php如何为php图像添加透明背景颜色？

Question

背景是白色的我要删除白色并放置transparent.please帮助

这是一张图片：http://funbusy.com/fbtest/user_image.php

?php

// Create the image
$im = imagecreatetruecolor(400, 25);

// Create some colors
$white = imagecolorallocate($im, 255, 255, 255);
$grey = imagecolorallocate($im, 128, 128, 128);
$black = imagecolorallocate($im, 22, 125, 0);
imagefilledrectangle($im, 0, 0, 399, 29, $white);

// The text to draw
$text = ucwords('tanuja sree');
// Replace path by your own font path
$font = 'OpenSans-Italic.ttf';

// Add some shadow to the text
imagettftext($im, 20, 0, 11, 21, $grey, $font, $text);

// Add the text
imagettftext($im, 20, 0, 10, 20, $black, $font, $text);

// Using imagepng() results in clearer text compared with imagejpeg()
ob_start();
imagepng($im);
$image_data = ob_get_clean();
$image_code = '<img id="image_code" src="data:image/png;base64,'.        base64_encode($image_data) . '">';
imagedestroy($im);

?>

Answer 1

尝试在imagettftext($im, 20, 0, 10, 20, $black, $font, $text);

之后添加这段代码

imagecolortransparent($im, $white);
imagesavealpha($im,true);
imagealphablending($im, true);