FTA (изд-во). Flexography: Principles And Practices. Vol.1-6

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variety of applications can be

used by a designer to create

artwork. It is common to cre-

ate different elements of the

completed design in a variety

of applications and then make

a composite file of these elements in one

program. The secret to creating an artwork

file that will successfully process during the

prepress stage is knowing which file types

can be combined to create the final compos-

ite artwork file. There are as many file types

as there are applications to create them and

each one has its own unique features to offer

(Table 7). A description of some of the more

commonly used file types follows:

PICT file format is a common file type used

most frequently for graphics that are only

used for monitor display. PICT file support

RGB channels, which make it a poor choice

for saving images. RGB channels are gener-

ally not supported by RIPs and can cause the

artwork file to fail or crash during the

RIPping process. PICT files should not be

used in finished artwork files that are ready

to be processed for film or plate output.

TIFF (Tagged-Image File Format) files are the

most commonly used and most widely sup-

ported file formats available in the desktop

environment. TIFF files support RGB, CMYK

and grayscale channels, which make this file

format an excellent choice for saving

scanned images. Some prepress systems

may have difficulty processing TIFF files. A

designer should check with the output

provider’s ability to support this format.

JPEG (Joint Photographic Experts Group)

images are commonly used for transporting

or displaying scanned images across the

World Wide Web. CMYK, RGB and grayscale

channels are supported by the JPEG format,

but JPEG files are automatically com-

pressed when saved to create smaller file

sizes. To accomplish this compression,

image data is discarded resulting in a lower

quality image. JPEG files are excellent for

displaying on a computer screen, but are a

poor choice for printing artwork files.

GIF (Graphics Interchange Format) is anoth-

er commonly used file format for transport-

ing or displaying scanned images across the

World Wide Web. This format supports

bitmap, grayscale or indexed color channels.

Index color is a limited color palette using

up to 256 colors. These limitations on the

supported color channels result in a much

smaller and more compressed file. The

smaller file size transfers quickly across

Internet lines, which makes it an excellent

choice for use on the World Wide Web.

These same color limitations make GIF files

a poor choice for artwork that will print on a

press; therefore, GIF files should never be

used in composite artwork files designed for

printing.

PDF (Portable Document Format) files are

self-contained files that can be created by

most desktop applications. These files con-

tain both line work and raster images and

are an excellent choice to send graphics to a

customer to soft proof. The customer cannot

edit the file but he/she can view it on a com-

DESIGN 57

File Formats of Imported

or Placed Graphics

58 FLEXOGRAPHY: PRINCIPLES & PRACTICES

Notes:

PICT = Macintosh format;

BMP = PC equivalent

2 Supports DCS format

3 Through Acrobat Distiller

Legend:

Vector-based art

Scalable/rotable bitmap

Editable bitmap

Allowable

APPLICATION FILE FORMAT SUPPORTED

EPS (vector) EPS (bitmap) PDF PICT

TIFF TXT

Adobe Illustrator

Canvas

CorelDraw

Macromedia FreeHand

Adobe Photoshop

Painter

Adobe InDesign

Adobe PageMaker

QuarkXpress

Import ExportImport ExportImport ExportImport ExportImport ExportImport Export

IMAGE PROCESSING

EPS (vector) EPS (bitmap) PDF

PICT

TIFF TXT

Import ExportImport ExportImport ExportImport ExportImport ExportImport Export

IMAGE PROCESSING

EPS (vector) EPS (bitmap) PDF

PICT

TIFF TXT

Import ExportImport ExportImport ExportImport ExportImport ExportImport Export

ILLUSTRATION

FILE FORMATS SUPPORTED BY COMMON DESKTOP APPLICATIONS

puter or download it to a color proofer. The

customer should know that the color proof

is not what the printed piece will look like,

unless that proofer has been adjusted to

flexo press specifications. PDF files are

compressed to reduce file size and they con-

tain all pertinent file elements, including

fonts and placed images. This file format is

relatively new to the desktop arena and is

not yet fully supported by all prepress sys-

tems or fully tested in the flexo packaging

industry. In addition, PDF files currently

have difficulty supporting spot colors. Flexo

compensations cannot be applied to a PDF

file, so don’t send this format to the separa-

tor unless it is to be output to film with

absolutely no adjustments.

