The two main families of Graphical file formats are Raster
and Vector files; both files are used in the Print based, moving image and
Interactive image sectors.
Raster files – Composed of a grid of pixels
each with a different colour in an arranged way to display an image. The term
rasterize means to convert into a grid pixels in order to display an image on a
computer or printing device. Raster files fit into the Bitmap subgroup.3
They are a larger file compared to Vector Graphic image files, and are used in
photographs, graphics with effects to create realistic graphics and images as
they are comprised of millions of pixels, this provides clear detail.1
They are easy to use and can be edited using common editing software.
Raster files are the most common image file type and are
quite accessible, these include:
Raster File Formats:
.BMP – Bitmap image File each pixel stores colour data
without compression. Providing a high quality and crisp image which can be
printed or displayed using Windows.Most graphics and image
applications display BMP format files on Microsoft Windows as they have
bitmapped displays.
.TIF – Tagged Image File stores data of colours and layers in
a tile format. Tagged Image File Format handles colour formats and was once the
universal format of the day. It has 2 main compression options of LZW (data
compression algorithm Lempel-Ziv-Welch- grouping of coloured pixles) and ZIP (referring
to ‘speed’) as it is specialised for storage without losing data therefore
providing a somewhat clear performance and can be resaved without losing image
quality.2
.JPEG – (Joint Photographic Experts Group) JPEG File the most
common method, it is a lossy compression technique for colour images which reduces
the size of a file while compressing its image quality. This file format
transmits photographs on the internet, this type of format is widely used in
many technological devices such as a Phone Camera, Camera and computers which
is why they are easily displayed and accessible. These are predominantly used
for Print based media. Can be accessed in applications such as photoshop, this file format is optimized in photoshop.
.GIF – Graphical Interchangeable Format File images, graphics
and illustration are shown as an animation due to its storage of up to 256
different colours which each frame can hold. These files are supported by the
World Wide Web and are able to be displayed, shared and sent. GIFs are widely
recognised in online advertising as multiple images are displayed and are
interesting than a basic JPEG. The disadvantage of a GIF is its file size as a
series of Raster images are used it can hold up to 20 frames providing a fluid
short animation.2
.PNG – Portable
Network Graphic supports lossless data compression which is applicable to the
internet its purpose was to transfer images, it is not the most appropriate
file extension for professional quality as it reduces image quality but is at
its optimum when a small icon and logos.
Applications used in this sector are raster based, such as
Adobe Photoshop
Vector Files – Are composed of pathways that
create a geometrical pattern such as curves, lines, or polygons. The term
‘Vector’ refers to a quantity with a direction and magnitude, which reflects
its use as a graphical file. Usually these files include computer generated
text, lines or curves. Vector files are resized which therefore means they are
a practical file for Logos to ensuring a clear, smooth and unpixelated. Vector
files are not as successfully supported compared to Raster files, as a JPEG is
commonly accessed where as an EPS is file rarely. The fact that a vector uses
‘pathway’ means the computer draws the image can affect the outcome of the
graphic meaning it may not reach its full definition.3
Vector File Formats:
.EPS – Encapsulated PostScript One of the most recognised
vector file extensions which used in Adobe illustrator for vector based images
this generally works with text as well as graphics.2
.AI – Adobe Illustrator Artwork previews single page vector
based drawings and are either recognised as EPS or PDF files. Vector file extensions
EPS, .Al and .PDF are common for apple products such as Macintosh, because
these files are supported on this software.
.SVG – Scalable Vector Graphics is a vector based format for
image and graphics which is commonly used for mobile devices. This file is
developed by W3C, the World Wide Web it enabled graphics to be shown on the web
which is read using XML text based format. This file is also exported using
Adobe programs but not as commonly known as .EPS or PDF.2
.DXF – Drawing eXchange format is a file extension for CAD
(Computer- Aided Design) this file format can be created on CorelDraw and
OpenDesign
Applications used to create Vector files include Adobe
Illustrator, freehand and fireworks, CorelDraw and Paintshop, Digital Line
Graph and OpenOffice.2
.PDF – Portable Document Format. Primarily usedbecause it is able to supply industry
standard print artwork from InDesign and illustrator without the need to supply
the actual artwork, links and fonts; as a PDF embeds the fonts and the images
within the file. This can only be achieved if created correctly. Its main
purpose is for its ‘portability’ as it is universal and can be accessed on the
web. In the modern day PDFs can be used for online magazines and print based
items. In optimum zooms of 800% the lines and curvature of text flow smoothly
this can be useful for publications for print such as posters, leaflets and
showcasing document.
The Moving Picture Experts Group (MPEG) is a working
group of authorities that was formed by ISO and IEC to set standards for audio
and video compression and transmission.5