AImageEnVectMaskP.IEBitmap.Width := ASourceImage.Width;
AImageEnVectMaskP.IEBitmap.Height := ASourceImage.Height; 
AImageEnVectMaskP.Proc.Random(0.8, 0.1);
AImageEnVectMaskP.Proc.ConvertToBWOrdered;
AImageEnVectMaskP.IEBitmap.PixelFormat := ie1g;

AImageEnVectMaskN.IEBitmap.Width := AImageEnVectMaskP.IEBitmap.Width;
AImageEnVectMaskN.IEBitmap.Height := AImageEnVectMaskP.IEBitmap.Height;
AImageEnVectMaskN.IEBitmap.AssignImage(AImageEnVectMaskP.IEBitmap);
AImageEnVectMaskN.Proc.Negative;
 
{
???
ASourceImage --> ADestImageP (only pixels using positive mask)
             --> ADestImageN (only pixels using negative mask)
}

// Assign an alpha channel to an image using a source file (which is a monochrome bitmap where the black pixels will become transparent)

aBMP := TIEBitmap.create( 'D:\alpha.bmp' );

// Range of values in image must be 0 to 255
aBMP.PixelFormat := ie8g;

// Size of alpha channel must match size of image
aBMP.Resample( ImageEnView1.IEBitmap.Width, ImageEnView1.IEBitmap.Height );

// Use our bitmap as the alpha channel
ImageEnView1.IEBitmap.AlphaChannel.Assign( aBMP );

// Advise that the Alpha channel has value range
ImageEnView1.IEBitmap.AlphaChannel.Full := False;

// Update the container
ImageEnView1.Update;

aBMP.free;