also High-resolution image; Link.
LPI (Lines per inch) • A measurement of screen frequency. The number of lines per inch printed on the separation. See also Frequency.
Mask • An opaque area in a separation that is used to prevent an image area from being exposed.
Moiré • An undesirable pattern caused by misregistration of the halftone screens.
Monochrome image • An image whose pixels are either one color or white. See also 1-bit image; Grayscale image.
Neutral • An area in an image with no color cast or hue (i.e., a gray).
OPI (Open Prepress Interface) • A PostScript file convention designed by Aldus Corporation to provide a standard format for sending files from color desktop publications to high-end prepress systems to minimize stripping and rework costs. (OPI comments include image position, cropping, sizing, and linking information.) When you open an OPI file, Aldus PrePrint displays the Links window, which lists any external image files that are linked to the publication. See also Links.
Optimize display • A Windows menu command used to redraw an image on an 8-bit screen using the best 256-color palette.
Overprint • A printing technique in which all overlapping inks print and transparent inks blend to form a new color. Overprint is the opposite of knockout. See also Knockout.
Page size • The page size specified in the original application (i.e., the page specified in Aldus PageMaker’s “Page setup” dialog box). The page size must be smaller than the paper size specified in the PrePrint “Print options” dialog box for all the printer marks to be printed. See also Paper size.
PageMaker • In Aldus PrePrint, this term refers to PageMaker Color Extension or to PageMaker version 4.0 or later.
Paint-type file • A file created in a paint application, such as MacPaint. When you open a paint-type file, Aldus PrePrint opens a copy of the file as a 1-bit TIFF image in an untitled window. If you save the file, Aldus PrePrint saves it as a 1-bit TIFF file. Note that Image and Color menu commands are not available when you are working in a paint-type file.
Palette TIFF file • An 8-bit color TIFF file that contains references to a color table (rather than containing actual color data). Because the table can contain a maximum of 256 colors, the image is limited to 256 colors. Palette TIFF files are typically created by color paint programs. In Aldus PrePrint, you can open and separate a palette TIFF file but you cannot use Image or Color menu commands to adjust the image.
PANTONE MATCHING SYSTEM • An internationally recognized language of color used for selection, specification, communication, and control of color reproduction.
Paper size • The actual size of the paper on which you’re printing. The paper size must be larger that the page setup boundary to contain all the printer marks. See also Page size.
PDX files • Printer Description Extension files. Aldus PrePrint uses a PDX file in conjunction with the corresponding PPD file to produce output on a specified device. See also PPD files.
PICT • A file format originally designed for object-oriented graphics. Though image files can be saved as PICT files, the PICT format is not recommended for use in files you intend for separations. PICT files should be printed on non-PostScript output devices.
Pixel • The display dots on a computer screen or a single sample of data in an image file. Abbreviated from “picture element.”
PostScript • A page description language, developed by Adobe Systems Inc., that is used by applications and high-resolution printers and typesetters. See also EPS (Encapsulated PostScript).
PPD files • PostScript Printer Description files. Printer description files, developed by Adobe Systems Inc. or a printer manufacturer, that contain detailed information about printers, including screen angle and frequency information designed to reduce moiré patterns in color separations. Aldus PrePrint uses a PPD file in conjunction with the corresponding PDX file to produce output on a specified device. See also PDX files.
PPI (Pixels per inch) • A designation for scanning resolution. The amount of data recorded per inch.
Printer marks • Marks printed outside the page setup boundary that help you calibrate imagesetter output, and help the commercial printer align the separations on the press and crop the printed page. These marks include crop marks, registration marks, and density control bars.
Process color • A method of printing colors in which the printer uses four colors of ink—cyan, magenta, yellow, and black—to create all the colors in the publication. See also CMYK; Subtractive colors.
Publication file • A general term that refers to any file that contains text, graphic elements, and/or images (e.g., an Aldus PageMaker publication or Aldus FreeHand illustration).
Registration marks • Crosshair lines that print in the margin as guides for positioning negatives and aligning separations.
Resample • To adjust the amount of data in an image file. For example, you may want to increase the amount of image data to eliminate a blocky pattern that appears in a printed image, or to reduce the amount of data to reduce print time or save storage space.
Resolution • The amount of data available to represent graphic detail in a given area: on a computer screen, the number of pixels in a linear inch; on a printer, the number of dots printed in a linear inch; on a scanner, the number of samples saved for a given area of the scanned image; in a halftone, the number of lines of halftone dots per inch.
RGB • A color model, based on the additive properties of transmitted light (video-type model), that mixes red, green, and blue to create all the colors in the spectrum. See also Additive colors; CMYK; Subtractive colors.
RGB TIFF file • A TIFF file containing image data described in Red, Green, and Blue components. During the separation process, Aldus PrePrint converts the RGB values to their CMYK equivalents using the Color conversion table. See also CMYK TIFF file; Color conversion table; RGB.
Ruling • See Frequency; LPI (Lines per inch).
Saturation • The intensity of a color—or how much color is present or absent—from completely saturated (full color) to gray (no color).
Scale • To reduce or enlarge an image or page proportionally.
Scanner • A hardware device that converts a two-dimensional image or a three-dimensional object into a computer file that can be placed into application files. See also DCS file; TIFF.
Separations • Printed pages (films)—one for each spot color and one for each process color—that show the locations and densities of ink necessary for reproducing all the colors in a publication or image file.
Separation file • The file that is created when you print separations to disk in Aldus PrePrint.
Sharpen • An Image menu command that brings out detail in the image.
Soften • An Image menu command that blurs the image and gives it a softer, less detailed look.
Spot color • A color that is produced by printing an ink of that specific color, rather than creating the color by combining transparent CMYK inks (e.g., printing orange ink as opposed to printing magenta ink on top of yellow ink).
Stripping • Assembling photographic negatives or positives and placing them in the correct positions on the film that will be used to make the printing plate.
Subtractive colors • Cyan, magenta, and yellow. See also CMYK; RGB.
SWOP • Acronym for Specifications for Web Offset Publications. A standard set of specifications for separations, proofs, and color printing.
TIFF (Tag Image File Format) • A document format developed by Aldus, Microsoft, and leading scanner vendors as a standard for bitmap graphics, including scanned images. A TIFF file contains data describing a single image. The image can be black-and-white (1-bit), grayscale (8-bit), or color (8-, 24-, or 32-bit). Color image data is typically written in RGB values, which PrePrint converts to CMYK equivalents for printing separations. In PrePrint, you can save image files in a variety of TIFF formats. You can also create a preseparated file, called a CMYK TIFF image file. See also CMYK; Palette TIFF file; RGB.
UCR (Under Color Removal) • A printing process in which black is substituted for equal parts of cyan, magenta, and yellow inks. Unlike GCR, which affects the entire image, UCR is applied primarily to neutral areas in the image. See also GCR (Gray Component Replacement).
Total ink coverage • The maximum total amount of cyan, magenta, yellow, and black ink that will be printed to create the image. Although 400% is allowed (100% for each of the CMYK inks), a maximum of 280–300% is recommended to reduce printing problems.
Transverse • A paper size extension. Transverse paper sizes are designed to save paper or film by printing separations side-by-side instead of end-to-end.
Trapping • A printing technique in which printed colors are slightly overlapped to minimize the effects of misregistration of the printing plates.
