imagepng ändert unerklärlicherweise Hintergrundfarbe

[Forumsgast]

Hallo Community,

ich bin seit Tagen am verzweifeln, wieso der Tranparente Hintergrund bei mit am ende des Scripts schwarz wird, kann man da einer bitte helfen...

<?php

function watermarkImage ($SourceFile, $WaterMarkText, $DestinationFile='') {
   list($width, $height) = getimagesize($SourceFile);
   $image_p = imagecreatetruecolor($width, $height);
   //$image = imagecreatefromjpeg($SourceFile);
   $image = imagecreatefrompng($SourceFile);
   imagecopyresampled($image_p, $image, 0, 0, 0, 0, $width, $height, $width, $height);
   $black = imagecolorallocate($image_p, 0, 0, 0);
   $font = 'arialbd.ttf';
   $font_size = 12;
   imagettftext($image_p, $font_size, 0, 82, 16, $black, $font, $WaterMarkText);
   if ($DestinationFile !== '') {
      //imagejpeg ($image_p, $DestinationFile, 100);
      imagepng ($image_p, $DestinationFile, 5);
   } else {
      //header('Content-Type: image/jpeg');
      header('Content-Type: image/png');
      //imagejpeg($image_p, null, 100);
      imagepng($image_p, null, 5);
   };
   imagedestroy($image);
   imagedestroy($image_p);
};

function watermarkImage_dt ($SourceFile_dt, $WaterMarkText_dt, $DestinationFile_dt='') {
   list($width, $height) = getimagesize($SourceFile_dt);
   $image_p_dt = imagecreatetruecolor($width, $height);
   //$image_dt = imagecreatefromjpeg($SourceFile_dt);
   $image_dt = imagecreatefrompng($SourceFile_dt);
   imagecopyresampled($image_p_dt, $image_dt, 0, 0, 0, 0, $width, $height, $width, $height);
   $black = imagecolorallocate($image_p_dt, 200, 200, 0);
   $font = 'arial.ttf';
   $font_size = 10;
   imagettftext($image_p_dt, $font_size, 0, 94, 38, $black, $font, $WaterMarkText_dt);
   if ($DestinationFile_dt !== '') {
     // imagejpeg ($image_p_dt, $DestinationFile_dt, 100);
      imagepng ($image_p_dt, $DestinationFile_dt, 5);
   } else {
      //header('Content-Type: image/jpeg');
      header('Content-Type: image/png');
      //imagejpeg($image_p_dt, null, 100);
      imagepng($image_p_dt, null, 5);
   };
   imagedestroy($image_dt);
   imagedestroy($image_p_dt);
};

?>
<form action='' method='post'>
Spanischer Posten: <input name='span' maxlength="21"/><br/>
Deutscher Posten: <input name='deut'  maxlength="25"/> 
<input type='submit' />
</form>





<?php
$span=$_POST["span"];
$deut=$_POST["deut"];



/*
$SourceFile = 'siegel_roh.jpg';
$DestinationFile = 'fertig.jpg';*/
$SourceFile = 'siegel_roh.png';
$DestinationFile = 'fertig.png';
$WaterMarkText = $span;
$SourceFile_dt = $DestinationFile;
$DestinationFile_dt = $DestinationFile;
$WaterMarkText_dt = "(".$deut.")";
watermarkImage ($SourceFile, $WaterMarkText, $DestinationFile);
watermarkImage_dt ($SourceFile_dt, $WaterMarkText_dt, $DestinationFile_dt);


echo "fertig";
?>

[Forumsgast]

Kommt ganz darauf an, was du als Watermark lädst. PNG ist nicht gleich PNG. Je nach dem wie du es abgespeichert hast kann sich die Bittiefe, Alpha-Blending etc im PNG unterscheiden.

Man findet übrigens im MANUAL als ERSTEN Kommentar

If you're trying to load a translucent png-24 image but are finding an absence of transparency (like it's black), you need to enable alpha channel AND save the setting. I'm new to GD and it took me almost two hours to figure this out.

<?php
$imgPng = imageCreateFromPng($strImagePath);
imageAlphaBlending($imgPng, true);
imageSaveAlpha($imgPng, true);

/* Output image to browser */
header("Content-type: image/png");
imagePng($imgPng); 
?>

[Forumsgast]

Na das "Watermark" ist ein TExtstring, welcher auf das Bild stehen soll.

[Forumsgast]

und auch mit dem alphakanal bleibt es schwarz