When wishing to print some text on a photograph and make that text sufficiently contrasting to the background image, use a 4 byte code for colour and transparency.
It is the same 4 byte code using by the parameter '-undercolor' in ImageMagick's command lime instruction 'convert'.
The first 3 bytes are the RGB colour code and the fourth byte is the transparency byte.
<?php
$draw = new ImagickDraw();
$draw->setFillColor('#ffff00');
$draw->setFont('Eurostile');
$draw->setFontSize(21);
$draw->setTextUnderColor('#ff000088');
$picin->annotateImage($draw,40,$height-10,0,"Hallo");
?>
The example code produces yellow text on a semi-transparent red background.
