note 52080 added to function.imagecolortransparent

I wanted to have non-rectangular images being displayed on various website-backgrounds. piece of cake with png-24 and sane browsers, but not with IE. GIF-files are useless since they tend to have ugly edges. So that's what i came up with, a script to merge a given PNG-24 against a background-image. The script only merges areas of partial transparency (think anti-aliased edges) of the PNG onto the background-image, leaving 100% transparent areas as they are. output is a 256-color gif with transparency. <?PHP function alphaishMerge(&$img_unten, &$img_oben, &$transCol) { $sx = imagesx($img_unten); $sy = imagesy($img_oben); // just be sure imagealphablending($img_unten, TRUE); imagealphablending($img_oben, TRUE); // imagecopy respects alpha channels imagecopy($img_unten, $img_oben, 0, 0, 0, 0, $sx, $sy); for ($x = 0; $x < $sx; $x++) { for ($y = 0; $y < $sy; $y++) { // get RGBA of upper image $pxloben = imagecolorat($img_oben, $x, $y); $pxloben = imagecolorsforindex($img_oben, $pxloben); if ($pxloben['alpha'] == 127) { // if this pixel is fully transparent... // ...set it to the transparent color imagesetpixel($img_unten,$x,$y,$transCol); } } } } // images have to be the same size $bg_file = "background.jpg"; $png_file ="kauscha.png"; // background-image (jpg) $img_bg = imagecreatefromjpeg($bg_file); // image which is supposed to be put on the background (PNG-24) $img_png = imagecreatefrompng($png_file); // This color is the one getting transparent in the gif-file $transCol = imagecolorallocate($img_bg, 0, 0, 0); // magic alphaishMerge($img_bg, $img_png, $transCol); // reduce color depth imagetruecolortopalette($img_bg, FALSE, 255); // make it transparent $transCol = imagecolortransparent($img_bg, $transCol); header("Content-type: image/gif"); imagegif($img_bg); ?> i hope thats useful for anyone. ---- Manual Page -- http://www.php.net/manual/en/function.imagecolortransparent.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+52080 Delete: added to the manual -- http://master.php.net/manage/user-notes.php?action=delete+52080&report=yes&reason=added+to+the+manual Delete: bad code -- http://master.php.net/manage/user-notes.php?action=delete+52080&report=yes&reason=bad+code Delete: spam -- http://master.php.net/manage/user-notes.php?action=delete+52080&report=yes&reason=spam Delete: useless -- http://master.php.net/manage/user-notes.php?action=delete+52080&report=yes&reason=useless Delete: other reasons -- http://master.php.net/manage/user-notes.php?action=delete+52080&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+52080&report=yes Search -- http://master.php.net/manage/user-notes.php