imagesavealpha

imagesavealpha

Whether to retain full alpha channel information when saving images

true **imagesavealpha** GdImage $image bool $enable

sets the flag which determines whether to retain

full alpha channel information (as opposed to single-color transparency) when saving images. This is only supported for image formats which support full alpha channel information, i.e. , and .

imagesavealpha``PNG``WebP``AVIF> Opmerking: > is only meaningful for

 images, since the full alpha channel is always saved for 
 and . It is not recommended to rely on this behavior,
 as it may change in the future. Thus, 
 should be called deliberately also for  and
  images.
`imagesavealpha``PNG``WebP``AVIF``imagesavealpha``WebP``AVIF`

Alphablending has to be disabled () to retain the alpha-channel in the first place. imagealphablending($im, false)

enableWhether to save the alpha channel or not. Defaults to false.

return.true.always

Voorbeeld: Basic 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);
?>

imagealphablending