Example

function setFillColor($strokeColor, $fillColor, $backgroundColor)
{
    $draw = new \ImagickDraw();

    $draw->setStrokeOpacity(1);
    $draw->setStrokeWidth(1.5);
    $draw->setStrokeColor($strokeColor);
    $draw->setFillColor($fillColor);
    $draw->rectangle(50, 50, 150, 150);

    $draw->setFillColor("rgb(200, 32, 32)");
    $draw->rectangle(200, 50, 300, 150);

    $image = new \Imagick();
    $image->newImage(500, 500, $backgroundColor);
    $image->setImageFormat("png");

    $image->drawImage($draw);

    header("Content-Type: image/png");
    echo $image->getImageBlob();
}