PHP Dynamic Image Has Undesired Border - php

Question

I'm having some problems with a project I'm doing using Google Maps.
I have the map functionality all figured out, and it works great. I want to add dynamically generated icons to the map, and I've figured out how to do that as well using PHP to dynamically add the text I want to the icon image.
However, the icon is changed beyond the text I want added. The border around the original is made much thicker when there is nothing in the PHP code that should be doing anything like that. The image I've attached to this post shows the two icons. The top icon is the original, and the bottom one has the text added to it by my PHP script. Notice the thicker border.
Here's my PHP code:
<?php
// GETS THE NUMBER TO ADD TO THE ICON
$number = $_GET['number'];
// THE SOURCE OF THE ICON THAT I WANT TO ADD THE TEXT TO
$src = $_GET['src'];
header ("Content-type: image/png");
$font = 4;
$im = imagecreatefrompng($src);
// POSITION THE TEXT TO THE PREFERRED LOCATION
$x = 5 ;
$y = 2;
$textColor = imagecolorallocate ($im, 0, 0,0);
imagestring ($im, $font, $x, $y, $number, $textColor);
imagepng($im);
?>
Keep in mind that all of this is working, except the image is changed beyond just adding the text. The icons look much nicer without the really thick border.

Answer 1

I don't know for sure if this is the case but something like this can be caused if your initial image used transparency at the margin to get an effect of rounded corners. if you want to keep the transparency from the initial image you need to research other functions also. something like this should help:
imagealphablending( $im, false );
imagesavealpha( $im, true );
*right after imagecreatefrompng