Generate randomized placement of objects

[ugeb318]

I'm trying to generate an image that has a lot of little objects (small images) randomly placed on the canvas.  I'd like to be able to control how dense the placement is, the variation in image sizes as well as the image I want to scatter.

An example would be to create an intricate snowflake and randomly scatter snowflake copies all over the canvas in different sizes.  I'm not generating snowflakes, but it is similar.

Is there a function/filter that does this? How can I achieve this effect?

[Semaphoric · Accepted solution]

You could make a brush of the objects, and use Scattering in the Brush Settings.

    

[blackopsben]

But this only works if the image is greyscale. (Eg, the color data of the image is not used.)

How would you achieve the same thing with an already colored image?