GettinG it PrintedAn Introduction to Print Production

ThePrepress Workflow

Janna Kay Jensen

Copyright © 2004 by Janna Jensen

Preface

The success of printing jobs depends as much on the graphic designer as on the printer that

produces them. The designer is often responsible for making decisions about inks, papers, and file formats and then writing these as specifications for the printer.

Most importantly, as the graphic designer, you are ultimately responsible for giving the okay for a job to be printed. As you review proofs and conduct press checks, you make sure that the job is ready for production. Because of this responsibility, you must understand the printing process and be able to effectively communicate with the vendor. This series of booklets will assist you in developing these skills.

This series of handbooks provides introductory discussions of printing processes and will assist you in learning how to work with printers to produce quality final products. The topics of these booklets are as follows:

• TheBusinessofPrinting• PreparingFilesforOutput• ColorBasics• ThePrepressWorkflow• PDFs• Film• Proofs• Plates• OffsetLithography• OtherMajorPrintingProcesses• DigitalPrinting• ConductingPressChecks• PaperBasics• FinishingandBinding

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These booklets will outline the various steps involved in the major printing processes, define key terminology (appearing in italics), and identify the most common and problematic errors made in file creation. Getting It Printed is aimed at providing the latest information on working in the printed medium.

This booklet provides an overview of the prepress workflow.

ContentsPreparing Files forOutput 1Choosing the Correct File Format 3Preflight Checklist 4Portable Document Format Files 6

P re f l i g h t 6Imposition 7

Raster Image Processing 8Film,Proofs,orPlate 9Film 10Proofs 10Plates 14

NowWhat 14Glossary A - 1

FiguresFigure1:ThePrepressWorkflow 2Figure2:FourFlats,PrintedonBothSideswillCreatea32-pageSignature 8Figure3:FilmforCyanandYellow 11Figure4:FilmforMagentaandBlack12Figure5:ACompositeProofwith Corresponding Color Bars 15

The prepress workflow consists of all the steps necessary to take a file from the creator's

desktoptotheprintingpress(seeFigure1).Although there are many variations in this process depending on the print house's technology, the major events within it remain constant. As you will see in this booklet, each step is crucial for producing a quality final product. Mechanicals, film, proofs, and plates are all output during this process and are dependent on the original electronic file for their success.

PreparingFilesforOutputQuarkXPress,PageMaker,FrameMaker,InDesign,Illustrator, and Photoshop are the application programs used by most professionals for creating documents for the press. They are also theprogramssupportedbymostprinters.Filesfrom other programs will sometimes be accepted; however, a fee is assessed. But no matter what software you choose to work in, make sure you are using the latest versions because printers switch to new versions as soonastheyarereleased.Stayingcurrentwillassure that the features you use are compatible with the printer's system.

Always provide your files in their native format (e.g.,QuarkXPressis.qxd,PageMakeris.pm6).This allows the printer to make any necessary changes without having to request a new file. This will save you time and money. Alternatively, you can submit a PDF(PortableDocumentFormat)ofyourdocumentaslongasitwascreatedataminimumof300dpi,withhigh-qualitygraphics.PDFsarequicklybecomingthefile format of choice for the printing industry.

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In addition to the document file, you must submit all linked graphic files and fonts. Even common fonts such as “Times” are different from computertocomputer.Youwantyourdocumentto be output using the same font files they were created with. If you are using a PC, be sure to send both the screen and printer files for each

Figure1:ThePrepressWorkflow

font.YoushouldbeawarethatifyouareusingaPC, your printer probably isn't. A study in 2000 showedthat88%ofU.S.printersusedMacsand38%usedMacsexclusively.

However, platform problems are not the only ones faced by printers. Here are the top ten problems with digital files sent to printers, accordingtoGRACoL(GeneralRequirementsforApplicationsinCommercialOffsetLithography):

1. Wrongormissingfonts2. Banding3. Incompleteorcorruptfiles4. Excessive sizing/rotating of graphic files in

the page layout program5. Spotcolorsnotconvertedtoprocesscolors

or vice versa6. TIFFfilesnotconvertedfromRGBtofour-

colorCMYKmode7. Wrong page size8. Lowresolutionimages9. Inadequatebleeds10.Impropertrappingornotrapping

Avoiding these common mistakes will help keep your job on schedule and on budget.

