Using A User Defined Alpha Channel Mask

What is a user defined alpha channel mask?

Since the addition of the Transparency page to the Preferences screen you have been able to automatically apply a fade effect to the edges of your images in order to seamlessly blend them onto the background. This is done by calculating an alpha , or transparency, channel to apply to the normal RGB channels of your images. Basically the alpha value for a pixel tells AWC how transparent the pixel should be when it is painted onto the screen backgraound. Alpha values can range from 0 to 255: 0 being completely opaque and 255 being completely transparent.

As of version 4.11.0 of AWC, instead of letting the software calculate the alpha values for you, you can use an image file to define the alpha channel. This is called an alpha channel mask. AWC opens the specified file, resizes it to be the same size as the main image and then uses the blue channel pixel value of the mask as the alpha value for displaying the pixel on the background. Thus, you can not only define your own fade gadients but also apply shaped masks to show off your pictures with a bit more pizazz.

Selecting a mask to use

It's easy to select an alpha channel mask. From the drop-down under Alpha Blended Fade on the Preferences screen go to the bottom of the list and choose Use Masking File. This will display a text box and browse button that you use to define the file you want to use. Just click on Browse and select the file you want to use. A few sample masks are provided in the AWC program folder but you can use one of your own if you want to. A few examples of how different masks look are shown below.

Circular mask with soft edge

Circular mask with hard edge

Use masks of any shape
that takes your fancy

Use masks of any shape that
takes your fancy

Combine with picture frame
to give non-rectangular results