What you need to know about your logo files

The advent of desktop publishing, and DIY websites means that we all have access to our business logo in many different file formats. Now that we have our digital logos in our hot little hands (or on our hard drives) we think we need never bother our designer again. But beware, if you're using an online business card printing service, you need to know a bit more about the file you need in order to avoid your business logo becoming blurry, pixelated, the wrong colour, or looking just plain weird.

Graphic design and printing have a spectrum of different file types that suit different applications. You don't need to know the tech speak for all of them, but you do need to know that they exist. Below is a brief summary of file types you may encounter when you work with printers and designers. Please note this only scratches the surface, but it's job is to enlighten you as to why designers require files in the formats that they do.

The file types

.ai (Adobe Illustrator)

The design industry's tool for drawing logos is typically Adobe Illustrator. This program allows the creation of logos that can be enlarged to the size of an aeroplane, or bigger and ensure that you don't get that square white patch behind a logo when you put it on a coloured background. It's typically the working file for a logo.

 These files are great because they are a 'vector' type file. Where some files are made up of pixels (much like a computer monitor), this file type creates a mathematical equation to determine how the file appears, which enables the image to be stretched to any size without distorting.

Until recent advances in Illustrator, it was not always possible for drop shadows and special bevelled effects to be included in an .ai file. If you do have these effects on your logo be careful as some odd things can happen when they go to print as this process requires further augmentation by software developers.

.eps (encapsulated postscript)

This is the more versatile version of the vector files. Many clients get confused when this file is supplied as it cannot be opened into most word processing programs (especially when you double-click on it, as your computer doesn't have a default program allocated to this file type to open it). But always store this file and use it as your first choice to send to printers or designers. Designers tend to use this file type as it is more easily opened by other design programs than the .ai file.

Note, a .eps file is not exclusively a vector file. Photoshop can also save images as .eps files. These types of files can not be blown up without limits, as they are made of pixels (also referred to as 'rasterized'). 

.jpg (Joint Photographic Experts Group)

Jpeg / .jpg files (Mac's often used to use four letters in their file tags instead of the now more standard three)  are a type of file that enables seemingly larger images to be compressed and appear the same visually to the eye. Much like an mp3 compresses a music track, some information is lost in compression but may not be evident to the naked eye. These files are great for emailing large photos and is a common file type for Internet imagery, where small file sizes are important.

Because of the different options for compressing a jpeg, never presume the jpeg is the best image quality for your logo. Never send your logo to a printer or designer if you've simply downloaded it from your website, as you'll be disappointed with the results. See below, about dpi for more information about why you cannot print a logo clearly from a small file.

.psd (Adobe Photoshop file)

Most people have heard of Photoshop as it's available in more affordable, stripped down, options. A .psd file is simply a working file created in Photoshop. It allows for the transport of your file in different 'layers' enabling such things as the background to be clear cut, or 'deep-etched' out, so it doesn't have the white box around it that a jpeg file does. Note, it is still made up of pixels, not vector equations.

Beware the designer that creates your logo in Photoshop, and likewise you should not create your logo yourself in this program. It may seem like a good quick fix, and allow effects that you may not be able to achieve in Illustrator (such as bevels, 3D fish-eyes and blurs), but you'll inevitably be confronted with the problem of needing your logo in a size that can't be reproduced. See about dpi below for more information about enlarging logos.

psd files are larger, and therefore not easily emailed because of the amount of information the file contains.

.tiff (tagged Image File Format)

Tiffs are the most popular of rasterized files as it tends to be more flexible, hold more information in the file and is widely supported by different software. These are a larger file, making them less easy to email and harder or slower for some older computers to process. 

Other points to note

About dpi

dpi stands for 'dots per inch' and is a graphic measurement standard - like centimetres. It is a way of describing how much information is in an image file. When an image is printed it is made up of a screen of dots printed on a page. Though we are in a country that uses the metric system inches are still the common measurement when we refer to dpi.

In computer terms, the reference is ppi, or pixels per inch, where the medium on a monitor is made up of a series of pixels. dpi and ppi are often transposed, but the general meaning is the same.

The ideal screen resolution (how many pixels to see an image clearly) is 76ppi. For every inch squared of the screen there are 76 pixels.

The ideal print resolution for most high gloss, or stationery publications is 300dpi. For every inch squared of a printed page, there needs to be 300 dots, and these dots will be finer to fit in the same square inch of space.

Why logos from the Internet pixelate when printed.
When information is deleted in a file to make it smaller and more easily transported, or downloaded (in the case of a website), it can not be added back in. If an image is 72dpi and 2cm wide, and we make it 144dpi (ie we double it), the file size will increase as you'd expect, but the computer will simply make each pixel twice the size as it was and no more detail can be added to the image. The printing process requires more information than a computer monitor, as there are more dots per inch of paper required to make an image look sharper.

Rasterized vs vector files

Rasterizing is the process of turning an image from the mathematical equation of a vector drawing to pixels per inch - such as when you save it as a jpeg, tiff or Photoshop file. A clever designer will always keep the vector file to go back to should a larger file be needed.

The best way to describe the difference is to think of a rasterized image like a digital photo, while a vector file is like film. Film goes through a very different process, and when a film image is enlarged, the image remains true (yes, depending on the film speed - how much image was gathered when the photo was taken). Digital photography technology is ever increasing, with more information being incorporated as a smaller file, but it still requires little square, or pixels, of an image to make up one picture.