(PHP3 >= 3.0.13, PHP4 >= 4.0b4)
ImagePNG -- 
     Output a PNG image to either the browser or a file
    
Description
int 
       imagepng
       (int im [, string filename])
     The ImagePng() outputs a GD image stream
     (im) in PNG format to standard output
     (usually the browser) or, if a filename is given by the
     filename it outputs the image to the file.