Electronic Prepress and Digital PrintingChapter 9
Computer Platforms The platform of an electronic imaging system is
the computer system (hardware) that is used to operate software Word processing Page composition Drawing creation
PC (IBM personal computer)
Macintosh (Apple)
Applications, formats, or devices that work on different platforms are CROSS-PLATFORM Common Hardware Reference Platform (CHRP)
Text (Content Creation) Word processing programs
Assign codes and format to text Styles or tags
Page composition programs Recognizes formats
ASCII files (American Standard Code for Information Exchange) Formatting is lost, but text can be repurposed Reusing content intended for one medium by reformatting it for
another Transfers data from one computer to another
IMPORTANT: Maintain original text and image files Make copies and work from copies
Creating Computer ImagesPaint programs
Draw programs
Digital photography
Electronic scanning
Paint ProgramsFreehand drawings, easily edited
Bitmaps or raster graphics
Grid of pixels, filled in or empty
Enlarging bitmaps creates jagged edges because resolution is reduced (aliasing)
Antialiasing diminishes jagged edges, fuzzier
Smoothing also reduces jagged edges
Draw ProgramsVector graphics, object-oriented graphics
line defined by start and end point
Can be scaled and represented at any resolution (high resolution output)
Bezier curve is a vector graphic defined by two endpoints and two or more other points that control shape (anchors, handles)
Review Questions1. What is meant by cross-platform?
2. Reusing content intended for one medium by reformatting it for another is called _______
3. List four methods that can be used to create computer images
4. What are two methods for diminishing jaggies that should be smooth?
Manipulating ImagesAdobe Photoshop
Cropping Color and Contrast Adding or removing visual information Combining images Sharpen, Blur, and Smudge edges Mix, Choose and Apply colors Paint and Draw Clone Apply Filters Create Gradients and Textures
Raster Image Processors (RIP)Vector graphics information is transferred from a design
workstation to a RIP Hardware-software combination that converts vector images into
bitmapped images at selected output resolution View screened files before imaging Supports many font types Offers different dot shapes Can drive multiple output devices simultaneously Interprets and separates color composite files directly High-quality screening technology, reducing moiré patterns Dot-gain calibration
ImagesettersTypesetting device used to output fully-paginated text and
graphic images at a high resolution onto photographic film, paper or plates
Output problems are likely to occur during the transmission of files from the RIP to the imagesetter
Uses laser technology to output the page or color separations on the selected medium
Manufactured by different companies and differ in speed, precision, resolution, screening technology, and media capability
Page Description Languages (PDLs)Serves as the interface between the page composition
workstation and the RIP
Format by which all the elements to be placed on the page, their respective positions on the page, and the page’s position within the larger document are identified in a manner the output device can understand
Adobe PostScript
Adobe portable document format (PDF)
Hewlett-Packard PCL (Printer Control Language)
Adobe PostScript and PDFPostScript
Describes the appearance of a page to an output device Interpreter receives PostScript page descriptions and translates
them into dot patterns for a printer or pixels for a display
PDF Based on the PostScript imaging model Preserves a page’s original layout, type fonts, and graphics as one
unit to electronic transfer and viewing Device-independent format- not specifically related to any
particular device, converts data without loss of information
PDF continuedAcrobat Distiller, Acrobat Exchange, Acrobat Catalog, Acrobat
Reader
Simple, compact, object-oriented files
Process quickly, page-independent, self-contained
Can be repurposed, downloaded
Contains extended job ticket Customer info, proofing directions, trapping, imposition and
ripping parameters, finishing and shipping instructions
Review Questions5. List at least five forms of manipulation that are allowed by image
