Keyfob: Anatomy of an Icon

Following on from a previous article on toolbar design we're going to tackle it's Big Brother, the Application Icon. The two serve slightly different functions within the program but adhere to the same idea. While we could start on an existing application, we’re going to embrace vaporware and produce an Icon for an Application that doesn’t exist. This is simply to show the process. This tutorial will follow the construction of an Icon for an imaginary application called “Keyfob”. We’ll say that it’s an application for locking and unlocking the Mac remotely. This is partly inspired by a process where someone managed to put their Mac to sleep using a SMS text message.

Where do we start?
A biro pen, a sketchpad and a cup of tea usually works well for me.
However above all these, the most important tool for developing Icons is?

A Dictionary
Every Icon is communicating a metaphor and because you are appealing to a wide audience, the accepted meaning for a term is very important. So the inclusion of a Dictionary with 10.4 Tiger was a boon for anyone who has ever tried to sum up “vertically integrated certification process” in a 16x16 square.
This process may sound a bit silly but every Icon needs to rely on a strong metaphor which is understood by the widest audience.Simplicity always wins out so in this case we will produce a key which looks like it attaches to a chain.

Sketching
Then the process of swirling out your ideas begins. It doesn't matter if the sketch looks like monotone roadkill, you are just throwing ideas down onto paper at the moment. If any aspiring filmmakers ever needed encouragement they should look at the Taxi Driver storyboards of Martin Scorcese. The man has incredible talent in filmaking but would be thrown out of kindergarden art class. Once you have placed some ideas down on paper you can scan them in and dive into your image editor of choice. I'm using Photoshop CS and IconBuilder Pro for this one. The method I use to create icons could be wildly different from someone else so go with whatever method feels comfortable. The end result will be a series of scaled resources that the OS will use in different views.

Blocking In Colours
From my sketch ideas I'm going to take the angled key with a button for operation at a distance. The icon is going to be built using vector shapes and layer styles so there is no need to build a huge source file and scale down as these will scale up quite well. First we draw out the base layer with the pen tool. It's usually helpful to have the sketch on a layer at the top set to overlay mode as you can then check you are following the rough idea. When we have the base layer laid down we can then start to fill in certain shapes with layer styles such as gradients and inner glows to give definition. The pattern overlay tool can be quite useful to give some texture in certain areas.

Highlights and Shadows
When we have filled in the base layers with colour and some effect we can start building up highlight layers for each of these examples. The main concern with the highlight layers is to reinforce the overall shape of the icon, be it a sphere, pipe, or circle. So on this Icon , we use a lighter shade of grey to build up the curve of the rubber. The surface would be quite dull so the edges ahd highlights would all be quite soft. Lastly some shadow layers complete the overall impression of the icon shape.
If you want to apply a nice edge highlight, try putting a inner and outer glow on a shape and then setting the fill content to 0%.Use a layer mask to knock out the shadowed side.)Make sure to click “Layer Mask Hides Effects” in the Blending options palette All through these layers, masks are used to bring down the edges of highlights or bring up shadows in certain areas.If you are unhappy with the angle of something , clicking on the approriate point with the Direct Selection tool and nudging the point with the arrow keys usually solves most issues.

Smaller Sizes & Exporting
While the Icon we’re building may look decent in 128x128, the majority of the time it is going to be viewed in a smaller size in the Dock, sidebar or Column/List view.So we have to think about what we do to make it look well at smaller sizes. Sometimes a simple scale and sharpen will work. Other times, it helps to build a version of the Icon specifically at that size.

The vector nature of this method helps making scaling or style changes at a later date without any loss of quality. This Icon could be scaled up to 256x256 or larger and only the layer effects and masks need a small cleanup to match the 128x128 look.With the 32 and 16 resouces we can zoom in and see what detail if any we can clear up. One tip is to sharpen the edges by judging the overall colour of the icon and applying a very subtle stroke using that shade to harden the edges of the icon. Thus in list and sidebar locations the icon can be more visible. The final step is to build the icon resouces in IconBuilder (using the IconBuilder Photoshop template, you can instantly fill in the various sizes by clicking QuickBuild) For most Application Icons, you will be creating a ICNS file.

Metaphors and Wild Fowl
An Icon is not a turkey. Stuffing it with extra elements will not give it more flavour. If the urge to fiddle is overwhelming, take a break from the Icon for a few hours and come back to it. The Icon can be given extra elements like little light indicators or graphics on the button but are they contributing to the meaning or just an excuse for pixel pushing? Simple is very hard to achieve consistently but it’s something that’s worth aiming for.

I’ve made a little movie of the process so you can see the general buildup of effects. I could have given the PSD but I think it’s better to show the general process rather than the exact settings and layers for one specific piece or artwork.

[View Quicktime Movie 2.7mb] or [Download the OS X Icon File 163k]

Cian Walsh is an Icon and Interface Designer who doesn’t smoke but is trying to cut down on his 20 tweaks a day habit.