Images should normally be saved at high resolution (usually 300dpi (dots per inch)) if they are going to be printed. If you’re creating exhibition graphics, you usually work slightly differently: You’ll need to produce your artwork either at 1/4 size at 300dpi, or at full size at 75dpi. Printers usually print in 4 colours (cyan, magenta, yellow and black, or CMYK). Image/logo industry-standard file formats are AI, EPS, PSD or TIF.

EPS and AI are vector files and these can be scaled to any size without losing image quality. Put simply, vector images are usually comprised of geometric shapes and lines. The information about these shapes and colours is stored as mathematical equations, which result in (usually) small file sizes. Very often, logos are produced using vector software packages such as Adobe Illustrator.

PSDs (PhotoShop Documents) and TIFs are rasterised images. This means that the image is made up of pixels, and because of this won’t scale up very well. Photographs are saved in rasterised formats.

These days all types of files mentioned above can be saved with layers, which means they can easily be edited at a later date.

For SCREEN

Images used on websites, emails and on-screen presentations can usually be saved at low resolution (usually 72dpi), and depending on format, will be saved as RGB (red, green and blue), index colour, or hexadecimal.

Web browsers can only display JPG, GIF or PNG image types, and choice of file format can depend on the result you want to achieve.

For photographic images which don’t require a transparent background, JPG could be the best choice, because the image will be displayed with smooth blending, and file size is reasonably small.

If you require a transparent background and smooth blending, then it’s the PNG file format for you. I’ve found Adobe Fireworks to be the best program to create PNGs with, because layers are preserved thus making the file fully editable at a later date, and vector files are supported.

If your image has few colours, and/or harsh/pixelated edges, then a GIF might work for you. File sizes can be really small, but do remember, if you need a transparent background, you will get some “matting” around the edge, so transparent GIFs work best when displayed on a solid background. You’ll need to know the colour of your background when saving your GIF so that you can set your matte colour to the same.

If you want to keep things simple, then that should be enough to get you going. There are loads of other file formats around, so if you have a particular favourite, please let us know!