(PECL imagick 2.0.0)
ImagickDraw::setStrokeOpacity — Specifies the opacity of stroked object outlines
$stroke_opacity
   )This function is currently not documented; only its argument list is available.
Specifies the opacity of stroked object outlines.
stroke_opacitystroke opacity. 1.0 is fully opaque
No value is returned.
Example #1 ImagickDraw::setStrokeOpacity()
<?php
function setStrokeOpacity($strokeColor, $fillColor, $backgroundColor) {
    $draw = new \ImagickDraw();
    $draw->setStrokeWidth(1);
    $draw->setStrokeColor($strokeColor);
    $draw->setFillColor($fillColor);
    $draw->setStrokeWidth(10);
    $draw->setStrokeOpacity(1);
    $draw->line(100, 80, 400, 125);
    $draw->rectangle(25, 200, 150, 350);
    $draw->setStrokeOpacity(0.5);
    $draw->line(100, 100, 400, 145);
    $draw->rectangle(200, 200, 325, 350);
    $draw->setStrokeOpacity(0.2);
    $draw->line(100, 120, 400, 165);
    $draw->rectangle(375, 200, 500, 350);
    $image = new \Imagick();
    $image->newImage(550, 400, $backgroundColor);
    $image->setImageFormat("png");
    $image->drawImage($draw);
    header("Content-Type: image/png");
    echo $image->getImageBlob();
}
?>