imagelayereffect

(PHP 4 >= 4.3.0, PHP 5)

imagelayereffect — Set the alpha blending flag to use the bundled libgd layering effects

Description

bool imagelayereffect ( resource $image , int $effect )

Set the alpha blending flag to use the bundled libgd 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.

Return Values

Returns TRUE on success or FALSE on failure.

Notes

Note: This function is only available if PHP is compiled with the bundled version of the GD library.

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

imageline

imagejpeg

Last updated: Fri, 27 Jun 2008

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imagelayereffect

[myname] at mac dot com
23-Feb-2008 07:45


^^ my name is coreyward ^^



imagelayereffect needs to be applied to the destination image, not the source image. As noted, the only useful "effect" as of this time is IMG_EFFECT_OVERLAY since the others are merely another way of setting the alpha blending flag. 



You can also use imagecopymerge with a lower pct argument to blend two images with more control over the opacity at which the top image is blended. 



<?



// overlays $im_src onto $im_dst properly (assuming same dims)



imagelayereffect($im_dst, IMG_EFFECT_OVERLAY);

imagecopy($im_dst, $im_src, 0, 0, 0, 0, $im_dst_x, $im_dst_y);



?>

Remon
05-Feb-2008 09:12


I found the following example on a Chinese site and translated and adjusted it. It creates a portrait from the sample picture.



<?php



// Portrait image

$im = imagecreatefromjpeg( "sample.jpg");



// Get width and height

$w = imagesx($im); 

$h = imagesy($im);



// Non-through

$c_visible = 0x007F7F7F;

// Background (black) 

$c_bg = 0x00000000; 



// Create mask

$im_mask = imagecreatetruecolor($w,$h);

imageFilledRectangle($im_mask, 0,0, $w,$h, $c_bg); 

imageFilledEllipse ($im_mask, $w/2,$h/2, $w*.9,$h*.9, $c_visible);



// Only overlay seems to something useful

imagelayereffect($im_mask, IMG_EFFECT_OVERLAY);



imagecopy($im_mask, $im, 0,0, 0,0, $w,$h); 

imagedestroy($im);



imagepng($im_mask);

imagedestroy($im_mask);



?>



Try removing the 'create mask' code and just add another image with 'createimagefromjpeg' to see 'normal' overlay. It blends the colors like different layers in Photoshop.

06-Feb-2005 12:36


I assume, that the specific effects are similiar to those used in Adobe Photoshop for blending layers.

There might be things like IMG_EFFECT_MULTIPLY resulting of that.

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imageline

imagejpeg

Last updated: Fri, 27 Jun 2008