image processing - Changing Black to Transparent in PHP -

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• how to remove colors image php or ruby? 3 answers

i'm trying replace black background gif/jpeg files transparent background, , because it's tiring manually 1 one via photoshop, thought of trying use php. code i'm using, doesn't work.

why that?

$image = imagecreatefromgif( 'items/item_spear06.gif' ); imagealphablending($image, true); $transparentcolour = imagecolorallocate($image, 0,0,0); imagecolortransparent($image, $transparentcolour); 

and image got same image last time in png format.

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update

$image = imagecreatefromgif( 'items/sword/iv_sword_refined19.gif' );  //get pixel data $rgb = imagecolorat($image, 10, 10); $r = ($rgb >> 16) & 0xff; $g = ($rgb >> 8) & 0xff; $b = $rgb & 0xff;  $index = imagecolorexact($image, $r, $g, $b);  if ($index === -1) {     $index = imagecolorallocate($image, $r, $g, $b); } imagecolortransparent($image, $index);  var_dump($r, $g, $b);  // save image imagepng($image, 'imagecolortransparent.png'); imagedestroy($image); 

now var_dump returns: int(0) int(0) int(0) when should int(4) int(2) int(4)

i'm little bit out on whim here guess color have chosen here (black) exists in palette. so, try find color in palette , set 1 transparent, if not exist, can use imagecolorallocate

$image = imagecreatefromgif( 'items/item_spear06.gif' ); $index = imagecolorexact($image, 0, 0, 0);  if ($index === -1) {     $index = imagecolorallocate($image, 0, 0, 0); } imagecolortransparent($image, $index); 

to top-left pixels color

$index = imagecolorat($image, 0, 0); $rgb = imagecolorsforindex($image, $index);