Digital graphics come in a variety of different file formats. Which format is used depends on how high the image quality needs to be, how large the graphics files can be, whether there will be text included and other considerations.
Here is a little guide to the most common image file formats that you may come across.
Pronounced “jay-peg” – most of the graphics on the internet are in .jpg format. This format compresses pictures so the file size is small. Many graphics programs allow one to adjust how much compression is used. More compression means a smaller file size, but the picture quality will be poorer. Over compressed jpgs often have coloured edges around elements in the picture, these are called artefacts, or ‘the jaggies’.
Pronounced “ping” – png format is the one usually used for images that need transparent backgrounds. There are other formats that can also handle transparency, but png is pretty much the standard nowadays as its files are small and high quality. If you buy digital clip art it will probably be png.
Pronounced “gif” – Gifs are not as popular online as they used to be, but you may still see them. They keep file sizes small by reducing the number of colours in the picture. This means they are great for things like line art or bold cartoon images, where they number of colours is very low. If used for photos they give rather blocky results. The one thing that makes gifs super useful is they can not only be static pictures.. but also animations. When you use a forum, and see a poster with an animated picture in their signature, that is almost certainly a gif.
Pronounced “pee-dee-eff” – PDFs are more complex files. They can include text and pictures. They are often searchable, and sometimes editable. They are often used for things like knitting patterns, ebooks, catalogues, promotional flyers, brochures, recipes etc. You need suitable software to open and read PDFs. Adobe Acrobat Reader is the most well known. It is free and often installed with other software because so many programs use PDF for their manuals and instructions. There are various other programs that can also read PDFs, including Photoshop.
Pronounced “bit-map”. Bmps were once very common but are now not used so often. They preserve a lot of details in the image, but are very large files. You may find older graphics in this format.
Pronounced “zip” – zip is not a graphics format but you may well be sent pictures in a zip file. Basically the creator has ‘zipped’ the pictures (or any sorts of files) into one compact one. The resultant zip file will be smaller than the sum of the individual components, making it easier to send.
You need a small program to ‘unzip’ the files. The Windows operating system has one built in and will just open any zipped files for you. Otherwise you can choose from many free programs that will do it.