}
if (imMask != null) {
// shrink the mask to fit the display
GrayShrink gs = new GrayShrink(nTargetWidth, nTargetHeight);
gs.Push(imMask);
imMask = (Gray8Image) gs.Front();
// combine the gray image and the mask to make a displayable image
ApplyMaskRgb am = new ApplyMaskRgb();
RgbImage rgb = am.Push((RgbImage)rs.Front(), imMask);
g.drawARGB(0, 0, 255, 0); // green
g.drawBitmap(