ChoosingtheCorrectFileFormatProfessionals use various file formats for saving and exchanging information across applications and platforms. Knowing which format is correct for graphics is especially important. Below are the main types of graphic file formats and their advantages and disadvantages:

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• EPS (Encapsulated Postscript): There are two typesofEPSfiles,rasterandvector.UnlikeTIFF,EPSrasterfilesholdspotcolorinformation, but only when defined through Photoshop's duotone settings. Vector (images created by mathematical relationships between pointsonadrawnobject)EPSfilesaretheperfect format for illustrations from programs likeIllustratorandFreeHand.Likerasterfiles,vectorEPSscanholdanyspotcolorinformation.

• JPEG (Joint Photographic Experts Group): This is a common format found on the Internet, but it is not suitable for print. When a JPEG is created, it "throws out" information in order to make the file smaller, thus creating gaps in the image.

• PICT (Picture): This format is another graphic format, but it is unreliable and creates lower-qualityimages.UseEPSorTIFFinstead.

• TIFF(TaggedImageFileFormat):TheTIFFformat is the best format for most printing uses and is the preferred format for four-color, grayscale, and bitmapped images. However, it isimportanttorememberthatTIFFscannothold spot color information and, instead, reformatsthemasCMYK.

Preflight ChecklistContact your printer ahead of time to confirm what media they would like your files submitted on (FTP,ZIP,JAZ,CD-Rom,etc.)orife-mailingthemisan option. If so, make sure they have a compatible compression program for accurate downloading. Also be sure how ever you send your files, that you keep a duplicate in case errors are made and you need to identify if they were yours or the printer's Any problems that have to be fixed will cost money and you only want to get charged for those that

are, in fact, yours.

Before submitting any job to your printer, complete the checklist below to help avoid missing or incorrect files. Identifying problems early and making sure all your files are complete and accurate will ensure the final quality of your product. This process is called preflighting, which is checking a document, its fonts, and its linked files to make sure thatitcanbeoutputcorrectly.Yourprinterwillcomplete a thorough preflight once they receive your files, but you can conduct your own in-house verification by using the checklist below.

Check for these characteristics in your files:❑ All colors are correctly defined.❑ Allbleedsextend1/8inch(.125inch)

beyond the pages edges.❑ All photographs are the proper resolution

andcolormode(atleast300dpi;CMYK,grayscale, or duotone).

❑ All graphics are linked, not embedded.❑ Allstrokesandrulesareatleast3/10ofa

point and are not defined as hairlines.❑ All folds are accurately measured and panels

are set-up accordingly.❑ A spellcheck has been completed.

Provide your printer with the following:❑ A directory of all files, including programs

and version numbers. ❑ A final laser printout of your file(s), at actual

size, showing everything as you would like it printed. If the piece folds or is double-sided, submit a mock-up.

❑ Laserseparationsshowingyourfilesseparated into the correct spot or process colors.

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❑ Native file on disk including the following:❑ All fonts used in your layout (printer

and screen fonts as well as all bold, italic, etc. versions).

❑ AllfontsusedinEPSgraphics(unlessyou have converted them to paths).

❑ All linked graphics.or

❑ APostscriptorPDFfile

PortableDocumentFormatFilesPDFsarequicklyreplacingnativefilesastheformat of choice for printers. Unlike files created inlayoutprograms,properlycreatedPDFscontainall the images and fonts necessary for their production. Many of the common errors that printersfaceareeliminatedbecauseofthis.PDFisregarded as the worldwide graphic format standard.

PDFsstillgothroughthepreflightingprocesstocheck to make sure the embedded images were created at the correct resolution and in the correct color system. If you choose to output yourfilesasPDFs,alwaysmakesurethatyourimagesareatleast300dpiandinCMYK,andthatyour fonts are embedded. An improperly created PDFisworthless.

PreflightPrepress operators are responsible for ensuring that documents are ready to move into production on time by checking prepared files ahead of time. They analyze the original document file plus all graphic files to make sure they are present and correct. All fonts must also

be present before the job moves forward. After all, if files weren't opened and checked until they were needed, the prepress process would come to a halt as pressmen scrambled to find or correct files.

The preflight of any job is an inventory that the operators go through as soon as the file is received. They first compare the specifications the designer has sent them with the actual documents they received. They examine each file for consistency in order to create a proof. If there are any problems, they notify the designer and either request new files or permission to change the ones they have. The fewer problems your file has, the lower your prepress costs will be. This is where the internal preflight checklist can help.

