Help！ How can I shadow the transparent gif image

[harian]

I have a gif image with a transparent hole on center, how can I shadow this image and keep the centeral hole transparent, I try shadowImage command but the transparency is override.

pls help me. thanks.

[anthony]

You will need to try and mask out white.

Trying to preserve the anti-aliasing edges of the masked image is going to be a real problem in this case, as you have white in the 'stones' of the image as well.

Some morphological mask filtering to try and recover the anti-aliasing may be needed. alternativally some type of mask feathering may be needed to 'fake' the anti-aliased edges of the image.

Without some attempt to recover the anti-aliasing, you will have end up with a highly aliased (staircase-like) edging to the stones that for this natural looking image will not look very nice.