Mask-R-Aid is a tool for creating masks.
Edit by : Mask-R-Aid is a tool for creating masks. An icon consists of an icon image and a mask that tells the system how to render the transparency of the icon. Normally the icon image is rendered with no transparency for most of the icon image (the interior Pixels). Transparency comes into play when you want to do shadows or use a photo-realistic icon.

Mask-R-Aid is useful for creating masks in general, but is especially useful when creating photorealistic icons. The problem with a photo-realistic icon is if you do not set the proper grayscale values for the edge pixels of the mask, you will see jagged edges. The problem with setting the grayscale pixels is that it is a tedious and error prone process. Mask-R-Aid makes this process simple and hassle free.

Mask-R-Aid provides three different converter algorithms for creating a mask.

Flat Mask - Every non-white pixel is converted to a black pixel. This converter is good for creating masks of icons that have solid well defined edges.

Edge bLend - All interior pixels of the icon are set to black while all edge pixels are set to a medium gray value. This is good if you wish to do value setting of the edge pixels yourself in another tool.

Grayscale Edge Blend - All interior pixels of the icon are set to black while all edge pixels are set to a grayscale value based on the corresponding pixel in the icon image. This is the converter to choose if you are doing a photo-realistic icon.

New Features with Version 4.1:

Added full support for exporting ICNS and ICO files from both the Macintosh and Windows version of Mask-R-Aid. This means you can Create ICNS and ICO files with the Macintosh or Windows version of Mask-R-Aid.
Added support for 256x256 (resolution Independent) and 24x24 icon sizes.
Added a Clear All menu item to clear all images in the Mask-R-Aid window.
New Features with Version 4.1.1:

Rearranged the main Mask-R-Aid window so that it fits on smaller screens.
Added mouse scroll wheel support. you can free download Mask-R-Aid for Mac OS X 4.1.1 now.