Updates to the format can be obtained

from the following two websites:

www.npes.org

www.seyboldpublications.com

TXT (text) files are files generated by any

computer and saved as an ASCII format.

TXT files are very easy to create and very

useful as a form of communication with

other suppliers. These files can be used to

communicate special instructions pertaining

to any portion of the graphics, colors, or the

project itself.

DCS (Desktop Color Separations) files are

“preseparated” EPS files containing the C,

M, Y and K channels and a low-resolution

placement file. DCS files make it very effi-

cient for designers to work with large

scanned images because the low-resolution

file is placed in the working file and the high-

resolution separations are not used until the

file is sent to the RIP for output. During the

RIP stage the low-resolution file “tags” the

high-resolution data and downloads the

high-resolution images when needed. If a

designer uses DCS files, he/she must remem-

ber to send all of the high-resolution files to

the output provider when releasing artwork

files for separation and output

Adobe PhotoShop has released DCS 2.0.

This latest version allows operators to create

halftone images that will reproduce CMYK

colors combined with spot color channels. It

also allows designers to create high-fidelity

color images. DCS 2.0 format may not be sup-

ported by all prepress systems, and the

designer should verify with the output

provider if this format is acceptable.

EPS (Encapsulated PostScript) file format is

the most commonly used and supported file

format available in the desktop environ-

ment. EPS stores files as a series of bezier

curves (vectors) and also includes a low-res-

olution bitmap representation of the file for

quick on-screen viewing. It supports all

color modes, excluding alpha channels.

(Alpha channels are channels or layers in

raster image programs that allow an artist to

create elements on a separate channel or

layer and activate or deactivate it for view-

ing and editing purposes. Alpha channels are

supported in some of the file formats men-

tioned here, but not all. Data that resides on

an alpha channel usually has to be merged

into a supported channel, i.e., CMYK, RGB).

When saving a file as an EPS format, infor-

mation in the alpha channel may be discard-

ed. EPS files contain almost all data for pro-

cessing an artwork file, excluding fonts and

DCS color information. The EPS file format

is a very stable format and is an excellent

choice to use when a file needs to be placed

into a document.

Embedded. In addition to using workable file

types, it is important to make sure embed-

ded files do not have any of their own hidden

problems. Text that is embedded in a file can

easily be overlooked when opening all fonts

in the composite file. It is best to convert the

embedded text into an outline so the font is

not required (Figure

). Other potential

problems to be aware of are patterns that

are embedded, colors that are not in the cus-

tom-ink color palette and an embedded

blend that has banding or a 0% to100% tonal

DESIGN 59

60 FLEXOGRAPHY: PRINCIPLES & PRACTICES

Convert the embedded

text into an outline so

the font is not required

for RIPping.

range. The artist should very carefully

review the items being used in an embedded

file to avoid hidden problems that usually

are not found until after film has been output

or sent to the RIP. Simply put, it is best to

avoid using embedded files or graphics for

trouble-free prepress and separation appli-

cations.

hen certain issues are

taken into considera-

tion prior to the art-

work file being handed

to a service bureau or

prepress department,

the final file has a much better chance of

successfully navigating through production

and processing accurately and efficiently. All

graphic elements must be within FIRST

compliance and in accordance with press-

characterization data.

The final design may seem very simple to

the designer, but it can be difficult to deci-

pher by another user at a different stage of

the production process. Fortunately, most

programs have the option of creating com-

ment layers or report features that can be

used to provide detailed information about

the file and design elements. These report

features can be used to provide much of the

documentation required by FIRST and the

separator.

