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Web browsers usually support two types of web images
on the browsers; however the third type PNG is also
gaining a lot of support. There are many other image
formats which are supported by the browsers but the
three most well used and supported are
GIF
JPG
PNG
GIF Files:
The GIF files commonly known as Graphic Interchange
Format were popularized by CompuServe in the 1980s.
The GIF files were initiated as a proficient method
of spreading images across the data networks. GIF files
include a compression system which keeps the file size
to a minimum and they also ensure that the images include
only web safe colours limited to 256 or fewer colours.
There are three types of GIF files.
1. Interlaced GIF- These files build a low-resolution
version of a full sized GIF picture on the screen while
the file is downloading hence giving the viewer a preview
of the entire image while the image downloads in the
browser.
2. Transparent GIF- This format allows picking colours
from the colour look up table of the GIF to be transparent.
The shortcoming of this file is that it makes every
pixel in the graphic that shares the particular colour
transparent causing unwanted results. It works best
with simple diagrammatic graphics.
3. Animated GIF- This format enables you to merge multiple
GIF image into a single file to create animation. This
format can not apply compression. The animation keeps
on playing and cause distraction to the viewer or reader.
JPEG Files:
JPEG files known as Joint Photographic Experts Group
minimize graphic file sizes and are true colour (24
bit) image format. This format works well for photographic
images with gradients, blends and inconsistent colour
variations.
JPEG is a lossy format i.e. it throws away bits which
means with creation of each image some information is
lost which invariably degrades the image quality. So
it is advisable to save the original image before working
on it.
Progressive JPEG is a newer form of JPEG file which
is similar to Interlaced GIF file. The viewer will see
a rough picture which will get refined as more and more
bits of the image are received. This is good for displaying
larger images.
PNG Files:
PNG (pronounced as ping) files or Portable
Network Graphics was developed by the graphic software
developers association as an alternative to GIF files.
This is a new format which is challenging the supremacy
of JPEG and GIF image formats.
Unlike JPEG files PNG files do not loose bits while
generating the images. PNG files can be made partially
transparent which is essential to display good quality
of graphics on the web. PNG files support colour depth
of more than 24 bits making it a better choice then
GIF formatting. This format can also hold short textual
descriptions of the image which helps in search engines
to index images based on their textual content.
The only shortcoming of PNG files is that they are not
as widely supported by web browsers as JPEG and GIF
file formats. Moreover, the present executions of PNG
graphics in the major web browsers do not completely
support all the features of PNG.
This article has been compiled by the content development
team at Pegasus InfoCorp which pulls subject matter
specialists from different work domains. They can be
contacted through the Pegasus InfoCorp website at info@pegasusinfocorp.com.
Pegasus InfoCorp is an India based web design, web development
and online/offline software development company. Please
visit http://www.pegasusinfocorp.com to read more articles
and know more about us!
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