Transcript ch9 - ArtWithFalk

Electronic Prepress
and Digital Printing
Chapter 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 Images
 Paint programs
 Draw programs
 Digital photography
 Electronic scanning
Paint Programs
 Freehand 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 Programs
 Vector 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 Questions
1.
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 Images
 Adobe 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
Imagesetters
 Typesetting 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 PDF
 PostScript
 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 continued
 Acrobat 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 Questions
5. 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 deviceindependent?
File Compression
 Files 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 Formats
 TIFF 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 Formats
 DCS 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 Naming
 Alpha-numeric characters, no symbols
 No space at beginning
 Unique
 Use appropriate file extensions (.TIFF, .EPS etc.)
Storage Devices
 Disk Storage: hard, floppy, CD-ROM, DVD
 Storage Tape
 Memory Cards
 USB Drives
Page Composition
 Formats 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 Questions
11. 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:
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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 Continued
 Begins 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 Management
 Printer 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 Proofing
 Nature 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 Technology
 Computer-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 Questions
15. What is preflighting and why is it so important in prepress
production?
16. List five of the most common recurring problems with customerfurnished 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?