Preflight Guidelines. All files should be pre-

flighted before they are given to any other

user. Preflighting can be done manually or

using automated preflight software. A disk

should be preflighted on a different comput-

er than the one that the graphics were creat-

ed on. In the Mac system, all fonts must be

turned off except the standard 35. The

designer should take the following steps for

a manual preflight or simply follow the

directions on the preflight software. Any

errors or problems encountered during this

process should be documented and then

corrected. After corrections, the entire pre-

flight is performed a second time.

1. Open the final graphic file to identify

any renamed or missing placed images

and list the name of fonts used.

2. Load the fonts to make sure all correct

fonts are present.

3. Print the file to a laser printer at 100%,

using tiling if necessary. This type of

proof has limitations but is usually the

best available at this stage.

4. Compare these laser proofs to

approved comps or anything that indi-

cates the graphics, text and other ele-

ments required on the packaging.

5. Make a PostScript file of the document

and output this to any laser printer. This

precaution gives the designer the

opportunity to work on correcting the

graphic file before sending it to the sep-

arator.

Media. The software, hardware and media

used for the final graphics must be compati-

ble with the separator’s hardware and soft-

ware. The designer does not have to alter his

hardware or software but the designer and

separator must communicate in advance

and devise a plan for compatibility.

Many final graphic files are very large and

are more easily handled when they are com-

pressed. The major consideration with com-

pressed graphics is verifying the receiver has

the ability to decompress files. In case the

receiver does not have the same utility soft-

ware that the designer is using, create the

files with a .sea extension (self extracting

archives). Some software allows a file to be

segmented onto different disks instead of

being compressed. But again, it is necessary

to make sure the receiver can open these

types of files.

DESIGN 61

Completed Design Guidelines

62 FLEXOGRAPHY: PRINCIPLES & PRACTICES

Proprietary Settings. Some programs like

QuarkXpress offer the option for a user to

create custom settings, such as kerning.

When the graphic file is sent to the separa-

tor, the designer must send any of these pro-

prietary settings as well.

Documentation. The required documentation

must be in hard-copy format. If any report

files or comment layers are used, they must

be listed on the hard-copy documentation. It

may be more efficient to create a form that is

filled out for the required documentation.

The checklist (Table 8) should be used and

can be modified.

After the documentation is complete, all of

the items going to the separator should be

pulled together and compared to the check-

list to ensure that nothing is missed.

Table 8

TASK

■ List and include key files and FPO files

within the key files.

■ List fonts used and correct names

(include if necessary).

■ List software used and version number.

■ List names of nested files.

■ Identify final graphic file name(s).

It is recommended to put all other support

files in a separate folder.

■ List all layers that are common.

■ List layers to be used with base design.

■ List the disk directory – make a hard-copy

printout of the disk directory and directory

for each folder.

■ List all colors: process, spot and mixture

colors.

■ Write instructions for blends.

■ Write instructions for special effects.

■ List items provided, including the disk

(transparency, color proof, etc.).

■ Write specifications on data compression,

if used.

■ Create a hard copy of final graphic file(s) at

100% size.

NOTE:

When more than one design file is sent, a

folder should be created with the design

file in it and another folder in it that con-

tains all of the support files.

DOCUMENTATION CHECKLIST

CHAPTER 2

Prepress

64 FLEXOGRAPHY: PRINCIPLES & PRACTICES

ACKNOWLEDGEMENTS

Author/Editor: Hassan Shareef, Imaging International Inc.

Contributors: James R. Kadlec, Advanced Prepress Graphics

Michael Masotti, New York Label & Box Corp.

Mark Samworth, PCC Artwork Systems

Pantone and PMS is a registered trademarks of Pantone, Inc. Apple, Macintosh are registered trademarks, and

TrueType is a trademark of Apple Computer, Inc. Adobe, Adobe Acrobat, Adobe Dimensions, Adobe Distiller, Adobe

Illustrator, Adobe Pagemaker, Adobe Photoshop and PostScript are trademarks of Adobe Systems Incorporated or

its subsidiaries and may be registered in certain jurisdictions. QuarkXpress is a registered trademark of Quark, Inc.

