Remove white from images

[maxi33]

Hey,

I am trying to set up a script to remove the white background from an image and make it transparent.

I managed to almost do this in GD by doing the following:

function maketransparent($oldfile,$newfile)
{
   $im = imagecreatefromjpeg($oldfile);
   $img = imagecreatetruecolor(500,424);
   $trans = imagecolorallocate($img, 0xFF, 0xFF, 0xFF);
   imagecolortransparent($img,$trans);
   imagecopy($img,$im,0,0,0,0,500,424);
   imagetruecolortopalette($img, true, 256);
   imageinterlace($img);
   imagepng($img,$newfile);
   imagedestroy($img);
}

That works however it only removes parts of the image that are exactly White (#FFFFFF), I need some sort of threshold so that it removes colours that are near white aswell.

Does anyone have an idea of how to do this?

Thanks Very much, Max

[bogu]

If u have an image with a white t shirt the t shirt color will become transparent how do u intend to compensate that?

[maxi33]

That would be fine, the user will be asked if they want to remove the white from the image and it should remove every bit of white.