GD and Image Functions
PHP Manual

imagelayereffect

Set the alpha blending flag to use layering effects

Description

bool imagelayereffect ( resource $image , int $effect )

Set the alpha blending flag to use layering effects.

Parameters

image

An image resource, returned by one of the image creation functions, such as imagecreatetruecolor.

effect

One of the following constants:

IMG_EFFECT_REPLACE
Use pixel replacement (equivalent of passing TRUE to imagealphablending)
IMG_EFFECT_ALPHABLEND
Use normal pixel blending (equivalent of passing FALSE to imagealphablending)
IMG_EFFECT_NORMAL
Same as IMG_EFFECT_ALPHABLEND.
IMG_EFFECT_OVERLAY
Overlay has the effect that black background pixels will remain black, white background pixels will remain white, but grey background pixels will take the colour of the foreground pixel.
IMG_EFFECT_MULTIPLY
Overlays with a multiply effect.

Return Values

Returns TRUE on success or FALSE on failure.

Changelog

Version Description
7.2.0 Added IMG_EFFECT_MULTIPLY (requires system libgd >= 2.1.1 or the bundled libgd).

Examples

Example #1 imagelayereffect example

<?php
// Setup an image
$im = imagecreatetruecolor(100, 100);

// Set a background
imagefilledrectangle($im, 0, 0, 100, 100, imagecolorallocate($im, 220, 220, 220));

// Apply the overlay alpha blending flag
imagelayereffect($im, IMG_EFFECT_OVERLAY);

// Draw two grey ellipses
imagefilledellipse($im, 50, 50, 40, 40, imagecolorallocate($im, 100, 255, 100));
imagefilledellipse($im, 50, 50, 50, 80, imagecolorallocate($im, 100, 100, 255));
imagefilledellipse($im, 50, 50, 80, 50, imagecolorallocate($im, 255, 100, 100));

// Output
header('Content-type: image/png');

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

The above example will output something similar to:

Output of example : imagelayereffect()

Notes

Before PHP 5.5.0, this function is only available if PHP is compiled with the bundled version of the GD library.