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DESIGN TIPS
FILE BASICS
Types of Digital Graphics
An understanding of the different types of digital
graphics can improve the final look of your printed piece.
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VECTOR ARTWORK
- Involves a mathematical definition of a graphical element's
position, size, shape, and color
- Files tend to be small and efficient
- Artwork is scalable (there is no loss of quality when enlarged)
- Suitable for web or print
- Used for images with line art or simple gradients
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RASTER/BITMAP ARTWORK
- Based on an array of picture elements ("pixels") tagged with color information
- Files tend to be large
- Not scalable - it is not recommended that you enlarge
raster artwork
- Images suitable for web are not suitable for commercial print
- Used for images with continuous tone or texture (such as photographs)
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Graphical File Formats
Different graphical file formats are suitable
for different purposes. They vary in compression, and
some are better for printing than others.
Compression is the encoding of information while
reducing the bandwidth or bits required. Lossy compression
results in the loss of some of the original data. Whereas lossless
compression results in a compression ratio of about 2:1,
lossy compression of image data can lead to ratios of between
10:1 and 50:1 without visibly degrading image quality.
The chart below summarizes the features of the
various formats of graphical files you might place into your layout
(please also see our list of preferred
layout software.)
Graphical File Formats |
| PSD
(Photoshop) |
Lossless |
Yes |
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X |
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| EPS
(Encapsulated PostScript) |
None |
Yes |
Good for duotone (two-color halftone reproduction from
a one-color photograph) |
X |
X |
| TIFF
(Tagged Image File Format) |
Lossless |
Yes |
Good for photographs and other continuous-tone artwork |
X |
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| JPG |
Lossy in variable quantities |
No |
Good for web usage |
X |
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| GIF |
Not applicable (indexed colored) |
No |
Good for web usage; 8-bit color space |
X |
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| PDF
(Portable Document Format) |
Several compression choices available |
May have color separation problems |
Avoid for photographs |
X |
X |
More About PDFs
Portable Document Format (PDF) was developed
as a means of delivering files to end users that would be the
equivalent of a paper document. The user is not required to own
the program that created the file (Adobe Acrobat.) It is viewable
with a free program from Adobe known as Acrobat
Reader.
Fonts and support graphics are simplified and
embedded into the file, allowing for universal compatability.
PDF supports both vector and raster art elements. Any layout developed
for print is easily repurposed for web using PDF. Best of all,
it can retain the integrity of the layout without compromise,
while keeping the file size to a minimum.
Adobe Acrobat is not a development application
used for creating layouts natively. Rather, layouts are created
in another program such as Adobe InDesign or Quark, then converted
to PDF format. However, Acrobat does allow for some editing of
text. It also allows for simple editing tasks such as spell check,
deletion, "Post-It" notes, and markup.
Acrobat Reader, on the other hand, does
not allow for any editing, only review. It will also not enable
you to create PDF files. In most cases, the creation of PDF files
will require that you own a copy of Acrobat.
Acrobat comes with an application called Acrobat
Distiller that does the following:
- interprets PostScript code
- resamples pixel-based images to a controllable standard
- embeds fonts or define font substitution parameters
- streamlines the PostScript code by eliminating any extraneous
instructions not necessary for the viewing or printing of the
document
- can eliminate PostScript errors
Acrobat Distiller has the following default output
settings:
- Press (best for printing presses)
- Print (for laser or inkjet printers)
- Screen (for monitors/web sites)
PDF files can be used as a sort of "prepress
package" containing all the data that an application-based layout
and its support files contain. This has pros and cons. When time
and expertise allow, control of the artwork is placed more in
the hands of the designer than in those of the prepress personnel.
However, when a PDF is provided to a printer, there are many limitations
in controlling, realigning, and editing the artwork if needed.
More
on the PDF file format from Adobe.com...
In most cases, The Forms Outlet, Inc. would prefer
that you provide us your native files instead, especially if any
revisions are required. Please see our
list of preferred software.
Next: SCANNING...
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