Imagettftext() With Transparency in PHP

I have used <img src="blah.php"> to use the PHP image functions to create a gif to display. My problem comes in when I use imagettftext() to display text generated in the php script. I want the text to be semi-transparent and used (correctly I believe)

$back = imagecolorallocatealpha($image, 0, 0, 0, 100);$textcolor = imagecolorallocatealpha($image, 0, 0, 255, 60);

to create the color ($text) that I want. The problem is that the code, imagettftext($image, 70, 0, 0, 96, $text, "/font/arial.ttf", $string); displays the text in the proper RGB color but lacking the transparency.

This is an example of what the image currently looks like (it is random text):

 

Another thing, is it possible to return the generated random text to the calling php script, or pass the text from the calling php script to the image php script without using post (and preferably without get too)?