1.  Explain the various file format such as PDF, TIFF, JPEG , MP3,
MPEG and its compression methodology and its
compression methodology.

2. In This Chapter, you’ll learn on:
 The various portable file formats
 The characteristics of these formats
 The advantages and disadvantages of these
formats

3.  The various portable file formats
Image file formats that we use most frequently in the
printing industry are TIF,EPS and PDF. Either one is
suitable and both have distinct technical
advantages for advanced computer users. If you
are manufacturing a "cutout" or "clipping path" in an
image program like Adobe Photoshop® its typical to
save the image as an EPS file since an EPS file format
is used to deal with path data commonly called
"vector" art. Adobe Illustrator® and Macromedia
Freehand® files must be saved as EPS format files for
this same reason.

4.  The various portable file formats
You may find that a TIF format is a little easier to work with since
it has a form of compression available to it called "LZW". "LZW" is
a form of "lossless" compression meaning it looks at the actual
data in the file and finds exact patterns of info which it can
account for in easier terms. For instance, if a large area of your
image made up of thousands of pixels is all white, instead of
remembering the color of each individual pixel a thousand
times over, it remembers that this particular area of pixels are all
the same. Much more efficient.
 If you are saving files as EPS's in Adobe Photoshop, please use
BINARY as your encoding method NOT JPEG.

5.  To Sum Image Formats
 When in doubt, you should be safe saving your
images at 100% of the size they will print, CMYK (or
grayscale if your printing 1 color), 300 Pixals per inch
for photos and 600 pixals per inch for hard-edged
line art, and in TIF format.

6.  Characteristics of these formats
 TIFF - Tag Image File Format
(.TIF file extension, pronounced Tiff) Its main strengths
are a highly flexible and platform-independent
format, which is supported by numerous image-
processing applications. TIFF is the format of choice
for archiving important images. TIFF is the leading
commercial and professional image standard. TIFF is
primarily designed for raster data interchange.

7.  TIFF - Tag Image File Format
The most common file format that popular imaging
applications support, and not to forget the printing
industry, is TIFF. TIFF supports most color spaces, RGB,
CMYK, etc. You can save both RGB and CMYK files
in TIFF-format and TIFF is supported both by Mac and
PC. TIFF is a flexible format with many options. All
major programs today can read TIFF either way, and
TIFF files can be exchanged without problem.

8.  TIFF - Tag Image File Format
TIFF format also saves your mask channels and in
Photoshop supports 24 channels. Even more
impressive is the nowadays with Photoshop 6 it also
supports several layers. When you save a file with
layers you check "layers" in the "Save as" dialogue
box. The TIFF dialogue box in Photoshop 6, lets you,
as one alternative, choose the lossless LZW
compression. It is a lossless compression and you
usually get a file that falls somewhere between 1/3
and 2/3 as large as the original. Another is ZIP. One
problem is that Photoshop is still one of the few
programs supporting ZIP in TIFF-files for the moment.

9.  TIFF - Tag Image File Format
A TIFF format is complex, so TIFF files are generally larger than
GIF or JPEG files. TIFF supports lossless LZW (Lempel-Ziv Welch)
compression; however, compressed TIFFs take longer to open..
Lossless means there is no quality loss due to compression.
Lossless guarantees that you can always read back exactly
what you thought you saved, bit-for-bit identical, without data
corruption. This is a critical factor for archiving master copies of
important images. Most image compression formats are lossless,
with JPG and Kodak PhotoCD PCD files being the main
exceptions.
 Compression works by recognizing repeated identical strings in
the data, and replacing the many instances with one instance,
in a way that allows unambiguous decoding without loss. This is
fairly intensive work, and any compression method makes files
slower to save or open.

10.  TIFF - Tag Image File Format
LZW is most effective when compressing solid indexed
colors (graphics), and is less effective for 24 bit continuous
photo images. Featureless areas compress better than
detailed areas. LZW is more effective for grayscale
images than color. It is often hardly effective at all for 48
bit images (VueScan 48 bit TIF LZW is an exception to this,
using an efficient data type that not all others use ).
 It is not necessary to say much about TIF. It works, it's
important, it's great, it's practical, it's the standard
universal format for high quality images, it simply does the
best job the best way. Give TIF very major consideration,
both for photos and documents, especially for archiving
anything where quality is important.

