Can I use an image in weight paint

this is my first post, so i don´t know if this is the correct part of the forum.
Well here, is my question
I want to know if its posible to use a greyscale image to define the weights of the vertices of a mesh instead of drawing it by hand.
I think it could be useful for particles an much more things
thank you

Hi, in Blender v2.48a, it is possible to use a texture to control the density of a particle system (hair particles for example) on a mesh. The Dens (Density button doesn’t work in 2.49, 249a and 2.49b).

This said, it is not really acting on vertex weight, and is not usable for rigging a character for example.

i want to use it to make the bubbles of top of a sea wave
so I think to do this I´ll need to use python because i need an animation controlling the density
thanks again