I have two PNG files, "red.png" and "blue.png"; they are both mostly transparent, but there is a few pixels of red or blue splotches in various places.
I want to make a PHP script that merges the two; it should be as simple as something like:
$original = getPNG('red.png');
$overlay = getPNG('blue.png');
imagecopymerge($original, $overlay, 0,0, 0,0, imagesx($original), imagesy($original), 100);
header('Content-Type: image/png');
imagepng($original);
When I run this script, all I get is the blue dots -- with the transparency lost. I saw that I should add these:
imagealphablending($original, false);
imagesavealpha($original, true);
(on both the original and the overlay?) And that doesn't seem to help any.
I saw a few workarounds on PHP.net, something to the tune of:
$throwAway = imagecreatefrompng($filename);
imagealphablending($throwAway, false);
imagesavealpha($throwAway, true);
$dstImage = imagecreatetruecolor(imagesx($throwAway), imagesy($throwAway));
imagecopyresampled($dstImage, $throwAway,0,0,0,0, imagesx($throwAway), imagesy($throwAway), imagesx($throwAway), imagesy($throwAway));
, which should convert the PNG to a "truecolor" image and retain transparency. It does seem to do so, but now all I see is blue on a black background.
What do I do?!
This works perfectly for me:
$img1 = imagecreatefrompng('red.png');
$img2 = imagecreatefrompng('blue.png');
$x1 = imagesx($img1);
$y1 = imagesy($img1);
$x2 = imagesx($img2);
$y2 = imagesy($img2);
imagecopyresampled(
$img1, $img2,
0, 0, 0, 0,
$x1, $y1,
$x2, $y2);
imagepng($img1, 'merged.png', 0);
PHP Version 5.3.2
GD Version 2.0
libPNG Version 1.2.42
Have you tried saving the image to a file and checking that?
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