11.  TIFF - Tag Image File Format
But TIF files for photo images are generally pretty large.
Uncompressed TIFF files are about the same size in bytes as the
image size in memory. Regardless of the novice view, this size is
a plus, not a disadvantage. Large means lots of detail, and it's
a good thing. 24 bit RGB image data is 3 bytes per pixel. That is
simply how large the image data is, and TIF LZW stores it with
recoverable full quality in a lossless format. When saving a file to
the TIFF format, add the file extension ".tif" to the end of its file
name.

12.  TIFF - Tag Image File Format
Description
Name: Tag Image File Format
Extension: TIF, TIFF
Type: Raster format
Colors: 1 to 24-bit
Color Spaces: Grayscale, RGB, CMYK
Versions: 1–6 (1992)
Compression: LZW (Lempel-Ziv-Welch), JPEG or Uncompressed
Standard: Adobe
Platforms: DOS, Windows, Macintosh and UNIX
 According to the standard all import filters for TIFF should
support the LZW-compression.
Purpose
Platform independent format for photos etc. TIFF has become a
defacto-standard for raster images.

13.  PDF – Portable Document Format
PDF stands for Portable Document Format. As the
name implies, it is a data format that can be used to
describe documents. Adobe, the developers of PDF,
market software to create, edit and visualize PDF
files. Because the specifications of the file format are
publicly available, a lot of other companies develop
software for PDF as well. In prepress, PDF is used more
and more as a format to exchange data between
applications.

14.  PDF – Portable Document Format
PDF files can contain text, images and tables such as those
produced by spreadsheets. Many documents are based on
standard paper sizes such as A4 and so can be readily printed.
However, the PDF format will handle documents up to five
metres square and so can accommodate the largest maps
and plans. The use of word processor files such as Microsoft
Word is not a real option for the publication of material since
not every one uses it and for even Word users the output from a
given file is just too dependent on version of the software and
the printer used. Similarly, publication using web pages is not
always a satisfactory option because what the reader sees
depends on his browser and monitor resolution. Of course
Apple Macintosh computer users don't use Windows at all but
happily the same PDF file works for Apple computers as well as
for Windows machines.

15.  PDF – Portable Document Format
The PDF format is therefore well worth consideration by local
historians looking for an alternative means of publishing their
work This might be in the familiar format of a printed article but
it could be an analysis performed using a spreadsheet, a listing
of the contents of a database or a map. This note provides links
to some of the many resources on the Internet concerning PDF
files.
 PDF supports security. The creator of a PDF file can set various
security options. It is possible to lock a PDF so it can only be
opened with a password. It is also possible to forbid changing
the content of a PDF or disable the option to print a PDF file.
 PDF files are not meant to be edited. Small changes can be
made to a PDF file but it is virtually impossible to add complete
blocks of text or images to an existing PDF file.

16.  PDF – Portable Document Format
Description
Name: Portable Document Format
Extension: PDF
Type: Page description language, Meta format
Compressions: JPEG, ZIP
Application: Adobe Acrobat
Platform: Mac, PC, Unix, Linux

Overview
PDF is produced by Adobe Acrobat or other applications with
add-ons.
 The format is based on PostScript (PS) format.
 Purpose
A cross application and platform description and publishing

17.  EPS - Encapsulated PostScript
Encapsulated PostScript language file. This is a very universal
format that can contain both vector and bitmap graphic
images. EPS files can be opened in Corel Draw, Adobe
Illustrator, Photoshop (the image is rasterized as opened),
Freehand and other programs (MAC or PC).
 The EPS file format can be used for vector images or bitmap
images and on a variety of platforms, including Macintosh and
Windows. When you place an EPS image into a document, you
can scale it up or down without information loss. The PostScript
language, which was developed by Adobe, is the industry
standard for desktop publishing software and hardware. EPS
files can be graphics or images of whole pages that include
text, font, graphic, and page layout information. When saving
a file in the EPS format, add the ".eps" file extension to the end
of its file name.

