Know your file types

by Darren | 4 February 2015

Knowing which file format to ask your designer to supply can be daunting. Having your file supplied correctly is crucial to the outcome of the final job for print or web. My clients don't need to worry. I always supply the correct file format. To help you understand the difference I'd like to share with you seven of the most common file types and a little description of each one.

Also known as an Encapsulated PostScript, this is the most versatile file format used when sending a job to print. It is a vector based format meaning that images and fonts are treated as a series of geometric shapes that can be enlarged without distortion. Vector based images are made using a series of lines, shapes and curves creating an image which viewed small on a business card or very large on a roller banner they always appear sharp. 

Also known as a Bitmap, this is a large grid made up of thousands of little squares or 'pixels' that create a photographic image. Coloured pixels allow an image to be built up square by square. The problem is that the appearance is determined by the size and the resolution or the density of the pixels otherwise known as the 'dots per inch' or DPI. The higher the DPI, the clearer the image will be, therefore 72 dpi will be fine for online use but for print you need your image to be at least 300dpi. 

Standing for Joint Photographic Experts Group, they are similar to a bitmap and often specified for photographic images. The quality of a JPEG depends on the resolution of the file. The problem with a JPEG is that it is lossy meaning that each time it is re saved some of the information is lost which affects the overall quality of the file, restricting the way the image can be edited.

Also known as a Tagged Image File Format, TIFFs are often used for photographic and continuous tone images as well as line art graphics and images involving text. Images saved as a TIFF are bitmapped and they can't be enlarged without the loss of image quality so it's important to supply a TIFF at the size it will be printed to avoid loss of quality or pixelation.

Also known as Portable Network Graphics, PNGs are raster graphics file formats which means they have a structure made up of a rectangular group of pixels which are lossless, in other words they allow the original data to be perfectly reconstructed from the compressed data not affecting the quality of the image. They were designed for transferring images on the internet and support the RGB colour space. The PNG file also has the best capacity for a transparency.

Also known as Graphics Interchange Format, GIFs can be used for small animations and low resolution film clips. They don't tend to produce colour photographs very well but are well suited for graphics with solid colour.

Also known as Scaleable Vector Graphics, a two-dimensional vector graphic format which allows vector graphics to be displayed on the web.