fade effect with images

[alcha]

Guys,
I'm trying to create a fade effect:
An image is shown in a JPanel and i want
another image to gradually paint over it while
the (initial) image from behind is fading.

I tried to use AlphaComposite, it worked , but the
outcome was really slow.

Another aproach was to get the alpha values of the images
by using   .getAlphaRaster() of the
BufferedImage class and then setting each pixel of the above raster by using .setPixels().Unforunately
(as you might have already guessed) that was also too slow. The image's dimension's are: 415x600.

Thank you for your time....