Image File Types

There are different types of file extension with images (the main few being: .jpg, .png, .bmp, .gif, .tiff, .raw) and these are used in differnet situations and different reasons.

For Print you need an image that looses the least amount of data possible meaning that the colour is more defined and more colourful. You would use such file formats as: .tiff, .bmp & .raw for this.

For Web use you need a file that can be shrunk down and still retain decent quality as well as in some cases use animation. For this you would use .gif & .png.

.Jpg is probably the most commonly used file format within pictures (digital cameras usually automatically save files as .jpgs, most programs will offer you a .jpg as default etc.) although the .jpg is in the middle. This is because it can be used for both print and web as it can be reduced down and still retain picture quality whilst also being able to print out and also not loose picture quality. This is because of the complex mathematics behind the .jpg file format.

There are two different sections of image file formats (print & web) for a reason. This reason is that web images must be smaller file size because of download limits and download speeds. You wouldn't want to be sitting on a webpage if you had say, 1MB broadband waiting for a website to load that had 12 images all at 4MB each, you would be there for minutes, get impatient and leave. In the same scenario if you had 512KB Dial-UP, you wouldn't want to be using up your bandwidth on 12 images which were all at 4MBs each.

With mobile devices such a smart phones or tablets, you will usually get a limit (even on "unlimitted internet plans" most of them are on a fair use policy meaning that you will get around 1GB of bandwidth for the month). If a website has 12 images each at 4MBs on a website that has 10 pages that's 480MBs for one website alone. That's half of your monthly allowance.

Because of this, you need to reduce the image sizes of web images so that people can view it across a multitude of platforms easily and quickly.