FreeHand is a trademark of Macromedia, Inc. DOS and Windows are trademarks of Microsoft Corporation. All other

trademarks are the property of their respective owners.

All trademarks have been used in an editorial fashion with no intention of infringement.

PREPRESS 65

n the current age of specialization, pre-

press has become an industry unto

itself. This is especially true in the flex-

ographic reproduction process. While

there are many designers and printers/

converters with prepress capabilities,

this chapter will center on prepress as a sep-

arate entity. Prepress facilities in all convert-

ing operations will generally follow the same

workflows and procedures.

Prepress involves several job functions,

each requiring its own skill set, software and

hardware:

Image Capture. The process of converting

reflective or transparent artwork into a

digital image. With today’s digital cameras,

it can also mean the direct capture of the

real-world image.

Preflight Quality Control. This function is sim-

ilar to the preflight function in that all

incoming materials are reviewed to ensure

a smooth workflow in production. The dif-

ference is that at this point, the customer-

supplied low resolution proofs are used to

check various aspects of the job. This

function is done before viewing the elec-

tronic files themselves.

Desktop/Preflight. This function involves

reviewing incoming electronic files,

checking the elements of the file in order

to process those files before creating

some type of postscript output which

adheres to flexographic printing specifica-

tions. Preflight, in conjunction with pre-

flight quality control seeks to screen out

potential production problems before the

actual production process is started.

Job Assembly/Layout. This process, when

done manually, is known as stripping. In

today’s environment, it is where the elec-

tronic files are assembled and trapped for

output of plate-ready films or direct-to-

plate systems. This is the start of the actu-

al production process.

Film Output/Imagesetting. This normally

entails the addition of distortions or com-

pensations and generation of plate-ready

films required for flexographic reproduc-

tion. These films are output on high-reso-

lution imagesetters. Plate output would

fall into this category when a direct-to-

plate system is being utilized.

Proofing. This process involves creating a

representation of the assembled file prior

to plate-ready film output or digital

platemaking.

Back-end Quality Control. In this process,

materials (usually proofs and films) are

inspected before release to the platemak-

er, converter or customer.

Customer Service. This function acts as the

liaison between the designer or generator

of the job and the printer/converter.

Introduction

PREPRESS 67

Image Capture

mage capture is the process of convert-

ing original photographic artwork into a

digital file. This process takes the con-

tinuous-tone reflective or transparent

artwork and “separates” it into its RGB

(red, green and blue) or CMYK (cyan,

magenta, yellow and black) components.

“Real world” images can be captured digital-

ly. By using a digital camera, the live image is

captured without first going through the

stage of a photograph or other artwork.

SCANNERS

Scanners record the data in red, green,

blue channels by measuring or sampling the

image and assigning the information in the

form of a single picture element or “pixel.”

Each pixel has either a red, green or blue-

color value associated to it. Some scanners

may also convert the original RGB image

and preset that as CMYK data.

The quality of a scanner is affected by its

optical mechanism, which controls the scan-

ner’s ability to capture a broad dynamic

range (variations in light and shadow), as

well as the resolution (number of samples

per inch) of the scan and the scanner’s pixel

depth, which controls the number of colors

it can capture. The scanner’s optical

mechanics or “optics” dictate the resolution,

the light-detection device and electronics

and color information.

Scanners come in two primary configura-

tions: drum and flatbed (Figure

). Drum

scanners require that the original artwork be

wrapped or mounted onto a clear acrylic

cylinder. The cylinder is rotated at high

speeds as the light source exposes and the

optics and electronics of the scanner record

the color information for each pixel. Flatbed

scanners have the same function, except

that the artwork is laid flat and the light

source passes over the image and records

the pixel information. With transparent art-

work, a scanning light passes through the

transparency, while with reflective art, the

light reflects off the artwork.

Typical flatbed and

drum scanners. These

are used to capture

original artwork and

convert it into digital

form.

Digital Methods of Image Capture

Scanner

• Flatbed

• Drum

Digital Camera

• Stuido Digital Camera Back

• 35mm SLR Digital Camera Back

• Point-and-Shoot