getWidth(); $height = $image->getHeight(); $mask = WideImage_TrueColorImage::create($width, $height); $mask->setTransparentColor(-1); $mask->alphaBlending(false); $mask->saveAlpha(false); for ($i = 0; $i <= 255; $i++) { $greyscale[$i] = ImageColorAllocate($mask->getHandle(), $i, $i, $i); } imagefilledrectangle($mask->getHandle(), 0, 0, $width, $height, $greyscale[255]); $transparentColor = $image->getTransparentColor(); $alphaToGreyRatio = 255 / 127; for ($x = 0; $x < $width; $x++) { for ($y = 0; $y < $height; $y++) { $color = $image->getColorAt($x, $y); if ($color == $transparentColor) { $rgba['alpha'] = 127; } else { $rgba = $image->getColorRGB($color); } imagesetpixel($mask->getHandle(), $x, $y, $greyscale[255 - round($rgba['alpha'] * $alphaToGreyRatio)]); } } return $mask; } }