editors/image manipulation programs
6. What is a raster image processor (RIP)? What is its major function?
7. What is am imagesetter? What is its major function?
8. What purpose does a page description language (PDL) serve?
9. What is portable document format (PDF) and what are some of its main advantages?
10. What does it mean when a file format is defined as device-independent?
File CompressionFiles should be reduced in size before being sent to printers
Lossless- no data is lost (PKZIP compression technology or zip files) Unzipping the file will decompress it (.ZIP Self-extracting are unzipped by opening (.EXE) Decompressed image is identical to original Preferred for images that are printed
Lossy- some data is lost (quantization, DPCM, and JPEG files) Most video compression technologies Eliminates redundant or unnecessary information
JPEG files Joint Photographic Experts Group
International data compression standard for continuous-tone digital still images
Open-system, cross-platform, cross-device
Contains bitmap information only and supports grayscale, RGB, and CMYK color models
Should only be used on final images, at maximum quality setting
File FormatsTIFF or TIF- Tagged Image File Format
Lossless or JPEG compression, grayscale, CMYK, RGB, indexed color
TIFF/IT-P1- Tagged Image File Format for Image Technology Device-dependent format, Color Electronic Prepress Systems
(CEPS)
EPS- Encapsulated PostScript Stable and reliable file format
WMF- Windows Metafile and PICT- Mac Bitmapped and Object-Oriented images
File FormatsDCS 1.0 and DCS 2.0-Desktop Color
Separations EPS graphic file, bitmapped and object-oriented
The Photo CD Compressed photographic images on CD-ROM,
raster images
GIF- Graphics Interchange Format Raster images, up to 256 colors, data compression
File NamingAlpha-numeric characters, no symbols
No space at beginning
Unique
Use appropriate file extensions (.TIFF, .EPS etc.)
Storage DevicesDisk Storage: hard, floppy, CD-ROM, DVD
Storage Tape
Memory Cards
USB Drives
Page CompositionFormats pages of text and graphics
Gives more control over text flow, kerning, and positioning of graphics
Allows importations of many graphic file formats
PageMaker, QuarkXPress, InDesign
Review Questions11. What is the main difference between lossless and lossy
compression?
12. Which type of compression technique is preferred for images that are to be printed? Why?
13. Name at least four of the commonly used file formats
14. Why is it better to use a page composition program to lay out material than a word-processing program?
Preflighting Orderly review of files to identify things that could cause problems
at the output or prepress stage
Discussion of file format and preparation with the service bureau or printer while the project is still in the design stage
Problems with customer-furnished files: Missing or incorrect fonts Missing or incorrect trapping File defined with incorrect color (RGB vs. CMYK) Scans supplied in wrong file format Graphics not linked Incorrectly defined or underdefined bleeds No laser proofs supplied Missing graphics Resolution too high or too low in customer-supplied scans
Preflighting ContinuedBegins with printing out color separations and composite
hard copies Can be referred to if problems occur
Graphics should be linked Original art should be included if linked files are noneditable
Outline software and fonts used, trapping requirements, print specifications, and other pertinent information
Font Format and ManagementPrinter should use same fonts used for original page
composition
Page will change if fonts are substituted Document reflow Bad word or line breaks Loss of kerning and tracking
Include fonts in files given to printer
Turnaround Time and ProofingNature and complexity of a job determine turnaround time
Review number of proofs Samples for customer and guidelines for press operators Made from digital files, generated from film, or run off on a proof
press Iris Proofs- produces four-color proofs from digital file Matchprints- produced from film that will create printing page Bluelines or Diazo Proofs- produced from imageset film Press Proofs- generated with a proof press that produces
photomechanical proofs Color Proofs- photographic or photomechanical proofing system
Digital Printing TechnologyComputer-to-plate (CTP)
Takes fully-paginated digital materials and exposes information to plates in platesetters or imagesetters without creating film intermediates
Long-run projects and short-run projects
Digital-to-paper Printing of images directly on the press from electronic files,
eliminating preparation of film, plates and ink Quick turnaround, flexibility, and cost-effective four-color short runs Also know as Totally Electronic Printing (TEP) Reimageable or no image carrier for transfer or ink-jet ink or toner to
paper, pixels (bitmapped images)
Review Questions15. What is preflighting and why is it so important in prepress
production?
16. List five of the most common recurring problems with customer-furnished files
17. What problems can occur if fonts are substituted in a final document file?
18. What are some of the ways in which prepress proofs are generated?
19. What is CTP?
20. What are some of the advantages of totally electronic printing?