$image = imagecreatetruecolor(200, 60);
$background = imagecolorallocate($image, 255, 255, 255);
imagefill($image, 0, 0, $background);

for ($i=0; $i < 300; $i++) { 
  $pixColor = imagecolorallocate($image, rand(150, 240), rand(150, 240), rand(150, 240));
  $pixX = rand(10, 190);
  $pixY = rand(5, 55);
  imagesetpixel($image, $pixX, $pixY, $pixColor);
}

//4条水平线
for ($i=0; $i < 5; $i++) { 
  $lineColor = imagecolorallocate($image, rand(50, 150), rand(50, 150), rand(50, 150));
  $lineX1 = 0;
  $lineX2 = 300;
  $lineY1 = ($i + 1) * 12;
  $lineY2 = ($i + 1) * 12;
  imageline($image, $lineX1, $lineY1, $lineX2, $lineY2, $lineColor);
}

//10条垂直线
for ($i=0; $i < 30; $i++) { 
  $lineColor = imagecolorallocate($image, rand(50, 150), rand(50, 150), rand(50, 150));
  $lineX1 = ($i + 1) * 10;
  $lineX2 = ($i + 1) * 10;
  $lineY1 = 0;
  $lineY2 = 60;
  imageline($image, $lineX1, $lineY1, $lineX2, $lineY2, $lineColor);
}

$text = array('栀', '子', '花', '开');
for ($i=0; $i < 4; $i++) {
  $textColor = imagecolorallocate($image, rand(20, 100), rand(20, 100), rand(20, 100));
  $textX = $i * 50 + 10;
  $textY = rand(40, 60);
  imagettftext($image, 30, rand(20, 50), $textX, $textY, $textColor, "/Library/Fonts/华文仿宋.ttf", $text[$i]);
}

header("Content-Type:image/png");
imagepng($image);

imagedestroy($image);