$dest = imagecreatefromjpeg($src);
 $src = imagecreatefrompng("images/geda.png");
 

 imagecopymerge($dest, $src, 10, 10, 0, 0, 100, 47, 75);
 
 imagejpeg($dest);
 
 imagedestroy($dest);
 imagedestroy($src);

Array
(
    [GD Version] => bundled (2.0.34 compatible)
    [FreeType Support] => 1
    [FreeType Linkage] => with freetype
    [T1Lib Support] => 1
    [GIF Read Support] => 1
    [GIF Create Support] => 1
    [JPG Support] => 1
    [PNG Support] => 1
    [WBMP Support] => 1
    [XPM Support] =>
    [XBM Support] => 1
    [JIS-mapped Japanese Font Support] =>
)

header("Content-type: image/jpeg");