How Many Kinds Of Image Whats The Difference?
February 2nd, 2010 | 
Author: How Many Kinds Of Image Whats The Difference?
Images of all sorts have a major role to play Images of all sorts have a major role to play in your website’s appeal to visitors. Many image formats including jpg and png are incorporated processed and manipulated to display your wares and brand your image into your customers eyeballs and encourage buying decisions. Image rich graphical devices are also the main image content of online advertisements.
There is an image group locked away in a dark cupboard somewhere I suspect who actually discuss evaluate and decide on the standards that allow jpgs and other graphical images to be used on websites around the world and the world’s many languages. These are the geeks who collectively are called W3C and their gatherings are responsible for defining image standards and formulating important specifications in the area of web graphics such as the jpg standard. This work is part of the great umbrella that allows all of the different image types web browser web authoring tools and word processors to generate the electronic network that we take so for granted these days.
Web images come in a variety of formats. For new web builders it must seem a daunting experience grasping the subtle differences between the jpg and the rest. For our purposes the main graphic formats we need to understand for the web are Portable Network Graphics PNG Joint Photographic Experts Group JPEG or JPG Graphics Interchange Format GIF and bitmaps bmp.
You’re almost certainly aware of the “good ole” jpg image; so what exactly are JPGs? JPEG Joint Photographic Experts Group is a popular format used for representation or display of images. JPG is a format that loses image information which means that the repeated patterns within the image data from the original are discarded while it is being compressed and stored in this format. A benefit of the jpg image is that disc space can be saved while reproducing the image with almost the same quality. The information that is discarded from a jpg image is generally of such a nature that it is not possible for human beings to detect the difference in image quality.
The JPG method is standardized by ISO International Standards Organization. A classic jpg scenario is when you download a full size image from NASA of one of their astounding images of Saturn or an image of one of its moons. These can still be pretty big image downloads. A variation of the jpg is the progressive jpg in which the image is reordered so that a vague view of the entire image is displayed which sharpens as the download progresses.
The png is a newer standard that is starting to give the jpg a run for its money. PNG is an image file format for wellcompressed storage of raster images. Pngs are a much more useful format than gifs and complement many aspects of the jpg format. PNG image format supports indexedcolor grayscale and truecolor images. It also has an optional alpha channel for image transparency. The color depth used is up to 16 bits per component up to 48 bit images for RGB or 64bit for an RGBA image.
The advantages of the PNG image are losslessness and portability. They retain more detail that a jpg loses and are more versatile without getting too big.
Alongside jpg images the Graphics Interchange Format GIF image was introduced by CompuServe in 1987. It is a bitmap image format. GIFs became widely used because of its wide support and portability. The image format allows 8 bits per pixel. This allows the use of 256 distinct colors in an image. Unlike jpg it supports animation and has 256 colors for each frame.
GIF images only have a small colour range which is a disadvantage and makes it unsuitable for reproducing color photographs and other images with continuous color. However it can reproduce simpler images. GIF uses LempelZivWelch LZW lossless data compression technique to reduce the image data file size.
The bitmap bmp is another format used to store digital images. In bitmap files images are stored with colour depth between 1 and 32 bits. Bmp files though well documented and simple are very large. Unfortunately file sizes can be nearly as big as TIFFs.
A last format you need to know is the PSD. Often used in generating complex images it is the underlying format of Adobe Photoshop allowing you to build an image up in layers with an enormous range of control over the effects you can achieve whether starting from a jpg or any other image format.
These are some of the most important image formats used to display images on the web. In setting up your own image rich websites particularly business orientated sites a good understanding of these subtle image differences will become very important as you strive to keep visitors eyes on your offer.
About the writer:nbsp;nbsp;Ray Cassidyhttp://www.cosmicrayimages.thenorthernview.bizWebsite header graphics cropped from stunningly atmospheric photos in a range of sizes ready for a variety of inspirational website headers.
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