This function is intended to serve as an example for the "imageCopyMerge"-function.
I hope it will help some of the less experienced php-coders here.
I wrote it to mark objects of a real estate broker as "sold" by copying the "sold"-picture right into the picture of the house.

<?php

//$sourcefile = Filename of the picture into that $insertfile will be inserted.
//$insertfile = Filename of the picture that is to be inserted into $sourcefile.
//$targetfile = Filename of the modified picture.
//$transition = Intensity of the transition (in percent)
//$pos          = Position where $insertfile will be inserted in $sourcefile
//                0 = middle
//                1 = top left
//                2 = top right
//                3 = bottom right
//                4 = bottom left
//                5 = top middle
//                6 = middle right
//                7 = bottom middle
//                8 = middle left
//
//
function mergePix($sourcefile,$insertfile, $targetfile, $pos=0,$transition=50)
{
    
//Get the resource id?s of the pictures
    $insertfile_id = imageCreateFromJPEG($insertfile);
    $sourcefile_id = imageCreateFromJPEG($sourcefile);

//Get the sizes of both pix    
    $sourcefile_width=imageSX($sourcefile_id);
    $sourcefile_height=imageSY($sourcefile_id);
    $insertfile_width=imageSX($insertfile_id);
    $insertfile_height=imageSY($insertfile_id);

//middle
    if( $pos == 0 )
    {
        $dest_x = ( $sourcefile_width / 2 ) - ( $insertfile_width / 2 );
        $dest_y = ( $sourcefile_height / 2 ) - ( $insertfile_height / 2 );
    }

//top left
    if( $pos == 1 )
    {
        $dest_x = 0;
        $dest_y = 0;
    }

//top right
    if( $pos == 2 )
    {
        $dest_x = $sourcefile_width - $insertfile_width;
        $dest_y = 0;
    }

//bottom right
    if( $pos == 3 )
    {
        $dest_x = $sourcefile_width - $insertfile_width;
        $dest_y = $sourcefile_height - $insertfile_height;
    }

//bottom left    
    if( $pos == 4 )
    {
        $dest_x = 0;
        $dest_y = $sourcefile_height - $insertfile_height;
    }

//top middle
    if( $pos == 5 )
    {
        $dest_x = ( ( $sourcefile_width - $insertfile_width ) / 2 );
        $dest_y = 0;
    }

//middle right
    if( $pos == 6 )
    {
        $dest_x = $sourcefile_width - $insertfile_width;
        $dest_y = ( $sourcefile_height / 2 ) - ( $insertfile_height / 2 );
    }
        
//bottom middle    
    if( $pos == 7 )
    {
        $dest_x = ( ( $sourcefile_width - $insertfile_width ) / 2 );
        $dest_y = $sourcefile_height - $insertfile_height;
    }

//middle left
    if( $pos == 8 )
    {
        $dest_x = 0;
        $dest_y = ( $sourcefile_height / 2 ) - ( $insertfile_height / 2 );
    }
    
//The main thing : merge the two pix    
    imageCopyMerge($sourcefile_id, $insertfile_id,$dest_x,$dest_y,0,0,$insertfile_width,$insertfile_height,$transition);

//Create a jpeg out of the modified picture
    imagejpeg ($sourcefile_id,"$targetfile");
    
}