ImpositionImposition is the process of arranging pages of a document so that when the sheets are printed and folded for binding, the pages will be in the properorder(seeFigure2).Theselargesheetsare called flats and require only one set of film and/or plates to be made for each set of pages. When the flats are printed on both sides and folded in groups, they are called a signature. All the signatures needed for the publication are then inserted inside and bound.

Imposition is done either manually (a labor-intensive process) or electronically with a programsuchasPressWise.Duringthisprocess,each page is adjusted slightly to account for the outward shifting of inner pages that occurs when signatures are formed. Imposition generally applies to multi-page documents that require post-bindery processing (trimming).

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Raster Image ProcessingRaster Image Processing, or RIP is the process of taking digital information and turning it into a form that can be produced by an output device. A file only has to be RIP’ed once and then it can be output using any device. This new technology has greatly reduced the time required for the prepress workflow and decreased turn around time on jobs. Because of these advantages, most printers now have dedicated computer equipment that is used for RIPs. However, there are software programs that can allow any desktop computer to perform this function and multiple users to do so at the same time.

Inordertorasterizeanimage,aPostScriptor

Figure2:FourFlats,PrintedonBothSideswillCreatea32-pageSignature

original native file is turned into individual dots. The resolution of these dots depends on the resolutioncapabilitiesoftheoutputdevice.(Forafull perspective on why images are output the way they are, see the booklet on film.) An imagesetter, a high-resolution output device, uses lasers or other means to impose the characters and graphics from the RIP data onto photosensitive paper,film,orplates.Despitethemediaoutputted,any impositioning performed in previous stages is reflected.

RIP also determines how the image should be separated, trapped, and screened based upon perimeters the user has input. These parameters are stored as preferences, scripts, and/or routines in the RIP software and, as jobs are sent to output devices, these specifications are applied. In the past, each of these functions was carried out by separatesoftwareapplicationsoutsideRIP.Sincethe RIP now carries out all these processes, larger files can be sent to output devices without having to be split into smaller files.

SincethecapabilitiesofRIPhaveincreased,sohasthe importance of the preflight process. If files are incorrect or missing, the job can crash the system during processing and require it to be rebooted. This wastes time that can put a job behind schedule.

Film,Proofs,orPlatesOnceafileisRIP’ed,itcaneitherbeoutputasfilm, a proof, or a plate.

FilmIf the file is output as film–a dark acetate material

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that has an emulsion side that is light sensitive– the imageappearsasanegative.Filmcanbeproducedconventionally using a graphic arts camera, or, more commonly, electronically using an imagesetter. In film-to-plate processing, the film is the most important component for determining the quality of the final product. A separate sheet of film has to bemadeforeachcolorused,e.g.,inCMYK,fourfilm sheets are output: one for cyan, one for magenta, one for yellow, and one for black (see Figures3and4).

In addition, each sheet contains a color control bar. These are used for assessing color accuracy on proofs once the job makes it to the press. A complete color bar should have the following characteristics:

• Screenareaswithvaluesof25%,50%,and75%for each primary color.

• Two-coloroverprintswithvaluesof25%,50%,and75%ofthesametints.

• Agraybalancebarwiththreedifferentvaluesof black.

ProofsA file can also be output as a proof after being RIP'ed. Proofs are test sheets produced to reveal errors or flaws in a file, predict results on the printing press, and record how a printing job(s) is intend to appear once completed. Proofs are quality control tools, however, it is important to remember when reviewing them that the press will never match the proof exactly: it is simply a simulation of the printed result.

There are two categories of proofs: analog and

Figure3:FilmforCyanandYellow

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Figure4:FilmforMagentaandBlack

digital. Analog proofs are produced photomechanically by making a positive from the film negative using ultraviolet light. The main types of analog proofs are:

• LaminatedProofs:Createdbyplacingfilmover a very thin photosensitive proofing material and exposing it to a light source. The exposed areas are set by the light and the unexposed portions get washed away during processing. A different color of proofing material is used for each color. The finished proofing films are then laminated together on a piece of heavy white paper.

