php man page for imagesavealpha

IMAGESAVEALPHA(3)							 1							 IMAGESAVEALPHA(3)

imagesavealpha - Set the flag to save full alpha channel information (as opposed to single-color transparency) when saving PNG images

SYNOPSIS
       bool imagesavealpha (resource  $image, bool  $saveflag)

DESCRIPTION
       imagesavealpha(3) sets the flag to attempt to save full alpha channel information (as opposed to single-color transparency) when saving PNG
       images.

	You have to unset alphablending ( imagealphablending($im, false)), to use it.

	Alpha channel is not supported by all browsers, if you have problem with your browser, try to load your script with an alpha channel  com-
       pliant browser, e.g. latest Mozilla.

PARAMETERS
	      o $
		image -An image resource, returned by one of the image creation functions, such as imagecreatetruecolor(3).

	      o $saveflag
		- Whether to save the alpha channel or not. Default to FALSE.

RETURN VALUES
	Returns TRUE on success or FALSE on failure.

EXAMPLES
       Example #1

	      imagesavealpha(3) example

	      <?php
	      // Load a png image with alpha channels
	      $png = imagecreatefrompng('./alphachannel_example.png');

	      // Do required operations

	      // Turn off alpha blending and set alpha flag
	      imagealphablending($png, false);
	      imagesavealpha($png, true);

	      // Output image to browser
	      header('Content-Type: image/png');

	      imagepng($png);
	      imagedestroy($png);
	      ?>

NOTES
       Note

	      This function requires GD 2.0.1 or later (2.0.28 or later is recommended).

SEE ALSO
       imagealphablending(3).

PHP Documentation Group 													 IMAGESAVEALPHA(3)