PHP imagecopy with transparent background - php

Question

I use this code to create an image from another png image, the background is black by default. My question is how to set a transparent background?
$input = imagecreatefrompng('image.png');
$output = imagecreatetruecolor(50, 50);
imagecopy($output, $input, 4,0, 8,8, 8,8);
imagecopy... etc.
header('Content-Type: image/png');
imagepng($output);
Is there a easy way of doing this? Thanks

Answer 1

Sets the transparent color in the given image.
int imagecolortransparent ( resource $image [, int $color ] )
Here's the link

Answer 2

Since the PHP function imagecopymerge doesn't work with the Alpha channel, you'll want to use the function from the first comment on this page imagecopymerge_alpha:
http://php.net/manual/en/function.imagecopymerge.php
Just have the transparent image as the base and merge it together with the image you need.
I've tried it out and it works fine for a project of mine.

Answer 3

None of the solutions worked for me, it would always convert transparent pixels on the source image to black on the destination image. What worked was changing imagecopy/imagecopymerge/imagecopymerge_alpha to imagecopyresampled and just passing the same width and height twice.
//Create destination image.
$png = imagecreatetruecolor(1024, 1024);
imagealphablending($png, false);
imagesavealpha($png, true);
//Make destination image be all transparent.
$color = imagecolorallocatealpha($png, 0, 0, 0, 127); //127 means completely transparent.
imagefill($png, 0, 0, $color);
//Load source image.
$png2 = imagecreatefrompng($sourceurl);
imagealphablending($png2, false);
imagesavealpha($png2, true);
$sizex = imagesx($png2);
$sizey = imagesy($png2);
//Copy to destination and save to file.
imagecopyresampled( $png, $png2,
0, 0,
0, 0,
$sizex, $sizey,
$sizex, $sizey);
imagepng($png, "result.png");

Answer 4

imagealphablending($input, true);
imagesavealpha($input, true);
imagealphablending($output, true);
imagesavealpha($output, true);

Answer 5

Or propably
int imagesavealpha($img,true);
http://www.php.net/manual/en/function.imagesavealpha.php

Answer 6

Full credit goes to:
http://consistentcoder.com/combine-a-transparent-png-image-on-top-of-another-image-with-php
The following code will overlay the foreground image onto the background image while preserving the transparency of the overlay:
//set the source image (foreground)
$sourceImage = 'table.png';
//set the destination image (background)
$destImage = 'create-a-surreal-head-of-tree-photo-manipulation.jpg';
//get the size of the source image, needed for imagecopy()
list($srcWidth, $srcHeight) = getimagesize($sourceImage);
//create a new image from the source image
$src = imagecreatefrompng($sourceImage);
//create a new image from the destination image
$dest = imagecreatefromjpeg($destImage);
//set the x and y positions of the source image on top of the destination image
$src_xPosition = 75; //75 pixels from the left
$src_yPosition = 50; //50 pixels from the top
//set the x and y positions of the source image to be copied to the destination image
$src_cropXposition = 0; //do not crop at the side
$src_cropYposition = 0; //do not crop on the top
//merge the source and destination images
imagecopy($dest,$src,$src_xPosition,$src_yPosition,
$src_cropXposition,$src_cropYposition,
$srcWidth,$srcHeight);
//output the merged images to a file
/*
* '100' is an optional parameter,
* it represents the quality of the image to be created,
* if not set, the default is about '75'
*/
imagejpeg($dest,
'combine-a-transparent-png-image-on-top-of-another-image-with-php-01.jpg',
100);
//destroy the source image
imagedestroy($src);
//destroy the destination image
imagedestroy($dest);