PDF has a powerful capabilities for colors representation.
Zend_Pdf module supports Gray Scale, RGB and CMYK color spaces.
Any of them can be used in any place, where
classes provide this functionality:
// $grayLevel (float number). 0.0 (black) - 1.0 (white)
$color1 = new Zend_Pdf_Color_GrayScale($grayLevel);
// $r, $g, $b (float numbers). 0.0 (min intensity) - 1.0 (max intensity)
$color2 = new Zend_Pdf_Color_Rgb($r, $g, $b);
// $c, $m, $y, $k (float numbers). 0.0 (min intensity) - 1.0 (max intensity)
$color3 = new Zend_Pdf_Color_Cmyk($c, $m, $y, $k);
HTML style colors are also provided with
$color1 = new Zend_Pdf_Color_Html('#3366FF');
$color2 = new Zend_Pdf_Color_Html('silver');
$color3 = new Zend_Pdf_Color_Html('forestgreen');