• Chromalins:Createdbyplacingfilmoveravery thin layer of pigment and exposing it to light. The exposed areas are set by the light and unexposed portions get washed away during processing. This process is repeated for each color. These proofs give a much larger selection of spot colors in this process than laminated proofs or bluelines.

• PressProofs:Createdbymakingactualplatesand then printing the piece or image to see how it reproduces under actual printing conditions. However, this is a very expensive way to create a proof.

• BluelinesorDyluxPProofs:Createdbyplacing the film over a specially coated paper and exposing it to a light source. The coating on the paper turns blue as it is exposed. This is the least inexpensive type of proof; however, it does not give a good simulation of the final product.

Digitalproofsaremadedirectlyfromtheelectronic file using a digital color-proofing device. Because film is not used in processing these types of proofs, they can be made earlier in the

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workflow process and multiple versions can be made throughout the process. There are many types of digital proofs. They include:

• LaserProofs:Createdbydesktoplaserprinters and used mainly for copy editing and checking for art placement. This is the least-expensive type of proof.

• ColorLaserProofs:Createdbyadesktopcolor laser printer but not used to simulate presscolor(seeFigure5).Likelaserproofs,they are mainly used for copy editing and for checking art placement.

Figure5:ACompositeProofwithCorrespondingColor Bars

PlatesBecause of advancements within the industry in the last decade, it is now possible to output RIP'ed files directly to plate. A plate is a piece of paper, metal, plastic, or rubber that carries the image to be reproduced on to the printing press. The material the plate is created from will affect the quality and number of times it can imprint an image. When smaller quantities are needed, paper plates are used to help reduce costs. When larger quantities are needed, a more stable plate needs to be created in metal. After the plate is made, it is mounted to the press and then inked.

Now WhatNow that you have an understanding of the prepress workflow, you are ready for more in-depth discussions of the specific components. Inthenextbooklet,PDFswillbeexplainedingreater detail as well as the processes by which they are created.

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GlossaryBanding Undesired, visible steps in image

density of a smooth gradient. Also called stair stepping.

Bleed The ink that extends beyond the trim marks of a page and is cut off during finishing. The final image will run right up to the edges of the printed sheet.

Blueline An analog proof used to check the layout and position of pages on a signature. The name comes from the blue color of all text and images on the layout.

EPS AcronymforEncapsulatedPostScript.Thisfileformatismainlyused for vector-based images.

Flats Asheetofimpositionedpagesthatwill be combined into a signature. Also, a collection of properly imposed negatives and positives attached to a goldenrod or film carrier sheet from which the plate will be exposed.

Imposition The positioning of pages on a press sheet so that when the press sheet is folded to form a signature, the pages are in the correct sequence. This is completed before a file is RIP'ed.

JPEG Acronym for Joint Photographic Experts Group. This file format is

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based upon a compression algorithm named after the committee that defined it. This format is usually used for Internet-based files and not for print production.

Mechanicals A hard-format version of a layout including type, illustrations, and design elements in their proper positions ready to be photographed using a graphic arts camera.

PDF AcronymforPortableDocumentFormat.Auniversalfileformatresulting in compact files with embedded fonts and graphics. In prepress,PDFisusedasaformattoexchange data between applications, computer systems, and users.

PICT OriginallythenativefileformatforApple computers, it is now all but obsolete. It is still used for both raster and vector graphics although TIFFandEPSfileformatsarebetterfor prepress work.

PostScript Auniversaldescriptionlanguageconsisting of a specific set of software commands and protocols that form images on output printers and film recorders when translated through RIP. The key feature of PostScriptisdeviceindependence,which allows many different output devices from different manufacturers to print the same file in more or less the same way.

Preflighting The inspecting of incoming or outgoing job files for accuracy as well as checking for font compatibility before trying to output.

Proof A check made at strategic intervals in the prepress process to ascertain quality, e.g., a photographic print made from plate-ready films or flats before the press run to check for the accuracy of layout, type, and color reproduction.

Raster Continual-tone image file composed of a pattern of dots such as a photograph or illustration.

Signature Thecollatedpagesofonefoldedandtrimmed document, making up one section of a publication. The larger the press used for a job, the more pages the signature will contain.

Trapping In prepress, trapping is a technique that minimizes the effects of misregistration (white gaps between colors) in print by slightly overlapping abutting colors.

Vector An image created by a series of points and connections that specify the start, the end, and the length of each line. These files are more compact than raster.

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