Icon Mask Maker (IMM) makes transparent masks to build transparent icons. IMM is $10 shareware. You can try IMM for five launches before registration is required.
Developers need icons for their applications. Lion applications use icons that are 512 x 512 pixels. Icons have two layers: the icon itself and the icon mask. If the mask is solid black, the icon will be opaque around the image, but if the mask is black only where the icon has color, then the icon will be transparent around the image.
For example, below you see three images. The left image is the icon (top layer) and the middle image is the mask layer. Using these icon layers gives you the icon on the right. Notice that the area around the image is opaque (you cannot see the desktop).
Below you see what happens when you make the mask black only where the icon (top layer) has color. The left image is the icon (top layer) and the middle image is the mask layer. Using these icon layers gives you the transparent icon on the right. Notice that you can see the desktop around the image within the icon area.
Icon Mask Maker lets you make the transparent mask with a few clicks. There is no need for complicated applications or drawing skills. Here are the steps to make a transparent mask.
Find a square image that you like at a royalty free web site. Fotolia.com is such a site and it has millions of images which can be licensed, downloaded and used for the icon itself. Pick an image that is white around the main image. The smallest size (also lowest cost) is sufficient to build 512 x 512 icons. The desired image format is "XXX.jpg". If the image format is not "XXX.jpg", use an application such as Preview to convert it to an image with "XXX.jpg" format.
When you first launch IMM, two folders are added to your desktop: Icon Source and IMM (the output folder).
Drag the downloaded image into the Icon Source folder on the desktop. This folder should have only the one jpg image and no folders.
The IMM window has two large areas, four buttons and a slider. Click on the "Load Icon" button to rescale the image in the Icon Source folder and display it in the left area.
Click the "Make Screenshot" button below the left area to make a 512 x 512 pixel image in the IMM folder on the desktop. This file will have "XXX Icon.jpg" format.
Click the "Make Mask" button. You will see the mask displayed in the right area. Both images have 262,144 pixels (512 x 512). If a pixel in the left image is white, that pixel in the mask will be white. If a pixel in the left image is any color except white, that pixel in the mask will be black. Try moving the "Fuzziness" slider back and forth to see how it changes the mask. The slider sets the tolerance for deciding whether the pixel is white or not. Select a slider setting that gives you a clean mask image.
Click the "Make Screenshot" button below the right image to make a 512 x 512 pixel image in the "IMM folder on the desktop. This file will will have "XXX Mask.jpg" format.
That's it! You now have the two images necessary to make a transparent icon.