18.  EPS - Encapsulated PostScript
Description
Name: Encapsulated PostScript
Extension: EPS, EPSF and EPSI
Type: Meta format
Versions: Level 1 and Level 2
Compression: LZW
Standard: Adobe
Platforms: DOS, Windows, Macintosh and UNIX

19.  EPS - Encapsulated PostScript
Overview
EPS is actually a page description language but is also used for
describing images.
 Some software can print but not display the EPS images on the
screen, since the software are not able to interpret the EPS
information. But it is able to send it to a Postscript printer.
 There are actually two images in one file, one Postscript image
and one low resolution image (e.g. TIF) that is used for preview.
 Purpose
A Platform-independent printing format. EPS should not be used
for screen presentation since the low-resolution image is not
always displayed correctly.

20.  The advantages and disadvantages of these formats
Before you save an image in an image processing application
(or scan system), you should make a decision on the file format
you want to choose. The advantages and disadvantages of
the different file formats are described below.
 Important: Again, the file formats have to be judged from
different points of view. Some characteristics of a given file
format may be advantageous in general and for OPI processes
but - at the same time - disadvantageous with regard to color
matching.

21.  Advantages
TIFF files can be edited by all popular image
processing applications.
o TIFF files are independent of the output device.
o For TIFF files, portions of an image can be sent to the output
device (in case you have selected only a specific part of
the image in the layout application).
o The resolution of TIFF files can be reduced during output and
thereby adapted to low-resolution output devices.
o The TIFF format supports many color modes.
o Platform independent (DOS, PC, Mac and UNIX)
o The format is supported in almost every image and word
processing software.
 TIFF is one of the most common formats.

22.  Disadvantages
o Clipping paths you have applied to the image in an image
processing application are usually not preserved for printing
o Large images require large storage space and takes a long
time to download.

23.  EPS
Advantages
o Clipping paths that have been defined in image processing
applications are preserved for printing
o EPS has been a de facto standard within the graphic
industry during the last fifteen years and offers a very good
printing quality
 EPS is mostly used for storing vector information,
which makes small files.

24.  EPS
Disadvantages
o Many image processing applications cannot re-edit EPS files.
o Complete images are sent to the output device, even if you
have selected only parts of the images in the layout
application.
o The generation of EPS files may already involve a given
output device. In that case, printing to different printer types
produces different results.
o The resolution of an EPS file remains unchanged (e.g. 1200
dpi) even if you are printing to an output device that only
allows lower resolutions (e.g. 300 dpi). Thus, printing may
become very slow.
o There are sometimes problems when printing these files on
printers that don't not support the Postscript format.

25.  PDF
Advantages
 Very good printing quality.
 De facto standard in desktop publishing.
 A PS-file can easily by converted into Acrobats PDF-
format.
 It is a cross platform standard. This means that
somebody can create a PDF file on a Unix workstation
and you can open it on a Mac or PC and still see the
document just like it was intended to be viewed.

26.  Advantages
 PDF files can be device independent. This means that a
PDF file can be printed on a cheap ink jet printer. This does
not necessarily mean that the output will be optimized for
each device. A lot depends on the way the document is
created.
 PDF files are compact. PDF supports a number of
sophisticated compression algorithms as well as a clever
file structure to keep the file size of PDF files down to an
absolute minimum.
 PDF files can contain multimedia elements like movies or
sound as well as hypertext elements like bookmarks, links to
e-mail addresses or web pages and thumbnail views of
pages.

27.  Disadvantages
o PDF is a proprietary file format.
o PDF tries to be everything to everybody, meaning that it may
not be as efficient for a specific task than a tool optimized for
that task. You can use PDF on the Internet but in most cases
an HTML document may be more efficient. You can use PDF
to exchange small graphic elements like ads, drawings or
pictures but more prepress applications can handle the EPS
file format.
o Very limited options to edit a PDF-file.