These code snippets have been used in GrafxShop for Image Editing through different filters. Please read the notice carefully ¹⁾ before using any of the contents.

• Inverting Colors
• Embossing Colors
• Posterization

• The code snippet shows how you can invert the colors of all pixels in an image.
• This is what the code does. It takes as input the image (src) whose colors need to be inverted.
• It determines the size of the image. It creates a new image (im2) with the same dimensions.
• It then traverses through every pixel in the image.
• It extracts the colors (r, g and b).
• It then employs the algorithm
• It puts the resultant colorto the new image (im2).

 
function Invert($image_path) {
	@header("Content-Type: image/jpeg");
	$m_width = 0;
	$m_height = 0;
	$i = 0;
	$j = 0;
 
	$src = imagecreatefromjpeg($image_path);
	$m_width = imagesx($src);
	$m_height = imagesy($src);
	$im2 = imagecreatetruecolor($m_width, $m_height);
 
	for ($i = 0; $i < $m_height; $i++) {
		for ($j = 0; $j < $m_width; $j++) {
			$rgb = imagecolorat($src, $j, $i);
			$r = ($rgb >> 16) & 0xFF;
			$g = ($rgb >> 8) & 0xFF;
			$b = $rgb & 0xFF;
			$r = 255 - $r;
			$g = 255 - $g;
			$b = 255 - $b;
			$newcolor = imagecolorallocate($im2, $r, $g, $b);
			imagesetpixel($im2, $j, $i, $newcolor);
		}
	}
	imagejpeg($im2);
	imagedestroy($im2);
	exit;
}

 
procedure Invert(src: tbitmap);
var 
  w, h, x, y: integer;
  p: pbytearray;
begin
  w := src.Width;
  h := src.Height;
  src.PixelFormat := pf24bit;
  for y := 0 to h - 1 do 
  begin
    p := src.scanline[y];
    for x := 0 to w - 1 do 
    begin
      p[x * 3] := not p[x * 3];
      p[x * 3 + 1] := not p[x * 3 + 1];
      p[x * 3 + 2] := not p[x * 3 + 2];
    end;
  end;
end;