/**
* Make the image greyscale
* $rv = red value, defaults to 38
* $gv = green value, defaults to 36
* $bv = blue value, defaults to 26
* Based (more or less entirely, with changes for readability) on code from http://www.teckis.com/scriptix/thumbnails/teck.html
*/
function greyscale($rv = 38, $gv = 36, $bv = 26)
{
$width = $this->width;
$height = $this->height;
$newGD = imagecreatetruecolor($this->width, $this->height);
$rt = $rv + $bv + $gv;
$rr = $rv == 0 ? 0 : 1 / ($rt / $rv);
$br = $bv == 0 ? 0 : 1 / ($rt / $bv);
$gr = $gv == 0 ? 0 : 1 / ($rt / $gv);
for ($dy = 0; $dy <= $height; $dy++) {
for ($dx = 0; $dx <= $width; $dx++) {
$pxrgb = imagecolorat($this->gd, $dx, $dy);
$heightgb = ImageColorsforIndex($this->gd, $pxrgb);
$newcol = $rr * $heightgb['red'] + $br * $heightgb['blue'] + $gr * $heightgb['green'];
$setcol = ImageColorAllocate($newGD, $newcol, $newcol, $newcol);
imagesetpixel($newGD, $dx, $dy, $setcol);
}
}
// imagecopyresampled($newGD, $this->gd, 0,0, $srcX, $srcY, $width, $height, $srcWidth, $srcHeight);
$output = new GD();
$output->setGD($newGD);
if ($this->quality) {
$output->setQuality($this->quality);
}
return $output;
}