The 'maskcolor' property

Not implemented under MacOS

Integer scalar or 3-element vector

Valid for: Tree

When you specify an image in an ImageList object using the imagenames property or Addimages method, you can provide a mask which indicates that certain portions of the image should be transparent. The maskcolor property provides an alternative way of achieving a similar effect. As new images are added, and provided no explicit mask is specified for a given image, any pixel in the bitmap which matches the color specified in maskcolor will be set to be transparent.

You can specify maskcolor as a three-element vector of Red, Green and Blue color values, each in the range 0 to 255, or as a single integer encoding the color as 256 ⊥ Blue Green Red.