PHP: Draw Border to any image.

gistfile1.php

/*------------------------------------------------------+
| Provide image resource, border color and thickness to 
| add border to the resource.
+------------------------------------------------------*/
function drawBorder(&$img, &$color, $thickness = 1) {
    $x1 = 0;
    $y1 = 0;
    $x2 = ImageSX($img) - 1;
    $y2 = ImageSY($img) - 1;

    for($i = 0; $i < $thickness; $i++) {
        ImageRectangle($img, $x1++, $y1++, $x2--, $y2--, $color);
    }
}