(PHP 4 >= 4.3.2, PHP 5, PHP 7, PHP 8)
imagesavealpha — Whether to retain full alpha channel information when saving PNG images
imagesavealpha() sets the flag which determines whether to retain full alpha channel information (as opposed to single-color transparency) when saving PNG images.
Alphablending has to be disabled (imagealphablending($im, false))
to retain the alpha-channel in the first place.
imageA GdImage object, returned by one of the image creation functions, such as imagecreatetruecolor().
enable
Whether to save the alpha channel or not. Defaults to false.
Returns true on success or false on failure.
| Version | Description |
|---|---|
| 8.0.0 |
image expects a GdImage
instance now; previously, a resource was expected.
|
Example #1 Basic imagesavealpha() Usage
<?php
// Load a png image with alpha channel
$png = imagecreatefrompng('./alphachannel_example.png');
// Turn off alpha blending
imagealphablending($png, false);
// Do desired operations
// Set alpha flag
imagesavealpha($png, true);
// Output image to browser
header('Content-Type: image/png');
imagepng($png);
imagedestroy($png);
?>