| Re: Scaling image is losing background transparency [message #171670 is a reply to message #171660] |
Sat, 15 January 2011 03:07  |
Chuck Anderson
Messages: 63
Registered: September 2010
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laredotornado(at)zipmail(dot)com wrote:
> Hi,
>
> I'm using PHP 5 and trying to scale png images programatically. Here
> is what I'm doing ...
>
> $src_img = imagecreatefrompng($imagefile);
> $hw = getimagesize($imagefile);
> $new_w = $w;
> $new_h = $hw["1"]/($hw["0"]/$w);
> $dst_img = @imagecreatetruecolor($new_w, $new_h);
> if(!$dst_img) {
> $dst_img = imageCreate($new_w, $new_h);
> }
> imagecopyresized($dst_img,$src_img,0,0,0,0,$new_w,
> $new_h,imagesx($src_img),imagesy($src_img));
> imagepng($dst_img);
>
> The problem is my scaled png image loses its background transparency.
> The short of this is, does anyone know how to scale PNG images
> effectively and what other information can I provide to help
> troubleshoot this further?
>
> Thanks, - Dave
>
When I was doing transparent png image overlays (on the fly, scaled
watermarks on top of web site images), I found that I had to use
imagecopyresampled as opposed to imagecopymerge or the transparent
overlay would lose it's transparency (sound familiar?). Try using
imagecopyresampled instead of imageycopyresized.
I made a very brief note about it here -
http://cycletourist.com/temp/watermark.php
--
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Chuck Anderson • Boulder, CO
http://cycletourist.com
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