Example

function roundRectangle($strokeColor, $fillColor, $backgroundColor, $startX, $startY, $endX, $endY, $roundX, $roundY)
{
    $draw = new \ImagickDraw();

    $draw->setStrokeColor($strokeColor);
    $draw->setFillColor($fillColor);
    $draw->setStrokeOpacity(1);
    $draw->setStrokeWidth(2);

    $draw->roundRectangle($startX, $startY, $endX, $endY, $roundX, $roundY);

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

    $imagick->drawImage($draw);

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