php man page for imagecolortransparent

IMAGECOLORTRANSPARENT(3)						 1						  IMAGECOLORTRANSPARENT(3)

imagecolortransparent - Define a color as transparent

SYNOPSIS
       int imagecolortransparent (resource  $image, [int  $color])

DESCRIPTION
	Sets the transparent color in the given $image.

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

	      o $color
		- A color identifier created with imagecolorallocate(3).

RETURN VALUES
	The  identifier of the new (or current, if none is specified) transparent color is returned. If $color is not specified, and the image has
       no transparent color, the returned identifier will be -1.

EXAMPLES
       Example #1

	      imagecolortransparent(3) example

	      <?php
	      // Create a 55x30 image
	      $im = imagecreatetruecolor(55, 30);
	      $red = imagecolorallocate($im, 255, 0, 0);
	      $black = imagecolorallocate($im, 0, 0, 0);

	      // Make the background transparent
	      imagecolortransparent($im, $black);

	      // Draw a red rectangle
	      imagefilledrectangle($im, 4, 4, 50, 25, $red);

	      // Save the image
	      imagepng($im, './imagecolortransparent.png');
	      imagedestroy($im);
	      ?>

	      The above example will output something similar to:[NOT DISPLAYABLE MEDIA]Output of example : imagecolortransparent()

NOTES
       Note

	       Transparency is copied only with imagecopymerge(3) and true color images, not with imagecopy(3) or pallete images.

       Note

	       The transparent color is a property of the image, transparency is not a property of the color. Once you have set a color to be  the
	      transparent color, any regions of the image in that color that were drawn previously will be transparent.

PHP Documentation Group 												  IMAGECOLORTRANSPARENT(3)