When you put a logo in an email you only need it to be a few centimetres high. Similarly, when you visit a website, you want images to appear quickly and not have to wait for them to download. You need smaller images both ‘on the page’ and in terms of ‘file size’. This is where image compression comes in.
What is image compression?
When printers and graphic designers create an image for you, it is very high resolution and huge in size (usually >2Mb), so that they can print in top quality and use the same image in any medium, from a letterhead to a 50-foot high projection.When these files get sent through the web, whether in an email or on a website, they need to be made smaller i.e. compressed.
Image compression makes the image size on the page and the depth and clarity of colour smaller, with no visible loss of quality.