Not transparent background after inserting png on pdf

Question

I'm trying to add png image on pdf file using Imagick on Ubuntu Server.

$background = imagecolorallocate($signature_place, 255, 255, 255);
imagefill($signature_place, 0, 0 , $background);
imagecolortransparent($signature_place, $background);

But the background has a dirty white color.

Example on Ubuntu Server

The interesting fact that it works correctly on Windows.

Example on Windows

I'm using:

• php7.0-fpm
• php-imagick 3.4.3

I really don't understand where the error could be.

Did anyone have such problem? Where should I find the error?

Answer 1

This is what I use for PNG

    $im = imagecreatefrompng($this->source);
    imagealphablending($newImg, false);
    imagesavealpha($newImg, true);
    $transparent = imagecolorallocatealpha($newImg, 255, 255, 255, 127);
    imagefilledrectangle($newImg, 0, 0, $newWidth, $newHeight, $transparent);
    imagecopyresampled($newImg, $im, 0, 0, 0, 0, $newWidth, $newHeight, $this->srcWidth, $this->srcHeight);
    imagepng($newImg, $this->destin);