blue screen effect with PHP?

[raffael3d]

hi
I have looked into some GD image manipulation tutorials how you can combine two images.

now I wonder is it possible to do a sort of "blue screen" effect, where I would have the following situation:
- a person captured in front of a blue, green or white background
- a background image.

now I would want to "cut out" that person from the blue/green/white background and map it onto the background image.

I know how to combine to images, but I have no idea how to do the "cut out" effect of teh blue screen.

any tips, tutorials, links or ideas?
thanks!

[n_wattam]

i've messed around my self with image manipulation with php..

Be very interesting to see if the above is possible.. I dont see why not, however the time to process such a task might take longer than allowed within a PHP script...

[bradgrafelman]

Well... what if you put the backdrop (replacement of the blue color) down first, and then in a new image resource, created an image and then used [man]imagecolortransparent/man to set the "blue" color as transparent, and then used [man]imagecopymerge[/man] to copy the foreground w/ transparent-blue pixels on top of the backdrop?