Thank you, Ty Rayner. If you aren’t familiar with the Instant Alpha tool in Mac OS X’s (Snow Leopard) Preview application, you’re missing out on the best alpha tool I know of.

Ty implemented that wonderful feature in Preview when he was an engineer at Apple.

To go from scanned artwork to a game sprite, it is important to get rid of the area around the artwork – the paper or whitespace surrounding the drawing. In digital graphics parlance, you create an alpha channel (in everyday terminology, you make the surrounding regions clear or transparent – the checker pattern in the image above represents the transparent area around the paper glider).

1. •Open the scanned image in Preview and select the Instant Alpha tool (from the Select button in the toolbar – see above).
   

2. •Click (and hold) in an area around the artwork – an area you intend to become transparent.
   

3. •Drag.
   

As you drag the tolerance of your “magic wand” increases. The visual feedback makes it simple to see what portion of the image you are selecting for alpha (elimination).

1. •When the desired area surrounding the artwork has been selected, release the mouse button and hit the Delete key to clear the selected region.
   

2. •As the tool’s name suggests you have instant alpha.
   

It’s easier to use actually than to describe.

(Continues.)