A common compression method for dealing with graphics is that of the JPEG. While in many cases these types of images will not be used in the actual development of a website, depending on the type of website, they may be used at a later point in time as part of the site’s content.
When it comes to the JPEG compression, the amount of compression can actually be adjusted but keep in mind that the more an image is compressed, the more it will appear grainy and pixelated. The typical JPEG image though will see a compression rate of roughly 10:1 in comparison to that of the RAW version of the same image. However, at 10:1, there is very little quality loss one will notice; especially if the eye is not trained to spot these issues.
When using a digital camera, in most cases the images will be stored using this or the JFIF format which is very similar. Likewise, when it comes to storing images on the World Wide Web, the JPE format is the most common one used. Websites like Flickr and more feature the vast majority of the images stored on their servers being that of the JPEG, while sites like PhotoBucket tend to be more gif formats as they are used for CSS.
It was back in 1986 when work on the JPEG compression format began but it would not be until 1992; the year the internet was born, that the format would officially be standardised. Known as the Joint Photographic Experts Group, the image compression received its name as an acronym. In the standardisation of the format, the codec as well as the manner in which the image is compressed is defined.
When it comes to photographs, paintings or anything in which a smooth colour transition and life-like appearance are needed, the JPEG is the most commonly used. This is important to remember because while most people have never had the opportunity of working with RAW images, those that have will tell you about the vast amounts of storage space needed to work with them.
Because it is better suited for smooth and life-like imagery, using a JPEG format for sharper images or ones in which the colours change greatly in degree over a few pixels, the JPEG is not suggested as it will cause pixilation of the final image. For these types of images, the use of formats like PNG or gif are more commonly used. Furthermore, editing the same JPEG image multiple times can also cause issues especially with pixilation, the more an image is edited, the more information that is lost; each and every single time it is compressed, edited and then compressed again. In these types of situations, it is suggested to convert the image to a lossless format like PNG in order to handle the multiple edits.
While JPEG is a lossy format, it is still most commonly used because where it counts, the space of storage saved is more than worth it. Imagine a digital camera that allows you to take 40 shots without upgrading the card slot; if the images were not saved and stored as a JPE, then you would only get 4 shots in the same space. Likewise the same can be said for storage on the web where as a webmaster can save tons of bandwidth simply by using JPEG over other raw or lossless formats.
Original Authors: Nick
Edit Update Authors: M.A.Harris
Updated On: 09/02/2009