Can PNG image transparency be preserved when using PHP's GDlib imagecopyresampled? Can PNG image transparency be preserved when using PHP's GDlib imagecopyresampled? php php

Can PNG image transparency be preserved when using PHP's GDlib imagecopyresampled?


imagealphablending( $targetImage, false );imagesavealpha( $targetImage, true );

did it for me. Thanks ceejayoz.

note, the target image needs the alpha settings, not the source image.

Edit:full replacement code. See also answers below and their comments. This is not guaranteed to be be perfect in any way, but did achieve my needs at the time.

$uploadTempFile = $myField[ 'tmp_name' ]list( $uploadWidth, $uploadHeight, $uploadType )   = getimagesize( $uploadTempFile );$srcImage = imagecreatefrompng( $uploadTempFile ); $targetImage = imagecreatetruecolor( 128, 128 );   imagealphablending( $targetImage, false );imagesavealpha( $targetImage, true );imagecopyresampled( $targetImage, $srcImage,                     0, 0,                     0, 0,                     128, 128,                     $uploadWidth, $uploadHeight );imagepng(  $targetImage, 'out.png', 9 );


Why do you make things so complicated? the following is what I use and so far it has done the job for me.

$im = ImageCreateFromPNG($source);$new_im = imagecreatetruecolor($new_size[0],$new_size[1]);imagecolortransparent($new_im, imagecolorallocate($new_im, 0, 0, 0));imagecopyresampled($new_im,$im,0,0,0,0,$new_size[0],$new_size[1],$size[0],$size[1]);


I believe this should do the trick:

$srcImage = imagecreatefrompng($uploadTempFile);imagealphablending($srcImage, false);imagesavealpha($srcImage, true);

edit: Someone in the PHP docs claims imagealphablending should be true, not false. YMMV.